Wide Area Network(WAN)
-
Upload
gonzalo-suarez -
Category
Documents
-
view
18 -
download
1
description
Transcript of Wide Area Network(WAN)
Wide Area Network
• WAN protocols
• WAN solutions
• Interface and cabling
• configuration
High-Level Data Link Control
• HDLC is the most important data link control protocol
• Widely used which forms basis of other data link control protocols
• Most WAN protocols use HDLC as data link control protocols
HDLC Station Types• Primary station (Unbalanced)
– Controls operation of link– Frames issued are called commands– Maintains separate logical link to each secondary
station
• Secondary station– Under control of primary station– Frames issued called responses
• Combined station (Balanced)– May issue commands and responses
HDLC Link Configurations
• Unbalanced– One primary and one or more secondary
stations– Supports full duplex and half duplex
• Balanced– Two combined stations– Supports full duplex and half duplex
HDLC Transfer Modes (1)
• Normal Response Mode (NRM)– Unbalanced configuration– Primary initiates transfer to secondary– Secondary may only transmit data in response
to command from primary– Used on multi-drop lines– Host computer as primary– Terminals as secondary
HDLC Transfer Modes (2)
• Asynchronous Balanced Mode (ABM)– Balanced configuration– Either station may initiate transmission without
receiving permission– Most widely used– No polling overhead
HDLC Transfer Modes (3)
• Asynchronous Response Mode (ARM)– Unbalanced configuration– Secondary may initiate transmission without
permission form primary– Primary responsible for line– rarely used
Frame Structure
• Synchronous transmission
• All transmissions in frames
• Single frame format for all data and control exchanges
Frame Structure Diagram
Flag Fields
• Delimit frame at both ends• 01111110• May close one frame and open another• Receiver hunts for flag sequence to synchronize• Bit stuffing used to avoid confusion with data containing
01111110– 0 inserted after every sequence of five 1s– If receiver detects five 1s it checks next bit– If 0, it is deleted– If 1 and seventh bit is 0, accept as flag– If sixth and seventh bits 1, sender is indicating abort
Bit Stuffing
• Example with possible errors
Address Field
• Identifies secondary station that sent or will receive frame• Usually 8 bits long• May be extended to multiples of 7 bits
– LSB of each octet indicates that it is the last octet (1) or not (0)
• All ones (11111111) is broadcast
Control Field
• Different for different frame type– Information - data to be transmitted to user (next l
ayer up)• Flow and error control piggybacked on information fra
mes
– Supervisory - ARQ when piggyback not used– Unnumbered - supplementary link control
• First one or two bits of control filed identify frame type
• Remaining bits explained later
Control Field Diagram
Poll/Final Bit
• Use depends on context
• Command frame– P bit– 1 to solicit (poll) response from peer
• Response frame– F bit– 1 indicates response to soliciting command
Information Field
• Only in information and some unnumbered frames
• Must contain integral number of octets
• Variable length
Frame Check Sequence Field
• FCS
• Error detection
• 16 bit CRC
• Optional 32 bit CRC
HDLC Operation
• Exchange of information, supervisory and unnumbered frames
• Three phases– Initialization– Data transfer– Disconnect
Supervisory Frames• Receive Ready --- RR
• Receive Not Ready --- RNR
• Reject --- REJ
• Selective Reject --- SREJ
Unnumbered Frames• Control operations
• Set up and take down communications link
• Maintenance
The unnumbered format.
SABME (SetAsynchronousBalanced Mode)
1111P110 C Request logical connection
DM (DisconnectMode)
1111F000 R Unable to establish or maintain logicalconnection
UI (UnnumberedInformation)
1100P000 C Used for unacknowledged informationtransfer
DISC(Disconnect)
1100P010 C Terminate logical connection
UA (UnnumberedAck )
1100F110 R Acknowledge SABME or DISC
FRMR (FrameReject )
1110F001 R Unacceptable frame report
XID (ExchangeIdentification)
1111*101 C/R Exchange identification information
Operations
• Connection Establishment– SABME ----> – <----- UA
• Data Transfer– I-frames and – S-frames for flow and error control.
• Disconnect– Either entity can issue a DISC.
Examples of Operation (1)
Examples of Operation (2)
Point to Point Data Link Control
• one sender, one receiver, one link: easier than broadcast link:
– no Media Access Control
– no need for explicit MAC addressing
– e.g., dialup link, ISDN line
• popular point-to-point DLC protocols:
– PPP (point-to-point protocol)
– HDLC: High level data link control
PPP Design Requirements [RFC 1557]• packet framing: encapsulation of network-layer datagram in
data link frame – carry network layer data of any network layer protocol (n
ot just IP) at same time– ability to demultiplex upwards
• bit transparency: must carry any bit pattern in the data field• error detection (no correction)• connection liveness: detect, signal link failure to network la
yer• network layer address negotiation: endpoint can learn/config
ure each other’s network address
PPP non-requirements
• no error correction/recovery
• no flow control
• out of order delivery OK
• no need to support multipoint links (e.g., polling)
Error recovery, flow control, data re-ordering all relegated to higher layers!|
PPP Data Frame• Flag: delimiter (framing)
• Address: does nothing (only one option)
• Control: does nothing; in the future possible multiple control fields
• Protocol: upper layer protocol to which frame delivered (eg, PPP-LCP, IP, IPCP, etc)
PPP Data Frame
• info: upper layer data being carried
• check: cyclic redundancy check for error detection
Byte Stuffing
• “data transparency” requirement: data field must be allowed to include flag pattern <01111110>– Q: is received <01111110> data or flag?
• Sender: adds (“stuffs”) extra < 01111110> byte after each < 01111110> data byte
• Receiver: – two 01111110 bytes in a row: discard first byte,
continue data reception– single 01111110: flag byte
Byte Stuffing
flag bytepatternin datato send
flag byte pattern plusstuffed byte in transmitted data
PPP Data Control ProtocolBefore exchanging network-l
ayer data, data link peers must
• configure PPP link (max. frame length, authentication)
• learn/configure network layer information
– for IP: carry IP Control Protocol (IPCP) msgs (protocol field: 8021) to configure/learn IP address
Other DLC Protocols (LAPB,LAPD)
• Link Access Procedure, Balanced (LAPB)– Part of X.25 (ITU-T)– Subset of HDLC - ABM– Point to point link between system and packet switching
network node
• Link Access Procedure, D-Channel– ISDN (ITU-D)– ABM– Always 7-bit sequence numbers (no 3-bit)– 16 bit address field contains two sub-addresses
• One for device and one for user (next layer up)
Other DLC Protocols (LLC)
• Logical Link Control (LLC)– IEEE 802– Different frame format– Link control split between medium access layer (MAC)
and LLC (on top of MAC)– No primary and secondary - all stations are peers– Two addresses needed
• Sender and receiver
– Error detection at MAC layer• 32 bit CRC
– Destination and source access points (DSAP, SSAP)
Other DLC Protocols (Frame Relay) (1)
• Streamlined capability over high speed packet switched networks
• Used in place of X.25• Uses Link Access Procedure for Frame-
Mode Bearer Services (LAPF)• Two protocols
– Control - similar to HDLC– Core - subset of control
Other DLC Protocols (Frame Relay) (2)
• ABM
• 7-bit sequence numbers
• 16 bit CRC
• 2, 3 or 4 octet address field– Data link connection identifier (DLCI)– Identifies logical connection
• More on frame relay later
Other DLC Protocols (ATM)
• Asynchronous Transfer Mode
• Streamlined capability across high speed networks
• Not HDLC based
• Frame format called “cell”
• Fixed 53 octet (424 bit)
• Details later
X.25
• 1976• Interface between host and packet switched
network• Almost universal on packet switched networks and
packet switching in ISDN• Defines three layers
– Physical– Link– Packet
X.25 - Physical
• Interface between attached station and link to node
• Data terminal equipment DTE (user equipment)
• Data circuit terminating equipment DCE (node)
• Uses physical layer specification X.21
X.25 - Link
• Link Access Protocol Balanced (LAPB)– Subset of HDLC– Point to point link between system and packet
switching network node
X.25 - Packet
• External virtual circuits
• Logical connections (virtual circuits) between subscribers
X.25 Use of Virtual Circuits
Virtual Circuit Service
• Virtual Call– Dynamically established
• Permanent virtual circuit– Fixed network assigned virtual circuit
Virtual Call
Packet Format
Multiplexing
• DTE can establish 4095 simultaneous virtual circuits with other DTEs over a single DTC-DCE link
• Packets contain 12 bit virtual circuit number
Virtual Circuit Numbering
Flow and Error Control
• HDLC at the link layer
• Sliding window at the VC layer
Packet Sequences
• Complete packet sequences• Allows longer blocks of data across network with
smaller packet size without loss of block integrity• A packets
– M bit 1, D bit 0
• B packets– The rest
• Zero or more A followed by B
Reset and Restart
• Reset– Reinitialize virtual circuit– Sequence numbers set to zero– Packets in transit lost– Up to higher level protocol to recover lost packets– Triggered by loss of packet, sequence number error,
congestion, loss of network internal virtual circuit
• Restart– Equivalent to a clear request on all virtual circuits– E.g. temporary loss of network access
Asynchronous Transfer Mode (ATM)
Protocol Architecture
• Similarities between ATM and packet switching– Transfer of data in discrete chunks– Multiple logical connections over single physical
interface
• In ATM flow on each logical connection is in fixed sized packets called cells
• Minimal error and flow control– Reduced overhead
• Data rates (physical layer) 25.6Mbps to 622.08Mbps
Protocol Architecture (diag)
ATM Logical Connections
• Virtual channel connections (VCC)• Analogous to virtual circuit in X.25• Basic unit of switching• Between two end users• Full duplex• Fixed size cells• Data, user-network exchange (control) and network-
network exchange (network management and routing)• Virtual path connection (VPC)
– Bundle of VCC with same end points
ATM Connection Relationships
Call Establishment
Using VPs
VP/VC Characteristics
• Quality of service• Switched and semi-permanent channel
connections• Call sequence integrity• Traffic parameter negotiation and usage
monitoring
• VPC only– Virtual channel identifier restriction within VPC
ATM Cells
• Fixed size• 5 octet header• 48 octet information field• Small cells reduce queuing delay for high
priority cells• Small cells can be switched more efficiently• Easier to implement switching of small cells
in hardware
ATM Cell Format
Header Format
• Generic flow control– Only at user to network interface– Controls flow only at this point
• Virtual path identifier• Virtual channel identifier• Payload type
– e.g. user info or network management
• Cell loss priority• Header error control
Generic Flow Control (GFC)• Control traffic flow at user to network interface
(UNI) to alleviate short term overload• Two sets of procedures
– Uncontrolled transmission– Controlled transmission
• Every connection either subject to flow control or not• Subject to flow control
– May be one group (A) default– May be two groups (A and B)
• Flow control is from subscriber to network– Controlled by network side
Single Group of Connections (1)
• Terminal equipment (TE) initializes two variables– TRANSMIT flag to 1– GO_CNTR (credit counter) to 0
• If TRANSMIT=1 cells on uncontrolled connection may be sent any time
• If TRANSMIT=0 no cells may be sent (on controlled or uncontrolled connections)
• If HALT received, TRANSMIT set to 0 and remains until NO_HALT
Single Group of Connections (2)
• If TRANSMIT=1 and no cell to transmit on any uncontrolled connection:– If GO_CNTR>0, TE may send cell on controlled
connection• Cell marked as being on controlled connection• GO_CNTR decremented
– If GO_CNTR=0, TE may not send on controlled connection
• TE sets GO_CNTR to GO_VALUE upon receiving SET signal– Null signal has no effect
Header Error Control
• 8 bit error control field
• Calculated on remaining 32 bits of header
• Allows some error correction
HEC Operation at Receiver
Cell Based Physical Layer
• No framing imposed
• Continuous stream of 53 octet cells
• Cell delineation based on header error control field
Cell Delineation State Diagram
ATM Service Categories
• Real time– Constant bit rate (CBR)– Real time variable bit rate (rt-VBR)
• Non-real time– Non-real time variable bit rate (nrt-VBR)– Available bit rate (ABR)– Unspecified bit rate (UBR)
Real Time Services
• Amount of delay
• Variation of delay (jitter)
ATM Adaptation Layer
• Support for information transfer protocol not based on ATM
• PCM (voice)– Assemble bits into cells– Re-assemble into constant flow
• IP– Map IP packets onto ATM cells– Fragment IP packets– Use LAPF over ATM to retain all IP infrastructure
Adaptation Layer Services
• Handle transmission errors
• Segmentation and re-assembly
• Handle lost and mis-inserted cells
• Flow control and timing
Frame Relay
• Designed to be more efficient than X.25
• Developed before ATM
• Larger installed base than ATM
• ATM now of more interest on high speed networks
Frame Relay Background - X.25
• Call control packets, in band signaling
• Multiplexing of virtual circuits at layer 3
• Layer 2 and 3 include flow and error control
• Considerable overhead
• Not appropriate for modern digital systems with high reliability
Frame Relay - Differences
• Call control carried in separate logical connection• Multiplexing and switching at layer 2
– Eliminates one layer of processing
• No hop by hop error or flow control• End to end flow and error control (if used) are
done by higher layer• Single user data frame sent from source to
destination and ACK (from higher layer) sent back
Advantages and Disadvantages
• Lost link by link error and flow control– Increased reliability makes this less of a
problem
• Streamlined communications process– Lower delay– Higher throughput
• ITU-T recommend frame relay above 2Mbps
User Data Transfer
• One frame type– User data– No control frame
• No inband signaling
• No sequence numbers– No flow nor error control
77
Objectives
• Explain the advantages and disadvantages of various WAN connection types
• Select the appropriate WAN connection types to interconnect multiple sites
• Select the equipment that will suit the specific needs of each site
• select the proper equipment
Upon completion of this chapter, you will be able to perform the following tasks:
Remote Access Overview
– Remote access networks connect sites– Connection requirements vary depending on
user requirements and cost
Service provider
WAN Connection Types
Telephonecompany
Serviceprovider
Circuit-switched
Dedicated
Packet-switched
Synchronous serial
Asynchronous serial, ISDN
Synchronous serial
Dedicated Connections
– Links are continuously available
Dedicated Serial Connections
CSU/DSUCSU/DSU
CSU/DSUCSU/DSU
EIA/TIA-232, EIA/TIA-449,V.35, X.21, EIA-530
Circuit Switching Connections
– Circuit switching requires call setup and call teardown– Circuit switching is used in the telephone company networks and works like a
telephone call
Telephonecompanynetwork
Fileserver
E-mailserver
Asynchronous Circuit-Switched Connections
– Connections are made only when traffic dictates a need
Modem
Modem
Modem
EIA/TIA-232
EIA/TIA-232
Telephonecompanynetwork
ISDNserviceprovider
Circuit-Switched ISDN Connections
CSU/DSU
PRI
BRI
NT1
Switch
CSU/DSU
Packet-Switched ConnectionsSynchronousserial
CSU/DSU
– VCs are established– Packet-switched networks generally share
bandwidth, but the cost is cheaper than a leased line
CSU/DSU
Synchronousserial
Typical WAN Protocols
Telephonecompany
Serviceprovider
Circuit-switched
Dedicated
Packet-switched
PPP, SLIP
PPP, HDLC, SLIP
X.25, Frame Relay, ATM
PPP Encapsulation
PPPencapsulation
Link setup and control using LCP in PPP
TCP/IP
IPX
Appletalk
Multiple protocol encapsulations using NCPs in PPP
X.25 and Frame Relay Encapsulations
Frame Relay,X.25
Connection Selection Considerations
– Availability– Bandwidth– Cost– Ease of management– Application traffic– Quality of service and reliability– Access control
Selecting WAN Configuration Types
Increasing
Bandwidth
Requirements
Delay- sensitive
voice/video
File transfer
Client/server
Terminalemulation
ISDN, VoFR, VoATM
Or
ISDN
0 1 2 3+
Analogdialup
Or
FrameRelay
Analog dialup
Hours/Day
WAN Connection Speed Comparison
Leased line, Frame Relay
9.6k 56/64 kbps 128 kbps E1/T1 E3/T3
Asynchronous Dialup
ISDN—PRI
X.25, ISDN—BRI
WA
N C
on
nec
tio
n
Theoretical Maximum WAN Speeds
WAN Connection SummaryConnection Type
Leased lines
Frame Relay
Asynchronousdialup
X.25
ISDN
ApplicationsHigh control, full bandwidth, high-cost enterprise networks, and last-mile accessMedium control, shared bandwidth, medium-cost enterprise backbones; branch sitesLow control, shared bandwidth, more bandwidth than dialupLow control, shared bandwidth, variable cost- effective for limited use connections, high reliabilityLow control, shared bandwidth, variable cost- effective for limited use connections like DDR
93
Company Sites
Windows95 PC
Modem
Remote site,remote office/branch office(ROBO)
ISDN/ analog
Telecommuter site,small office/home office (SOHO),mobile (remote telecommuters)
Central site,headquarters,enterprise
Packet-switched service
94
Central Site Considerations
Central site,headquarters,enterprise
ISDN/analog Packet-
switchedservice
– Must provide access to multiple users and control the network costs
95
Branch Office Considerations
ISDN/analog
Packet-switched
service
– Must be able to access the central site
Remote site,remote office/branch office(ROBO)
96
Telecommuter SiteConsiderations
Windows95 PC
Modem
Small office/ home office (SOHO),
mobile (remote telecommuters)
– Must access company information on demand from various remote locations
ISDN/analog
Packet-switched
service
Determining the Appropriate Interfaces—Fixed Interfaces
Fixed-configuration router
Determining Appropriate Interfaces—Modular Interfaces
1-Ethernet 2-WAN interface card module Modular-configuration router
8-port A/S serial module
Serial WAN interface card
99
Summary
• Determine if each site is a central site, branch office, or telecommuter site
• Select the products that will suit the specific needs of each site
• select the proper equipment
After completing this chapter, you should be able to perform the following tasks:
Review Questions
• Identify the types of WAN connections discussed in this chapter and the appropriate protocols used on each connection.
• Describe the considerations when implementing a WAN connection at a central site, branch office, and telecommuter site.
• Identify available equipment designed for a telecommuter site, a branch office, and a central site.
Assembling and Cabling the WAN
Components
3-101
102
Objectives
• Identify and connect necessary components to connect a central site router to other users
• Identify and connect necessary components to connect a branch office router to other sites
• Identify and connect necessary components to connect a telecommuter site router to other sites
• Identify and connect necessary components to connect a mobile user to other sites
Upon completion of this chapter, you will be able to perform the following tasks:
103
Typical Network Topology
Windows 95 PC Modem
Branch office
ISDN/analog
Telecommuter site
Central site
Serial
Frame Relay
service
PRI
BRI
BRI
Serial
Async
AAA server
Modem
1-Ethernet 2-WAN card slot network module
Digital modem network module
Central Site Router Equipment4-port serial WAN network module
Module slot 1
Module slot 2
Module slot 3
Module slot 0
1-port CT1/PRI-CSU network module
Branch Office Router Equipment
Console
1603 router—rear view
Flash card slot
1600 router—front view
Ethernet AUI
Serial WAN interface card
Ethernet 10BaseT
ISDN BRI
Telecommuter Site Router Equipment
ISDN BRI U
766 router—rear view
760 router—front view
Console
Ethernet 10BaseT
Power switch
Power connectorISDN BRI S/T Phone 1
Phone 2
107
5
1
3 or 4
5
1
2
2
Assembling the Network
Windows 95 PC
Cisco 700
Internal PCmodem
Branch office
ISDN/analog
Cisco 3600
Telecommuter site
Cisco 1600
Central site
Frame Relay
service
T1 (E1) for PRIRJ-48 (DB-15)
BRI (RJ-45)
BRI (RJ-45)
RJ-11
AAA server
Modem
Serial
EthernetSerialRS232
RJ-11Ethernet
Serial V.35, X.21, RS232,EIA/TIA-449, EIA-530
Serial V.35, X.21, RS232,EIA/TIA-449, EIA-530
Verifying Central Site Installation
Enable LED
MICA module bank LEDs
CN/LP, RXC, RXD,TXC, and TXD LEDs
Enable LED
EnableLED
Remote Alarm, Local Alarm, Loopback,and Carrier Detect LEDs
ActivityLED
LinkLED
Verifying Branch Office Installation
• The system power and OK LEDs indicate the router is on and has successfully booted
CONN LEDSerialSystem power
System OK
Verifying Telecommuter Site Installation
• The ready LED indicates the router is on and has passed its self tests
Ready LED
113
Summary
After completing this chapter, you should be able to perform the following tasks:
• Identify and connect necessary components to connect a central site router to other users
• Identify and connect necessary components to connect a branch office router to other sites
• Identify and connect necessary components to connect a telecommuter site router to other sites
• Identify and connect necessary components to connect a mobile user to other sites
Review Questions
• Which cables are necessary to make the proper physical asynchronous serial, ISDN, and synchronous serial connections?
• How can you verify that you properly installed a network module into a modular router?
Configuring Asynchronous Connections to a Central Site
with Modems
Objectives
Upon completion of this chapter, youwill be able to perform the following tasks: • Configure an access server for an attached modem
• Use reverse Telnet to configure an external modem
• Configure a modem using autoconfigure
Chapter Activities
Windows 95 PC
Cisco 700
Modem
Branch office
ISDN/analog
Analog host-LAN dialup
Small office
Central site
Frame Relay
Frame Relay
service
PRI
BRI
BRI
Frame Relay
Async
AAA server
Async
A Typical Modem Connection
Analog AnalogDigitalPCM-encoded analog data
Digital Digital
Telco
Switch Switch
ModemModem
Host
The DTE-DCE Interface
• DTE = Data terminal equipment
• DCE = Data communications equipment
DTE DCE
EIA/TIA-232 or X.21
DTEDCE
EIA/TIA-232 or X.21
Modem Signaling—Data
DatatransferGround
TxD RxDGRD
DTE DCE
DB-25 pins
{ 237
237
TxD RxDGRD
Asynchronous communication
Startbit
Stopbit
0 1 1 0 1 0 0
P bits per packet
IdealRX Clock
ActualRX Clock
Asynchronous communications sometimes used for links with short packets.
Modem Control Example
Two ways to terminate an existing connection:• DTE-initiated
—Access server drops DTR
—Modem must be programmed to terminate connection on loss of DTR and restore to saved settings in its NVRAM
• DCE-initiated—Access server detects Carrier Detect (CD) low and
terminates connection
—Modem must be programmed so that CD reflects the state of the carrier
Modem Operation
Buffer
Compressor
Modulator/ demodulator
Buffer
Compressor
Modulator/ demodulator
RTSCTS
TxD RxD
Flow control
Compress
Decompress
Checksum
RetransmitPacketizer
(error control)Packetizer
(error control)
DTE-to-DTE Wiring
Datatransfer
Hardwareflow control
Modemcontrol
TxD
RxD
GND
RTS
CTS
DTR
DSR
TxD
RxD
GND
RTS
CTS
DTR
DSR
Null modem cable(with DB-25 connectors)
2
3
7
4
5
20
6
2
3
7
4
5
20
6
Error Control and Data Compression Standards
• Error detection/correction— Microcom Networking Protocol (MNP)
• MNP 2–4 in public domain
• MNP 10 for cellular
— CCITT V.42• LAP-M
• MNP 4
• Data compression— MNP 5: 2:1 ratio
— V.42bis: 4:1 ratio
Data
Modem Modulation Standards
• ITU standards:– V.22: 1200 bps
– V.22bis: 2400 bps
– V.32: 9600 bps
– V.32bis: 14.4 kbps
– V.34: 28.8 kbps
– V.34 annex 1201H: 33.6 kbps
– V.90: 56 kbps
• Proprietary methods:– V.32 terbo: 19.2 kbps
– V.fast: 28.8 kbps
– V.FC: 28.8 kbps
– K56Flex: 56 kbps
– X2: 56 kbps
DCEDCE
Modem Speeds and Compression
4:1Compression
ratio
DTE DTEDCEDCE
115.2 kbps
28.8 kbps
• The speeds and compression ratios shown assume ideal conditions
4:1Compression
ratio
115.2 kbps
Theoretical Speeds
V.32
V.32bis
V.32 turbo
V.34
Maximum speed with 4:1 V.42bis compressionSpeed
38400
57600
76800
1152002880028800
1920019200
1440014400
96009600
bps
V.90 5600056000 224000
Maximum Capacity/Data Rate
Shannon Capacity:
)/1(log2 NSBC Bandwidth of link Signal-to-Noise ratio
For example: Bandwidth of telephone link from telephone to a typical home is approx 3300Hz – 300Hz = 3kHz Signal-to-noise ratio is approx 30dB = 10log10(S/N) Therefore, C = 3000*log2(1001) ~= 30kb/s
Connecting to the Modem
Forward connection to a router to login
Reverse connectionto a modem to configure it
Asynchronous line
Basictelephone
service
Configuring PPP and Controlling Network Access
with PAP and CHAP
Objectives
Upon completion of this chapter, youwill be able to perform the followingtasks:• Configure PPP between a central site and a remote site
• Configure PAP or CHAP authentication
• Verify and troubleshoot a PPP link
Chapter Activities
Windows 95 PC
Cisco 700
Modem
Branch office
ISDN/analog
Cisco 3640
PPP, CHAP
Analog host-LAN dialup
Small office
Cisco 1600
Central site
Frame Relay
Frame Relay
service
PRI
BRI
BRI
Frame Relay
Async
PP
P, C
HA
P
AAA server
Async
Remote Node Connections
Novell IPXTCP/IP
AppleTalk
TCP/IPPPP
SLIPARAP
AppleTalk
PPP Architecture
Physical Layer(such as EIA/TIA-232, V.24, V.35, ISDN)
High-Level Data Link Control (HDLC)
Link Control Protocol (LCP)
Network Control Protocol (NCP) (specific to each network-layer protocol)
Upper-layer protocols
OSI layer
2
1
(such as IP, IPX, AppleTalk)3
Autoselect
User dials in
Autoselect on?
Start PPP
Start SLIP
Start ARAP
(Start as if run from EXEC)
Start EXEC (or dedicated
mode)
Parse start sequence for each enabled protocol
CR PPP frame
SLIP frame
ARAP frame
No
Yes
Enabling PPP and Async Interface Commands
Router(config-if)#encapsulation {ppp | slip}Router(config-if)#encapsulation {ppp | slip}
Router(config-if)#async mode interactiveRouter(config-if)#async mode interactive
Router(config-if)#async mode dedicatedRouter(config-if)#async mode dedicated
• Defines encapsulation type
• Places the line in dedicated PPP/SLIP mode
• Places the interface in interactive mode (allows an EXEC process)
OR
Async Interface Commands for Addressing
Router(config-if)#peer default ip address {address | pool pool-name | dhcp}
Router(config-if)#peer default ip address {address | pool pool-name | dhcp}
Router(config-if)#ip unnumbered type number Router(config-if)#ip unnumbered type number
Router(config-if)#async dynamic addressRouter(config-if)#async dynamic address
• Assigns an IP address to a remote node
• Allows a remote user to specify the IP address
• Configures the asynchronous interface to be unnumbered
PAP or CHAP
Authentication PSTN/ISDN
PPP LCP Options
PSTN/ISDNCallback
Compression
Multilink
Bundle
Data
PPP AuthenticationChecklocal
database
Querysecurityserver
database
Incoming PPPnegotiation
Determineauthentication
method
Local
Fail
Pass
Noauthentication
Disconnect Start PPP
Pass
Security
server
PPP Negotiating PAP Authentication
Inputs name andpassword when prompted
username johnpassword urbiz
Remote user John
Access server Cisco1
Run PPP
Use PAP
“john, urbiz”
Accept or reject
Local userdatabase
• One-way PAP
Configuring PAP Example
hostname right
int async 0
encapsulation ppp
ppp authentication PAP
ip add 10.0.0.2 255.255.255.0
dialer-map ip 10.0.0.1 name left 555-4321
ppp pap sent-username rightpassword right1
hostname right
int async 0
encapsulation ppp
ppp authentication PAP
ip add 10.0.0.2 255.255.255.0
dialer-map ip 10.0.0.1 name left 555-4321
ppp pap sent-username rightpassword right1
hostname left
int async 0
encapsulation ppp
ppp authentication PAP
ip add 10.0.0.1 255.255.255.0
dialer-map ip 10.0.0.2 name right 555-2345
ppp pap sent-username leftpassword left1
hostname left
int async 0
encapsulation ppp
ppp authentication PAP
ip add 10.0.0.1 255.255.255.0
dialer-map ip 10.0.0.2 name right 555-2345
ppp pap sent-username leftpassword left1
Leftrouter
Rightrouter
PSTN/ISDN
• Two-way PAP
PPP Using CHAP Authentication
username johnpassword urbiz
Remote userJohn
Access serverCisco1 Run PPP
Use CHAP
Response
Accept or reject
Challenge
Request for challenge
Local userdatabase
Name: johnPassword: urbiz
• One-way CHAP
CHAP in Action—Call
766-13640-1
User dials in
CHAP in Action—Challenge
01 random 3640-1id
User dials in766-1
3640-1
CHAP in Action—Response
MD5
hash
01 random 3640-1iduser pass3640-1 pc1
User dials in766-1
3640-1
CHAP in Action—Response (cont.)
01
02
random 3640-1id
id hash 766-1
user pass3640-1 pc1
User dials in766-1
3640-1
MD5
hash
CHAP in Action—Verification
01
02
random 3640-1id
id hash 766-1
user pass766-1 pc1
user pass3640-1 pc1
=?
User dials in766-1
3640-1
MD5
hash
MD5
hash
CHAP in Action—Result
01
02
03
random 3640-1id
id hash 766-1
id “Welcome in”
user pass766-1 pc1
user pass3640-1 pc1
User dials in766-1
3640-1
MD5
hash
MD5
hash
Configuring CHAP Example
hostname left
username right password sameone
int async 0
encapsulation ppp
ppp authentication CHAP
hostname left
username right password sameone
int async 0
encapsulation ppp
ppp authentication CHAP
hostname right
username left password sameone
int async 0
encapsulation ppp
ppp authentication CHAP
hostname right
username left password sameone
int async 0
encapsulation ppp
ppp authentication CHAP
Leftrouter
Rightrouter
PSTN/ISDN
PPP Callback Implementation Considerations
Return call is not made if:• The last interface is in use when callback is attempted• A DDR interesting packet used last available interface
Initiating call
Hold-queue started
Rotary group (all busy)
Callbackserver
Callbackclient
Callbackclient
Callbackserver
Client called X
Yes
Asynchronous Callback Operation Flowchart
CHAPCHAPAutoselectprotocol
Call
Authenticate
Callback
No
End
Authen.OK?
Hangup
PPP Callback Operation
Call initiation
Call acknowledgment
User authentication
Callback client Callback server
Initiating call disconnected
Server-to-client dial string identified
Client called
Authentication
Connection proceeds
1
2
3
4
5
6
7
8
Asynchronous Callback Global Commands
Router(config)#username username [password password][callback-dialstring phone-number][callback-line line-number][callback-rotary rotary-group-number]
Router(config)#username username [password password][callback-dialstring phone-number][callback-line line-number][callback-rotary rotary-group-number]
• On the callback server
Asynchronous Callback Line/Interface Commands
Router(config)#line line-number
Router(config-line)#callback forced-wait seconds
Router(config-line)#script callback script-name
Router(config)#line line-number
Router(config-line)#callback forced-wait seconds
Router(config-line)#script callback script-name
Router(config-if)#ppp callback acceptRouter(config-if)#ppp callback accept
Router(config-if)#ppp callback initiateRouter(config-if)#ppp callback initiate
• On the callback server
7
Configuring a PPP Callback Server
Plano(config)#interface s2Plano(config-if)#ip address 10.1.1.7 255.255.255.0Plano(config-if)#encapsulation pppPlano(config-if)#dialer callback-securePlano(config-if)#dialer map ip 10.1.1.8 name Dallas class dial1 5555678 Plano(config-if)#dialer-group1
Plano(config-if)#ppp authentication chap!Plano(config)#map-class dialer dial1Plano(config-map-class)#dialer callback-server usernamePlano(config-map-class)#dialer hold-queue timeout 60
Plano(config)#interface s2Plano(config-if)#ip address 10.1.1.7 255.255.255.0Plano(config-if)#encapsulation pppPlano(config-if)#dialer callback-securePlano(config-if)#dialer map ip 10.1.1.8 name Dallas class dial1 5555678 Plano(config-if)#dialer-group1
Plano(config-if)#ppp authentication chap!Plano(config)#map-class dialer dial1Plano(config-map-class)#dialer callback-server usernamePlano(config-map-class)#dialer hold-queue timeout 60
1
23
45
6
Plano(config-if)#ppp callback accept
Callback client Callback server
Dallas 10.1.1.8 5555678Plano 10.1.1.7 5551234
Configuring a PPP Callback Client
Dallas(config)#interface s0Dallas(config-if)#ip address 10.1.1.8 255.255.255.0Dallas(config-if)#encapsulation pppDallas(config-if)#dialer map ip 10.1.1.7 name Plano 5551234Dallas(config-if)#dialer-group 1
Dallas(config-if)#ppp authentication chap
Dallas(config)#interface s0Dallas(config-if)#ip address 10.1.1.8 255.255.255.0Dallas(config-if)#encapsulation pppDallas(config-if)#dialer map ip 10.1.1.7 name Plano 5551234Dallas(config-if)#dialer-group 1
Dallas(config-if)#ppp authentication chap
12
34
Dallas(config-if)#ppp callback request
Callback client Callback server
Dallas 10.1.1.8 5555678Plano 10.1.1.7 5551234
Supported Compression Algorithms
128–384 kbps
2:1 to 3:1Compression
ratios
Compresseddata
Data
128–384 kbps
Compression Decompression
• Predictor
• Stacker
• MPPC
• TCP header
128 kbps
Configuring Compression
• Interface compression algorithms
Router(config)#int s2Router(config-if)#compress {predictor | stac | mppc}Router(config)#int s2Router(config-if)#compress {predictor | stac | mppc}
• TCP header
Router(config)#int async 2Router(config-int)#ip tcp header-compressionRouter(config)#int async 2Router(config-int)#ip tcp header-compression
Router(config)#int async 2Router(config-int)#ip tcp header-compression passiveRouter(config)#int async 2Router(config-int)#ip tcp header-compression passive
Why Use Multilink PPP?Not Cisco
Ciscoaccessserver
Bundle
Bundle
Ciscoaccessserver
BrandX
Multilink PPP Operation
LCP option negotiation
Bundle
MRRU
• Synchronize multiple PPP data streams
Summary
After completing this chapter, you shouldbe able to perform the following tasks:• Configure PPP between a central site and a remote site
• Configure PAP or CHAP authentication
• Verify and troubleshoot a PPP link
Review Questions
• What are the LCP options for PPP?
• Describe why PPP callback is important.
• Describe how CHAP provides security.
• IP• AppleTalk• Novell IPX• Banyan VINES• XNS
• DECnet• ISO-CLNS• Compressed TCP• Bridging
X.25 cloud
X.25
Virtualcircuit
X.25
An Introduction to X.25
LANprotocol
LANprotocol
OSI Reference Model X.25 Protocol
Application
Presentation
Session
Transport
Network
Data Link
Physical1
2
3
4
5
6
7 •
•
•
•
X.25
LAPB
Physical 1
2
3
X.25 Protocol Stack
– X.25 DTE—Usually a subscriber's router or PAD – X.25 DCE—Usually a PDN's switch or concentrator
Public data network (PDN)
X.25 DTE X.25 DTEX.25DCE
X.25DCE
X.25 DTE and DCE
– PAD collects data and outputs it into X.25 packets
DTEDTE host
Identifying the PAD
DCEDCE
X.25 X.25
PAD
Asynchronousterminals
Public data network (PDN)
Data network ID code Network terminal number
4 decimal digits Up to 10 or 11 decimal digits
X.25 (X.121) Addressing Format
– Addressing set by service provider
X.25
ARP X.25 map
ETH DestinationMAC
SourceMAC
IP IPX.25 Source DestinationX.121X.121
TokenRing
X.25 Address Resolution
X.25
IP network IP network
IP datagram (L3)X.25 header (L3)
Data-linkframe(LAPB) (L2)
X.25 Encapsulation
– Protocol datagrams are reliably carried inside LAPB frames and X.25 packets
Switched virtual circuits(SVCs)
Permanent virtual circuits(PVCs)
X.25 Virtual Circuits
– Numbering for up to 4095 VCs per X.25 interface
IPX
Host
– SVCs may be combined to improve throughput for a particular protocol
SVC Usage
TCP/IP
AppleTalk
– Each network-layer protocol is associated with its own virtual circuit
Single-Protocol Virtual Circuits
IPX
Host
Multiprotocol Virtual Circuits
– Multiple protocols are carried within a virtual circuit to a single destination
– A maximum of nine protocols may be mapped to a host
TCP/IP
AppleTalk
IPX
Host
– Interface configuration– Select X.25 DTE or DCE encapsulation
– Configure parameters for X.25 network attachment
–Map protocol address to X.121 address
– Additional configuration steps
X.25 Configuration Tasks
– Defines encapsulation type
– Establishes interface address
Router(config-if)#encapsulation x25 [dte | dce]
Router(config-if)#x25 address x.121-address
Configuring X.25 SVCs—Steps 1 and 2Step 1
Step 2
– Specifies how a single protocol reaches a destination
– Specifies how multiple protocols reach a single destination using one SVC
Router(config-if)#x25 map protocol address x.121-address [options]
Router(config-if)#x25 map protocol address [protocol2 address2]*x.121-address [options]
Configuring X.25 SVCs—Step 3
or
Configuring X.25 SVC Example
IP address: 10.60.8.2
X.121 address: 311082191234
S1
X.25IP address: 10.60.8.1
X.121 address: 311082194567
Central siteS0Token
Ring
Central(config)#interface serial 1
Central(config-if)#encapsulation x25
Central(config-if)#x25 address 311082194567
Central(config-if)#ip address 10.60.8.1 255.255.248.0
Central(config-if)#x25 map ip 10.60.8.2 311082191234 broadcast
Central site
Branch(config)#interface serial 0
Branch(config-if)#encapsulation x25
Branch(config-if)#x25 address 311082191234
Branch(config-if)#ip address 10.60.8.2 255.255.248.0
Branch(config-if)#x25 map ip 10.60.8.1 311082194567 broadcast
Branch office
Branch office
S0
Configuring X.25 SVC Example Central(config)#interface serial 1
Central(config-if)#encapsulation x25
Central(config-if)#x25 address 311082194567
Central(config-if)#ip address 10.60.8.1 255.255.248.0
Central(config-if)#x25 map ip 10.60.8.2 311082191234 broadcast
Central(config-if)#x25 map ip 10.60.8.3 311082198901 broadcast
Central site
IP address: 10.60.8.3X.121 address: 311082198901
IP address: 10.60.8.2X.121 address: 311082191234
S1
X.25IP address: 10.60.8.1X.121 address: 311082194567
Central siteS0Token
Ring
Branch office
Branch office
– Specifies how protocols reach a destination using a PVC
Router(config-if)#x25 pvc circuit protocol address [protocol2 address2]* x.121-address [options]
Configuring X.25 PVCs—Steps 1 to 3
– Defines encapsulation type
– Establishes interface address
Router(config-if)#encapsulation x25 [dte | dce]
Router(config-if)#x25 address x.121-address
Step 1
Step 2
Step 3
IP address: 10.60.8.2X.121 address: 311082191234
IP address: 10.60.8.1X.121 address: 311082194567
Central(config)#interface serial 1
Central(config-if)#encapsulation x25
Central(config-if)#x25 address 311082194567
Central(config-if)#ip address 10.60.8.1 255.255.248.0
Central(config-if)#x25 pvc 4 ip 10.60.8.2 311082191234 broadcast
Central site
Branch(config)#interface serial 0
Branch(config-if)#encapsulation x25
Branch(config-if)#x25 address 311082191234
Branch(config-if)#ip address 10.60.8.2 255.255.248.0
Branch(config-if)#x25 pvc 3 ip 10.60.8.1 311082194567 broadcast
Branch office
Configuring X.25 PVC Example
PVC 4
S1
X.25
Central siteS0Token
Ring
Branch office
Additional X.25 Configuration Tasks
– Configure interface for X.25 Layer 3 parameters– Virtual circuits
– Packet size
– Window size
– Window modulus
PVCs
Incoming only
Two-way
Outgoing only
SVC
SVC
SVC
1–4095
1–40951–4095
1–40951–4095
1–40951–4095
00
11024
00
x25 pvc circuit
x25 lic circuitx25 hic circuit
x25 ltc circuitx25 htc circuit
x25 loc circuitx25 hoc circuit
Range Default Command
Configuring X.25 VC Ranges
– Specifies default incoming packet size
– Specifies default outgoing packet size
Router(config-if)#x25 ips bytes
Router(config-if)#x25 ops bytes
Configuring X.25 Packet Sizes
– Specifies default unacknowledged packet limits
– Defines packet-level window counter limit
Configuring Window Parameters
Router(config-if)#x25 win packets Router(config-if)#x25 wout packets
Router(config-if)#x25 modulo modulus
Additional X.25 Configuration Options Example
Router(config)#interface serial 0Router(config-if)#encapsulation x25
Router(config-if)#x25 address 311082198756Router(config-if)#x25 ips 1024Router(config-if)#x25 ops 1024Router(config-if)#x25 win 7Router(config-if)#x25 wout 7
S0
X.25 network
Verifying X.25 ConfigurationCentralA#sh int s 3/1Serial3/1 is up, line protocol is upHardware is CD2430 in sync modeInternet address is 10.140.1.1/24MTU 1500 bytes, BW 128 Kbit, DLY 20000 usec, rely 255/255, load 1/255Encapsulation X25, loopback not setX.25 DTE, address 311010100101, state R1, modulo 8, timer 0Defaults: idle VC timeout 0cisco encapsulationinput/output window sizes 2/2, packet sizes 128/128Timers: T20 180, T21 200, T22 180, T23 180Channels: Incoming-only none, Two-way 1-1024, Outgoing-only noneRESTARTs 1/0 CALLs 0+0/0+0/0+0 DIAGs 0/0LAPB DTE, state CONNECT, modulo 8, k 7, N1 12056, N2 20T1 3000, T2 0, interface outage (partial T3) 0, T4 0VS 5, VR 3, tx NR 3, Remote VR 5, Retransmissions 0Queues: U/S frames 0, I frames 0, unack. 0, reTx 0IFRAMEs 5/3 RNRs 0/0 REJs 0/0 SABM/Es 0/1 FRMRs 0/0 DISCs 0/0Last input 00:00:29, output 00:00:29, output hang neverLast clearing of "show interface" counters neverQueueing strategy: fifoOutput queue 0/40, 0 drops; input queue 0/75, 0 drops5 minute input rate 0 bits/sec, 0 packets/sec5 minute output rate 0 bits/sec, 0 packets/sec<Output Omitted>
Laboratory Exercise: Visual Objective
Branch office
Cisco 3640
Cisco 1600
Central site
X.25
X.25service
X.25
S3/1X.121 address: 31101010XXX1
S0 X.121 address: 31101010XXX2
Summary
•After completing this chapter, you should be able to perform the following tasks:• Configure an X.25 WAN connection
• Assign X.121 addresses to router interfaces and map higher-level addresses to X.25 addresses
• Verify X.25 configuration in the router
Review Questions
• Explain the difference between an X.25 DTE and DCE.
• Assume you want an IP connection over an X.25 link. What must you do to map the network layer address to the X.121 address?
• How can you limit traffic by lowering the amount of acknowledgements sent across the X.25 link?
Using ISDN and DDR Technologies to Enhance Remote
Connectivity
Objectives
• Upon completion of this chapter, you will be able to complete the following tasks:– Select BRI or PRI service for a particular
application– Identify Q.921 and Q.931 signaling and call
sequences– Configure ISDN BRI– Configure ISDN PRI– Configure ISDN DDR
Chapter Activities
Windows 95 PC Modem
Branch office
ISDN/analog
Small office
Central site
Frame Relay
Frame Relay
service
PRI
BRI
BRI
Frame Relay
Async
ISD
N, P
PP
, CH
AP
, DD
R
AAA server
Async
Asynchronous Versus ISDN
• Analog converted to digital and back
Channelbank
Channelbank
SWSW SWSW
• Digital end-to-end
Channelbank
Channelbank
SWSW SWSW
ISDN Services and Channelized E1 and T1
56/64 kbps56/64 kbps
16 kbps
144 kbps
2B
D }{BRI
T1 1.544 Mbps
or
E1 2.048 Mbps (includes sync)
23B (T1) or30B (E1)
D
64 kbpseach
64 kbps}PRI
2.048 Mbps(includes sync)
31 64 kbpschannels }E1
1.544 Mbps(includes sync)
24DS0s }T1
31
BRI Call Processing
ISDNservice provider
4
B channel
D channel/SS7 signaling
2 SS7
Q.931 signaling Q.931 signaling
TE1 NT1 LE
Local loop terminator
ISDN local exchange
ISDN terminal equipment
NT2
Customer premises switching equipment
TE2 TA
Non-ISDN terminal
equipment
Terminal adapter
Non-U.S. demarcations
U.S. demarcation
S U
R
T
BRI Functional Groups and Reference Points
Physical Representation of BRI Reference Points
Cisco ISDNrouter
To ISDNservice
Walljack
4-wirecircuit
2-wirecircuit
S/T UTA NT1NT1
S/T bus
S/T bus
S/T interface as a multipoint connection
To non-ISDNdevice (TE2)
R
ISDNphone
PRI—Layer 1 Standards and Reference Points
LE
U
ITU-T I.431ANSI
T1.601
TE CSU/DSU
S/T
ITU-TI.430
ISDN Protocol Layers
Layer 3
LAPD (Q.921)
D Channel B Channel
I.430/I.431/ANSI T1.601I.430/I.431/ANSI T1.601
HDLC/PPP/FR/LAPB
Layer 1
Layer 2
DSS1 (Q.931) IP/IPX
BRI Layer 1—I.430 FramingNT TE Frame
1 111111111111111 8 8 8 8
F FDL L L L L L L L LD D DB2B1B2B1L
1 111111111111111 8 8 8 8
F FDE A F E S E S E SD D DB2B1B2B1L
TE NT Frame
ISDN
NT1
Daisy-chainS/T bus
TEI/SAPI
TEI/SAPI LE
ISDN Layer 2
– ITU-T Q.920 and Q.921– Defines logical link between TE/TA and NT2/LE– Carries Layer 3 D-channel messages
ISDN Layer 3—D Channel Q.931
• Q.931 defines call control between the TE and local switch
TE ETNT1 LTQ.931
ISDN switch (LE)
Q.931 Messaging—Call Setup ExampleCalling
partyCalled
party
Setup
Connect acknowledge Connect
acknowledge
Setup
Setup acknowledge
Call proceeding
Alerting
Connect
Alerting
Connect
Call proceeding
Tim
e
ISDN service provider
ISDNswitch
ISDNswitch
Q.931 Messaging—Call Teardown Example
Released
Disconnect
Calling party Called partyDisconnect
Released
Release complete
Release complete
Release
Tim
e
ISDN service provider
ISDNswitch
ISDNswitch
DDR OperationInteresting
?
Connected?
Phone #?
Connected?
Dial
No
Yes
Yes
No
No
Send
Incoming packet
ResetIdle
TimerYes
NoInterface
up?
Yes
Yes
No
Using DDR with ISDN
ISDN service provider
BRI or
PRI
1.
2. Remoterouter
1. Packet arrives2. Switch packet to DDR interface, determine if interesting 3. If interesting, dial DDR destination via ISDN 4. Connect to remote router
3.
4.
ISDN Configuration Tasks
–Global configuration–Select switch type–Specify traffic to trigger DDR call
–Interface configuration–Select interface specifications–Configure ISDN addressing
–Optional feature configuration
ISDN
ISDN Configuration Commands
– Set global parameters with this command:• isdn switch-type
– Set interface parameters with these commands:• encapsulation ppp (CHAP and Multilink PPP)
• ip address
• isdn spid1
Router(config)#isdn switch-type switch-typeRouter(config)#isdn switch-type switch-type
Router(config-if)#isdn switch-type switch-typeRouter(config-if)#isdn switch-type switch-type
Selecting the ISDN Switch Type
– Specifies the type of ISDN switch with which the router communicates
– Global or interface command
Setting Interface Protocols
Router(config-if)#encapsulation {ppp | hdlc}Router(config-if)#encapsulation {ppp | hdlc}
• Selects framing for that ISDN BRI
Router(config-if)#ppp authentication {pap | chap | ms-chap}
Router(config-if)#ppp authentication {pap | chap | ms-chap}
• Selects PPP authentication type
Setting SPIDs if Necessary
Router(config-if)#isdn spid1 spid-number [ldn] Router(config-if)#isdn spid1 spid-number [ldn]
• Sets a B channel SPID required by many service providers
Router(config-if)#isdn spid2 spid-number [ldn] Router(config-if)#isdn spid2 spid-number [ldn]
• Sets an SPID for the second B channel
DDR Configuration Tasks
1. Define interesting traffic2. Assign interesting traffic definition
to ISDN interface 3. Define destination 4. Define call parameters
ISDNserviceprovider
BRI or
PRIRemoterouter
Interesting traffic arrives
Dial destination
Defining Interesting Traffic Router(config)#dialer-list dialer-group-number
protocol protocol-name {permit | deny} list access-list-number
Router(config)#dialer-list dialer-group-numberprotocol protocol-name {permit | deny} list access-list-number
• Defines interesting packets for DDR • Associated with the dialer group assigned to the interface
Router(config-if)#dialer-group group-number Router(config-if)#dialer-group group-number
• Assigns an interface to the dialer access group specified in the dialer-list command
Using Access Lists for DDR Router(config)#access-list access-list-number {permit|deny} {protocol | protocol-keyword } {source source-wildcard | any} {destination destination-wildcard | any} [protocol-specific-options] [log]
Router(config)#access-list access-list-number {permit|deny} {protocol | protocol-keyword } {source source-wildcard | any} {destination destination-wildcard | any} [protocol-specific-options] [log]
• Gives tighter control over “interesting” traffic and uses standard or extended access lists
• Associates an access list with a dialer access group
Router(config)#dialer-list dialer-group list access-list-number
Router(config)#dialer-list dialer-group list access-list-number
Defining Destination Parameters
Router(config-if)#dialer map protocol next-hop-address [name hostname] [broadcast] dial-string Router(config-if)#dialer map protocol next-hop-address [name hostname] [broadcast] dial-string
• Defines how to reach a remote ISDN destination
Setting Default/Static Routes
Default route istoward cloud
Static route is towardthe remote site
TCP/IP
Setting Static Routes
Router(config)#ip route 172.108.0.0 255.255.0.0 192.254.35.2 Router(config)#ip route 172.108.0.0 255.255.0.0 192.254.35.2
172.108.0.0
192.254.35.2
BRI 0
Setting Default Routes
172.254.50.0
172.254.30.0
172.254.45.2 172.254.45.1
Router(config)#ip route 172.254.50.0 255.255.255.0 172.254.45.1
Router(config)#ip default-network 172.254.50.0
Router(config)#ip route 0.0.0.0 0.0.0.0 172.254.45.1
Router(config)#ip route 172.254.50.0 255.255.255.0 172.254.45.1
Router(config)#ip default-network 172.254.50.0
Router(config)#ip route 0.0.0.0 0.0.0.0 172.254.45.1
Setting Route Redistribution
• This router advertises static routes to other routers
192.150.42.0
Router(config)#router igrp 109Router(config-router)#network 172.108.0.0Router(config-router)#redistribute staticRouter(config)#ip route 192.150.42.0
255.255.255.0 10.0.0.2
Router(config)#router igrp 109Router(config-router)#network 172.108.0.0Router(config-router)#redistribute staticRouter(config)#ip route 192.150.42.0
255.255.255.0 10.0.0.2
10.0.0.1
10.0.0.2
172.108.0.0
Deactivating Routing Updates on an Interface
• Does not broadcast routes on that interface
Router(config)#router igrp 100Router(config-router)#passive-interface bri0Router(config)#router igrp 100Router(config-router)#passive-interface bri0
BRI 0
Configuring a Simple ISDN Call
– Use PPP encapsulation– All IP traffic to destination triggers ISDN call– Carrier uses a 5ESS basic rate switch– Service provider assigns connection parameters
192.168.1.1
NT1
E0
BRI 0E0
10.170.0.1
Cisco-a
Cisco-bISDN
NT1
10.170.0.2
BRI 0
192.168.2.1
51055512344085554000
Configuration Example, Cisco-a
192.168.1.1
BRI 0
10.170.0.1
Cisco-aCisco-b
ISDN10.170.0.2
4085554000
hostname Cisco-aisdn switch-type basic-5essusername Cisco-b password samepassinterface bri 0 ip address 10.170.0.1 255.255.0.0 encapsulation ppp dialer idle-timeout 300 dialer map ip 10.170.0.2 name Cisco-b 4085554000 dialer-group 1 ppp authentication chap!ip route 192.168.1.0 255.255.255.0 10.170.0.2dialer-list 1 protocol ip permit
hostname Cisco-aisdn switch-type basic-5essusername Cisco-b password samepassinterface bri 0 ip address 10.170.0.1 255.255.0.0 encapsulation ppp dialer idle-timeout 300 dialer map ip 10.170.0.2 name Cisco-b 4085554000 dialer-group 1 ppp authentication chap!ip route 192.168.1.0 255.255.255.0 10.170.0.2dialer-list 1 protocol ip permit
Configuration Example, Cisco-b
BRI 0
10.170.0.1 10.170.0.2
5105551234
192.168.2.1
hostname Cisco-bisdn switch-type basic-5essusername Cisco-a password samepass interface bri 0 ip address 10.170.0.2 255.255.0.0 encapsulation ppp dialer idle-timeout 300 dialer map ip 10.170.0.1 name Cisco-a 5105551234 dialer-group 1 ppp authentication chap!ip route 192.168.2.0 255.255.255.0 10.170.0.1dialer-list 1 protocol ip permit
hostname Cisco-bisdn switch-type basic-5essusername Cisco-a password samepass interface bri 0 ip address 10.170.0.2 255.255.0.0 encapsulation ppp dialer idle-timeout 300 dialer map ip 10.170.0.1 name Cisco-a 5105551234 dialer-group 1 ppp authentication chap!ip route 192.168.2.0 255.255.255.0 10.170.0.1dialer-list 1 protocol ip permit
ISDN
Cisco-aCisco-b
BRI 0
Access Lists and DDR for ISDN
– Cisco-a allows all IP traffic except Telnet and FTP to trigger ISDN calls to Cisco-b, and access subnet 192.168.1.0
10.170.0.3NT1
ISDN ServiceProvider
NT1
NT1
10.170.0.1
10.170.0.2
192.168.1.1
Cisco-c192.168.3.1
4085554000
4085551234
Cisco-a
Cisco-b
Access List Configuration Example, Cisco-a
hostname Cisco-aisdn switch-type basic-dms100username Cisco-b password samepassusername Cisco-c password samepassinterface bri 0 ip address 10.170.0.1 255.255.0.0 encapsulation pppdialer idle-timeout 300dialer map ip 10.170.0.2 name Cisco-b 4085554000dialer map ip 10.170.0.3 name Cisco-c 4085551234dialer-group 2 ppp authentication chap(continued on next figure)
hostname Cisco-aisdn switch-type basic-dms100username Cisco-b password samepassusername Cisco-c password samepassinterface bri 0 ip address 10.170.0.1 255.255.0.0 encapsulation pppdialer idle-timeout 300dialer map ip 10.170.0.2 name Cisco-b 4085554000dialer map ip 10.170.0.3 name Cisco-c 4085551234dialer-group 2 ppp authentication chap(continued on next figure)
10.170.0.3
ISDN Service Provider
BRI 0
10.170.0.1 10.170.0.2192.168.1.1Cisco-a
Cisco-b
Cisco-c
192.168.3.1
4085554000
4085551234
Access List Configuration Example, Cisco-a (cont.)
ip route 192.168.1.0 255.255.255.0 10.170.0.2ip route 192.168.3.0 255.255.255.0 10.170.0.3access-list 101 deny tcp any any eq ftpaccess-list 101 deny tcp any any eq telnet access-list 101 permit ip any anydialer-list 2 protocol ip list 101
ip route 192.168.1.0 255.255.255.0 10.170.0.2ip route 192.168.3.0 255.255.255.0 10.170.0.3access-list 101 deny tcp any any eq ftpaccess-list 101 deny tcp any any eq telnet access-list 101 permit ip any anydialer-list 2 protocol ip list 101
10.170.0.3
ISDN Service Provider
BRI 0
10.170.0.1 10.170.0.2192.168.1.1Cisco-a
Cisco-b
Cisco-c
192.168.3.1
4085554000
4085551234
ISDNservice provider
Optional ISDN Configurations
– Specify Multilink PPP or BOD– Enable caller ID screening– Configure rate adaptation– Called number answer
SpeedLimit128
kbpsB2
B1With BODor MP64 kbps
64 kbps
B Channel Aggregation
– Available on all Cisco IOS platforms with ISDN– Accomplished via Cisco proprietary BOD or
Multilink PPP
Cisco Proprietary BOD
Traffic Buffer
B1
Router(config)#int bri0
Router(config-if)#dialer load—threshold load
Router(config)#int bri0
Router(config-if)#dialer load—threshold load
B2
ISDNRouter
B Channel Aggregation Using Multilink PPP
Data in
BB AAB1B1
B2B2
Sequencing andfragmentation
Data out
Sequencing andreassembly
ISDNservice provider
A1A1
A2A2
Router(config)#int bri0
Router(config-if)#dialer load-threshold load [inbound | outbound | either]
Router(config-if)#ppp multilink
Router(config)#int bri0
Router(config-if)#dialer load-threshold load [inbound | outbound | either]
Router(config-if)#ppp multilink
B1B1
B2B2
A1A1
A2A2BB AA
Configuring Multilink PPP
– MLP can be configured on:• Asynchronous serial interfaces
• Synchronous serial interfaces
• Basic Rate Interfaces (BRI)
• Primary Rate Interfaces (PRI)
Configuring Multilink PPP (cont.)Rotary group
Router(config-if)#dialer load-threshold load [outbound | inbound | either]Router(config-if)#dialer load-threshold load [outbound | inbound | either]
Router(config-if)#ppp multilink
• Enables Multilink PPP on a dialer rotary group
• Defines the threshold to bring up another link
ISDN
Configuring Multilink PPP (cont.)
Router(config)#interface bri0Router(config-if)#no ip addressRouter(config-if)#encapsulation pppRouter(config-if)#ppp multilinkRouter(config-if)#dialer idle-timeout 30
Router(config)#interface bri0Router(config-if)#no ip addressRouter(config-if)#encapsulation pppRouter(config-if)#ppp multilinkRouter(config-if)#dialer idle-timeout 30Router(config-if)#dialer load-threshold 128 either
ISDN
Configuring Multilink PPP (cont.)
Router(config)#interface dialer1Router(config-if)#ip address 10.10.10.7 255.255.255.0Router(config-if)#encapsulation pppRouter(config-if)#dialer idle-timeout 30Router(config-if)#dialer map ip 10.10.10.8 name Router 81012345678901
Router(config-if)#dialer-group 1Router(config-if)#ppp authentication chap
Router(config)#interface dialer1Router(config-if)#ip address 10.10.10.7 255.255.255.0Router(config-if)#encapsulation pppRouter(config-if)#dialer idle-timeout 30Router(config-if)#dialer map ip 10.10.10.8 name Router 81012345678901
Router(config-if)#dialer-group 1Router(config-if)#ppp authentication chap
Router(config-if)#dialer load-threshold 128 either
Router(config-if)#ppp multilink
ISDN
Rotary group
Caller Identification Screening
Call setup message with local ISDN
numbers
5551234
Router A Router B
RouterISDN
number
A 5551234
Compare with allowed numbers
Accept call
– Extra level of call management– Call not set up (or charged) until acceptance– An alternative: PPP encapsulation and CHAP
ISDN
Configuring Caller ID Screening
Router(config-if)#isdn caller number Router(config-if)#isdn caller number
• Enables caller ID screening
56 kbps
Selecting ISDN Rate Adaptation
– Configured for outgoing calls– Requested lower speed from call is honored– Assigned on a per-destination basis
56 kbps
BRI 0BRI 0
BRI 1
64 kbps64 kbps
ISDN
Configuring Rate Adaptation
Router(config-if)#dialer map protocol next-hop-address [name name] [speed speed] [broadcast] [dial-string]
• Negotiates speed for calls to a destination
Configuring Called-Number Answer
• Sets the number to allow the interface to respond/answer
Router(config-if)#isdn answer1 [called-party-number] Router(config-if)#isdn answer1 [called-party-number]
Router(config-if)#isdn answer2 [called-party-number] Router(config-if)#isdn answer2 [called-party-number]
or
Monitoring PPP on BRIBranchF#sh int bri 0 1BRI0:1 is up, line protocol is up Hardware is BRI MTU 1500 bytes, BW 64 Kbit, DLY 20000 usec, rely 255/255, load 1/255 Encapsulation PPP, loopback not set, keepalive set (10 sec) LCP Open Open: IPCP, CDPCP Last input 00:00:02, output 00:00:02, output hang never Last clearing of "show interface" counters never Input queue: 0/75/0 (size/max/drops); Total output drops: 0 Queueing strategy: weighted fair Output queue: 0/1000/64/0 (size/max total/threshold/drops) Conversations 0/1/256 (active/max active/max total) Reserved Conversations 0/0 (allocated/max allocated) 5 minute input rate 0 bits/sec, 0 packets/sec 5 minute output rate 0 bits/sec, 0 packets/sec 45 packets input, 1448 bytes, 0 no buffer Received 45 broadcasts, 0 runts, 0 giants, 0 throttles 0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored, 0 abort 45 packets output, 1444 bytes, 0 underruns 0 output errors, 0 collisions, 0 interface resets 0 output buffer failures, 0 output buffers swapped out 3 carrier transitions
Monitoring ISDN BRI D Channel
•BranchF#sh int bri 0•BRI0 is up, line protocol is up (spoofing)• Hardware is BRI• Internet address is 10.155.0.1/24• MTU 1500 bytes, BW 64 Kbit, DLY 20000 usec, rely 255/255, load 1/255• Encapsulation PPP, loopback not set• Last input 00:00:04, output never, output hang never• Last clearing of "show interface" counters never• Input queue: 0/75/0 (size/max/drops); Total output drops: 0• Queueing strategy: weighted fair• Output queue: 0/1000/64/0 (size/max total/threshold/drops)• Conversations 0/1/256 (active/max active/max total)• Reserved Conversations 0/0 (allocated/max allocated)• 5 minute input rate 0 bits/sec, 0 packets/sec• 5 minute output rate 0 bits/sec, 0 packets/sec• 680 packets input, 3651 bytes, 0 no buffer• Received 223 broadcasts, 0 runts, 0 giants, 0 throttles• 0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored, 0 abort• 680 packets output, 3697 bytes, 0 underruns• 0 output errors, 0 collisions, 5 interface resets• 0 output buffer failures, 0 output buffers swapped out• 3 carrier transitions
Monitoring ISDN BRI B ChannelsBranchF#sh int bri 0 1 2BRI0:1 is up, line protocol is up Hardware is BRI MTU 1500 bytes, BW 64 Kbit, DLY 20000 usec, rely 255/255, load 1/255 Encapsulation PPP, loopback not set, keepalive set (10 sec) LCP Open Open: IPCP, CDPCP Last input 00:00:01, output 00:00:01, output hang never Last clearing of "show interface" counters never Input queue: 0/75/0 (size/max/drops); Total output drops: 0 Queueing strategy: weighted fair Output queue: 0/1000/64/0 (size/max total/threshold/drops) Conversations 0/1/256 (active/max active/max total) Reserved Conversations 0/0 (allocated/max allocated) 5 minute input rate 0 bits/sec, 0 packets/sec 5 minute output rate 0 bits/sec, 0 packets/sec 82 packets input, 2844 bytes, 0 no buffer Received 82 broadcasts, 0 runts, 0 giants, 0 throttles 0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored, 0 abort 82 packets output, 2838 bytes, 0 underruns 0 output errors, 0 collisions, 0 interface resets 0 output buffer failures, 0 output buffers swapped out 5 carrier transitions(output omitted)
Monitoring ISDN BRIRouter#show isdn status
The current ISDN Switchtype = basic-5essISDN BRI0 interface Layer 1 Status: ACTIVE Layer 2 Status: TEI = 65, State = MULTIPLE_FRAME_ESTABLISHED Layer 3 Status: 1 Active Layer 3 Call(s) Activated dsl 0 CCBs = 1 CCB:callid=2, sapi=0, ces=1, B-chan=1 Total Allocated ISDN CCBs = 1
Router#show isdn status
The current ISDN Switchtype = basic-5essISDN BRI0 interface Layer 1 Status: ACTIVE Layer 2 Status: TEI = 65, State = MULTIPLE_FRAME_ESTABLISHED Layer 3 Status: 1 Active Layer 3 Call(s) Activated dsl 0 CCBs = 1 CCB:callid=2, sapi=0, ces=1, B-chan=1 Total Allocated ISDN CCBs = 1
Verifying Multilink PPPRouter#show ppp multilinkBundle rudder, 3 members, first link is BRI0: B-Channel 10 lost fragments, 8 reordered, 0 unassigned, sequence 0x1E/0x1E rcvd/sentBundle dallas, 4 members, first link is BRI2: B-Channel 10 lost fragments, 28 reordered, 0 unassigned, sequence 0x12E/0x12E rcvd/sent
Router#show ppp multilinkBundle rudder, 3 members, first link is BRI0: B-Channel 10 lost fragments, 8 reordered, 0 unassigned, sequence 0x1E/0x1E rcvd/sentBundle dallas, 4 members, first link is BRI2: B-Channel 10 lost fragments, 28 reordered, 0 unassigned, sequence 0x12E/0x12E rcvd/sent
Verifying Multilink PPP (cont.)Router# show interface bri0 1 BRI0: B-Channel 1 is up, line protocol is up Hardware is BRI MTU 1500 bytes, BW 64 Kbit, DLY 20000 usec, rely 255/255, load 1/255 Encapsulation PPP, loopback not set, keepalive not set lcp = OPEN multilink = OPEN ipcp = OPEN Last input 0:05:51, output 0:05:52, output hang never Last clearing of "show interface" counters never Input queue: 0/75/0 (size/max/drops); Total output drops: 0 Output queue: 0/64/0 (size/threshold/drops) Conversations 0/1 (active/max active) Reserved Conversations 0/0 (allocated/max allocated) 5 minute input rate 0 bits/sec, 0 packets/sec 5 minute output rate 0 bits/sec, 0 packets/sec 15 packets input, 804 bytes, 0 no buffer Received 0 broadcasts, 0 runts, 0 giants 0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored, 0 abort 14 packets output, 806 bytes, 0 underruns 0 output errors, 0 collisions, 19 interface resets, 0 restarts 0 output buffer failures, 0 output buffers swapped out 1 carrier transitions
Troubleshooting Multilink PPP
BranchF#debug dialerBranchF#ping 10.115.0.135
Type escape sequence to abort.Sending 5, 100-byte ICMP Echos to 10.115.0.135, timeout is 2 seconds:
BRI0: Dialing cause ip (s=10.155.0.1, d=10.115.0.135)BRI0: Attempting to dial 6000%LINK-3-UPDOWN: Interface BRI0:2, changed state to updialer Protocol up for BR0:2.%LINEPROTO-5-UPDOWN: Line protocol on Interface BRI0:2, changed state to up!!!!Success rate is 80 percent (4/5), round-trip min/avg/max = 32/34/36 msBranchF#BRI0: rotary group to 6000 overloaded (1)BRI0: Attempting to dial 6000%ISDN-6-CONNECT: Interface BRI0:2 is now connected to 6000 CentralF
BranchF#debug dialerBranchF#ping 10.115.0.135
Type escape sequence to abort.Sending 5, 100-byte ICMP Echos to 10.115.0.135, timeout is 2 seconds:
BRI0: Dialing cause ip (s=10.155.0.1, d=10.115.0.135)BRI0: Attempting to dial 6000%LINK-3-UPDOWN: Interface BRI0:2, changed state to updialer Protocol up for BR0:2.%LINEPROTO-5-UPDOWN: Line protocol on Interface BRI0:2, changed state to up!!!!Success rate is 80 percent (4/5), round-trip min/avg/max = 32/34/36 msBranchF#BRI0: rotary group to 6000 overloaded (1)BRI0: Attempting to dial 6000%ISDN-6-CONNECT: Interface BRI0:2 is now connected to 6000 CentralF
Troubleshooting Multilink PPP (cont.)
• CHAP/PAP/caller ID on answering router?• Dialer load threshold on one router?• Fair queuing turned on?
Bundle
Router#debug isdn q921Router#debug isdn q921
Router#debug isdn q931Router#debug isdn q931
• Shows call setup and teardown of ISDN network connections (Layer 3) between the access router and the ISDN switch
ISDN debug Commands
– Shows data link layer messages (Layer 2) on the D channel between the access router and the ISDN switch
Configuration Tasks for PRI
– Select the PRI switch type
– Specify T1/E1 controller, framing, and line coding for the facility
– Set PRI group timeslots for T1/E1 and indicate the speed used
– Specify the interface on the router that you will configure for DDR
T1/E1 PRI23B (T1) or30B (E1)
D
ISDN PRI Configuration
Router(config)#controller {t1 | e1} {slot/port | unit-number}
Router(config)#controller {t1 | e1} {slot/port | unit-number}
Router(config)#isdn switch-type switch-type Router(config)#isdn switch-type switch-type
• Configures the ISDN PRI switch type
• Configures the ISDN PRI controller
T1/E1 Controller Parameters
Router(config-controller)#framing {sf | | crc4 | no-crc4}
• Selects the line-code type on the controller
Router(config-controller)#linecode {ami | | hdb3}
• Selects the framing type on the controller
• Specifies the T1 clock source
Router(config-controller)#clock source {line [primary | secondary] | internal} Router(config-controller)#clock source {line [primary | secondary] | internal}
esf
b8zs
Additional ISDN PRI Configuration Parameters
• Specifies ISDN PRI on the T1 or E1 controller
• Specifies the serial port for the PRI D channel
Router(config)#interface serial {slot/port: | unit:}{23 | 15} Router(config)#interface serial {slot/port: | unit:}{23 | 15}
Router(config-controller)#pri-group [timeslots range] Router(config-controller)#pri-group [timeslots range]
• Switches incoming analog calls to internal modems
Router(config-if)#isdn incoming-voice modem Router(config-if)#isdn incoming-voice modem
PRI Configuration ExampleCisco 3600
T1 PRI
isdn switch-type primary-5ess!controller t1 0/0pri-group timeslots 1-24framing esflinecode b8zsclock source line!interface serial 0/0:23ip address 192.168.11.2 255.255.255.0isdn incoming-voice modem
ISDN5ESS
Laboratory Exercise: Visual Objective
Branch office
Central site
PRI
BRI
ISDN
ISDN, PPP,CHAP, DDR
Summary
• After completing this chapter, you should be able to perform the following tasks:– Select BRI or PRI service for a particular
application
– Identify Q.921 and Q.931 signaling and call sequences
– Configure ISDN BRI
– Configure ISDN PRI
– Configure ISDN DDR
Review Questions
– Compare ISDN BRI with ISDN PRI.
– If you are not sure what your ISDN switch type is, where would you obtain this information?
– What are Q.921 and Q.931?
Establishing a Dedicated Frame
Relay Connection and Controlling Traffic
Flow
Objectives• Upon completion of this chapter, you will be able to p
erform the following tasks:– Configure Frame Relay– Configure Frame Relay subinterfaces– Configure Frame Relay traffic shaping– Verify Frame Relay operation
261
Chapter Activities
Windows 95 PC Modem
Branch office
ISDN/analog
Small office
Central site
Frame Relay
Frame Relay
service
PRI
BRI
BRI
Frame Relay
Async
AAA server
Async
Frame Relay Overview
– Virtual circuits make connections
– Connection-oriented service
DTE or CPE
routers
Frame Relayworks here
TokenRing
CSU/DSU
DCE or FrameRelay switches
Frame Relay Operation
– Get locally significant DLCIs from your Frame Relay provider
– Map your network addresses to DLCIs
CSU/DSU
DLCI=500
PVC
10.1.1.1
ARPInverse ARP or
Frame Relay map
ETH DestinationMAC
SourceMAC
IP IP(10.1.1.1)
FrameRelay
DestinationDLCI (500)
CSU/DSU
Frame Relay Signaling
•Cisco supports three LMI standards:– ANSI T1.617 Annex D
– ITU-T Q.933 Annex A
– “The gang of four”
DLCI=500 PVC
LMI500=Active400=Inactive
DLCI=400PVC
Keepalive
Configuring Basic Frame Relay
Central Branch
Central(config)#interface Serial1Central(config-if)#ip address 10.16.0.1 255.255.255.0Central(config-if)#encapsulation frame-relay
Configuring Address Mapping
Branch
Non-Cisco
Central(config)#interface Serial1Central(config-if)#ip address 10.16.0.1 255.255.255.0Central(config-if)#encapsulation frame-relayCentral(config-if)#bandwidth 56Central(config-if)#frame-relay map ip 10.16.0.2 110 broadcastCentral(config-if)#frame-relay map ip 10.16.0.3 120 broadcast ietf
Central Branch
DLCI to Branch=110DLCI to Non-Cisco=12010.16.0.1/24
10.16.0.2/24
Central siteVC
VC
10.16.0.3/24
Verifying Frame Relay Operation
– Displays line, protocol, DLCI, and LMI information
Router#show interface serial 0Serial0 is up, line protocol is up Hardware is CD2430 in sync mode MTU 1500 bytes, BW 128 Kbit, DLY 20000 usec, rely 255/255, load 1/255 Encapsulation FRAME-RELAY, loopback not set, keepalive set (10 sec) LMI enq sent 112971, LMI stat recvd 112971, LMI upd recvd 0, DTE LMI up LMI enq recvd 0, LMI stat sent 0, LMI upd sent 0 LMI DLCI 1023 LMI type is CISCO frame relay DTE FR SVC disabled, LAPF state down Broadcast queue 0/64, broadcasts sent/dropped 32776/0, interface broadcasts 14 Last input 00:00:00, output 00:00:03, output hang never Last clearing of "show interface" counters never Input queue: 0/75/0 (size/max/drops); Total output drops: 0 Queueing strategy: weighted fair <Output Omitted>
Verifying Frame Relay Operation (cont.)
– Displays PVC traffic statistics
Router#show frame-relay pvc 110 PVC Statistics for interface Serial0 (Frame Relay DTE) DLCI = 110, DLCI USAGE = LOCAL, PVC STATUS = ACTIVE, INTERFACE = Serial0 input pkts 14055 output pkts 32795 in bytes 1096228 out bytes 6216155 dropped pkts 0 in FECN pkts 0 in BECN pkts 0 out FECN pkts 0 out BECN pkts 0 in DE pkts 0 out DE pkts 0 out bcast pkts 32795 out bcast bytes 6216155
<Output Omitted>
Verifying Frame Relay Operation (cont.)
– Displays the route maps, either static or dynamic
Router#show frame-relay mapSerial0 (up): ip 10.140.2.1 dlci 120(0x78,0x1C80), dynamic, broadcast,, status defined, active
Verifying Frame Relay Operation (cont.)
– Displays LMI information
Router#show frame-relay lmi LMI Statistics for interface Serial0 (Frame Relay DTE) LMI TYPE = CISCO Invalid Unnumbered info 0 Invalid Prot Disc 0 Invalid dummy Call Ref 0 Invalid Msg Type 0 Invalid Status Message 0 Invalid Lock Shift 0 Invalid Information ID 0 Invalid Report IE Len 0 Invalid Report Request 0 Invalid Keep IE Len 0 Num Status Enq. Sent 113100 Num Status msgs Rcvd 113100 Num Update Status Rcvd 0 Num Status Timeouts 0
Verifying Frame Relay Operation (cont.)
– Displays LMI debug information
Router#debug frame-relay lmiSerial3/1(in): Status, myseq 214RT IE 1, length 1, type 0KA IE 3, length 2, yourseq 214, myseq 214PVC IE 0x7 , length 0x6 , dlci 130, status 0x2 , bw 0Serial3/1(out): StEnq, myseq 215, yourseen 214, DTE updatagramstart = 0x1959DF4, datagramsize = 13FR encap = 0xFCF1030900 75 01 01 01 03 02 D7 D6 Serial3/1(in): Status, myseq 215RT IE 1, length 1, type 1KA IE 3, length 2, yourseq 215, myseq 215Serial3/1(out): StEnq, myseq 216, yourseen 215, DTE updatagramstart = 0x1959DF4, datagramsize = 13FR encap = 0xFCF1030900 75 01 01 01 03 02 D8 D7
Verifying Frame Relay Operation (cont.)
– Clears dynamically created Frame Relay maps
Router#sh frame mapSerial0 (up): ip 10.140.2.1 dlci 120(0x78,0x1C80), dynamic, broadcast,, status defined, activeRouter#clear frame-relay-inarpRouter#sh frame mapRouter#
Selecting a Frame Relay Topology
Star (hub and spoke)
Full mesh
Partial mesh
– Broadcast traffic must be replicated for each active connection
Reachability Issues with Routing Updates
Routingupdate
A
Circuit #21
Circuit #22
Circuit #23
D
C
B
B
C
D
2
3
1
Resolving Reachability Issues
– Split horizon can cause problems in NBMA environments
– A single physical interface simulates multiple logical interfaces
– Subinterfaces can resolve split horizon issues
Subnet A
Subnet B
Subnet C
S0
PhysicalinterfaceLogical interface
S0.1S0.2S0.3
Configuring Subinterfaces–Multipoint– Subinterfaces act as default NBMA network
–Can save subnets because uses single subnet
–Good for full-mesh topology
–Point-to-point– Subinterfaces act as leased line
–Each point-to-point connection requires its own subnet
–Good for star or partial-mesh topologies
Central(config)#<Output Omitted>Central(config-if)#interface Serial0Central(config-if)#no ip addressCentral(config-if)#encapsulation frame-relay!Central(config)#interface Serial0.2 point-to-pointCentral(config-subif)#ip address 10.17.0.1 255.255.255.0Central(config-subif)#frame-relay interface-dlci 110!Central(config)#interface Serial0.3 multipointCentral(config-subif)#ip address 10.18.0.1 255.255.255.0Central(config-subif)#frame-relay interface-dlci 120Central(config-subif)#frame-relay interface-dlci 130!<Output Omitted>
Configuring Subinterfaces Example10.17.0.1S0.2-DLCI=110
10.18.0.2S0
Branch
Central
Branch
10.18.0.1S0.3-DLCI=120S0.3-DLCI=130
10.18.0.3S0
120
130
10.17.0.2S0
Branch110
56 kbpsT1
Branch office Central site
Frame Relay cloud
Frame Relay Traffic Shaping Overview
CIR=32 kbps
Frame Relay Traffic Flow Terminology
I am congested.
T1
Bc=64 kbps
Local accessloop=T1
Local accessloop=64 kbps
Traffic flow
FECN
BECN
Frame Relay Traffic Flow Terminology (cont.)
Time (T=Bc/CIR)
Discard
Bc
Bc + Be
Access rate
Discard frame
DE=1
DE=0CIR
Frame 1 Frame 2 Frame 3 Frame 4
Bit
s
56 kbps T1
Branchoffice
Frame Relaycloud
Bottleneck Centralsite
I need to reduce the pace at which
I send packets.
Why Use Traffic Shaping over Frame Relay?
56 kbps T1
Frame Relay cloud
Why use Traffic Shaping over Frame Relay? (cont.)
Branchoffice
Centralsite
BECN
– Enters map class configuration mode so you can define a map class
Router(config)#map-class frame-relay map-class-name
Configuring Frame Relay Traffic Shaping—Steps 1 and 2
Configuring Frame Relay Traffic Shaping—Step 2 (cont.)
– Defines the average and peak rates
or
Router(config-map-class)#frame-relay traffic-rate average [peak]
– Specifies that the router fluctuates the sending rate based on the BECNs received
Router(config-map-class)#frame-relay adaptive-shaping becn
– Specifies a custom queue list
or
Router(config-map-class)#frame-relay custom-queue-list number
– Specifies a priority group
Router(config-map-class)#frame-relay priority-group number
or
Configuring Frame Relay Traffic Shaping—Step 2 (cont.)
– Enables Frame Relay on an interface
Router(config-if)#encapsulation frame-relay
Router(config-if)#frame-relay traffic-shaping
– Enables Frame Relay traffic shaping on an interface
Router(config-if)#frame-relay class map-class-name
– Maps the map class to virtual circuits on the interface
Step 3
Step 4
Step 5
Configuring Frame Relay Traffic Shaping—Steps 3 to 5
Traffic Shaping Rate Enforcement Example
T1
Frame Relay cloud
9.6 kbps
9.6 kbpsBranch office
Central site
I need to send packets at the CIR
for each VC.
CIR=9.6 kbps
CIR=9.6 kbps
Branch office
Egress point
Configuring Traffic Shaping Rate Enforcement Example
Central(config)#interface Serial2Central(config-if)#no ip address Central(config-if)#encapsulation frame-relayCentral(config-if)#frame-relay traffic-shapingCentral(config-if)#frame-relay class branch!…!Central(config)#map-class frame-relay branchCentral(config-map-class)#frame-relay traffic-rate 9600 18000
T1
Frame Relay cloud
Branch office
Central site
Branch office
I need to adjust my transmit speed
because of BECNs.
Traffic Shaping BECN Support Example
56 kbps T1
Frame Relay cloud
Branchoffice
Centralsite
BECNBECN
BECN
Configuring Traffic Shaping BECN Support Example
Central(config)#interface serial 0Central(config-if)#no ip address Central(config-if)#encapsulation frame-relayCentral(config-if)#frame-relay traffic-shapingCentral(config-if)#frame-relay class becnnotify!…!Central(config)#map-class frame-relay becnnotifyCentral(config-map-class)#frame-relay adaptive-shaping becn
56 kbps T1
Frame Relay cloud
Branchoffice
Centralsite
BECN
BECN
interface Serial0 no ip address encapsulation frame-relay frame-relay lmi-type ansi frame-relay traffic-shaping frame-relay class slow_vcs!interface Serial0.1 point-to-point ip address 10.128.30.1 255.255.255.248 ip ospf cost 200 bandwidth 10 frame-relay interface-dlci 101!interface Serial0.2 point-to-point ip address 10.128.30.9 255.255.255.248 ip ospf cost 400 bandwidth 10 frame-relay interface-dlci 102 class fast_vcs! interface Serial0.3 point-to-point ip address 10.128.30.17 255.255.255.248 ip ospf cost 200 bandwidth 10 frame-relay interface-dlci 103
!map-class frame-relay slow_vcs frame-relay traffic-rate 4800 9600 frame-relay custom-queue-list 1!map-class frame-relay fast_vcs frame-relay traffic-rate 16000 64000 frame-relay priority-group 2!access-list 100 permit tcp any any eq 2065access-list 115 permit tcp any any eq 256!priority-list 2 protocol decnet highpriority-list 2 protocol ip normalpriority-list 2 default medium!queue-list 1 protocol ip 1 list 100queue-list 1 protocol ip 2 list 115queue-list 1 default 3queue-list 1 queue 1 byte-count 1600 limit 200queue-list 1 queue 2 byte-count 600 limit 200queue-list 1 queue 3 byte-count 500 limit 200
Configuring Traffic Shaping Queuing Example
Verifying Frame Relay Traffic Shaping
CentralA#sh frame-relay pvc
PVC Statistics for interface Serial3/1 (Frame Relay DTE)
DLCI = 110, DLCI USAGE = LOCAL, PVC STATUS = ACTIVE, INTERFACE = Serial3/1.1
input pkts 35 output pkts 40 in bytes 4324 out bytes 6684 dropped pkts 0 in FECN pkts 0 in BECN pkts 0 out FECN pkts 0 out BECN pkts 0 in DE pkts 0 out DE pkts 0 out bcast pkts 25 out bcast bytes 5124 Shaping adapts to BECN pvc create time 00:12:55, last time pvc status changed 00:12:55
Laboratory Exercise: Visual Objective
Cisco 3640Central site
Frame Relay
Frame Relay
S3/1
BE
CN
Branch officeCisco 1600
S0 Frame Relayservice
Summary
– Configure Frame Relay
– Configure Frame Relay subinterfaces
– Configure Frame Relay traffic shaping
– Verify Frame Relay operation
After completing this chapter, you shouldbe able to perform the following tasks:
– What is a DLCI and how is it used to route Frame Relay traffic?
– Why would you use Frame Relay subinterfaces?
– List and describe three Frame Relay traffic shaping features.
Review Questions