LAN and WAN Technologies Networking/internetworking Hardware ...
-
Upload
networkingcentral -
Category
Documents
-
view
9.406 -
download
2
Transcript of LAN and WAN Technologies Networking/internetworking Hardware ...
LAN and WAN Technologies
Networking/internetworking Hardware and Software
Preliminaries in Network Design
nd eie507 03/04 1
LAN and WAN Technologies
LAN and WAN Technologies
Networking and internetworking
• Networking
connecting of a computer or device (station, host, end-system,
end-node) to another
• Internetworking
connecting of a network to another
• Protocol
a set of rules that controls how communications take place
• Local Area Network (LAN):
in general connecting stations geographically close to each other,
e.g., within a building
nd eie507 03/04 2
LAN and WAN Technologies
• Wide Area Network (WAN):
connecting multiple LANs
Remark: Speed cannot be used to differentiate LANs from WANs any
more. Traditionally, WANs were slower in speed than LANs. WANs
can be faster than LANs nowadays however – the maximum speed of
a WAN can be higher than that of a LAN.
nd eie507 03/04 3
LAN and WAN Technologies
Internetworking Technology��
��The OSI Model
• developed by the International Organization for Standardization
(ISO)
• Seven layers: physical, data link, network, transport, session, pre-
sentation, and application layers
– Physical
defines the electrical, mechanical, procedural, and functional spe-
cifications – transmission of (raw) signals (bits)
– Data link
provides a reliable transit of data across a physical link, concerned
with physical addressing, network topology, line discipline, error
notification, the ordered delivery of frames, and flow control.
nd eie507 03/04 4
LAN and WAN Technologies
– Network layer
It provides connectivity and path selection between two end
systems. Routing occurs at this layer.
Protocols examples
• TCP/IP
– Layer 3 and above protocol
– can be implemented on a LAN or WAN
• LAN Protocols
– layers 1 and 2 of the OSI model
– Ethernet (derivatives: Fast Ethernet, Gigabit Ethernet and 10
Gigabit Ethernet)
nd eie507 03/04 5
LAN and WAN Technologies
– Token ring
– FDDI (Fiber Distributed Data Interface)
• WAN Protocols
– ATM
– X.25
– Frame relay
��
��WAN Protocols
operates at layers 1 and 2 of the OSI model
• High Level Data Link Control (HDLC)
HDLC is the primary protocol used for point-to-point serial lines
• Frame Relay
– a packet-switched service
nd eie507 03/04 6
LAN and WAN Technologies
– permanent virtual circuits (PVCs)
– switched virtual circuits (SVCs)
– lower rate, not so expensive
• Asynchronous Transfer Mode (ATM)
– packet-switched network
– packets are of fixed length, called cells of 53 bytes long
– can carry both voice and data
– in general expensive
• Integrated Services Digital Network (ISDN)
a circuit-switched service digital dial-up, use the existing telephone
local loop circuits offers two simultaneous connections (each of 64
kbps)
• Digital Subscriber Line (DSL)/Cable modem
rate of a few Mbps
nd eie507 03/04 7
LAN and WAN Technologies
Routed versus Routing Protocols
• A routed protocol contains network, Layer 3, and addressing infor-
mation
enables the protocol to be directed from one network to another.
• A routing protocol provides support to a routed protocol by sharing
routing information
distributed among routers.
Routed protocols Routing Protocols
TCP/IP RIP, OSPF, EIGRP,BGP
IPX/SPX RIP, EIGRP, NLSP
AppleTalk RTMP, EIGRP
nd eie507 03/04 8
LAN and WAN Technologies
��
��Protocols in other layers
Transmission Control Protocol/Internet Protocol (TCP/IP)
• most commonly used protocol
• used on the Internet exclusively
TCP/IP protocols does not quite follow the OSI model.
nd eie507 03/04 9
LAN and WAN Technologies
OSI model TCP/IP
Application FTP, HTTP, Telnet
Presentation
Session
Transport TCP, UDP
Network IP, ARP, ICMP
Data link LAN/WAN Protocols
Physical Physical
• The Internet Protocol IP
provides a best-effort, connectionless packet delivery service
• The Address Resolution Protocol (ARP)
used to discover the link address (e.g., IP address), or media access
control (MAC, also known as hardware address) (e.g. Ethernet
address)
nd eie507 03/04 10
LAN and WAN Technologies
• The Internet Control Message Protocol (ICMP)
– used to report network errors, refer to the ping command.
TCP/IP Transport layer
• the basis for all user data traffic
• TCP
TCP is a connection-oriented.
• UDP
UDP is a connectionless protocol.
nd eie507 03/04 11
LAN and WAN Technologies
TCP/IP application layer
• File Transfer Protocol (FTP)
to transfer files between hosts
• Hypertext Transfer Protocol (HTTP)
web page access
• Telnet
a terminal emulation application
TCP/IP Routing Protocols
• RIP
– the first TCP/IP routing protocol
nd eie507 03/04 12
LAN and WAN Technologies
– distance vector protocol, uses a hop count metric
– at most 15 hops
– does not support multiple subnet masks
– RIP version 2
∗ enables multiple subnet masks, 255 hops
∗ a classless protocol
• Interior Gateway Routing Protocol (IGRP)
– Cisco proprietary
– distance vector routing protocol
– The Enhanced IGRP (EIGRP)
∗ integrates several link-state
∗ capabilities with several distance vector capabilities
∗ supports multiple subnet masks and is a classless protocol
nd eie507 03/04 13
LAN and WAN Technologies
• Open Shortest Path First (OSPF)
– a link-state routing protocol
– supports multiple subnet masks
– a classless protocol
– supports an unlimited number of hops
• The Border Gateway Protocol (BGP)
– the routing protocol of the Internet
– performs routing between multiple autonomous systems (ASs)
– also a classless protocol
nd eie507 03/04 14
LAN and WAN Technologies
��
��IP Addressing
• An IP address is composed of 32 bits.
• can be represented in binary dotted or decimal dotted
– artificially inserting three dots to divide the 32 bits into four
groups, each of 8 bits
• divided to a network portion and a host portion
• Devices on the same LAN will have the same network portion but
a unique host portion.
To determine the network portion, a mask is used.
nd eie507 03/04 15
LAN and WAN Technologies
��
��Network (subnet) mask
• A network mask (32 bits) is used to determine the network portion
• format: all 1’s followed by all 0’s
• The network is always represented by a binary 1 in the subnet mask.
– Classical (classful) IP divides the address space into Class A, B,
and C networks by dividing the 32-bit address on 8-bit (byte)
boundaries.
– Classless IP divides, or subnets, these classic networks into smaller
networks by breaking them on bit boundaries.
• Subnetting:
borrows bits from the host portion
nd eie507 03/04 16
LAN and WAN Technologies
Internetwork Packet Exchange/Sequenced Packet Exchange
(IPX/SPX) protocol suite
• Novell NetWare
AppleTalk protocol
• Apple Computer Inc.
nd eie507 03/04 17
LAN and WAN Technologies
Network Topology Overview
• Ethernet
• Ring
nd eie507 03/04 18
LAN and WAN Technologies
Basic Ethernet
• developed in the late 70s at the Palo Alto Research Center (PARC)
of Xerox
• Variation: 10 Gigabit, Gigabit and Fast Ethernet
• Ethernet is simply a group of devices that access a common shared
medium, a cable, to exchange information.
– Operations: Carrier Sense Multiple Access and Collision Detection
(CSMA/CD) – collisions deterorate throughput performance
– A broadcast network: collison domain and broadcast domain
• Network equipment for an Ethernet network: hubs, bridges/switches,
and routers.
nd eie507 03/04 19
LAN and WAN Technologies
Ethernet types
• denoted as e.g., 10BaseT, Speed-Signaling-Media
• Speed (the first part): the speed in Mbps
• Signaling: the signaling type
Base: baseband signaling
• Media: the media type
Media type:
• T: unshielded twisted pair (UTP) cable
The maximum transmission distance is 100 meters
• F: fiber-optic cable.
nd eie507 03/04 20
LAN and WAN Technologies
The maximum transmission distance depends on the specific sub-
type. e.g., for FB, the maximum transmission distance is 2000
meters.
Hubs
• Networking equipment, also known as repeaters since they just
repeat what they receive
• can be used to extend networks
• may not have too many hubs
• not suitable for large and complex networks
– Maximum 4 repeaters between source and destination (Ethernet)
nd eie507 03/04 21
LAN and WAN Technologies
Bridges/Switches
• Networking equipment that operate at layer 2 of the OSI model
• segment traffic based on layer-2 or MAC addresses
• to isolate user traffic
• To reduce the number of users in a collision domain
– Collision domain:
the same shared media
nd eie507 03/04 22
LAN and WAN Technologies
• Bridges segment a network into several collision domains
• The collision domains are still considered the same LAN
• The use of more repeaters (for Ethernet) is made possible
��
��Routers
• Segment broadcast domains (the whole LAN network)
• Routers will never propagate a broadcast.
nd eie507 03/04 23
LAN and WAN Technologies
• A router is also the boundary of a LAN.
• Connects two LANs or connects a LAN with a WAN
• Operates at layer 3 of the OSI model
• more complex and expensive
• require more configuration
Routers base their decisions on network and sub-network addresses. A
subnet mask is used to extract the network address. For example (IP)
nd eie507 03/04 24
LAN and WAN Technologies
• host address 158.132.148.222 AND subnet mask 255.255.254.0 gi-
ves net address 158.132.148.0
• host address 158.132.149.222 AND subnet mask 255.255.254.0 gi-
ves net address 158.132.148.0
Routing protocols classification
• distance vector
• link state
Distance Vector Link StateRIP OSPF
IGRP NLSP
IPX RIP IS-IS
nd eie507 03/04 25
LAN and WAN Technologies
NLSP: the NetWare Link-Service Protocol, similar to OSPF and
Intermediate System-to-Intermediate System (IS-IS), developed to
overcome many of the issues associated with IPX RIP.
Seven layer model and networking equipment
Commonly used symbols
nd eie507 03/04 26
LAN and WAN Technologies
Ring Topology
Stations are (logically) connected in a ring topology.
Physically, stations are connected in a star topology. (Remarks: stations
in an Ethernet are connected in a star topology.)
Bridges, switches, and routers behave almost identically to their Ether-
net counterparts.��
��Fiber Distributed Data Interface (FDDI)
• 100 Mbps
• token-passing LAN technology
• dual fiber-optic rings
• often used as a high-speed backbone.
nd eie507 03/04 27
Networking/internetworking Hardware and Software
Networking/internetworking Hardware and Software
LAN to LAN/WAN Routers
LAN Hubs, bridges, switches, (switch-routers)
WAN to LAN Firewall, network address translation (NAT)
��
��Routers
• small-office
inexpensive, does not support FDDI and ATM
Example: Cisco 2500 series
(fixed LAN ports, 2 WAN interface cards (WICs))
• mid-range
Example: Cisco 4000/3600 series
three modular slots for network processing modules (NPMs);
nd eie507 03/04 28
Networking/internetworking Hardware and Software
(Each NPM holds one or more (Ethernet/ATM/DS3) ports.) A
maximum of two high-speed interfaces
• high-end routers
Examples: 7000/7500 series and the Cisco 12000 Gigabit Switch
Router (GSR) series
used at the core of your network as a backbone router or the
core of service provider and enterprise IP backbones
��
��LAN Switches
• used to connect end users to the network
• provide large quantities of ports
• Examples: Cisco 2900XL and 3500XL series, Cisco Catalyst 1900
switches
nd eie507 03/04 29
Networking/internetworking Hardware and Software
��
��Other Hardware
• ISDN/DSL routers
Example: Cisco 700 and 800 series
• Remote Access Routers
• Firewall
Example: Cisco’s PIX
• ATM switches
nd eie507 03/04 30
Networking/internetworking Hardware and Software
��
��Software
• Internetworking Operating System (IOS) Software
Example: Cisco
makes the routing decisions on a router
• The Linux OS
– the route command (for static routing)
– zebra: a set of programs that implement various routing algorithms
(e.g., RIP, OSPF)
– iptables: firewall and NAT
nd eie507 03/04 31
Preliminaries in Network Design
Preliminaries in Network Design
Related issues
• Networking technology used
• Hardware
��
��Framework Triplet (Triangle)
Media Protocols
Transport
• related to layers 2 and 3 of the OSI model
• helps identify possible solutions
– Protocol problems
nd eie507 03/04 32
Preliminaries in Network Design
– Media problems
– Transport problems
��
��Protocols problems
Examples:
• RIP cannot be used with Variable Length Subnet Masks (VLSMs)
• NETBIOS cannot be routed
��
��Media
• related to layer 2
• Example
nd eie507 03/04 33
Preliminaries in Network Design
– 10 stations to a hub in a 10 Mpsb Ethernet, maximum 1 Mbps
for each station
– 10 stations to switch in 10 Mbps Ethernet, maximum 10 Mbps
for each station
∗ microsegmenting: each station resides in their own collision
domain
• Similarly in a token ring network: a layer 2 device can reduce the
number of devices in a ring and hence reduce the waiting time.
• Media problem example in a WAN:
100Kbps of traffic cannot be transmitted on a circuit of rate 64
Kbps
nd eie507 03/04 34
Preliminaries in Network Design
��
��Transport
• Specific types of traffic cannot be carried in a network
• Example
analog (native voice) signal cannot be carried on Ethernet
• speed of the network:
use a faster network
• voice and data traffic over a WAN circuit
– ATM
– Multiprotocol label switching (MPLS)
nd eie507 03/04 35
Preliminaries in Network Design
Design Principles��
��Example: Hierarchical Design - The Three-Layer Approach
Three layers
• the core layer
provides the backbone transport services
• the distribution layer
provides policybased connectivity
• the access layer
provides end-user access to the network
nd eie507 03/04 36
Preliminaries in Network Design
Advantages
• Easier to understand
• Easier to troubleshoot
• Easier to grow
��
��The Core Layer
• the backbone of the network
• provides reliable, high-speed communications to all distribution
layers of the network
• can encompass both WAN and LAN technologies
nd eie507 03/04 37
Preliminaries in Network Design
• High reliability: crucial
• Redundancy and fault tolerance
• Adaptability
• Limited size or diameter
• Low latency and fast processing
• Manageability
��
��The Distribution Layer
• the interface between the core and the access layers
• policy-based connectivity
nd eie507 03/04 38
Preliminaries in Network Design
• implemented in routers and switches
• Route redistribution and address summarization:
various routing protocols
• Media translations
• Network Address Translation (NAT)
• QoS
• Access-list filtering: restrict any unwanted traffic
• Encryption:
not in the core layer since it will introduces latency
not in the access layer (it would imply multiple encryption processes.)
nd eie507 03/04 39
��
��The Access Layer
• provides network access for all end stations
• generally implemented with hubs and switches
• raw network connectivity
��
��Summary
• Two design fundamentals
– the framework triangle
– the three-layer hierarchy
• Fundamentals of technology and equipment
nd eie507 03/04 40