Open Shortest Path First OSPF (Part 2) George Macri E-mail: [email protected]@homemail.com 6...
-
Upload
earl-barrett -
Category
Documents
-
view
216 -
download
0
Transcript of Open Shortest Path First OSPF (Part 2) George Macri E-mail: [email protected]@homemail.com 6...
Open Shortest Path FirstOSPF
(Part 2)
George MacriE-mail: [email protected]
6th CEENET Workshop, Budapest 2000
Interior IP Routing Protocols
Routing Information Protocol (RIP)
Interior Gateway RoutingProtocol (IGRP)
Open Shortest Path First (OSPF) Protocol
Enhanced IGRP (EIGRP)
Routing Information Protocol (RIP)
Interior Gateway RoutingProtocol (IGRP)
Open Shortest Path First (OSPF) Protocol
Enhanced IGRP (EIGRP)
Application
Transport
Internet
Network Interface
Hardware
IP Routing Configuration Tasks
Network 172.30.0.0
IGRP,RIP
• Global configuration
Select routing protocol(s)
Network 160.89.0.0
Network 172.16.0.0
Specify network(s)
IP Routing Configuration Tasks
Network 172.30.0.0
Network 160.89.0.0
IGRP,RIP
Network 172.16.0.0
RIP
RIP
• Global configuration
Select routing protocol(s)
Specify network(s)
• Interface configuration
Verify address/subnet mask
• Defines an IP routing protocol
router protocol [ keyword ]
Router (config) #
Dynamic Routing Configuration
network network-numberRouter (config-router) #
• The network subcommand is a mandatory configuration command for each IP routing process
Router (config) #
router ospf process-id
OSPF Basic Configuration Commands
• Enables an OSPF routing process
Router (config-router) #
network address wildcard-mask area area-id
• Selects participating interfaces
OSPF Basic Configuration Example
router ospf 63network 172.16.5.3 0.0.0.0. area 1network 172.16.0.0 0.0.255.255 area 0network 192.168.10.5 0.0.0.0 area 1
Area 0
Area 1
172.16.1.1
172.16.3.2
192.168.10.5 E1
T0
E0
172.16.5.3E2
TokenRing
• Minimizes routing table entries
• Localizes impact of a topology change
OSPF Route Summarization
Area 0 Backbone
ABRs
Area 1
Summarization
xx
O 131.108.4.0 255.255.252.0O 131.108.8.0 255.255.252.0O 131.108.12.0 255.255.252.0O 131.108.16.0 255.255.252.0O 131.108.20.0 255.255.252.0O 131.108.24.0 255.255.252.0O 131.108.28.0 255.255.252.0
Routing Table for B
Routing Table for C
IA 131.108.16.0 255.255.240.0
• Inter-area (IA) summary link carries mask
• One entry can represent several subnets
Route Summarization (cont.)
Area 1 Area 0ABR
Summarization
BA C
Summary Route
131.108.12.0 255.255.240.0Mask = 240Address = 12
Existing Subnet
131.108.12.0 255.255.252.0
Mask = 252Address = 12
1111 11 000000 11 00
1111 00000000 1100
Valid 3rd Subnet
Invalid Subnet Zero
• Some addresses may need reallocating
Route Summarization Issue
Router (config-router) #
area area-id range address mask
Route Summarization Commands
• Consolidates IA routes on an ABR
Router (config-router) #
summary-address address mask
• Consolidates external routes on an ASBR
Route Summarization Example
R2
R2#
router ospf 100
network 172.16.64.0 0.0.31.255 area 2
network 172.16.96.0 0.0.31.255 area 0
area 0 range 172.16.96.0 255.255.224.0
area 2 range 172.16.64.0 255.255.224.0
R1#
router ospf 100
network 172.16.32.0 0.0.31.255 area 1
network 172.16.96.0 0.0.31.255 area 0
area 0 range 172.16.96.0 255.255.224.0
area 1 range 172.16.32.0 255.255.224.0
172.16.64.0 - 172.16.95.0
255.255.255.0
Area 2
172.16.64.1
172.16.96.0 - 172.16.127.0
255.255.255.0 172.16.127.1172.16.96.1
172.16.32.0 - 172.16.63.0
255.255.255.0
Area 1
172.16.32.1
Interface Addresses(255.255.255.0 mask)
Interface Addresses(255.255.255.0 mask)
R1 R2
Area 0
• Allows routing-information exchange between OSPF and other routing protocols
OSPF Route Redistribution
OSPF
RIPIGRPEnhanced IGRPIS-IS
BGPEGP
Router (config-router) #
redistribute protocol [ process-id ] [ metric value ] [ metric-type value ] [ subnets ]
OSPF Redistribution Command
• Redistributes routes from OSPF into other routing protocols (and vice versa)
OSPF Redistribution Example 1
Redistribution between RIP and OSPF
RIP
172.16.9.1
172.16.8.1
172.16.62.1
172.16.63.1
OSPF Area 0
S0
S1R1
OSPF Redistribution Example 1OSPF Redistribution Example 1
router ospf 109network 172.16.62.0 0.0.0.255 area 0network 172.16.63.0 0.0.0.255 area 0redistribute rip subnets metric-type 1 metric 20
router ripnetwork 172.16.0.0passive-interface serial 0passive-interface serial 1default-metric 10redistribute ospf 109 match internal external 1 external 2
Redistribution Example 2
"Back door" creates potential loopRIP
RIP
172.16.9.1
172.16.8.1
OSPF Area 0
RIP
Avoiding Loops
R2
R3
R2
R1
Redistribution Example 2 contRedistribution Example 2 cont
router ospf 109network 172.16.62.0 0.0.0.255 area 0network 172.16.63.0 0.0.0.255 area 0redistribute rip subnets metric-type 1 metric 20 distribute-list 11 out rip
access-list 11 permit 172.16.8.0 0.0.7.255
• Verifies interfaces are in correct areas
Router# show ip ospf interface e 0Ethernet0 is up, line protocol is up
Internet Address 203.250.14.1 255.255.255.0, Area 0.0.0.0 Process ID 10, Router ID 203.250.13.41, Network Type BROADCAST,
Cost: 10 Transmit Delay is 1 sec, State BDR, Priority 1 Designated Router (ID) 203.250.15.1, Interface address 203.250.14.2 Backup Designated router (ID) 203.250.13.41, Interface address
203.250.14.1 Timer intervals configured, Hello 10, Dead 40, Wait 40, Retransmit 5 Hello due in 0:00:02 Neighbor Count is 3, Adjacent neighbor count is 3 Adjacent with neighbor 203.250.15.1 (Designated Router)Loopback0 is up, line protocol is up Internet Address 203.250.13.41 255.255.255.255, Area 1 Process ID 10, Router ID 203.250.13.41, Network Type LOOPBACK, Cost: 1 Loopback interface is treated as a stub Host
show ip ospf interface Command
• Displays general information about the OSPF routing process
Router # show ip ospfRouting Process "ospf 1" with ID 2.2.2.2Supports only single TOS (TOS0) routesSPF schedule delay 5 secs, Hold time between two SPFs 10 secsNumber of areas in this router is 1
Area 23Number of interfaces in this area is 3Area has no authenticationSPF algorithm executed 19 timesArea ranges areLink State Update Interval is 0:30:00 and due in 0:04:55Link State Age Interval is 0:20:00 and due in 0:04:55
show ip ospf Command
Router# show ip ospf database
OSPF Router with ID (3.3.3.3) (Process ID 1)
Router Link States (Area 23)
Link ID ADV Router
Age Seq#
3.3.3.3 3.3.3.3 78 0x800000324.4.4.4 4.4.4.4 1691 0x8000002B 12.2.2.2 2.2.2.2 1693 0x80000030
Checksum
0x80B60xE11C0xE35E
Link count
5
51.1.1.1 1.1.1.1 1696 0x80000026 0x80A1 1
Net Link States (Area 23)
Link ID ADV Router Age Seq# Checksum150.100.4.2 4.4.4.4 1691 0x80000030 0x2FCE150.100.1.2 2.2.2.2 1693 0x80000024 0xFB29
show ip ospf database Command
Router> show ip protocolRouting Protocol is “ospf 300”
Sending updates every 0 secondsInvalid after 0 seconds, hold down 0, flushed after 0Outgoing update filter list for all interfaces is not setIncoming update filter list for all interfaces is not setRedistributing: ospf 300
Routing for Networks:183.8.0.0/0.0.255.255144.253.100.0/0.0.0.255
Routing Information Sources:Gateway Distance Last Update144.253.100.0 110 6d21183.8.128.12 110 0:17:32192.3.63.192 110 0:17:33192.3.63.194 110 0:17:33183.8.128.0 110 6d21153.50.192.0 110 0:17:33153.50.193.1 110 0:17:33183.8.64.130 110 6d19183.8.64.128 110 0:17:33133.3.4.0 110 0:17:33131.108.100.3 110 0:17:33
Distance: (default is 110)- - More - -
show ip protocol Command