Cisco OSPF Route Redistribution
- Configuration Example 1: Redistributing Classful Routes into OSPF with the Default Type and Metric
- Configuration Example 2: Redistributing Classful Routes into OSPF with the Default Type and Specific Metric
- Configuration Example 3: Redistributing Classful Routes into OSPF as Type 1 Routes Using a Specific Metric
- Configuration Example 4: Redistributing Subnet Routes into OSPF as Type 1 Routes Using a Specific Metric
- Configuration Example 5: Redistributing Subnet Routes into OSPF as Type 1 Routes Using a Specific Metric and Route Tag
- Configuration Example 6: Controlling the Routes to Be Redistributed Based on IP Address
- Configuration Example 7: Modifying the Metric of Redistributed Routes Using a Route Map
- Configuration Example 8: Modifying the Metric Type of Redistributed Routes Using a Route Map
- Configuration Example 9: Modifying the Tag Value of Redistributed Routes Using a Route Map
- Configuration Example 10: Controlling Route Redistribution Based on Tag Values
- Troubleshooting
This chapter is from the book
This chapter is from the book
This chapter is from the book
14-1: redistribute routing-process process-id
14-2: redistribute routing-process process-id metric ospf-metric
14-3: redistribute routing-process process-id metric-type metric-type
14-4: redistribute routing-process process-id subnets
14-5: redistribute routing-process process-id tag tag-value
Syntax Description:
routing-process—Routing process to redistribute into OSPF. The routing process can be BGP, Connected, EGP, EIGRP, IGRP, ISIS, ISO-IGRP, Mobile, ODR, OSPF, RIP, or Static.
process-id—The process ID of the routing process (if applicable).
ospf-metric—The metric or cost to assign to the redistributed routes. If this option is not used, a default metric of 1 will be used for redistributed BGP routes and a default metric of 20 will be used for all other protocols. The range of values is 0–16,777,214.
metric-type—Routes are redistributed into OSPF as either type 1 or type 2 routes. The default is type 2.
tag-value—A 32-bit value that is attached to the redistributed routes. The route tag is not used by OSPF but can be referenced in a route map for making policy decisions. One possible use is to base the decision to redistribute a route based on the route tag(see Section 14-6). The default tag value is 0. The range of values for the tag is 0–4,294,967,295.
Purpose: To redistribute routes learned from another routing process into OSPF. Redistributed routes become OSPF external type 2 routes by default. The default cost or metric of a redistributed route is 1 for BGP and 20 for all other protocols. This command will redistribute classful routes into OSPF only if the subnets keyword is not used. There are three general types of classful routes:
A Class A address with an 8-bit subnet mask
A Class B address with a 16-bit subnet mask
A Class C address with a 24-bit subnet mask
Initial Cisco IOS Software Release: 10.0
Configuration Example 1: Redistributing Classful Routes into OSPF with the Default Type and Metric
In Figure 14-1, Router B is receiving six routes from Router C via EIGRP. Three of the EIGRP routes are classful (5.0.0.0/8, 145.5.0.0/16, 205.5.5.0/24) and three are classless (6.0.0.0/12, 146.6.0.0/20, 206.6.6.0/28). Before redistributing the EIGRP routes into OSPF on Router B, configure the routers as shown in the listing that follows.
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Figure 14-1 By Default, OSPF Will Redistribute Only Classful Routes
Router A interface Loopback0 ip address 1.1.1.1 255.255.255.255 ! interface Serial0/1 ip address 10.1.1.1 255.255.255.252 clockrate 64000 ! router ospf 1 network 10.1.1.0 0.0.0.3 area 0
Router B interface Loopback0 ip address 2.2.2.2 255.255.255.255 ! interface Serial0 ip address 10.1.1.2 255.255.255.252 ! interface Serial 1 ip address 10.1.1.5 255.255.255.252 ! router eigrp 1 network 10.0.0.0 ! router ospf 1 network 10.1.1.0 0.0.0.3 area 0
Router C interface Loopback0 ip address 3.3.3.3 255.255.255.255 ! interface Loopback1 ip address 5.5.5.5 255.0.0.0 ! interface Loopback2 ip address 6.6.6.6 255.240.0.0 ! interface Loopback3 ip address 145.5.5.5 255.255.0.0 ! interface Loopback4 ip address 146.6.6.6 255.255.240.0 ! interface Loopback5 ip address 205.5.5.5 255.255.255.0 ! interface Loopback6 ip address 206.6.6.6 255.255.255.240 ! interface Serial0 ip address 10.1.1.6 255.255.255.252 ! router eigrp 1 network 5.0.0.0 network 6.0.0.0 network 10.0.0.0 network 145.5.0.0 network 146.6.0.0 network 205.5.5.0 network 206.6.6.0 no auto-summary
Verify that Routers A and B have established an OSPF neighbor relationship.
rtrA#show ip ospf neighbor Neighbor ID Pri State Dead Time Address Interface 2.2.2.2 1 FULL/ - 00:00:36 10.1.1.2 Serial0/1
Verify that Routers B and C have formed an EIGRP neighbor relationship.
rtrB#show ip eigrp neighbors
IP-EIGRP neighbors for process 1
H Address Interface Hold Uptime SRTT RTO Q Seq
(sec) (ms) Cnt Num
0 10.1.1.6 Se1 11 00:25:42 308 2280 0 4
Verify that Router B is receiving the six EIGRP routes from Router C.
rtrB#show ip route
Codes: C - connected, S - static, I - IGRP, R - RIP, M - mobile, B - BGP
D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area
N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2
E1 - OSPF external type 1, E2 - OSPF external type 2, E - EGP
i - IS-IS, L1 - IS-IS level-1, L2 - IS-IS level-2, * - candidate default
U - per-user static route, o - ODR
Gateway of last resort is not set
2.0.0.0/32 is subnetted, 1 subnets
C 2.2.2.2 is directly connected, Loopback0
D 205.5.5.0/24 [90/40640000] via 10.1.1.6, 00:26:25, Serial1
206.6.6.0/28 is subnetted, 1 subnets
D 206.6.6.0 [90/40640000] via 10.1.1.6, 00:26:25, Serial1
D 5.0.0.0/8 [90/40640000] via 10.1.1.6, 00:26:25, Serial1
6.0.0.0/12 is subnetted, 1 subnets
D 6.0.0.0 [90/40640000] via 10.1.1.6, 00:26:25, Serial1
D 145.5.0.0/16 [90/40640000] via 10.1.1.6, 00:26:25, Serial1
10.0.0.0/30 is subnetted, 2 subnets
C 10.1.1.0 is directly connected, Serial0
C 10.1.1.4 is directly connected, Serial1
146.6.0.0/20 is subnetted, 1 subnets
D 146.6.0.0 [90/40640000] via 10.1.1.6, 00:26:27, Serial1
Modify the configuration on Router B to redistribute the classful EIGRP routes into OSPF.
router ospf 1 redistribute eigrp 1
When the command redistribute eigrp 1 is entered, the router will give you the following friendly reminder:
rtrB(config-router)#redistribute eigrp 1 % Only classful networks will be redistributed
Verification
Determine the routes that have been redistributed by examining the IP routing table on Router A.
rtrA#show ip route
Codes: C - connected, S - static, I - IGRP, R - RIP, M - mobile, B - BGP
D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area
N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2
E1 - OSPF external type 1, E2 - OSPF external type 2, E - EGP
i - IS-IS, L1 - IS-IS level-1, L2 - IS-IS level-2, ia - IS-IS inter area
* - candidate default, U - per-user static route, o - ODR
P - periodic downloaded static route
Gateway of last resort is not set
1.0.0.0/32 is subnetted, 1 subnets
C 1.1.1.1 is directly connected, Loopback0
O E2 205.5.5.0/24 [110/20] via 10.1.1.2, 00:33:23, Serial0/1
O E2 5.0.0.0/8 [110/20] via 10.1.1.2, 00:33:23, Serial0/1
O E2 145.5.0.0/16 [110/20] via 10.1.1.2, 00:33:23, Serial0/1
10.0.0.0/30 is subnetted, 1 subnets
C 10.1.1.0 is directly connected, Serial0/1
Only the EIGRP classful routes were redistributed into OSPF. As you can see in the routing table on Router A, EIGRP routes were redistributed as external type 2 with a cost or metric of 20. This information can also be found by inspecting the OSPF database on Router B.
rtrB#show ip ospf database external
OSPF Router with ID (2.2.2.2) (Process ID 1)
Type-5 AS External Link States
LS age: 410
Options: (No TOS-capability, DC)
LS Type: AS External Link
Link State ID: 5.0.0.0 (External Network Number )
Advertising Router: 2.2.2.2
LS Seq Number: 80000004
Checksum: 0x642C
Length: 36
Network Mask: /8
Metric Type: 2 (Larger than any link state path)
TOS: 0
Metric: 20
Forward Address: 0.0.0.0
External Route Tag: 0
LS age: 419
Options: (No TOS-capability, DC)
LS Type: AS External Link
Link State ID: 145.5.0.0 (External Network Number )
Advertising Router: 2.2.2.2
LS Seq Number: 80000004
Checksum: 0x5F9
Length: 36
Network Mask: /16
Metric Type: 2 (Larger than any link state path)
TOS: 0
Metric: 20
Forward Address: 0.0.0.0
External Route Tag: 0
LS age: 435
Options: (No TOS-capability, DC)
LS Type: AS External Link
Link State ID: 205.5.5.0 (External Network Number )
Advertising Router: 2.2.2.2
LS Seq Number: 80000004
Checksum: 0xBEFE
Length: 36
Network Mask: /24
Metric Type: 2 (Larger than any link state path)
TOS: 0
Metric: 20
Forward Address: 0.0.0.0
External Route Tag: 0