CCNP ROUTE TSHOOT Lab: Redistributing RIP Into EIGRP

Here’s the topology for this EIGRP route redistribution lab.  The last octet of each router’s IP address will be the router number — R1 has 172.12.123.1 /24 on the serial network, and so forth.

Lab Topology For EIGRP RIP Route Redistribution

We’re going to perform one-way route redistribution in this lab, moving that one RIP route (10.1.1.0 /24) into EIGRP.

EIGRP requires a seed metric that’s just a tad more complex than that of RIP, and there are two different ways to define that seed metric.   We can apply a seed metric for routes from a specific source as part of the redistribute command itself, or we can use default-metric to set that value for all routes learned via redistribution.

R3(config)#router eigrp 100

R3(config-router)#no auto

R3(config-router)#?

Router configuration commands:

  address-family       Enter Address Family command mode

  auto-summary         Enable automatic network number summarization

  bfd                  BFD configuration commands

  default              Set a command to its defaults

  default-information  Control distribution of default information

  default-metric       Set metric of redistributed routes

In this lab, we’ll take the first approach, defining the five necessary metrics as we go along in the command.   Before we get started, let’s make sure R3 has that RIP route in its routing table:

R3#show ip route rip

      10.0.0.0/24 is subnetted, 1 subnets

R        10.1.1.0 [120/1] via 172.12.123.1, 00:00:23, Serial0/1/0

Thar she blows!  Let’s get that route redistributed.  I’ll use IOS Help to show you the five required values.

R3(config)#router eigrp 100

R3(config-router)#redistribute rip ?

  metric     Metric for redistributed routes

  route-map  Route map reference

  <cr>

R3(config-router)#redistribute rip metric ?

  <1-4294967295>  Bandwidth metric in Kbits per second

R3(config-router)#redistribute rip metric 1544 ?

  <0-4294967295>  EIGRP delay metric, in 10 microsecond units

R3(config-router)#redistribute rip metric 1544 10 ?

  <0-255>  EIGRP reliability metric where 255 is 100% reliable

R3(config-router)#redistribute rip metric 1544 10 255 ?

  <1-255>  EIGRP Effective bandwidth metric (Loading) where 255 is 100% loaded

R3(config-router)#redistribute rip metric 1544 10 255 1 ?

  <1-65535>  EIGRP MTU of the path

R3(config-router)#redistribute rip metric 1544 10 255 1 1544 ?

  route-map  Route map reference

  <cr>

R3(config-router)#redistribute rip metric 1544 10 255 1 1544

Previous IOS versions mentioned “IGRP” where you see “EIGRP” in IOS Help above.  That’s just an IOS quirk – don’t sweat it if you see it.   Right now, let’s have a look at the EIGRP tables on R4 and R5.

R4#show ip route eigrp 100

Codes: L - local, C - connected, S - static, R - RIP, M - mobile, B - BGP

      10.0.0.0/24 is subnetted, 1 subnets

D EX     10.1.1.0 [170/1662976] via 30.1.1.3, 00:01:25, FastEthernet0/0

      172.12.0.0/24 is subnetted, 1 subnets

D EX     172.12.123.0 [170/1662976] via 30.1.1.3, 00:01:25, FastEthernet0/0
R5#show ip route eigrp

      10.0.0.0/24 is subnetted, 1 subnets

D EX     10.1.1.0 [170/1662976] via 30.1.1.3, 00:00:26, GigabitEthernet0/0

      172.12.0.0/24 is subnetted, 1 subnets

D EX     172.12.123.0 [170/1662976] via 30.1.1.3, 00:00:26, GigabitEthernet0/0

Victory!   The routes are both marked “D EX,” indicating an EIGRP External route — in other words, a route learned via redistribution.  The AD of each route is 170, as opposed to an EIGRP Internal route (90).

We always check the point-of-redistribution router for any routing shenanigans, so let’s have a look at R2’s routing table, before and after redistribution.

Before:

R2#show ip route

      10.0.0.0/24 is subnetted, 1 subnets

R        10.1.1.0 [120/1] via 172.12.123.1, 00:00:17, Serial0/1/0

 

After:

R2#show ip route

      10.0.0.0/24 is subnetted, 1 subnets

R        10.1.1.0 [120/1] via 172.12.123.1, 00:00:26, Serial0/1/0

R2 has this route as a RIP route before and after redistribution, even though R2 hears about the route via EIGRP and RIP.  We do tend to think of EIGRP as superior to RIP, so what’s going on here?

R2 Gets Same Route From RIP and EIGRP

The EIGRP external route AD of 170 is higher than that of RIP’s 120, so the RIP route is preferred over the EIGRP external route.    That’s all there is to it. Should R2’s serial interface mysteriously go down again (heh heh heh), the EIGRP external path will be put into the routing table.

R2(config)#int serial 0/1/0

R2(config-if)#shut

R2#show ip route

      10.0.0.0/24 is subnetted, 1 subnets

D EX     10.1.1.0 [170/1662976] via 30.1.1.3, 00:00:04, FastEthernet0/0

I’ll reopen that interface, the route is again a RIP route, and we press on!

R2(config)#int serial 0/1/0

R2(config-if)#no shut

R2#show ip route

      10.0.0.0/24 is subnetted, 1 subnets

R        10.1.1.0 [120/1] via 172.12.123.1, 00:00:02, Serial0/1/0

Let’s say we want the EIGRP route to be preferred over the RIP route.  We’ll change the AD of EIGRP external routes on R2 to 119, just one less than RIP’s AD, and that should do it. This particular command requires you to enter both the internal and external AD, even if you’re just changing one.

R2(config)#router eigrp 100

R2(config-router)#distance ?

  <1-255>  Set route administrative distance

  eigrp    Set distance for internal and external routes


R2(config-router)#distance eigrp ?

  <1-255>  Distance for internal routes


R2(config-router)#distance eigrp 90 ?

  <1-255>  Distance for external routes


R2(config-router)#distance eigrp 90 119 ?

  <cr>

R2(config-router)#distance eigrp 90 119

This command will not take effect immediately.   At the very least, you have to clear your routing table.  You could tear the EIGRP adjacencies down, but we’ll just clear the routing table and see what happens.

R2#clear ip route *

%DUAL-5-NBRCHANGE: EIGRP-IPv4 100: Neighbor 30.1.1.5 (FastEthernet0/0) is down: route configuration changed

%DUAL-5-NBRCHANGE: EIGRP-IPv4 100: Neighbor 30.1.1.3 (FastEthernet0/0) is down: route configuration changed

%DUAL-5-NBRCHANGE: EIGRP-IPv4 100: Neighbor 30.1.1.4 (FastEthernet0/0) is down: route configuration changed

%DUAL-5-NBRCHANGE: EIGRP-IPv4 100: Neighbor 30.1.1.5 (FastEthernet0/0) is up: new adjacency

%DUAL-5-NBRCHANGE: EIGRP-IPv4 100: Neighbor 30.1.1.4 (FastEthernet0/0) is up: new adjacency

%DUAL-5-NBRCHANGE: EIGRP-IPv4 100: Neighbor 30.1.1.3 (FastEthernet0/0) is up: new adjacency

And that’s what happens!  The adjacencies came down due to the change in the AD.  That’s something to keep in mind when you work with this command in a production network.  In the lab, as long as the adjacencies come back up, we’re fine with the very temporary down.

Coming up next, we’ll introduce ACLs to our redistribution labs.   That’s coming up on July 26, 2018.   Right now, follow these links to learn from other labs on the site.   There’s also a huge (and free!)  CCNP ROUTE playlist on YouTube with tons of great redistribution info.

CCNP ROUTE Exam:  RIP And OSPF 2-Way Redistribution

CCNP ROUTE Exam:  Administrative Distance and Redistribution