EIGRP Stub Configuration

ccnp-routing

Lab walkthrough of EIGRP stub routing showing how the stub connected summary and receive-only options change what routes a router advertises.

Published

Dec 13, 2017

Basic Router and EIGRP Configuration R1

hostname R1
!
interface Loopback0
 ip address 1.1.1.1 255.255.255.0
!
interface Loopback1
 ip address 11.11.11.11 255.255.255.0
!
interface GigabitEthernet0/2
 ip address 192.168.12.1 255.255.255.252
!
router eigrp R1
 !
 address-family ipv4 unicast autonomous-system 1
  !
  topology base
   redistribute connected
  exit-af-topology
  network 192.168.12.1 0.0.0.0
 exit-address-family

hostname R2
!
interface GigabitEthernet0/1
 ip address 192.168.12.2 255.255.255.252
!
interface GigabitEthernet0/3
 ip address 192.168.23.2 255.255.255.248
!
interface GigabitEthernet0/4
 ip address 192.168.24.2 255.255.255.248
!
router eigrp R2
 !
 address-family ipv4 unicast autonomous-system 1
  !
  topology base
  exit-af-topology
  network 192.168.12.2 0.0.0.0
  network 192.168.23.2 0.0.0.0
  network 192.168.24.2 0.0.0.0
 exit-address-family

!
hostname R3
!
interface Loopback0
 ip address 10.10.3.3 255.255.255.0
!
interface GigabitEthernet0/2
 ip address 192.168.23.3 255.255.255.248
!
router eigrp R3
 !
 address-family ipv4 unicast autonomous-system 1
  !
  topology base
  exit-af-topology
  network 10.10.3.3 0.0.0.0
  network 192.168.23.3 0.0.0.0
 exit-address-family

hostname R4
!
interface Loopback0
 ip address 10.10.4.4 255.255.255.0
!
interface GigabitEthernet0/2
 ip address 192.168.24.4 255.255.255.248
!
router eigrp R4
 !
 address-family ipv4 unicast autonomous-system 1
  !
  topology base
  exit-af-topology
  network 10.10.4.4 0.0.0.0
  network 192.168.24.4 0.0.0.0
 exit-address-family

Detailed neighbor information on R2:

R2#show ip eigrp neighbors detail
EIGRP-IPv4 VR(R2) Address-Family Neighbors for AS(1)
H   Address                 Interface              Hold Uptime   SRTT   RTO  Q  Seq
                                                   (sec)         (ms)       Cnt Num
0   192.168.12.1            Gi0/1                    10 00:00:38 1604  5000  0  17
   Version 20.0/2.0, Retrans: 1, Retries: 0, Prefixes: 2
   Topology-ids from peer - 0
   Topologies advertised to peer:   base

2   192.168.24.4            Gi0/4                    11 00:26:23   27   162  0  11
   Time since Restart 00:06:24
   Version 20.0/2.0, Retrans: 1, Retries: 0, Prefixes: 1
   Topology-ids from peer - 0
   Topologies advertised to peer:   base

1   192.168.23.3            Gi0/3                    10 00:27:02   22   132  0  12
   Time since Restart 00:06:24
   Version 20.0/2.0, Retrans: 1, Retries: 0, Prefixes: 1
   Topology-ids from peer - 0
   Topologies advertised to peer:   base

Max Nbrs: 0, Current Nbrs: 0

Now I am going to make R1 an eigrp stub connected summary

R1(config-router-af)#eigrp stub
*Dec 14 02:30:33.757: %DUAL-5-NBRCHANGE: EIGRP-IPv4 1: Neighbor 192.168.12.2 (GigabitEthernet0/2) is down: peer info changed
*Dec 14 02:30:34.455: %DUAL-5-NBRCHANGE: EIGRP-IPv4 1: Neighbor 192.168.12.2 (GigabitEthernet0/2) is up: new adjacency

Now let us see the result on R2

R2#show ip eigrp neighbors detail
EIGRP-IPv4 VR(R2) Address-Family Neighbors for AS(1)
H   Address                 Interface              Hold Uptime   SRTT   RTO  Q  Seq
                                                   (sec)         (ms)       Cnt Num
0   192.168.12.1            Gi0/1                    10 00:01:44 1602  5000  0  19
   Version 20.0/2.0, Retrans: 1, Retries: 0, Prefixes: 2
   Topology-ids from peer - 0
   Topologies advertised to peer:   base

   Stub Peer Advertising (CONNECTED SUMMARY ) Routes
   Suppressing queries
2   192.168.24.4            Gi0/4                    14 00:28:58   25   150  0  13
   Time since Restart 00:08:59
   Version 20.0/2.0, Retrans: 1, Retries: 0, Prefixes: 1
   Topology-ids from peer - 0
   Topologies advertised to peer:   base

1   192.168.23.3            Gi0/3                    13 00:29:37   22   132  0  14
   Time since Restart 00:08:59
   Version 20.0/2.0, Retrans: 1, Retries: 0, Prefixes: 1
   Topology-ids from peer - 0
   Topologies advertised to peer:   base

Max Nbrs: 0, Current Nbrs: 0

Let us see the routing table on R3

R3#show ip route eigrp
Gateway of last resort is not set

      1.0.0.0/24 is subnetted, 1 subnets
D EX     1.1.1.0 [170/16000] via 192.168.23.2, 00:03:36, GigabitEthernet0/2
      10.0.0.0/8 is variably subnetted, 3 subnets, 2 masks
D        10.10.4.0/24
           [90/16000] via 192.168.23.2, 00:30:57, GigabitEthernet0/2
      11.0.0.0/24 is subnetted, 1 subnets
D EX     11.11.11.0 [170/16000] via 192.168.23.2, 00:03:36, GigabitEthernet0/2
      192.168.12.0/30 is subnetted, 1 subnets
D        192.168.12.0
           [90/15360] via 192.168.23.2, 00:10:55, GigabitEthernet0/2
      192.168.24.0/29 is subnetted, 1 subnets
D        192.168.24.0
           [90/15360] via 192.168.23.2, 00:10:55, GigabitEthernet0/2

We can still see the redistributed route while R1 is stub connected, not stub redistributed. Why? Because a redistributed connected route is considered connected.

Now I am going to make R1 an eigrp stub receive-only

R1(config-router-af)#eigrp stub receive-only
*Dec 14 02:34:33.874: %DUAL-5-NBRCHANGE: EIGRP-IPv4 1: Neighbor 192.168.12.2 (GigabitEthernet0/2) is down: peer info changed
*Dec 14 02:34:37.520: %DUAL-5-NBRCHANGE: EIGRP-IPv4 1: Neighbor 192.168.12.2 (GigabitEthernet0/2) is up: new adjacency

Now let us see the results in R2 and R3

R2#show ip eigrp neighbors detail
EIGRP-IPv4 VR(R2) Address-Family Neighbors for AS(1)
H   Address                 Interface              Hold Uptime   SRTT   RTO  Q  Seq
                                                   (sec)         (ms)       Cnt Num
0   192.168.12.1            Gi0/1                    13 00:03:44    3   100  0  21
   Version 20.0/2.0, Retrans: 0, Retries: 0
   Topology-ids from peer - 0
   Topologies advertised to peer:   base

   Receive-Only Peer Advertising (No) Routes
   Suppressing queries
2   192.168.24.4            Gi0/4                    12 00:35:00   24   144  0  14
   Time since Restart 00:15:01
   Version 20.0/2.0, Retrans: 1, Retries: 0, Prefixes: 1
   Topology-ids from peer - 0
   Topologies advertised to peer:   base

1   192.168.23.3            Gi0/3                    12 00:35:39   20   120  0  15
   Time since Restart 00:15:01
   Version 20.0/2.0, Retrans: 1, Retries: 0, Prefixes: 1
   Topology-ids from peer - 0
   Topologies advertised to peer:   base

Max Nbrs: 0, Current Nbrs: 0

R3#show ip route eigrp
Gateway of last resort is not set

      10.0.0.0/8 is variably subnetted, 3 subnets, 2 masks
D        10.10.4.0/24
           [90/16000] via 192.168.23.2, 00:31:26, GigabitEthernet0/2
      192.168.12.0/30 is subnetted, 1 subnets
D        192.168.12.0
           [90/15360] via 192.168.23.2, 00:11:24, GigabitEthernet0/2
      192.168.24.0/29 is subnetted, 1 subnets
D        192.168.24.0
           [90/15360] via 192.168.23.2, 00:11:24, GigabitEthernet0/2