EIGRP Stubs

Let's play EIGRP stubs today. All will know how to configure EIGRP router. It's really easy by typing two commands ; "eigrp 123" and announcing network number.

But, stub is not a familiar term and I have prepare lab for testing different terms of stub networks and how it will effect the routing.

Below is the topology picture. All are configured in my GNS3 lab with "eigrp stub" configuration. Try to test using different "eigrp stub" commands.

Download completed GNS3 file from here https://docs.google.com/leaf?id=0B889ogd4ltI2NGFiZDZmYjMtOGJlNC00YWYwLTlkYzktMzA1YzZlN2MzNmM1&hl=en&authkey=CLH03cYI

Four networks and R3 is for testing stub router.

R1 routes:


     2.0.0.0/32 is subnetted, 1 subnets
D       2.2.2.2 [90/2300416] via 10.2.3.2, 00:00:18, Serial1/0
     100.0.0.0/24 is subnetted, 1 subnets
D       100.100.100.0 [90/2174976] via 10.2.3.2, 00:00:18, Serial1/0
     3.0.0.0/32 is subnetted, 1 subnets
D       3.3.3.3 [90/2172416] via 10.2.3.2, 00:00:18, Serial1/0
     172.16.0.0/24 is subnetted, 1 subnets
C       172.16.1.0 is directly connected, FastEthernet0/1
     172.30.0.0/16 is variably subnetted, 2 subnets, 2 masks

D       172.30.0.0/21 [90/2300416] via 10.2.3.2, 00:00:18, Serial1/0

D       172.30.8.0/24 [90/2300416] via 10.2.3.2, 00:00:18, Serial1/0

     10.0.0.0/24 is subnetted, 2 subnets
D       10.2.2.0 [90/2172416] via 10.2.3.2, 00:46:33, Serial1/0
C       10.2.3.0 is directly connected, Serial1/0

Noted that there is already summary route for 172.30 networks because I did summary address injected to EIGRP for stub network testing.

The original R1 routing table will be like this.

     2.0.0.0/32 is subnetted, 1 subnets

D       2.2.2.2 [90/2300416] via 10.2.3.2, 00:00:01, Serial1/0

     100.0.0.0/24 is subnetted, 1 subnets
D       100.100.100.0 [90/2174976] via 10.2.3.2, 00:00:01, Serial1/0
     3.0.0.0/32 is subnetted, 1 subnets

D       3.3.3.3 [90/2172416] via 10.2.3.2, 00:00:01, Serial1/0

     172.16.0.0/24 is subnetted, 1 subnets
C       172.16.1.0 is directly connected, FastEthernet0/1
     172.30.0.0/24 is subnetted, 9 subnets
D       172.30.2.0 [90/2300416] via 10.2.3.2, 00:00:01, Serial1/0
D       172.30.3.0 [90/2300416] via 10.2.3.2, 00:00:01, Serial1/0
D       172.30.0.0 [90/2300416] via 10.2.3.2, 00:00:01, Serial1/0
D       172.30.1.0 [90/2300416] via 10.2.3.2, 00:00:01, Serial1/0
D       172.30.6.0 [90/2300416] via 10.2.3.2, 00:00:02, Serial1/0
D       172.30.7.0 [90/2300416] via 10.2.3.2, 00:00:02, Serial1/0
D       172.30.4.0 [90/2300416] via 10.2.3.2, 00:00:02, Serial1/0
D       172.30.5.0 [90/2300416] via 10.2.3.2, 00:00:02, Serial1/0
D       172.30.8.0 [90/2300416] via 10.2.3.2, 00:00:02, Serial1/0
     10.0.0.0/24 is subnetted, 2 subnets
D       10.2.2.0 [90/2172416] via 10.2.3.2, 00:50:14, Serial1/0
C       10.2.3.0 is directly connected, Serial1/0

---------------------------------

R2 Routes:

     2.0.0.0/32 is subnetted, 1 subnets
D       2.2.2.2 [90/156160] via 10.2.2.3, 00:00:10, FastEthernet0/1
     100.0.0.0/24 is subnetted, 1 subnets
D       100.100.100.0 [90/30720] via 10.2.2.3, 00:00:10, FastEthernet0/1
     3.0.0.0/32 is subnetted, 1 subnets
D       3.3.3.3 [90/28160] via 10.2.2.3, 00:00:10, FastEthernet0/1
     172.16.0.0/24 is subnetted, 1 subnets
D       172.16.1.0 [90/2172416] via 10.2.3.1, 00:51:16, Serial1/0
     172.30.0.0/16 is variably subnetted, 2 subnets, 2 masks
D       172.30.0.0/21 [90/156160] via 10.2.2.3, 00:00:10, FastEthernet0/1
D       172.30.8.0/24 [90/156160] via 10.2.2.3, 00:00:10, FastEthernet0/1
     10.0.0.0/24 is subnetted, 2 subnets
C       10.2.2.0 is directly connected, FastEthernet0/1
C       10.2.3.0 is directly connected, Serial1/0
---------------------------------

R3 Routes:

     2.0.0.0/32 is subnetted, 1 subnets
C       2.2.2.2 is directly connected, Loopback2
     100.0.0.0/24 is subnetted, 1 subnets
C       100.100.100.0 is directly connected, FastEthernet0/1
     3.0.0.0/32 is subnetted, 1 subnets
S       3.3.3.3 is directly connected, Null0
     172.16.0.0/24 is subnetted, 1 subnets
D       172.16.1.0 [90/2174976] via 10.2.2.1, 00:00:33, FastEthernet0/0
     172.30.0.0/16 is variably subnetted, 10 subnets, 2 masks
C       172.30.2.0/24 is directly connected, Loopback5
C       172.30.3.0/24 is directly connected, Loopback6
C       172.30.0.0/24 is directly connected, Loopback3
D       172.30.0.0/21 is a summary, 00:00:38, Null0
C       172.30.1.0/24 is directly connected, Loopback4
C       172.30.6.0/24 is directly connected, Loopback9
C       172.30.7.0/24 is directly connected, Loopback10
C       172.30.4.0/24 is directly connected, Loopback7
C       172.30.5.0/24 is directly connected, Loopback8
C       172.30.8.0/24 is directly connected, Loopback11
     10.0.0.0/24 is subnetted, 2 subnets
C       10.2.2.0 is directly connected, FastEthernet0/0
D       10.2.3.0 [90/2172416] via 10.2.2.1, 00:00:34, FastEthernet0/0
---------------------------------------------------

R4 routes:

     2.0.0.0/32 is subnetted, 1 subnets
D       2.2.2.2 [90/2302976] via 172.16.1.1, 00:01:04, FastEthernet0/0
     100.0.0.0/24 is subnetted, 1 subnets
D       100.100.100.0 [90/2177536] via 172.16.1.1, 00:01:04, FastEthernet0/0
     3.0.0.0/32 is subnetted, 1 subnets
D       3.3.3.3 [90/2174976] via 172.16.1.1, 00:01:04, FastEthernet0/0
     172.16.0.0/24 is subnetted, 1 subnets
C       172.16.1.0 is directly connected, FastEthernet0/0
     172.30.0.0/16 is variably subnetted, 2 subnets, 2 masks
D       172.30.0.0/21 [90/2302976] via 172.16.1.1, 00:01:04, FastEthernet0/0
D       172.30.8.0/24 [90/2302976] via 172.16.1.1, 00:01:04, FastEthernet0/0
     10.0.0.0/24 is subnetted, 2 subnets
D       10.2.2.0 [90/2174976] via 172.16.1.1, 00:13:42, FastEthernet0/0
D       10.2.3.0 [90/2172416] via 172.16.1.1, 00:13:42, FastEthernet0/0
-------------------------------

R5 routes:

     2.0.0.0/32 is subnetted, 1 subnets
D       2.2.2.2 [90/156160] via 100.100.100.3, 00:06:20, FastEthernet0/0
     100.0.0.0/24 is subnetted, 1 subnets
C       100.100.100.0 is directly connected, FastEthernet0/0
     3.0.0.0/32 is subnetted, 1 subnets
D       3.3.3.3 [90/28160] via 100.100.100.3, 00:06:20, FastEthernet0/0
     172.16.0.0/24 is subnetted, 1 subnets
D       172.16.1.0 [90/2177536] via 100.100.100.3, 00:01:29, FastEthernet0/0
     172.30.0.0/24 is subnetted, 9 subnets
D       172.30.2.0 [90/156160] via 100.100.100.3, 00:06:20, FastEthernet0/0
D       172.30.3.0 [90/156160] via 100.100.100.3, 00:06:20, FastEthernet0/0
D       172.30.0.0 [90/156160] via 100.100.100.3, 00:06:20, FastEthernet0/0
D       172.30.1.0 [90/156160] via 100.100.100.3, 00:06:20, FastEthernet0/0
D       172.30.6.0 [90/156160] via 100.100.100.3, 00:06:20, FastEthernet0/0
D       172.30.7.0 [90/156160] via 100.100.100.3, 00:06:20, FastEthernet0/0
D       172.30.4.0 [90/156160] via 100.100.100.3, 00:06:20, FastEthernet0/0
D       172.30.5.0 [90/156160] via 100.100.100.3, 00:06:20, FastEthernet0/0
D       172.30.8.0 [90/156160] via 100.100.100.3, 00:06:20, FastEthernet0/0
     10.0.0.0/24 is subnetted, 2 subnets
D       10.2.2.0 [90/30720] via 100.100.100.3, 00:06:20, FastEthernet0/0
D       10.2.3.0 [90/2174976] via 100.100.100.3, 00:01:30, FastEthernet0/0
---------------------------

OK, let's start play EIGRP stub routes.

(1) First, let's start with eigrp stub command in router enable mode.

(2) Type, "eigrp stub" in R3 which will be stub router.

Check in router R1's route.

     2.0.0.0/32 is subnetted, 1 subnets
D       2.2.2.2 [90/2300416] via 10.2.3.2, 00:00:14, Serial1/0
     100.0.0.0/24 is subnetted, 1 subnets
D       100.100.100.0 [90/2174976] via 10.2.3.2, 00:00:14, Serial1/0
     172.16.0.0/24 is subnetted, 1 subnets
C       172.16.1.0 is directly connected, FastEthernet0/1
     172.30.0.0/16 is variably subnetted, 2 subnets, 2 masks
D       172.30.0.0/21 [90/2300416] via 10.2.3.2, 00:00:14, Serial1/0
D       172.30.8.0/24 [90/2300416] via 10.2.3.2, 00:00:14, Serial1/0
     10.0.0.0/24 is subnetted, 2 subnets
D       10.2.2.0 [90/2172416] via 10.2.3.2, 00:56:25, Serial1/0
C       10.2.3.0 is directly connected, Serial1/0
------------------

• You can't ping to R5 (100.100.100.5) becuase of it's behind stub router
• Static route (3.3.3.3) is missing because default "eigrp stub" command means "eigrp stub connected summary"
• That's why static router is missing but strangely summary route (172.30.0.0/21) is appearing because of summary key is included by default.
• Let's try to type "eigrp stub static connected" and see in R1 routes.

--------
     2.0.0.0/32 is subnetted, 1 subnets
D       2.2.2.2 [90/2300416] via 10.2.3.2, 00:00:11, Serial1/0
     100.0.0.0/24 is subnetted, 1 subnets
D       100.100.100.0 [90/2174976] via 10.2.3.2, 00:00:11, Serial1/0
     3.0.0.0/32 is subnetted, 1 subnets
D       3.3.3.3 [90/2172416] via 10.2.3.2, 00:00:11, Serial1/0
     172.16.0.0/24 is subnetted, 1 subnets
C       172.16.1.0 is directly connected, FastEthernet0/1
     172.30.0.0/24 is subnetted, 9 subnets
D       172.30.2.0 [90/2300416] via 10.2.3.2, 00:00:11, Serial1/0
D       172.30.3.0 [90/2300416] via 10.2.3.2, 00:00:11, Serial1/0
D       172.30.0.0 [90/2300416] via 10.2.3.2, 00:00:11, Serial1/0
D       172.30.1.0 [90/2300416] via 10.2.3.2, 00:00:11, Serial1/0
D       172.30.6.0 [90/2300416] via 10.2.3.2, 00:00:12, Serial1/0
D       172.30.7.0 [90/2300416] via 10.2.3.2, 00:00:12, Serial1/0
D       172.30.4.0 [90/2300416] via 10.2.3.2, 00:00:12, Serial1/0
D       172.30.5.0 [90/2300416] via 10.2.3.2, 00:00:12, Serial1/0
D       172.30.8.0 [90/2300416] via 10.2.3.2, 00:00:12, Serial1/0
     10.0.0.0/24 is subnetted, 2 subnets
D       10.2.2.0 [90/2172416] via 10.2.3.2, 01:00:24, Serial1/0
C       10.2.3.0 is directly connected, Serial1/0
-----------

All 172.30.0.0 networks are appearing even though I summaried these.

Only one static route 3.3.3.3 is reappearing as EIGRP route.

OK, this time, try to type "eigrp stub received-only" in R3 router.

Check in R1 again.

     172.16.0.0/24 is subnetted, 1 subnets
C       172.16.1.0 is directly connected, FastEthernet0/1
     10.0.0.0/24 is subnetted, 2 subnets
D       10.2.2.0 [90/2172416] via 10.2.3.2, 01:04:54, Serial1/0
C       10.2.3.0 is directly connected, Serial1/0
------------------

All routes are gone only showing connnected routes 10.2.3.0, 172.16.1.0 and one EIGRP route

10.2.2.0 before stub router R3 appearing.

Stub router stop sending all routers and only received from others.