EIGRP: Configuration and verification part1.1

*Mar  2 11:52:53.472: EIGRP: Received HELLO on Loopback1 nbr 10.1.1.1
*Mar  2 11:52:53.472:   AS 100, Flags 0x0, Seq 0/0 idbQ 0/0
*Mar  2 11:52:53.472: EIGRP: Packet from ourselves ignored

I made R1 advertise the route of the loopback1 interface, hello from loopback1 is ignored.

R1#sh ip eigrp interfaces 100
IP-EIGRP interfaces for process 100
Xmit Queue   Mean   Pacing Time   Multicast    Pending
Interface        Peers  Un/Reliable  SRTT   Un/Reliable   Flow Timer   Routes
Fa0/0              2        0/0         8       0/1           50           0
Lo1                0        0/0         0       0/1            0           0

This is to see the EIGRP interfaces with specific ASN.

R1#sh ip eigrp neighbors
IP-EIGRP neighbors for process 100
H   Address                 Interface       Hold Uptime   SRTT   RTO  Q  Seq
(sec)         (ms)       Cnt Num
1   10.0.0.3                Fa0/0             14 00:55:24   12   200  0  6
0   10.0.0.2                Fa0/0             13 00:59:16    5   200  0  9

This command is to show EIGRP neighbours. All known neighbours of the same AS will be shown here. This neighbour table is like a phone book of yours. Your friend’s contacts are in here… 😀

R2#sh ip eigrp neighbors
IP-EIGRP neighbors for process 100
H   Address                 Interface       Hold Uptime   SRTT   RTO  Q  Seq
(sec)         (ms)       Cnt Num
1   10.0.0.3                Fa0/0             13 00:57:15    9   200  0  6
0   10.0.0.1                Fa0/0             12 01:01:06 1024  5000  0  9

R3#sh ip eigrp neighbors
IP-EIGRP neighbors for process 100
H   Address                 Interface       Hold Uptime   SRTT   RTO  Q  Seq
(sec)         (ms)       Cnt Num
1   10.0.0.2                Fa0/0             14 00:59:14 1027  5000  0  9
0   10.0.0.1                Fa0/0             13 00:59:14   13   200  0  9
R3#

R3#sh ip eigrp topology
IP-EIGRP Topology Table for AS(100)/ID(10.1.3.1)
Codes: P – Passive, A – Active, U – Update, Q – Query, R – Reply,
r – reply Status, s – sia Status

P 10.1.1.0/24, 1 successors, FD is 156160
via 10.0.0.1 (156160/128256), FastEthernet0/0
P 10.0.0.0/24, 1 successors, FD is 28160
via Connected, FastEthernet0/0

This is the EIGRP topology table learned from neighbours, remember the several update exchanges in the debug output? This is not the whole picture of the actual network, this table is formed through updates of neighbours.

P 10.1.1.0/24, 1 successors, FD is 156160
via 10.0.0.1 (156160/128256), FastEthernet0/0

Look at the bold numbers, left is feasible distance, distance of R3 to the destination network, right is the advertised distance; distance of R3’s neighbour to reach the destination network.

R3#sh ip route eigrp
10.0.0.0/24 is subnetted, 3 subnets
D       10.1.1.0 [90/156160] via 10.0.0.1, 00:12:45, FastEthernet0/0

loopback1 network of R1 was advertised, hence it should be shown in the routing table of R3 as well as R2. This command specifically examines EIGRP routing table.

To show the entire routing table:

R3#sh ip route
Codes: C – connected, S – static, 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
i – IS-IS, su – IS-IS summary, 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

10.0.0.0/24 is subnetted, 3 subnets
C       10.1.3.0 is directly connected, Loopback3
D       10.1.1.0 [90/156160] via 10.0.0.1, 00:14:06, FastEthernet0/0
C       10.0.0.0 is directly connected, FastEthernet0/0

D       10.1.1.0 [90/156160] via 10.0.0.1, 00:14:06, FastEthernet0/0

D stands for DUAL, Diffusing Update ALgorithm, aka EIGRP. This algorithm computes the loop-free path to the destination.

The number 90 is the default administrative distance of EIGRP, the lower the AD the more trusted is the path. The number to the right of AD is the feasible distance (FD).

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