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Sunday, February 27, 2011

EIGRP Neighbor

EIGRP sends hello packets every 5 seconds on high bandwidth links and every 60 seconds on low bandwidth multipoint links.


Common reasons of eigrp neighbor adjacency are as followings.

  • Unidirectional link
  • Uncommon subnet, primary, and secondary address mismatch
  • Mismatched masks
  • K value mismatches
  • Mismatched AS numbers
  • Stuck in active
  • Layer 2 problem
  • Access list denying multicast packets
  • Manual change (summary router, metric change, route filter)


***For this post, we will talk about K-value mismatch****


Example

R1#show ip protocols
Routing Protocol is "eigrp 1"
  Outgoing update filter list for all interfaces is not set
  Incoming update filter list for all interfaces is not set
  Default networks flagged in outgoing updates
  Default networks accepted from incoming updates
  EIGRP metric weight K1=1, K2=0, K3=1, K4=0, K5=0
  EIGRP maximum hopcount 100
  EIGRP maximum metric variance 1
  Redistributing: eigrp 1
  EIGRP NSF-aware route hold timer is 240s
  Automatic network summarization is in effect
  Automatic address summarization:
    192.168.2.0/24 for FastEthernet0/0, Loopback0
    192.168.1.0/24 for FastEthernet0/1, Loopback0
    1.0.0.0/8 for FastEthernet0/0, FastEthernet0/1
      Summarizing with metric 128256
  Maximum path: 4
  Routing for Networks:
    1.0.0.0
    192.168.1.0
    192.168.2.0
  Routing Information Sources:
    Gateway         Distance      Last Update
    Gateway         Distance      Last Update
    (this router)         90      00:11:26
    192.168.2.2           90      00:07:45
    192.168.1.2           90      00:07:45
  Distance: internal 90 external 170


Change Metric to mismatch condition

router eigrp 1
 network 1.0.0.0
 network 192.168.1.0
 metric weights 0 1 1 1 0 0

Logging  (Neighbor relationship down)

3w2d: EIGRP: Received HELLO on Ethernet0 nbr 192.168.1.2
3w2d:   AS 100, Flags 0x0, Seq 0/0 idbQ 0/0
3w2d:        K-value mismatch
3w2d: %DUAL-5-NBRCHANGE: IP-EIGRP 100: Neighbor 192.168.1.2 (Ethernet0) is down:
 K-value mismatch

In sum, the K-value of these eigrp processes need to be matched.

Reference


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