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In the previous blog, I have discussed complete insights to EIGRP and its messages and you can read the blog on our website.

Stuck in active in EIGRP

When a router notices a route failure and there is no feasible successor, that route moves in active state from passive. That route sends a query message to its neighbour, and it will wait 3 minutes for the reply. If a router does not receive a reply within the active timer, that route will consider a stuck-in-active state. If the router does not receive a reply within 3 minutes router will flap the neighborship with its neighbour.

Solution of stuck in active

Disable active timers

Router(config-router)# timers active-time disabled

Stub router

Router(config-router)# eigrp stub

Types of the table in EIGRP

1. Neighbor Table

Information about its neighbor will be available in the neighbor table.

Router# show ip eigrp neighbor

2. Topology Table

It contains all destination advertise routes by neighbor routers that come from the neighbor routing table.

Router# show ip eigrp topology

Router# show ip eigrp topology all-links

3. Routing Table

 It contains the best route to each remote network and its path is called successor. It will contain three types of routes- internal, external, summary.

Router# show ip route

Router# show ip route 2.2.2.0

Router# show ip route eigrp

Router# show ip route eigrp 100

Null 0

It is a loop avoidance mechanism entry stored in the routing table, null 0 will be created only in case of summarization(auto&manual). If any traffic goes towards null 0 then it will drop by EIGRP.

Metric value

It uses a composite metric for route selection.

  • K1*1 = Bandwidth (measured in kilobytes per second)
  • K2*0 = Load (numbers from 1 to 255)
  • K3*1 = Delay (measured in 10’s of a microsecond)
  • K4*0 = Reliability (numbers from 1 to 255, 255 is most reliable)
  • K5*0 = MTU

Serial- Bandwidth 1544kbps, delay 20,000 microseconds

Fast Ethernet- Bandwidth 100000kbps, delay 1000 microsecond

Loopback- Delay 5000 microsecond

How to change metric weights

Router(config-router)# metric weights 0 1 1 1 1 0

Passive interface

Router(config-router)# passive-interface default

Router(config-router)# passive-interface ethernet 0/0

Unequal-cost load-balancing

EIGRP automatically supports load balancing over four equal-cost routes. EIGRP supports up to 32 equal-cost paths with ios version 15.0, in the previous ios version we have 16 paths.

Offset-list

It is used for equal-cost load-balancing or path manipulation

Router(config)# access-list 1 permit 2.2.2.0 0.0.0.255

Router(config-router)# offset-list 1 in 100 (on all interface)

Router(config-router)# offset-list 1 in 100 ethernet 0/0 (for specific interface)

Router# show ip protocol (to check the offset list)

How to change the maximum path

By default, EIGRP supports equal-cost load balancing in 4 paths. We can modify it up to 32 in ios version 15.0 and above.

Router(config-router)# maximum-path 8 (1 to 32)

Here you can get more information about configuration.

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Author
Lokesh Sharma
Associate Consultant

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