Cisco – EIGRP topology table – unexpected behavior

ciscoeigrp

Prepping for CCNP – In my topology the path R1 takes to a Loopback Ip is via R2 by default. My goal is to have a feasible successor route through R3. I've attached a diagram of topology.

http://imgur.com/a/6KZPz#4

Problem is: R1 only has one entry for the loopback ip of 3.3.3.3 in it's topology table. When I look at R3, it has two entries for this network, but somehow it's not sharing it..

I had planned to manipulate delay to add the FS route in R1, so I tried that on all links from R3 to the loopback (reduced delay to 10 usec), and for one update I saw R1 have both entries.. after another update though it removed it..

My understanding was that even if it wasn't a FS the topology table (using the 'detail' switch) would show all possibilities? What am I missing?

Best Answer

Try using the command

show ip eigrp topology all-links

This should allow you to view all routes including non-successor/non-feasible routes

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Cisco – OSPF LSA maximum age (max age) default value

OSPF MAXAGE is 3600 seconds (1 hour).

Quoting from RFC 2328 - OSPFv2; Appendix B "Architectural Constants"

MaxAge
    The maximum age that an LSA can attain. When an LSA's LS age
    field reaches MaxAge, it is reflooded in an attempt to flush the
    LSA from the routing domain (See Section 14). LSAs of age MaxAge
    are not used in the routing table calculation.  The value of
    MaxAge is set to 1 hour.)

Finally, a useful google query in case you're interested in how I found the first link... ospf lsa maxage

Cisco OSPF – Type 5 /32 Routes in Database but Not in Routing Table

As pointed out by DanielDib, the problem is the wrong forward address set in the type 5 LSA.

According to the Cisco documentation, the forward address is basically set, if the next hop Interface of the static route generated by RRI participates in the OSPF routing process. Further details can be found in the linked documentation.

The next-hop of the RRI static routes is set to the default gateway of the ASA interface where the crypto map is applied, in our case the outside interface pointing to the MLS. This next-hop IP is the IP of the interface of the MLS.

At the MLS, the forward address of the LSA (xx.xx.192.21) is an IP address of one of its own interfaces. As the foward address needs to be known as internal OSPF route, the route is not considered to be added to the routing table. The solution hence may be either to have a correct forward address, or to supress the forward address, if required. This question may include further details on this solution.

Best Answer

Related Solutions

Cisco – OSPF LSA maximum age (max age) default value

Cisco OSPF – Type 5 /32 Routes in Database but Not in Routing Table

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