Friday 21 May 2010

BSCI - EIGRP terms

Advertised Distance = Metric reported FROM a neighbor, alos known as 'Reported Distance'
Feasible Distance = The metric of the best path
Successor = Best/Primary path assed in to the routing table
Feasible Successor = Secondary/backup path retained in the topology table, must meet the 'Feasibility Condition'
Feasibility Condition = To be considered a Feasible Successor, the Advertised Distance MUST be lower than the Feasible Distance (full path) to be considered a Feasible Successor
- If the Advertised Distance is larger than the Feasible Distance then by definition the path must longer and therefore not as good.
- The Feasible Successor means that a new path can be selected with out recalculation therefore the protocol is fast

BSCI - EIGRP configuration review

Configure EIGRP:
R1(config)#router eigrp 1
R1(config-router)#no auto-summary
Where 1 = The EIGRP AS number which must match with adjacency neighbors
           no auto-summary = prevents route summarisation and advertises subnets
            Network = states which network to advertise AND which interface to advertise it out of

Verify EIGRP:
#sh ip eigrp neighbors
    -displays status of neighbor relationships

#sh ip eigrp topology
    - displays the topology of the eigrp AS
Where - P=Passive, network is available and installed in the routing table
    A = Active, network is currently unavailable and EIGRP is working to source a new route
    U = Update, network is being updated
    Q = Query, applied if an outstanding packet query exists for the network i.e. waiting for an ACK
    R = Reply, router is generating a reply for this network or waiting on an ACK to a reply packet
    SIA = Stuck-In-Active, signifies EIGRP convergence issue.
    *SIA status must be reset when one or more queries to a neighbor do not return before the Active timer expires (usually 3 minutes)

Review Documents

It's been a while since I last posted. Mainly due to personal commitments at home and work but also through a lack of inspiration.

Out of the blue I had a message for an old colleague at the weekend to say that one of my posts got him out of a fix in his new role and that made me think again.

Since my last post I've been covering Redistribution, Distribution Lists, and Route Maps. I'm also about half way through my BGP studies which on the face of it seem fine. That said I haven't got in to the fine tuning of the protocol  yet and that doesn't look pretty.

I'm intending on covering of the main configuration and verification commands of the previous topics mainly to keep them fresh in my mind as I look forward to Multicasting, IPv6 and the case studies on my BSCI Networking Academy course.