From: Howard C. Berkowitz (hcb@gettcomm.com)
Date: Fri Oct 03 2003 - 14:46:26 GMT-3
At 3:55 PM +0100 10/3/03, Ken.Farrington@barclayscapital.com wrote:
>Many thx for this guys
>
>"By default, Open Shortest Path First (OSPF) supports four equal cost paths
>to a destination. In this scenario Router B is configured with maximum-paths
>equal to one. Hence Router B will choose only one path amongst the possible
>equal paths based on which one it received first. Router B starts by
>selecting Serial 2 as the single path to the 194.168.20.0 network. "
I don't believe this to be true under all circumstances. It is true
if the paths are intra-area or inter-area, but if you dig into the
internal data structures, it won't do it for externals. This actually
is reasonable given several theoretical methods for preventing loop
formation.
>
>As per the statment above, we can assume that EIGRP is the same and any
>other routing protocol.
>
>Correct?
With reservations about externals, yes. Also, remember that a
routing protocol only can offer eligible equal cost paths to the
routing table installation process. It is the latter process that
actually implements load-shared forwarding.
>
>-----Original Message-----
>From: Micah Byers [mailto:mbyers@gramtel.net]
>Sent: 03 October 2003 15:31
>To: Ken.Farrington@barclayscapital.com; ccielab@groupstudy.com
>Subject: RE: Maximum-Paths 4 (Router has 6 paths - what 4 paths does the
>routi ng table choose)
>
>
>Ken,
>
> Good question. The paths that will be selected are those which are
>received first.
>
>http://www.cisco.com/en/US/tech/tk827/tk831/technologies_tech_note09186a0080
>094806.shtml
>
>
>
>Micah J. Byers- CCIE #12079
>Senior Network Engineer
>Hypervine
>mbyers@hypervine.net
>P: 574-472-4726
>F: 574-472-0904
>
>-----Original Message-----
>From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
>Ken.Farrington@barclayscapital.com
>Sent: Friday, October 03, 2003 3:51 AM
>To: ccielab@groupstudy.com
>
>Work question here. - sorry if not appropriate to the forum.
>
>If you have 6 equal cost paths to a destination, and you have in IGRP/EIGRP
>or OSPF the default max-paths set to 4.
>
>Which 4 paths does the routing table pick to be entered into the routing
>table.
>
>Is it based on neighbour IP?
>
>Many thx
>Ken
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