Rules based on RFC1812 with industry extensions:
1. If route is not in table, add it.
2. If route is more specific than one in the table, add it, keeping the old
one.
3. If the routes are of equal length, install the one with highest
preference
(GateD, Juniper, Bay) or lowest AD (Cisco). Replace any route from
another
source.
On Cisco, if the routes are from a static source and have the same AD,
add the new route to the table (up to maximum-paths) and mark it
eligible
for load-sharing.
4. If the routes are of the same AD/preference, and the protocol has a
metric,
replace the one in the table if the new one has a lower metric. If the
metrics are the same, add the route and make it eligible for
load-sharing.
>I believe its distance to determine the protocol, then the longest
>match after that...
>
>Larry Letterman
>Cisco Systems
>[EMAIL PROTECTED]
>----- Original Message -----
>From: "Sean Wolfe"
>To:
>Sent: Tuesday, April 16, 2002 7:08 PM
>Subject: longest match vs. other metrics [7:41692]
>
>
>> Quick question, hope it's not too trivial:
>>
>> When a router decides to forward a packet based on the longest match
>> principle, does this supersede other factors?
>>
>> For example, if there is a route to network A via EIGRP, but a more
>specific
>> route available via OSPF, does it choose OSPF because of longest match,
or
>> EIGRP because of lower administrative distance (90 vs. 110)?
>>
>> Thanks folks, fun reading your posts as always. Wish me luck as I take
>BCSN
>> this week. -Sean.
Message Posted at:
http://www.groupstudy.com/form/read.php?f=7&i=41711&t=41692
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