From: Bob Sinclair (bsin@xxxxxxxxx)
Date: Sat Feb 16 2002 - 18:41:06 GMT-3
Steve,
Good suggestion. My guess is mutual redistribution at two points a is very lik
ely scenario in the lab. Tried this out in my home lab using OSPF as the backbo
ne and RIP mutually redistributed at two points. Used the following command un
der OSFP on the border routers:
distance ospf external 130
Which seemed to work well in this scenario, setting ospf external routes above
RIP's 120. One might consider just lowering the RIP distance below 110, but th
is ends up making my RIP area a "transit" area for backbone traffic.
There is also the ability to set distance for particular routes from particular
route sources as follows:
distance 130 172.16.8.1 0.0.0.0 2
Where 2 is an access-list identifying the routes and 8.1 is a route source. Bu
t I think this latter approach is only good for DV protocols, including EIGRP,
since OSPF does not "get routes" from neighbors.
Thanks for the suggestion. I think I may need this later...
-Bob
----- Original Message -----
From: "Stephen Oliver" <stevie_oliver@hotmail.com>
To: <ccielab@groupstudy.com>
Sent: Saturday, February 16, 2002 1:32 PM
Subject: Routing loops.
> Would anyone like to comment on their methods of stopping routing loops when
> you have multiple mutual redistribution points in your network.
>
> I try to look at what I will be sending out to another protocol and build an
> access-list permitting these routes. I use this in a route-map with a
> permit to send the routes to another protocol and in another route-map to
> allow them to come back into the protocol they originated from but with a
> higher than default administrative distance. This way if the routes are
> coming back into the protocol the higher AD ensures if they exist already in
> say ospf they won't be used unless they disappear from OSPF.
>
> So say I send 125.0.0.0 into eigrp from ospf then at the points where I
> redistribute into OSPF I manipulate any occurance of this route to have an
> AD of say 150. If it exists in OSPF the 110 AD is chosen. If it disappears
> from OSPF and it still comes in via redistribution then it's a valid
> external source and it can still be used with the 150 AD.
>
> Anyone care to comment, criticise or add their opinions.
>
> Stephen
>
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