From: Paul Borghese (pborghese@groupstudy.com)
Date: Wed Nov 30 2005 - 19:30:17 GMT-3
Oops. Did not read the question close enough. That is what happens when
work gets in the way of fun :-)
If the single blacklisted neighbor is to be prevented from forming an
adjacency with any neighbor on the multi-access network, you may simply turn
on authentication.
But if the blacklisted neighbor is allowed to form an adjacency with all
other neighbors except our router, that is a slightly more difficult
problem.
Let's assume the interface is of OSPF network type "broadcast" which is the
default network type of Ethernet interfaces. One option would be to set the
priority on both routers to 0 (ip ospf priority 0 under the interface).
This would prevent either router from becoming a DR or BDR, thus they would
not form an adjacency (but may reside in the 2-way state for a period of
time).
Another option would be to set the OSPF network type to non-broadcast or
point-to-multipoint non-broadcast forcing a manual configuration of the
neighbor statements.
Take care,
Paul Borghese
-----Original Message-----
From: Mike Ollington [mailto:Mike.Ollington@uk.didata.com]
Sent: Wednesday, November 30, 2005 10:19 AM
To: Paul Borghese
Cc: ccielab@groupstudy.com
Subject: RE: Preventing an EIGRP/OSPF Neighbor Forming
Paul,
Changing those values would break all neighbours on an interface,
anything to kill just the one?
For example:
172.16.1.1
172.16.1.2
172.16.1.3 <- I temporarily want to prevent this neighbour.
172.16.1.4
Thanks,
Mike
-----Original Message-----
From: Paul Borghese [mailto:pborghese@groupstudy.com]
Sent: 30 November 2005 15:10
To: Mike Ollington
Cc: ccielab@groupstudy.com
Subject: Re: Preventing an EIGRP/OSPF Neighbor Forming
In OSPF a neighbor relationship will not be formed if any of the
following
mismatch:
hello/dead interval
area id
stub flag
authentication
subnet mask
mtu
So for example, if you change the hello interval on one side, the
neighbor
will not form. You can see this by doing a "debug ip ospf adj".
For EIGRP, you can try changing the K values or Autonomous System
number.
EIGRP will for a relationship even if the hello values do not match.
Take care,
Paul Borghese
> Hello,
>
>
>
> Hypothetical - you have an interface with many EIGRP/OSPF neighbours.
> You want to prevent one; you don't want to use an interface access
list.
>
>
>
> In BGP there is the neighbour shutdown command, PIM has a neighbour
> list. Any thing similar for OSPF or EIGRP?
>
>
>
> Thanks,
>
> Mike
>
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