Re: Passive or neigbour command

Thanks for clarifying Joe. I was struggling with the connection.

Charles Henson

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  |Joe Astorino <joe_astorino_at_comcast.net> |
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  |kennypual <pdaramol_at_gmail.com> |
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  |ccielab_at_groupstudy.com |
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  |06/17/2010 05:07 PM |
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  |Re: Passive or neigbour command |
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Well you are talking about two different things that can be used
simultaneously in a very specific case, which would be with RIPv2. Passive
interface by itself means one of a few different things depending on the
protocol. With RIP it simply means you receive updates but do not send
them. With EIGRP or OSPF it will essentially prohibit anything from
happening, as hello's will not be sent out and thus the adjacency's will
never come up.

The neighbor command is used with RIP, EIGRP and OSPF to unicast updates.
As I'm sure you are aware, RIPv2, EIGRP and OSPF all use multicast updates
by default. Using the neighbor command allows you to unicast updates to a
particular host.

NOW -- The confusion comes when you would use both together. This is a very
specific case usually seen with RIPv2. As I said, RIPv2 will by default
multicast updates to 224.0.0.9. When you use the neighbor command in RIPv2
BY ITSELF, it will indeed send unicast updates. Additionally, it will send
multicast updates as well. You can verify this with "debug ip rip" or
"debug ip packet". Now, if you ONLY want to unicast the updates, you need
to use the neighbor command in conjunction with passive interface. In that
one specific case the passive interface command is essentially turning off
the multicast capability.

HTH

Regards,
Joe Astorino, CCIE #24347

"He not busy being born is busy dying" -- Dylan

----- Original Message -----
From: "kennypual" <pdaramol_at_gmail.com>
To: ccielab_at_groupstudy.com
Sent: Thursday, June 17, 2010 2:16:09 PM GMT -05:00 US/Canada Eastern
Subject: Passive or neigbour command

Can someone help me with explanation of the two? What situations will you
use one or not use another.

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Received on Fri Jun 18 2010 - 07:52:39 ART