From: Brian McGahan (bmcgahan@internetworkexpert.com)
Date: Thu Jul 06 2006 - 14:13:34 ART
Triggered extensions to RIP are not a Cisco specific feature;
they are defined in RFC 2091.
http://www.internetworkexpert.com/rfc/index.php?rfc=2091
If you read through the RFC and tested the behavior you would
see that your explanation is not correct.
Routes in the RIP database learned on an interface running
triggered extensions behave like DNA LSAs in the OSPF database. In
other words the invalid timer does not apply to them. Instead RIP
relies on the point-to-point nature of the WAN link to invalidate
installed updates when the link goes down.
As Brian pointed out this configuration is not valid on
multipoint interfaces because the layer 1 status of the interface does
not necessarily reflect end-to-end reachability on the segment, i.e. one
side of the link can be up while the other side is down.
HTH,
Brian McGahan, CCIE #8593
bmcgahan@internetworkexpert.com
Internetwork Expert, Inc.
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> -----Original Message-----
> From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf
Of
> Narbik Kocharians
> Sent: Thursday, July 06, 2006 11:47 AM
> To: Brian Dennis
> Cc: Sami; ccielab@groupstudy.com
> Subject: Re: RIP triggered
>
> RIP does not care if the other end point is down or not, if RIP does
not
> receive the updates from a router on a point-to-point or multipoint
> interface, it has two timers that it will use to handle that
situation,
> invalidation timer and Flush timer.
>
> There are two reasons that Cisco came up with this extension:
>
> The periodic updates (every 30 seconds be default) can keep the
circuit
> up,
> and the second reason is to cut down on the number of periodic updates
> even
> on a Point-to-point connections.
> Its because of these two points that the command "ip rip triggered" is
> only
> available on the wan interfaces and it has nothing to do with neighbor
> down
> detection, it has provisions for that already. I am sorry but I have
to
> disagree.
>
> Narbik Kocharians
> CCIE# 12410 (R&S, SP, Security)
> CCSI# 30832
> Network Learning, Inc. (CCIE class Instructor)
> www.ccbootcamp.com (CCIE Training)
>
>
> On 7/6/06, Brian Dennis <bdennis@internetworkexpert.com> wrote:
> >
> > Think about it like this. If you run RIP triggered across a P2P
serial
> > link and the remote end goes down, your local interface should also
go
> > down. This will allow your local router to detect that the remote
> > router's routes should be removed from the routing table. Now if
it's a
> > multipoint interface like Ethernet (more than one endpoint possible)
> > then if the remote router goes down, the Ethernet interface will not
> > normally go down assuming a hub or switch is being used. This means
> > that even though the remote router is down, its routes will not be
> > removed from your local router's routing table since you are not
> > expecting periodic updates and you can not determine based on the
> > interface state if the remote router is down.
> >
> > HTH,
> >
> > Brian Dennis, CCIE #2210 (R&S/ISP-Dial/Security)
> > bdennis@internetworkexpert.com
> >
> > Internetwork Expert, Inc.
> > http://www.InternetworkExpert.com
> > Toll Free: 877-224-8987
> > Direct: 775-745-6404 (Outside the US and Canada)
> >
> >
> > -----Original Message-----
> > From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf
Of
> > Sami
> > Sent: Thursday, July 06, 2006 4:56 AM
> > To: ccielab@groupstudy.com
> > Subject: RIP triggered
> >
> > Group,
> >
> > ip rip triggered command is not under ethernet interface ? is there
any
> > speific reason for not having it ?
> >
> > R4(config)#int fastEthernet 0/0
> > R4(config-if)#ip rip ?
> > advertise Specify update interval
> > authentication Authentication control
> > receive advertisement reception
> > send advertisement transmission
> > v2-broadcast send ip broadcast v2 update
> >
> > R4(config)#int s0/0/0
> >
> > R4(config-if)#ip rip ?
> > advertise Specify update interval
> > authentication Authentication control
> > receive advertisement reception
> > send advertisement transmission
> > triggered enable rfc2091 triggered rip
> > v2-broadcast send ip broadcast v2 update
> >
> >
This archive was generated by hypermail 2.1.4 : Tue Aug 01 2006 - 07:13:46 ART