configuring igrp

configuring igrp

Post by die.. » Thu, 25 Jan 2001 17:15:29

I am main instructor for the CCNA program at a school in germany. We
have passed the first and second semester of the CISCO Curriculum. Now
I am teaching the third semester. By configuring IGRP on a CISCO Router
the following question occured:
if i set the sleeptime on 60 seconds to restrain the immediatly flush
update, and by the way i set also the holddown timer on 120 seconds,
what would be lawfully?? What time do the router wait until updating,
if there is a change on one of itsown interfaces??

Sent via


1. Need Advice on Configuring Default Routes in IGRP

I need some advice on configuring IGRP.  I have read several books on the
subject but I still do not understand how to configure default routes
(default networks? candidate default routes? classful? classless?)

I have the following configuration:

A Cisco 2948G-L3 which is the backbone router for my small network.  It is
configured in the following way:

BVI1 (ports 1-6) ip addr
BVI2 (ports 7-12 ip addr
BVI3 (ports 13-18 ip addr
BVI4 (ports 19-24 ip addr

Switches are attached to the ports and end-nodes are attached to the
switches.  The router is named BB.

On subnet I have a firewall (ip addr

I currently have a default gateway on the 2948G-L3: to route traffic to our public network via the firewall and on
to the Internet via our edge router.  This all works fine.

We acquired a small company at a remote location.  We want to connect them
to our network.  I thought I would use IGRP as my routing protocol.

The remote site currently has its own connection to the Internet via a
firewall.  I will give them the network address and give their
firewall the ip addr

I will add a Cisco 2621XM to network at headquarters.  The
router name will be HQ.  I will add a Cisco 2621XM to network at
the branch office.  The router name will be BR.

The router configurations will be as follows:

Router BB
BVI1 (ports 1-6) ip addr
BVI2 (ports 7-12 ip addr
BVI3 (ports 8-13 ip addr
BVI4 (ports 14-19 ip addr
router igrp 10

All nodes on the above subnets use .1 as their default gateway e.g.,,, and

Router HQ
interface fastEthernet 0 ip addr
interface serial 0 ip addr
router igrp 10

Router BR
interface fastethernet 0 ip addr
interface serial 0 ip addr
router igrp 10

All nodes on  subnet will use as their default

The L3 switch and the other two routers will swap routing tables via igrp to
be able to route internal traffic both locally and across the WAN.

What do I need to do to route Internet traffic from subnets,,, and to the Firewall (ip addr at headquarters?

What do I need to do to route Internet traffic from subnet to
the Internet via Firewall ip addr at the branch office?

Should I configure igrp to advertise routes out of all interfaces on all
routers, even the 2948G-L3 as I have indicated with the above

Is it o.k. to go to the gateway on BR via fastethernet 0 ip addr
and back out of the same interface to the firewall ip addr


Tom Naves

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