Unanswered Question
Jul 10th, 2008

I hv attached a rough network dia to understand any alternate way to configured EIGRP with Transparent lan service ( TLS ).

We hv core location as mentioned as R1 & other remote location R3,R4,R5,56 with their repective network( ip's mentioned in dia). All the remote location has a backup FR link to core through R2.

R1- 100 Mbps port

R3,R4,R5,R6 - 10 Mbps port

EIGRP has been used as routing protocol and all the remote location to be access core through TLS and FR should be the back.

I hv configured EIGRP as remote location as mentioned and also at core. Vlan 10 is acting as a transit vlan for all remote location. so all remote location talks to core through vlan 10 transit vlan.

The issue with this is since we put in eigrp domain all the remote location establish the neighbour relation along with core location having 100 Mbps port. As per the hello and hold interval they try to maintain neigbour relationship.

But it also goes through a frequent EIGRP recalcuation as the hold time expires disrupting the network. I tried to increase the hello and hold time but still it goes through recalculation but the frequecy reduce. Definately there seems not be any issue with TLS but this happen of the TLS broadcast(layer 2) domain. Core port is 100 Mbps and each remote location port is 10 Mbps

Is there any better way to configure EIGRP as there is no possibility I can change much at core location...

Can the direct neighbour statement to at remote R3,R4,R5,R6 can solve for frequent recalcuation ??? What can be an impact on remote location and core side

Need ur help ..

I have this problem too.
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Giuseppe Larosa Wed, 07/16/2008 - 11:52

Hello Sandeep,

if the core router has a 100 Mbps connection to the TLS service you may overload the access links of the remote routers that are 10 Mbps only.

You can do the following:

on the core router use the bandwidth command and set it to 10000 Kbps.

If this is not enough ,as I'm afraid, you will need to shape the traffic that the core sends on Vlan10.

In this case you can shape user traffic and let the eigrp traffic to go out in another class map.

For this you need to use modular QoS.

If you bought a subrate FE at the core you need to shape in any case even if using static routes.

For QoS see the following link


as a starting point

A nested service policy could shape all traffic a little less to the access rate at the core. Then you can shape traffic to every tremote to something less of 10 Mbps.

Hope to help


sandeepatel Wed, 07/16/2008 - 12:03

Thanks a lot.

One more thing I wanted to reconfirm on that is ... If I get 1G connection at core and want to hook all the Remote office location(10Mbsp) to layer2 instead of layer3 what would be the impact of broadcast counters on the core and remote side. Is there any rough equation to calculate it....

Giuseppe Larosa Sun, 07/20/2008 - 02:06

Hello Sandeep,

more bandwidth at ther hub will allow you to support more remote sites but you need to shape carefully.

You are already getting a layer2 service from provider.

I wouldn't go to a solution L2 only with remote sites as L2 LAN swithes.

Broadcast will go everywhere and having a 1Gbps link at the hub and 10 Mbps is not easy

However, you can use broadcast storm-control to limit basdwidth used by broadcast

Hope to help



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