HSRP & EIGRP

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Jul 31st, 2008
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Hi,


Network A,B and C are on a Cat-6506 with HSRP running for each of the VLANs created.


Please have a look at the attachment.I would like to run EIGRP for dynamic routing.All the remote sites via network C.At present I am just running static routes on MSFC-1 and MSFC-2 and I would like to know


1. How can I run EIGRP in this scenario. 2. If I run EIGRP what are the networks I should publish in MSFC-1 and MSFC-2.

3. Will it create any routing loops when forming neighbor relationship.


Please explain.


Thanks in advance,


subra






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Edison Ortiz Thu, 07/31/2008 - 09:28
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Subra,


Based on the diagram you've provided, I don't see how a loop will be created.


Remember, EIGRP will be enabled on the physical interfaces, not the HSRP VIP.


The end-devices will continue using the HSRP VIP for default gateway and routers using EIGRP will learn about all the subnets via the dynamic routing protocol.


HTH,


__


Edison.

subra4u Sat, 08/02/2008 - 02:01
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Hi,


Thanks for your response. According to the setup, the network-C is also on a HSRP group and lets say msfc-b is actively switching traffic. In that case while forming a eigrp neighbor relationship, should i form the relationship with both the msfc-a and msfc-b to the same router in the network-c and if so the traffic will be equally shared between the msfc-a and b.


I am bit confused here on how the eigrp and hsrp will reach when there is a failover happenening between the msfcs.


thanks in advance


subra

Edison Ortiz Sat, 08/02/2008 - 18:54
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Subra,


Traffic sourced behind Routers 1-3 will be load-balanced towards Network A-B-C.


However, the return traffic - if the device is configured with a default gateway pointing to the HSRP VIP - will use the active HSRP router on that segment and traffic will not be load-balanced.


This isn't a network loop but you may see some asymmetrical routing. Most applications work without problems under these conditions, however I've seen some applications break with this kind of configuration.


HTH,


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Edison.

subra4u Sun, 08/03/2008 - 02:13
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Hi,


Thanks for your Timely response. In that case, can i have 2 different IP's set for the vlan created for network-c and then do individual neighbor relationship between all of the routers 1,2 and 3 without running HSRP. Will that work, if not please give an idea as in how should i go about with this setup.


Thanks

subra

Edison Ortiz Sun, 08/03/2008 - 06:31
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Subra,


As I stated before, EIGRP neighbor relationship isn't maintained with the HSRP Virtual IP Address but with the physical interface IP address.


What you stated here:


can i have 2 different IP's set for the vlan created for network-c and then do individual neighbor relationship between all of the routers 1,2 and 3 without running HSRP


it's the way it's going to work when you configure EIGRP.


Again, HSRP is for end-devices that need a redundant default gateway.


Again, EIGRP is for devices running a dynamic routing protocol.


One protocol does not interfere with the other BUT the traffic pattern needs to be examined when you are using both AND I've already covered this.


__


Edison.

subra4u Mon, 08/04/2008 - 01:12
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Thanks for your help. Let me try and get back to you.

jschweng Fri, 08/29/2008 - 07:57
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You might want to try using OSPF instead and then adjusting cost on the various links so you can get more deterministic routing and avoid asymmetric routing. You should be able to do this with EIGRP but not totally sure.

subra4u Thu, 12/04/2008 - 06:17
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Hi,


Does any has a similar setup. If so, please post configuration.


Thanks in advance,


Subra



Terry Vasquez Jr Thu, 07/30/2015 - 12:34
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Hi,

 

Edison was right. EIGRP does not form neighbor relationship to the HRSP virtual IP. Though you point the neighbor to the HSRP virtual IP, EIGRP will use the active HSRP device's physical interface IP.

 

The question now is how can we achieve load balancing? This is might the 2 routers in HSRP group have unequal distances to the routes. As EIGRP supports unequal-cost load balancing, you may configure your EIGRP with variance. This is to achieve the load balance going to the HSRP group.

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