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HSRP on routers need some advices.

Please see the attached figure.

I 'll really appreciate if someone can answer the below questions according to attached figure.

two routers on the central office are configured as HSRP. they are redundantly connected to the two branch office. (total 4 Leased Lines)

1. as far as I read, HSRP means router A (active) forwards packets as virtual router while the Router B (Standby) doesnt forward anything.

which means Altought I have two leased lines to office 1, I can use only one of the lines because the second line is connected to standby router. can it be configured to forward packets even when it is a standby router?

2. I want to use all 4 lines at the same time, is it possible? (Router A and B are running in HSRP group)

I have also questions about redundancy of lines but better ask them after above questions are clarified.

Thanks in advance.

7 REPLIES

Re: HSRP on routers need some advices.

hi

If you have configured multiple HSRP groups in your HSRP config that will take care of the load sharing part.

do check this link which talks about the same hope you can compare the configs which you have in your router from which you can identify whether you have really configured loadbalancing with reduandncy.

http://www.cisco.com/en/US/tech/tk648/tk362/technologies_configuration_example09186a0080094e90.shtml

regds

Re: HSRP on routers need some advices.

Probably the following will help you solve the issue:

http://www.cisco.com/en/US/products/ps6600/products_data_sheet0900aecd803a546c.html

It states between the lines that HSRP cannot serve your goal but gives a possible alternative.

Regards,

Leo

New Member

Re: HSRP on routers need some advices.

You are correct that with HSRP, one router is Active and the other is Standby. Keep in mind, however, that HSRP is primarily a mechanism to provide a redundant default gateway for host workstations or servers. In your setup, the traffic from a workstation at the central office would go to the Active router and across the directly connected leased line to office 1. The return traffic, however, will travel across the path determined by your routing protocol, so you may have a certain amount of traffic on both leased lines with a basic HSRP configuration.

Using multiple HSRP groups allows you to define each router as Active for different groups, but requires that you use a second default gateway address for the second group. This may be difficult to implement in a DHCP environment unless you have multiple DHCP servers or some other mechanism to hand out different gateway addresses to local workstations.

Another option to consider is Gateway Load Balancing Protocol. This provides load balancing in addition to redundancy by handing out both routers MAC addresses for the same IP address in response to successive ARP requests. It may require pretty new IOS code depending on the platforms involved, but might be worth taking a look.

Hope this helps,

John Sayer

New Member

Re: HSRP on routers need some advices.

All information you mates supplied was useful, tx a lot.

It seems HSRP is not the best option in this case. Because I have to push things to limits. I want to use both dual leased lines, in case one of the lines fails, all trafic should flow through the other line.

How about this: Please see attached file, I tried to make the topology more suitable to my requirements. I will really appreciate if someone can confirm I am on the right way. :)

I already have two 4506 multilayer switches in my LAN. I can run HSRP on these switches instead of routers. in this case

1) I will take advantage of the ASIC of the switch,

2) Routers will be able to work as I wish.

Do you agree if this is a better solution compare to first topology (first attached file)

Thank you very much in advance.

Re: HSRP on routers need some advices.

Hello,

the proposed setup will allow you to have redundant default gateways for your workstations and also to have load sharing to your branch offices.

To acomplish the latter you would need to setup dynamic IP routing. Protocols like OSPF or EIGRP will allow you to utilize both T1s to each branch office, as long as the metric to the destination is the same for both pathes.

Hope this helps! Please rate all posts.

Regards, Martin

New Member

Re: HSRP on routers need some advices.

hi Martin,

thank you for your comments. I suppose your comments based on the "proposed setup" points the last attached drawing (drawing101.png)

According to this setup(drawing101);

Sure I am gonna use a dynamic routing protocol.

metrics are identical.

But I was planning to give the IP of the virtual router as PCs default gataway address. do I have to setup a secondary gateway address?

tx for helping

New Member

Re: HSRP on routers need some advices.

If the PC's are all in the same VLAN and all get the same default gateway, then all outbound traffic from these PC's will go to the same 4506. This switch then determines how to get the traffic to its destination at one of the remote sites. So, unless you use a routing protocol that allows load-balancing over non-equal cost metrics, the traffic will still use only one of the circuits to the remote site.

If the routers have an extra ethernet port, you could connect each of the 4506's to both of the routers. This would provide two paths with equal costs utilizing both circuits to the remote. Path 1 = 4506A-RouterA-Branch1 (via A1). Path 2 = 4506A-RouterB-Branch1 (via B1).

Keep in mind that the return traffic path should be designed in a similar fashion to get full load-balancing in both directions. Also, remember that load-balancing is typically session-based, not packet-by-packet.

Hope this helps,

John

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