Active/Active HSRP configuration

[bender.mike]

All,

I'm trying to confirm a proof-of-concept. Within the next couple months we're migrating our WAN to an MPLS solution and relocating our data center.

My question focuses on the feasibility of running an active/active HSRP configuration on a pair of Cisco 3750s. I seem to remember reading this can be done somewhere, but now I can't find it. I believe it's just a matter of creating two HSRP groups on each interface. I've seen some configuration for this on PIX firewalls, but not standard IOS routers.

One noteworthy point- the original proposal was to run two T1s with IMA on each router, but now the customer is contemplating the need for a third T1 on one of the routers. Can we do this without running into issues with assymetrical bandwidth or will this function as a true round-robin configuration?

Thanks for any input.

Mike

[russell.chaudoin]

Mike, Your HSRP idea is very feasible. This can be done. The answer to your question regarding IMA will have to come from another source.

[bender.mike]

Does anyone have any sample configs to illustrate what I'm wanting to do?

This article shows HSRP, but it's not really what I'm wanting.

(http://www.cisco.com/univercd/cc/td/doc/cisintwk/ics/cs009.htm#wp3389)

This would only work if half my clients pointed at one router, the other half at one of the other routers. Within a DHCP-environment, you can't do that unless you get really tricky with VLANs and this is more admin-intensive than I'd like to get.

[Aaron Harrison]

Hi

Maybe you're thinking of GLBP?

http://www.cisco.com/en/US/products/sw/iosswrel/ps1839/products_white_paper09186a00801541c8.shtml

I don't think it's supported on 3750s though.

What is it you're trying to achieve?

A single 3750 will route pretty fast, and if you have a layer 2 network with STP running half your links are likely shut down - so an optimal option would be to make one 3750 the STP root and HSRP active router.

[bender.mike]

OK, I'll give more detail on the setup:

We're migrating an existing 85-site frame relay network to MPLS. At the same time, we're relocating our DC. The DC site currently has a single 3640, but we're installing a pair of 3750s with 2 circuits running IMA into each router.

We want to be able to utilize all 6 Mb available to us. AT&T is proposing an active-active environment, but I haven't seen this done before.

This morning a manager threw out the notion to add a third T1 to one router, but my colleague and I question whether this will cause some asymmetrical routing issues.

That's pretty much it in a nutshell...

[bender.mike]

Aaron, I looked over that GLBP article that you referenced and it sounds like it might be closer to what I'm looking for.

I see that round-robin is the load-balancing default, but based on what I read, it doesn't appear to be true round-robin. Meaning, packets are truly load-balanced across the two routers so that they are both essentially running in active mode.

Am I just not understanding that correctly?

[ja1064]

we are also planning a migration from frame to MPLS. I will have about 39 sites connected. I am trying to get a handle on the ability for our 3640 to handle it.

I currently have 6MB of host circuit capacity that is frequently close to peak. So, i expect i'll be regularly using more than 6M. Moreover, we want to increase the port speed on some links.

I will have a 12MB DS3 coming into an nm-1hssi.

i will max the mem on the 3640. Do you think it can handle it?

[s.vyas]

U will put config some thing like this...

interface FastEthernet0/0

ip address 10.10.33.33 255.255.255.224

no ip redirects

no ip proxy-arp

no ip mroute-cache

speed auto

duplex auto

standby use-bia

standby 1 timers 3 10

standby 1 priority 110 preempt delay 120

standby 1 authentication HSRP_G1

standby 1 ip 10.10.33.34

standby 1 track Serial0/0 10

standby 2 timers 3 10

standby 2 priority 105 preempt

standby 2 authentication HSRP_G2

standby 2 ip 10.10.33.36

standby 2 track Serial0/0 5

interface FastEthernet0/0

ip address 10.10.33.35 255.255.255.224

no ip redirects

no ip proxy-arp

no ip mroute-cache

speed auto

duplex auto

standby use-bia

standby 1 timers 3 10

standby 1 priority 105 preempt

standby 1 authentication HSRP_G1

standby 1 ip 10.10.33.34

standby 1 track Serial0/0 5

standby 2 timers 3 10

standby 2 priority 110 preempt delay 120

standby 2 authentication HSRP_G2

standby 2 ip 10.10.33.36

standby 2 track Serial0/0 10

If u have more then one WAN int on the router u will have to change the track command and the weight drop parameters attached ot it.

With MPLS u will have to come with the plan , which is going to be your primary site and and anouce the default from that site for the rest of the spoke site...U can also - design- fail-over...