BGP Loadsharing using HSRP

[abushayeed.anwarali]

Hi,

In our branch office we had Two MPLS link by different ISPs (both in same ASN For example 100) both the links terminates in our two separate intetnal cisco 2900 routers and we use ebgp to ISP and Ibgp between our internal routers

Both our internal routers were in same ASN (For ex 200). and we had our Local LAN L3 configured on the cisco 2900 router itself (router on stick method) and we had configured HSRP with Active/Standby mode. 

As of now we are using one link as primary and other one as secondary active/failover. And i have four VLANs(with intervlan routing) configured internally and the default route is injected from the DATACENTER.

I would like to send the traffic from VLAN 1 and 2 both inbound/outbound via ISP1 and VLAN 3 and 4 via ISP2 and incase of link failure all the traffic should goes through single link.

Please help on how can i plan my configuration without Asymmetric or routing loop

[Jon Marshall]

For outbound to DC just make ISP1 router HSRP active for vlans 1 and 2 and ISP2 router active for vlans 3 and 4 and as long as both routers receive the default route via EBGP it should work fine. 

For return traffic from the DC it depends on the setup there which you don't explain. 

If there are two routers there as well with EBGP/IBGP as per your site and you are advertising the vlan/IP subnets individually ie not as a summary route you could use local preference to influence return traffic. 

Or you could use summary vs more specifc addressing etc. depending on the addressing. 

Difficult to say without more details 

Jon

[Joseph W. Doherty]

You could also use PBR, on either side to insure certain prefixes go via certain paths (if paths available). However, what Jon suggests, if possible, may be a less complex setup, as PBR gets a bit ugly when dealing with failover path usage.

You also might consider whether avoiding asymmetrical routing, or having preferred paths for some traffic is the best approach. If your concern is to insure better service for some traffic over other traffic, QoS is often, I believe, a "better" approach (it also deals much better when you have a path failure and all traffic on the same remaining path).

If your two paths offer different bandwidth capacity, to which you're trying to balance proportionally, something like GLBP and/or PfR might be a better approach for that.

[Jon Marshall]

Not sure why you are posting the configuration ?

Jon