load balancing

[billyj1900]

I have a 4500 which is connected to a ATT router. The 4500 is connect to a 3750 by layer 2 running HSRP out the 4500. I will be setting up another ATT router off the 3750. ATT will be setting up the BGP. How do I do dynamic routing protocol fail-over with both ATT connections using BGP.

 

[unclerico]

1) is either the 4500 or the 3750 primary for all HSRP vlans or do you have both primary for one or more vlans??
2) why are you using BGP?? it really only makes sense to use BGP if you're multihoming (for the most part, i don't want to make a blanket statement). since ATT is your ISP for both connections you're not really multihoming.
3) do you want load sharing or do you want failover??

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[billyj1900]

1) the 4500 will be primary
2) ATT is the ISP on both connections.
3) I want to do failover. If the 4500 or 3750 goes out I can use the other ISP connections.

 

[unclerico]

Honestly, the easiest thing to do in this scenario is just use a floating static route. Eliminate the BGP config since it will do you no good. BGP will only complicate things.

Just a thought, if you have multiple VLANs on the network (which I'm assuming you do) then configure the 3750 to be primary for one or more VLANs and then do the same for other VLANs on the 4500. You can then utilize both links to the Internet and not waste money. What are you using for firewalls??

I hate all Uppercase... I don't want my groups to seem angry at me all the time! =)
- ColdFlame (vbscript forum)

 

[billyj1900]

You mention utilizing both links for the internet which is PBR. What about load balancing both ISP links.

 

[unclerico]

no, it's not necessarily PBR because you aren't taking the packets out of the normal routing process. you can easily load share both links with equal cost default routes.

I hate all Uppercase... I don't want my groups to seem angry at me all the time! =)
- ColdFlame (vbscript forum)

 

[billyj1900]

Can you provide an example of the load sharing config?

 

[unclerico]

sure:

ip route 0.0.0.0 0.0.0.0 <att_gateway_1>
ip route 0.0.0.0 0.0.0.0 <att_gateway_2>

this will give you equal cost paths out to the Internet and do per destination load balancing.

I hate all Uppercase... I don't want my groups to seem angry at me all the time! =)
- ColdFlame (vbscript forum)

 

[billyj1900]

Would this work if the internal routing protocol is using OSPF. Do I have "no passive interface" to both the 4500 and 3750.

 

[dgrizzard]

Wouldn't matter which routing protocol you are using since a static route would have a lower AD than the routes coming out of OSPF.