Load balancing / fault tolerance question

[30362]

I currently have a T1 for Internet connected to a 2503 which is in turn connected to a Pix 515e, I would like to add a second T1 for the Internet (testing a different vendor) and would like to add it to the router as well so that I don't have to invest in a second Pix.

Is the 2500 capable of supporting load balancing / fault tolerance so that I can combine both T1's into one larger pipe? If not, what router would be recommended?

Finally, can I get some help configuring this, I have the existing T1 on Ser0 and would be adding the second on Ser1, since the T1s are from different providers there are different IP ranges for each, and different subnet masks. I want to make sure that the users can benefit from the added bandwidth but also want to make sure that if one T1 goes down that our users can keep on surfing...

Thanks.

 

[eabbink]

Hi,

I *think* what you want is not possible with said hardware, but I'm not familiar enough with the 2503.

for such a setup you need to use BGP since you are going to two different ISP's. And since you want load-balancing you need to have the full internet routing table loaded which I think the 2503 cant do. If you only do a default-route BGP setup you can get fault-tolerance to work though. You also will need to get your own AS number.

Please note that I havent actually done such a setup, so I might be slightly wrong or totally off base. Someone please correct me in that case...

Esger

 

[wybnormal]

BGP is one way but.. BGP is not user friendly and many ISPs will not let you configure BGP on their side of the link since it's so easy to make a mistake. OSPF can do something like this but what I might toss out is this.. policy route mapping. Take a quick look at the types of traffic, smtp, pop, http etc.. and use policy maps to point all smtp to one leg, all pop to the 2nd and then split your internal IP range across both legs.

A second design note is failover.. a cool way to provide failover is to have a set of static routes.. one static route will point to S0 (example) but the second static route will point to S2 but with a cost of 200. The high cost prevents it from being used until the first static fails and then the rule of a static route always be used first falls into place.

There are many ways to do this.. a bit of research on Cisco's web site for sample configurations will have some "gold" for you.

MikeS


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[eabbink]

hmm, I'm not sure I understand how this will work. But that could be me

you certainly can load-balance outgoing traffic with static routes etc but how would that balance incoming traffic?

And with regard to fault tolerance, if you dont use BGP that means (afaik) that a certain ip address is only routed (in) through a certain ISP. So a failing T1 or ISP would take out connectivity of half your ip range. Of course this is better than losing all connectivity but still.

Esger

 

[30362]

We only use our Internet connection for SMTP and browsing, our website is hosted externally. Almost all of our business processes require Internet access so users can get to the external apps, so the only things I am worried about are:

1) more bandwidth
2) fault tolerance

If our primary link goes down, which handles STMP and HTML I would be most concerned about our internal users getting to the web, mail can always be down for a day without too much discomfort. With that in mind, and the fact that each ISP is providing us a different IP range, what would be the fastest / easiest way to do this?

I don't mind using a second CSU or router (I have spares), I just can't swing another Pix.

Thanks...

 

[eabbink]

then I think wybnormal suggestions will work fine. If you balance your outbound traffic by ip range/ISP the return traffic will take the same way which effectively balances your return traffic.

I was talking with a situation in mind where there's (also) a lot of inbound traffic, like indeed your website.

If you set up your mail server and dns/mx records with two ip's, one in each range you should also be able to keep your incoming mail up I think.

btw, a second pix wouldnt do much to help you? You still would have to solve the same problem with balancing your internet traffic I'd guess.

Esger