Load balancing multiple WAN links

[pat2006]

Hi.

If I have 2 links between my sites, 1 Metro Ethernet and the other a broadband solution from my cable TV provider, how can I use the 8600 to load balance these 2 links.

Both links terminate with an RJ45 connector.

The links are not Internet links.

For the Metro Ethernet connection, do I need the 8668 Metro Ethernet card?

Can the Alteon be used for this purpose instead of the 8600 and is this recommended?

Thanks.

 

[anthonyanderberg]

If both links act like a simple layer 2 connections you'd be able to use something like equal cost multi path routing, which is built into the 8600.

Before doing anything you'll want to understand both links and make sure they don't have wildly different latency and capacity. For example if the broadband solution has much smaller capacity or a lot longer latency you probably don't want to split the traffic between the links evenly - in that case you might be better off just using the slower link as a hot-standby... again a good routing protocol like OSPF would allow you to weight the standby link higher so traffic only flowed across it if the faster link went down.

 

[pat2006]

Thanks for the info. It gives me something to work with.

If the links have different characteristics, would it make sense to use the Alteon for load balancing?

With regards to the 8668 Metro card, I've been reading some stuff on the Nortel site and I get the impression that this is really meant for carriers.

I'm I correct in assuming that this card is not required for customers to install in their network equipment?

Thanks again.

 

[andy88]

The 8668 card is for the Metro passport, not the enterprise passport.

 

[andy88]

Try equal cost multipath with OSPF.

 

[anthonyanderberg]

I don't have much first-hand experience with the Alteon, but I think you could load-balance the links with a pair of them.

A lot will depend on what the two links look like, which will determine how you want to divide your traffic. For example if one of the links has lots of bandwidth but also more latency you may want to route VoIP and interactive traffic across the other (smaller but faster) link. These kind of configurations require a detailed knowledge of your traffic and the link characteristics, and can be hard to maintain and troubleshoot as time passes and traffic changes - you'll want to take that into account as well.

Its worth noting that generally OSPF and similar protocols try to keep individual conversations on the same path so packets don't arrive out-of-order. This can be changed using per-packet multipath schemes, but I don't think you'd want that unless you had two identical links.