I am the IT administrator for a small para-church organization that opperates out of Dallas, TX. I have been asked to aggregate 2 ISP connections, a T1 and a DSL line, using the router leased by the T1 provider, the Modem provided by the DSL provider, and another cisco router that we will soon purchase to get the most out of our available bandwidth. Originally I was looking at a 2621XM, I had read that Load Balancing is a standard feature on all cisco routers, but then realized that 2621XM's doesnt support extra FE ports. So now we are looking at 3725 routers but i am being told that the 12.2(15)T IOS and GLBP will not do the job since GLBP cannot be emplimented to load balance between 2 ports on the same router. I'm now told that I need a 12.4(11)T IOS or later because what I need to load share between two FE ports on the same router, is PfR. I'm looking for suggestions, confirmations, configuration tips and tricks, whatever you got!
Streams Minsitries Int.
Are you planning to use a lot of Real Time protocols? (Voice over IP, Video over IP, real time streaming...). Then PfR might help, but otherwise I don't see a very big improvment as I understand that you have just a small to medium network there.
Next in regard to load balancing the traffic. How do you connect to this 2 providers? Do you have a BGP session with them or they just push two default routes to you. You have to know that BGP is not the most friendly protocol in regard to load balancing, but something can be achieve. Anyway there are other things that you should be more concerned. You have the same speed on the DSL and T1 line? I don't think so... Then again what is the RTT on the lines? If the values are different, as I more than sure they are, then load balancing can give you problems like packets arriving out of order. Yes, you'll be able to use both lines, but with the packet retransmission in case of TCP you will have more headache than benefits.
Depending on your available bandwidth and utilisation, I would suggest better to use one line as the primary one and the second one as a backup in case that the primary one fails.
Please let me know if this helps!
PfR provides the capability to optimize routing based on application requirements. PfR is able to provide load balancing for inbound and outbound traffic specific to Internet edge demarcation points and internal network segments. If you are to deploy PfR on your Internet routers BGP will be required for connection to your ISP.
If you have further questions let me know.
Steve Lyons - Cisco