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WAN Redundancy

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itd17

IS-IT--Management
Jan 24, 2002
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My company runs frame relay hub and spoke. We have 60 sites ranging in pipe sizes of 128kbps to 512kbps connecting to a 3600 router here. We are now in the midst of a win2k active directory migration and I am worried about replication crushing the pipes. Anyway, we don't have a redundant WAN in place and I don't think DDR will efficient enough due to replication traffic. Any ideas of an efficient redundancy plan? Thanks in advance!
 
What exactly do you mean by "won't be efficient enough"? What are requirements for efficiency?
 
Well, our pipes seemed to always be pegged now, so I could only imagine what will happen when AD replication comes into play. Upper mgmt. doesn't seem to think we will need to upgrade our pipes, but I disagree. Anyway, with as much data as we have pumping through our WAN on top of AD replication, I don't think an ISDN DDR solution will work for us.
 
Typically when you have a backup solution in place, it is not to keep things up at full speed, but to not let critical traffic fail. Putting in fully redundant links at full speed is usually not an economical option.

Sometimes DSL can be used, but often that is public traffic unless your carrier provides a DSL to Frame option. However, DSL has limited availability and is not exactly a very trustworthy technology yet.

ISDN is usually your best bet. Often access lists are used to filter out all but critical traffic so that mission critical apps continue to function throughout an outage. Other than that, you're kind of asking to have your cake and eat it too. If there were cheaper alternatives, you'd probably be using that as your primary technology rather than as a backup!
 
ISDN is the only only method that I would recommend.

We went through the same migration with our network implementing AD with even smaller CIR (56K, 64K). To be honest we had some connection delays, but overall the conversion went smoothly.
 
Not sure if this is what you wanted, but setting up QOS would be a start if you can't upgrade your pipes. This will at least get the traffic through that you want, and supress the stuff you dont. You could also do some policy based routing with the ddr connection, but like scraig84 said, ddr is usually used for failover.

stoney.
 
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