You have a low speed serial connection that is being used only as a backup to a frame relay network. Which routing method could you use on your internal routers to minimize the bandwidth wasted for frivolous routing updates?
A. Use dial-on-demand routing.
B. Use route summarization.
I think the answer should be A but my friends say B. What do you guys think?
Your friend is correct. Answer is B,
1, frame does not use ddr 2, the statement specifically says what to use to minimize wasted bw for updatesYes, B is correct.
The serail line is the backup to the frame connection so it is a permanent back-up and has nothing to do with dial-on-demand routing.
Because the back-up serial connection is "low speed" 56 or 64k you dont want to use up all the bandwidth with routing updates so summarization will help in that it reduces the number of routes that need to be advertised over the link if the primary frame connection fails.
Peter.
Were these all the answers?
If I saw that question on a test I would be looking for:
C) snapshot routing
or
D) ip ospf demand-circuit
As dial-on-demand won't slow routing updates, and summarization may not.
I think A is most correct. I'm guessing 'low speed' serial to mean ISDN. If you are using ISDN as a backup, you configure DDR to only respond to interesting traffic (www, ftp, pop etc). An access list is used to define the interesting traffic. Everything else is ignored unless the line is already up. Otherwise, your ISDN line goes active for every routing update, ping or burp.
Summarization might save a few bytes, but not sending frivolous routing updates on a line not in use will save more.
Bill
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