policy routing

Discussion in 'Linux Networking' started by Alex Harsch, Nov 22, 2004.

  1. Alex Harsch

    Alex Harsch Guest

    Hello,

    I have the task to implement a routing protocol as a kernel module. The
    algorithm for the routing protocol is dynamic, meaning, that it may change
    the routing table once in a second. During heavy traffic even more
    frequently.
    Now I wonder how it will affect performance if I change the rules so
    frequently. Basically, all I need to change often is the weights of the
    routes, e.g.
    for destination A route
    2/3 of the packets over interface1 and 1/3 over interface2
    to
    1/3 of the packets over interface1 and and 2/3 over interface2

    I know that there is a cache for routing, because it is way faster than
    doing a lookup on the routing table. Now I wonder:
    1. is it possible to change the routing table so often?
    2. how much CPU is it going to cost me?
    3. can I change the cache directly?
    4. how much faster is a cache lookup compared to a routing table lookup?
    5. should I ask all these questions in a kernel developer NG?

    Thanks in advance.
    With kind regards, Alex
     
    Alex Harsch, Nov 22, 2004
    #1
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