What is the most standard subnet length on internet

Brett Frankenberger rbf+nanog at panix.com
Wed Dec 24 13:02:17 CST 2008


On Tue, Dec 23, 2008 at 08:25:40AM -0600, Alex H. Ryu wrote:
> Also one of the reason why not putting default route may be because of
> recursive lookup from routing table.
> If you have multi-homed site within your network with static route, and
> if you use next-hop IP address instead of named interface, you will see
> the problem when you have default route in routing table.
> For an example, if you have "ip route 1.0.0.0 255.0.0.0 2.2.2.2".
> If the interface for 2.2.2.2 is down, 1.0.0.0/8 will be still be in the
> routing table because 2.2.2.2 can be reached via default route
> (0.0.0.0/0) from routing table recursive lookup.
> Therefore the traffic for 1.0.0.0/8 will be forwarded to "0.0.0.0/0"
> next-hop ip address, and customer fail-over scenario will not be working
> at all.
> 
> Only way to resolve this problem is... Actually three...
> 1) Use named interface such as "serial 1/0" instead of "x.x.x.x" IP
> next-hop address.
> But sometimes this is not an option if you use ethernet circuit or
> something like Broadcast or NBMA network.

ip route 1.0.0.0 255.0.0.0 fa0/0 2.2.2.2

     -- Brett




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