Hi, is this only an exercise or you really need to do this? If the latter, then I would be curious to know why this would be useful. I feel a slight contradiction in that you can't control whether a /24 or two /25 routes reach you yet you seem to know what is in one half versus the other half of the /24 network and want to make some routing decision based on this knowledge.
Anyway, to answer your question, the obvious solution is to point the two /25 static routes towards where you learn the /24 route from, not to Null0. If you have only one IGP peer, then simply point them towards it. If you have multiple IGP peers, then it gets a bit ugly. You could create a loopback address on the router where x.x.x.x/24 (or the two /25 networks) is directly connected, advertise the loopback(s) through the same IGP protocol which carries the x.x.x.x/24 route, and point the two /25 static routes to the loopback address(es). Or (assuming the IGP is OSPF and x.x.x.x/24 is in another area) you could use the loopback address of some backbone routers (possibly creating multiple pairs of static routes, each with different admin distance pointing to a different backbone router). The main thing to note in either case is that if you ever, for any reason, happen to advertise back these /25 routes towards where you learn the /24 route from, or if the router you pointed your static route to ever thinks that your router is the best way to get to x.x.x.x/24, then you just created a routing loop. Btw, why is it that "the IGP will only send the /24 and not the two /25s"? Getting the two /25s instead of the one /24 might be as easy as configuring a secondary IP address on that interface or (selectively) disabling summarization. This of course depends on your situation, so just something to think about... Thanks, Zsombor At 11:39 PM 6/21/2003 +0000, p b wrote: >Suppose I have a router which has a subnet x.x.x.0/24 defined >on some interface. Over one iBGP session I'd like to >advertise the x.x.x.0/24 subnet. Over another iBGP session, >I'd like to advertise x.x.x.0/25 and x.x.x.128/25. When >I config three network statements for these subnets in BGP, >only the /24 seems to be sent to the one iBGP peer. > >If I define a static null route for each subnet (x.x.x.0/24, >x.x.x.0/25, and x.x.x.128/25), all three routes are advetised. > >Is there a way to get the /24 and two /25s sent without >the null route? In actuallity, the /24 will be learned >via some IGP, so can't use the nulls and the IGP will >only send the /24 and not the two /25s. > >Thanks Message Posted at: http://www.groupstudy.com/form/read.php?f=7&i=71210&t=71073 -------------------------------------------------- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
