On Thu, 11 Nov 1999, Mike Andrews wrote:
On Thu, 11 Nov 1999, Mike Andrews wrote:
A while back I mentioned a problem I had where my ARCs would stop routing correctly after various Ciscos in my network rebooted. The general consensus was that it was related to Designated Router/Backup Designated Router designations... and that maybe the ARCs were becoming a DR/BDR. [munch]
More on the above problem:
A quick search around suggests one possible reason the routers won't negotiate is a subnet mask mismatch. Here's the routing table on the sick ARC:
fra-ts2> list ip route
IP ROUTES Destination Prot NextHop Metric Interface 0.0.0.0/0 NetMgr 206.240.130.1 1 eth:1 127.0.0.1/H LOCAL 127.0.0.1 1 loopback 206.240.130.0/23 LOCAL 206.240.130.1 1 eth:1 206.240.130.14/H LOCAL 206.240.130.14 1 eth:1
This points out a problem I've brought up before. The subnet mask on this LAN should be /25, not /23. There is a /23 route being advertised by the Cisco that points at fra1's Null0 though (for BGP4 purposes) and this is somehow getting confused with the local netmask set on the eth:1 interface, which is set correctly:
Ok, fra1 is that your border? Are you injecting static routes into the IGP at all? I use tiedowns for my BGP routes as well.........you want to set these with a HIGH administrative weight, of like 250 though, so they don't get used. Do you have a weight set on them? Also, using null0 as a tiedown used to be slow switched, so people used loopbacks, but I think now in later ios's this is not the case, and both can be used, but if you are running an older version you may want to consider that.
fra-ts2> show ip network ip
SHOW IP NETWORK ip SETTINGS: Interface: eth:1 Network Address: 206.240.130.14/25 Frame Type: ETHERNET_II Status: ENABLED Reconfigure Needed: FALSE Mask: 255.255.255.128 Station: 206.240.130.14 [munch]
So maybe the two bugs I'm running into are related after all?
Guess I'll go turn on OSPF debugging on the DR and see what comes up.
Mike Andrews (MA12) * mandrews@dcr.net * http://www.bit0.com/ VP, sysadmin, & network guy, Digital Crescent Inc, Frankfort KY Internet services for Frankfort, Lawrenceburg, Owenton, & Shelbyville "With sufficient thrust, pigs fly just fine." -- RFC 1925
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----------------------------------------------------- Brian Feeny (BF304) signal@shreve.net 318-222-2638 x 109 http://www.shreve.net/~signal Network Administrator ShreveNet Inc. (ASN 11881) - To unsubscribe to usr-tc, send an email to "majordomo@xmission.com" with "unsubscribe usr-tc" in the body of the message. For information on digests or retrieving files and old messages send "help" to the same address. Do not use quotes in your message.