Loopback address broadcasting??!?!?!

[NettableWalker]

I've had a stange one.
An ISDN line kept coming up hundreds of times, tests showed that the interesting traffic was from the loopback address to 255.255.255.255

Adding a deny line to the ACL stopped this happening, but why oh why should a loopback address broadcast anything? No services were using Lo0 as their source interface.

Any ideas?

 

[burtsbees]

Post a sh run and let's see...

Burt

 

[t0mm0]

What protocol was being used?

 

[NettableWalker]

No protocol was being used, it was static routing and a DDR ACL to bring up the ISDN.

the ACL encompassed traffic from the Lo0 source address, so it later emerged that the traffic repsonsible was a 255.255.255.255 boradcasst from the Lo0 address.

Weird....

 

[t0mm0]

I understand that the default of DDR allows interesting & non-interesting traffic to cross related link, hence when you assigned the ACL this scrutinised the traffic flow.

Your fix of changing the IP, resolve the matter, as it was not looking at a broadcast (225.255.255.225)??

 

[burtsbees]

I still say post a config...
Burt

 

[NettableWalker]

I can't supply a config as it was one of 2000 routers, and i'm not sure which one anymore. It's been changed by now anyway.

not a lot of use i know....