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Cisco >224.0/3 problems..

  • From: James Rishaw
  • Date: Mon Feb 01 14:33:07 1999
  • Rfc_violation: You saw it here first!

Hello all,

  Ran into a problem, thought maybe someone else has run into this and
knows of a "fix", if this is intentional or what not.

  It seems that Cisco IOS has a problem dealing with addresses above

  This came up in an e-mail with Paul Vixie about MAPS RBL, where I asked
him why 224+ wasn't filtered.  The reply was: IOS ignores it.  GateD likes
it, IOS doesn't.

  I'm finding that IOS isn't propagating routes, etc., (nor will it even
seem to *recognize*) address space above 224.

  To wit:

As a /3:
bordercore1.chi(config)#ip route Null0
%Invalid destination prefix

/8, close to the end of address space:
bordercore1.chi(config)#ip route null0
%Invalid destination prefix

As a /24:
bordercore1.chi(config)#ip route Null0
%Invalid destination prefix

bordercore1.chi(config)#ip route Null0
%Invalid destination prefix

It's not Null0:

bordercore1.chi(config)#ip route h9/0
%Invalid destination prefix

bordercore1.chi(config)#ip route atm4/0  
%Invalid destination prefix

I know this is all "multicast" space, but considering classless routing
and CIDR, shouldn't this space be usable and able to be manipulated ?

jamie rishaw (efnet:gavroche) @ AIS / Exodus
"I want peace on earth and goodwill towards men."
"We are the United States Government.  We don't do that sort of thing."