North American Network Operators Group

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Re: too many routes

  • From: David Paul Zimmerman
  • Date: Tue Sep 16 19:27:27 1997

>Some people seem to view CIDR as an opportunity to
>subdivide their traditional 'Class B' networks.  I would classify
>most of these announcements as 'mistakes' because they usually also
>announce the supernet, and have the same path.

I could see the intentional announcement of both if you've got diverse -- 
but ultimately equal -- paths into your B.  So site X might advertise 
B.0/17 to normally receive the low half of the address range, site Y 
might advertise B.128/17 to normally receive the high half, and both 
sites would advertise B/16 so that if one site went down in that 
scenario, the other's B/16 advertisement would take over for the failed 
site's /17.  In a normal case, though, you'd see the /16 and /17 with the 
same path.

Does this pattern seem to apply to any of the announcements you see?