.255 addresses still not usable after all these years?

Ian Henderson ianh at chime.net.au
Sat Jun 14 03:42:31 UTC 2008

Valdis.Kletnieks at vt.edu wrote on 2008-06-14:

> RFC1519 is 15 years old now.  I *still* heard a trainer (in a Cisco
> class no less) mention class A/B/C in the last few months.  Some evil
> will obviously take generations to fully stamp out.

We've faced two issues with .255 and .0:

- Using /31 links Windows tracert * * *'s on .0 addresses. Had many users who thought they knew better complain about it.

- Using a .255 loopback on a Cisco 6500 SNMP requests would return from the closest interface IP address. Combined with a specific version of SNMP libraries (which I can't recall right now), this caused queries to fail.


- I.

Ian Henderson, CCIE #14721
Senior Network Engineer, iiNet Limited

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