[c-nsp] Loopback IP set to .255 - 6500 responds to ICMP echo-request from wrong interface

Ian Henderson ianh at ianh.net.au
Sun Jan 1 06:15:48 EST 2012

On 01/01/2012, at 4:33 PM, Eric Rosenberry wrote:

> When pinging the loopback IP's of these devices from the Internet, one
> responds as expected (from the IP of the loopback), and the other (.255)
> responds from a *different* IP address (one of it's interface IP's rather
> than the loopback IP).

Yep, ran into this one a few years ago. Its not just ping, SNMP does it too. TAC support request tool is offline at the moment, so I can't look up the bug ID, but we eventually just made a rule to never use .255/32 for loopbacks (along with .0/31 and .254/31 to avoid Windows users complaining about failed traceroutes…).


- I.

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