nanog mailing list archives

Re: Issues encountered with assigning .0 and .255 as usable addresses?


From: "Scott Weeks" <surfer () mauigateway com>
Date: Mon, 22 Oct 2012 15:57:18 -0700



--- job () instituut net wrote:
From: Job Snijders <job () instituut net>

Curious whether it's commonplace to find systems that automatically regard 
.0 and .255 IP addresses (ipv4) as src/dst in packets as traffic that should 
be considered invalid. When you have a pool of assignable addresses, you 
should expect to see x.x.x.0 and x.x.x.255 in passing traffic (ie. VIP or NAT 
pool, or subnets larger than /24). Yet I've run into a commercial IP mgmt product 
and getting reports of M$ ISA proxy that is specifically blocking traffic for an 
IP ending in .0 or .255.



I used about a /15s worth of /23s for DHCP at a previous employer for 5 years 
(2005 - 2010) and they're still using them today years later.  Never got one 
complaint AFAIK.  I even got one of the .0 or .255 addresses for a while and
never had trouble.  This was discussed in detail a while back.  Look in the 
archives.

scott


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