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

David Hubbard dhubbard at dino.hostasaurus.com
Mon Oct 22 22:40:33 UTC 2012


From: Paul Zugnoni [mailto:paul.zugnoni at jivesoftware.com] 
> 
> 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.
> 
> Any experience or recommendations? Besides replace the ISA 
> proxy.... Since it's not mine to replace. Also curious whether 
> there's an RFC recommending against the use of .0 or .255 
> addresses for this reason.
> 

We're a web host and over the past 12 years we've randomly
attempted to put non-critical customer sites on .0 and .255
addresses and found customers fairly consistently had
problems accessing them.  These would typically be sites
for development, etc. where the customer was the only one
accessing it and even then it has been a high percentage
of failures.  It is nearly always the customer's small biz
/ home office cheap-o router that is the issue even in this
day and age but occassionally it has been the ISP as well.
I haven't kept a list of vendors/isp's unfortunately so I
don't have more useful information to offer you other
than that it's still a problem.  We still use those
addresses for that purpose since they'd otherwise go to
waste but most of the time it ends up being changed when
the customer tries to access it from somewhere and can't.

David



More information about the NANOG mailing list