Hi Paul, On Oct 22, 2012, at 5:07 PM, Paul Zugnoni <paul.zugn...@jivesoftware.com> wrote:
> 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. In the post-classfull routing world .0 and .255 should be normal IP addresses. CIDR was only recently defined (somewhere in 1993) so I understand it might take companies some time to adjust to this novel situation. Ok, enough snarkyness! Quite recently a participant of the NLNOG RING had a problem related to an .255 IP address. You can read more about it here: https://ring.nlnog.net/news/2012/10/ring-success-the-ipv4-255-problem/ So yes, apparently problems like these still arise once in a while. My recommendation would be to fix the equipment and not blame it on .0 or .255. Kind regards, Job Snijders
