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North American Network Operators Group Date Prev | Date Next | Date Index | Thread Index | Author Index | Historical RE: Using x.x.x.0 and x.x.x.255 host addresses in supernets.
> Historically, .0 and .255 have been avoided because a lot of servers > (windows) wouldn't work using that as a host address or would flag it > as invalid if you tried to connect to it or a myriad of other > problems. Note that this was a limitation of the host, not anything to > do with the network or any of the network equipment. > > This issue has not existed with any prevelance for quite some time and > almost everything of recent manufacture is quite happy to be assigned > in a supernet as well as on the .0 and .255 addresses. > > So my oppinion is don't hesistate to use it until you find a real, > reproducible problem. > > -Wayne I have seen networks where traffic to these addresses was filtered in an attempt to mitigate broadcast address amplification. Typically, end users filter their inbound Internet traffic to their own addresses. They know they don't use .0 or .255 addresses and they found this is a quick way to prevent any nodes on their internal network from being used as amplifiers without having to audit/fix their entire internal network. As we know, the "workaround" may remain in their edge router(s) long after it has outlived its usefulness. A few years ago, I noticed that an ISP blocked all traffic from its customers bound for any .0 or .255 address to prevent drones from flooding those addresses. I doubt this is typical, but I bet it's still around in at least a few places. If you're seriously considering using these addresses, these are other possible issue you need to consider. DS
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