Just to add a comment. Some people confuse it, including me sometimes... :-) Even a router or a system with Classfull (without CIDR) the address z.y.x.0 or z.y.x.255 can be considered valid host addresses. For instance, if you have a class B 128.3.0.0 (CIDR equivalent of 128.3.0.0/16) The addresses: 128.3.10.0 is a valid host address 128.3.10.255 is a valid host address But using class C, the .255 and .0 are invalid host addresses. Good reference at: http://tools.ietf.org/html/rfc4632 Cheers, Claus T >All major vendors support 0 and 255 as loopback in the last octet. o if >you >are using J or C for instance, your safe. If you use an obscure >small vendor, >the choice to use 0 and 255 can come back and bite >you in the ***. >Cheers >Patrik >Mark Tinka wrote: > On Saturday 28 February 2009 06:31:15 pm Cougar wrote: > >> What kind of exception is this? In CIDR world you can use any address >> you like except first and last _LAN_ addresses when netmask is /30 or >> less. With /31 and /32 can use any address and so far I haven't seen >> any problems using x.x.x.0 or x.x.x.255 in Junipers. > > That may very well be - but my suggestion is just because it can be > done, doesn't mean it's a great idea "all around". > These are the types of practices that come back and bite you due to > varying levels of support for implementing .0 and > .255 across various pieces of software. I'm not presuming the OP has > only Junipers to deal with in their network. > > Given the number of addresses one may potentially save in, say, a /24 > sliced only for Loopbacks vs. not getting stressed by why this may > break some things in the network; I'd much rather sacrifice those two > addresses, thank-you- very-much. > > Keep it simple, keep it stupid, keep it unambiguous. The physics don't > change, just how you apply them. > > Then again, to each his own... > > You probably want to spend some time wading through: > > http://tinyurl.com/dzw4cj > http://tinyurl.com/av8rwm > http://tinyurl.com/chwjms > > Mark. > > > ---------------------------------------------------------------------- > -- > > _______________________________________________ > juniper-nsp mailing list juniper-nsp@puck.nether.net > https://puck.nether.net/mailman/listinfo/juniper-nsp
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