Re: .255 and .0 addresses

[Gert Doering <]

hi,

On Sun, Sep 12, 2004 at 08:05:55PM +0300, Volodymyr Yakovenko wrote:
>  I am trying to push one BIG telecom equipment vendor TAC to consider wrong 
>  situation with assignment of IP addresses like xxx.xxx.xxx.0 and 
>  xxx.xxx.xxx.255 from dynamic IP pools bigger than or equal to /24.

Strictly speaking, this is not a software bug.  Inside a larger network,
say a /23 going from .0.0 - .3.255, the "inside" .0 and .255 addresses
are not special, and could be used just fine, just as any other address.

OTOH, in the Internet, a fair number of people are now filtering .0 and
.255 addresses due to the common exploiting of the "smurf" packet
amplifying method.  So the addresses cannot really be used for Internet
connectivity anymore.

We work around that by defining the pools in multiple steps:

ip local pool dial-in-block a.b.52.1 a.b.52.254
ip local pool dial-in-block a.b.53.1 a.b.53.254
ip local pool dial-in-block a.b.54.1 a.b.54.254
ip local pool dial-in-block a.b.55.1 a.b.55.254

that way, "one of the big vendors"' equipment will not assign .0 and
.255 out of the pool.

Gert Doering
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