[[nsp] 127.0.0.0/8 unroutable?]

[joshua sahala]

Hank Nussbacher <hank at att.net.il> wrote:

> IOS 12.0(25)S2:
> 
> ip route 10.0.0.0 255.0.0.0 FastEthernet1/0/0
> ip route 127.0.0.0 255.0.0.0 FastEthernet1/0/0
> 
> TAU-gp1#sho ip rou 127.0.0.0
> % Network not in table
> TAU-gp1#sho ip rou 10.0.0.0
> Routing entry for 10.0.0.0/8
>    Known via "static", distance 1, metric 0 (connected)
>    Redistributing via ospf 378
>    Routing Descriptor Blocks:
>    * directly connected, via FastEthernet1/0/0
>        Route metric is 0, traffic share count is 1
> 
> Something magical that 127.0.0.0/8 can't be statically routed?
> 
> -Hank

from rfc1700:
(g)   {127, <any>}

         Internal host loopback address.  Should never appear outside
         a host.

from rfc 3330:
127.0.0.0/8 - This block is assigned for use as the Internet host
   loopback address.  A datagram sent by a higher level protocol to an
   address anywhere within this block should loop back inside the host.
   This is ordinarily implemented using only 127.0.0.1/32 for loopback,
   but no addresses within this block should ever appear on any network
   anywhere [RFC1700, page 5].

so in this case, it looks like cisco is following the rfc ;)

/joshua

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