Please help: ptp links addresses

On Tue, 25 Jun 1996, Antonio_Blasco Bonito wrote:

> I need some advice on the following:
> 
> An italian ISP, which we run its delegated LIR, is planning its
> backbone network where there are *A LOT* of point-to-point links (on
> leased lines, on channelized lines, on Frame Relay PVCs, etc.).
> 
> I know about two ways of managing the links in terms of IP addresses:
> 
> 1- using a /30 subnet for each link:
[...]

> 2- using unnumbered interfaces for each link and, on cisco routers,
>    associating another interface IP address (the loopback interface
>    is quite useful for this purpose):
>    in this way addresses are not wasted but certain functionalities
>    are lost, i.e. SNMP monitoring of each physical interface, etc.
> 
> Are you aware of any other way to deal with this issue so that it
> is possible to have IP addresses for each interface without wasting
> address space? 

Hmm... I tried to do the following... it makes a bit sense to me, but my 
Cisco didn't like it (makes more sense if it rfc1918 address space). I 
took a quick glance at RFC1812 as well, but it didn't give a solution.

interface s0
  ip unnumbered e0
  ip addr 193.88.45.1 255.255.255.252 secondary

What happened though, was that the traffic looped between the two
interfaces.

What would be the good about this solution was that on a traceroute it
would still map back to a host in your domain, but you can still ping/SNMP
to the interface. 

So if someone has a good contact at Cisco, please ask them if they'd 
consider adding this to the code in the future. :-)

-- Robert Martin-Legène (RM59), Network Manager (AS2109)
   DKnet, Fruebjergvej 3, DK-2100 København Ø, Denmark, +45 39 17 99 00