Please help: ptp links addresses

Dear Local Registries,


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:
   in this way both ends of the link have a unique address (binary
   01 and 10), but two addresses (binary 00 and 11) cannot be used,
   so 50% of the address space used is wasted. This should be
   avoided if possible because the address space required is
   really large.

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? 

Thank you very much in advance.

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Antonio-Blasco Bonito                          E-Mail: bonito at nis.garr.it
GARR - Network Information Service      c=it;a=garr;p=garr;o=nis;s=bonito
c/o CNUCE - Istituto del CNR                           Tel: +39 50 593246
Via S. Maria, 36                                       Fax: +39 50 904052
I-56126 PISA                                        Telex: 500371 CNUCE I
Italy                   Url: http://www.nis.garr.it/nis/staff/bonito.html
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