At 13:15 25/06/96 DST, Antonio_Blasco Bonito wrote:

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.

Of course ! You can use RFC1597 addresses which are routed only in your domain, so that your SNMP managers can reach each Interface. The problem is for somebody from the outside wanting to address the interface (which is frequent with tools like traceroute), who will not see any answers from your routers. Anyway, this is a good solution if you want access to your interfaces only from you domain (and, as a side effect, it increase security on your routers). We are currently using this scheme for our ISDN links. Regards, --

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