Prefix list formats: advice needed

Sun Jan 14 22:12:46 UTC 2007

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Howdy.  For a tool we're writing, we need to be able to accept lists  
of prefixes people might want to BGP advertise.

We'd like to be "liberal in what we accept" and recognize lists  
formatted in as many ways as people think they might reasonably  
have.  There are some obvious ones:

   - Delimited lists of CIDR-format addresses.  This would include  
addresses in "slash" notation, with some punctuation or whitespace  
between them.  That would cover a lot of hand-typed and tool- 
generated lists, as well as Juniper-format prefix lists.

   - One-address-per-line, CIDR-format, with other non-address stuff  
in the line.  This would include Cisco ip prefix-list format, most  
IRR whois, and some RIR whois.

   - One-address-per-line, with separate address mask in normal order  
(ones values on the left, zeros values on the right), with other non- 
address stuff in the line, some of which might look like more  
addresses.  This would include Cisco ip route statements.

   - One-address-per-line, with separate address mask in reverse  
order (zeros values on the left, ones values on the right), with  
other non-address stuff in the line, some of which might look like  
more addresses.  This would include Cisco ip access-list statements.

   - Address-ranges, characterized by a starting address and an  
ending address, perhaps with a hyphen between them.  This would  
include many older RIR whois entries.

Can anyone think of any other formats people are likely to have lists  
of prefixes in?

Thanks much,

                                        -Bill

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