On 2012-06-12, at 04:14, Jamie Baddeley wrote:
ISTR a tool that some dodgy geezer called jabley wrote years ago called "aggregate" or "aggregate-ios" that might help. Rumour has it he lurks on this list so he might be able to expound it's virtues.
I dare say Joe might insist using things like awk or sed to help with parsing the input file or something.
aggregate-ios was in fact once an awk script. But then Michael Shields at AboveNet re-wrote it in perl. aggregate is written in C, though, which you'd think would make it fast and efficient. You'd think.
ftp://ftp.isc.org/isc/aggregate/aggregate-1.6.tar.gz
Joe
AGGREGATE(1) AGGREGATE(1)
NAME
aggregate - optimise a list of route prefixes to help make nice short
filters
SYNOPSIS
aggregate [-m max-length] [-o max-opt-length] [-p default-length] [-q]
[-t] [-v]
DESCRIPTION
Takes a list of prefixes in conventional format on stdin, and performs
two optimisations to attempt to reduce the length of the prefix list.
The first optimisation is to remove any supplied prefixes which are
superfluous because they are already included in another supplied pre-
fix. For example, 203.97.2.0/24 would be removed if 203.97.0.0/17 was
also supplied.
The second optimisation identifies adjacent prefixes that can be com-
bined under a single, shorter-length prefix. For example, 203.97.2.0/24
and 203.97.3.0/24 can be combined into the single prefix 203.97.2.0/23.
OPTIONS
-m max-length
Sets the maximum prefix length for entries read from stdin
max_length bits. The default is 32. Prefixes with longer lengths
will be discarded prior to processing.
-o max-opt-length
Sets the maximum prefix length for optimisation to max-opt-
length bits. The default is 32. Prefixes with longer lengths
will not be subject to optimisation.
-p default-length
Sets the default prefix length. There is no default; without
this option a prefix without a mask length is treated as
invalid. Use -p 32 -m 32 -o 32 to aggregate a list of host
routes specified as bare addresses, for example.
-q Sets quiet mode -- instructs aggregate never to generate warning
messages or other output on stderr.
-t Silently truncate prefixes that seem to have an inconsistent
prefix: e.g. an input prefix 203.97.2.226/24 would be truncated
to 203.97.2.0/24. Without this option an input prefix
203.97.2.226/24 would not be accepted, and a warning about the
inconsistent mask would be generated.
-v Sets verbose mode. This changes the output format to display the
source line number that the prefix was obtained from, together
with a preceding "-" to indicate a route that can be suppressed,
or a "+" to indicate a shorter-prefix aggregate that was added
by aggregate as an adjacency optimisation. Note that verbose
output continues even if -q is selected.
DIAGNOSTICS
Aggregate exits 0 on success, and >0 if an error occurs.
EXAMPLES
The following list of prefixes:
193.58.204.0/22
193.58.208.0/22
193.193.160.0/22
193.193.168.0/22
193.243.164.0/22
194.126.128.0/22
194.126.132.0/22
194.126.134.0/23
194.151.128.0/19
195.42.240.0/21
195.240.0.0/16
195.241.0.0/16
is optimised as followed by aggregate (output shown using the -v flag):
aggregate: maximum prefix length permitted will be 24
[ 0] + 193.58.204.0/21
[ 1] - 193.58.204.0/22
[ 2] - 193.58.208.0/22
[ 3] 193.193.160.0/22
[ 4] 193.193.168.0/22
[ 5] 193.243.164.0/22
[ 0] + 194.126.128.0/21
[ 6] - 194.126.128.0/22
[ 7] - 194.126.132.0/22
[ 8] - 194.126.134.0/23
[ 9] 194.151.128.0/19
[ 10] 195.42.240.0/21
[ 0] + 195.240.0.0/15
[ 11] - 195.240.0.0/16
[ 12] - 195.241.0.0/16
Note that 193.58.204.0/22 and 193.58.208.0/22 were combined under the
single prefix 193.58.204.0/21, and 194.126.134.0/23 was suppressed
because it was included in 194.126.132.0/22. The number in square
brackets at the beginning of each line indicates the original line num-
ber, or zero for new prefixes that were introduced by aggregate.
The output without the -v flag is as follows:
193.58.204.0/21
193.193.160.0/22
193.193.168.0/22
193.243.164.0/22
194.126.128.0/21
194.151.128.0/19
195.42.240.0/21
195.240.0.0/15
SEE ALSO
aggregate-ios(1)
HISTORY
Aggregate was written by Joe Abley