table of contents
AGGREGATE(1) | General Commands Manual | AGGREGATE(1) |
NAME¶
aggregate - optimise a list of route prefixes to help make nice short filtersSYNOPSIS¶
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 prefix. 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 combined 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
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
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 <jabley@mfnx.net>, and has been reasonably well tested. It is suitable for reducing customer prefix filters for production use without extensive hand-proving of results.BUGS¶
Common unix parsing of IPv4 addresses understands the representation of individual octets in octal or hexadecimal, following a "0" or "0x" prefix, respectively. That convention has been deliberately disabled here, since resources such as the IRR do not follow the convention, and confusion can result.2001 November 2 | Joe Abley |