CIDRAdvisor examines the address prefixes of <as-no> and the polices registered in the IRR and identifies aggregates that do not violate any policy constraints. If <as-no> is not specified it is deduced for your system from the IP address of your host and IRR. The amount of policy and topology considered by the tool in forming the aggregates is configurable as described below.
The tool computes aggregates that can be safely advertised by an AS to each of its neighbours. An AS encountered during the computation of the aggregates for a particular neighbour AS, X is said to be at distance k if it is k AS hops away from X (considering the shortest path from that AS to X that does not go through the aggregator). Note that X is at distance 0 from itself by the above definition. The tool can be made to examine policies of only those ASes within distance k from the neighbour X (in addition to examining the aggregator's policies) by setting a parameter called radius to k.
The definition of radius has been extended to contain -1 and -2. For radius -1, only the aggregator's policies are examined while for radius -2 policies are not examined in forming the aggregates. A radius of infinity is denoted as -3 in which case the policies of all the ASes in the Internet are examined.
If the address prefixes of the aggregator AS that can be aggregated are multihomed then for each such address prefix the program asks the user if it should be included in the aggregate. If it can be included the user must type 'y' in response to that question otherwise it is not considered for aggregation. An option is provided to include all such multihomed address prefixes in the aggregates. In the case of proxy aggregation it ensures that the address prefixes being proxy aggregated are reachable only through paths via the proxy aggregator. This is so that there are no policy violations by the formed aggregates due to longest match routing.
The program outputs the best possible aggregation that can be done with the given address prefixes. In addition it prints for each neighbour the aggregates that can be advertised to it without violating the policy constraints of ASes within the specified radius .
Command line options take precedence over environment variables.
% CIDRAdvisor -as AS226 -radius -1 196.2.40.0/24 Origins: AS174 AS1220 AS226 Can the address be aggregated?y 196.2.41.0/24 Origins: AS174 AS1220 AS226 Can the address be aggregated?y Best possible aggregation: 196.2.40.0/23 Components: 196.2.40.0/24 ( AS226 ) 196.2.41.0/24 ( AS226 ) 198.178.204.0/23 Components: 198.178.204.0/24 ( AS226 ) 198.178.205.0/24 ( AS226 ) 199.249.180.0/23 Components: 199.249.180.0/24 ( AS226 ) 199.249.181.0/24 ( AS226 ) AS226->AS2150 196.2.40.0/23 198.178.204.0/23 199.249.180.0/23 % CIDRAdvisor -as AS5400 -proxy AS1922,AS2605,AS1902 -radius -3 Best possible aggregation: 192.108.132.0/22 Components: 192.108.132.0/22 ( AS1922 ) 192.108.134.0/24 ( AS2605 ) 192.108.135.0/24 ( AS1902 ) . . . AS5400->AS2611 192.108.134.0/23 . . .
Connection to IRR host failed. This can be caused by various reasons, see Errors manpage, IRR Communication errors.
Warning: No autnum record found for AS
Aut-num object for <source_as> cannot be found on specified IRR for specified source(s). You might mistype the source, host or AS-number, or the object is non-existent.