Colt implements community marking on it's network to control the announcement of routes and hence flow of traffic into and out of the network. Customers can set some of these communities on prefixes announced to Colt.
Advertisements to Colt Peers
Using the following format 8220:63aee a customer can control how their routes are advertised to peers.
Possible values for a:
|0||Do not advertise.|
|2||Prepend 8220 8220.|
|3||Prepend 8220 8220 8220.|
Possible values for ee:
|92||All Upstreams.||99||All Upstreams and Peers|
For example setting 8220:63008 on an advertised route will not announce that route to all peers in Amsterdam and setting 8220:63210 will prepend 8220 8220 on the route to all peers in Zurich.
The following communities allow a customer to blackhole or not advertise a prefix.
|8220:63099||Do not advertise to any peer.|
|8220:63999||Blackhole all traffic. Can be exact customer prefix or /32 host route.|
The following communities allow a customer to set a local preference on an advertised prefix. It is useful for a customer with multiple connections to Colt or other providers. The default local preference set on all received customer routes is 111.
|8220:63700||Set local preference to 120.|
|8220:63600||Set local preference to 110.|
|8220:63900||Set local preference to 40.|