4. BGP-IV protocol developments

4.1 COMMUNITIES attribute (code 8)

The BGP protocol enables routing policies to be applied to transit traffic (traffic passing through an autonomous system), thanks to a controlled distribution of routing information, based essentially on IP addresses (prefixes) and the value recorded in the AS_PATH attribute conveyed in the UPDATE message.

To simplify the control of routing information, the [RFC-1997] document introduces the notion of "destination group", a group for which a homogeneous routing policy (for all the prefixes making up this group) can be applied. In this context, a community is a group of destinations (prefixes) which share a common characteristic, such as being addresses whose...