Present disclosure relates to methods for preparing BGP update messages for transmission and processing received update messages. The methods are based on grouping path attributes common to a plurality of IP address prefixes into respective sets identified with respective set identifiers and, instead of duplicating path attributes in each BGP update message, including a respective identifier referring to a certain set of path attributes provided in an earlier BGP update message when sending subsequent update messages. Grouping of path attributes into individual sets associated with respective identifiers provides significant advantages by enabling re-use of the results of previous processing on both the sending and receiving sides associated with transmission of BGP update messages. In addition, such an approach limits the amount of information transmitted in the control plane because duplicate sets of path attributes may only be transmitted once and merely be referred to in subsequent update messages.