Virtual Private LAN Services
7750 SR OS Services Guide Page 485
Each of the FEC fields are designed as a sub-TLV equipped with its own type and length
providing support for new applications. To accommodate the BGP AD information model the
following FEC formats are used:
• AGI (type 1) is identical in format and content with the BGP extended community
attribute used to carry the VPLS-ID value.
• Source AII (type 1) is a 4 bytes value destined to carry the local VSI-id (outgoing NLRI
minus the RD).
• Target AII (type 1) is a 4 bytes value destined to carry the remote VSI-ID (incoming NLRI
minus the RD).
BGP-AD and Target LDP (T-LDP) Interaction
BGP is responsible for discovering the location of VSIs that share the same VPLS membership.
LDP protocol is responsible for setting up the pseudowire infrastructure between the related VSIs
by exchanging service specific labels between them.
Once the local VPLS information is provisioned in the local PE, the related PEs participating in
the same VPLS are identified through BGP AD exchanges. A list of far end PEs is generated and
will trigger the creation, if required, of the necessary T-LDP sessions to these PEs and the
exchange of the service specific VPN labels. The steps for the BGP AD discovery process and
LDP session establishment and label exchange are shown in Figure 78 below.
To Next Page
Loading...
