A BGP route for a specific NLRI is distinguished from other BGP routes for the same NLRI by its set of path attributes. Each path attribute is encoded as a TLV in the Path Attributes field of the Update message, and describes a property of the path. The type field of the TLV identifies the path attribute and the value field carries data specific to the attribute type.
The 7210 SAS supports the following path attributes:
ORIGIN (well-known mandatory)
AS_PATH (well-known mandatory)
NEXT_HOP (well-known; required only in Update messages that have IPv4 prefixes in the NLRI field); see Next-hop indirection for information about the NEXT_HOP attribute
MED (optional non-transitive)
LOCAL_PREF (well-known; required only in Update messages sent to iBGP peers)
ATOMIC_AGGR (well-known discretionary)
AGGREGATOR (optional transitive)
COMMUNITY (optional transitive)
ORIGINATOR_ID (optional non-transitive)
CLUSTER_LIST (optional non-transitive)
MP_REACH_NLRI (optional non-transitive)
MP_UNREACH_NLRI (optional non-transitive)
EXT_COMMUNITY (optional transitive)
AS4_PATH (optional transitive)
AS4_AGGREGATOR (optional transitive)
CONNECTOR (optional transitive)
PMSI_TUNNEL (supported only on platforms that support NG-MVPN with BGP signaling; see the 7210 SAS Software Release Notes 22.x.Rx for more information about NG-MVPN with BGP signaling).