This field controls the operation of the alternative local AS number specified by the bgpPeergrConfAltLocalAs field for peers in this peer group. It has no effect unless bgpPeergrConfAltLocalAs specifies a valid non-zero value. This field controls the use of the alternative local AS number in the following BGP operations: - establishing the peering session - updating the AS_PATH when importing a route received from the peer (EBGP only) - updating the AS_PATH when exporting a route to the peer (EBGP only). These operations are described in full in the BGP Configuration and Management Guide (bgp_config_mgmt.doc) and summarized in the following table. Mode |Session |AS_PATH In|AS_PATH Out ============+==========+==========+================== Standard BGP|Primary AS|- |Primary AS Mode 1 |Either |- |Selected As Mode 2 |Alt AS |Alt AS |Alt AS, Primary AS Mode 3 |Alt AS |- |Alt AS, Primary AS Mode 4 |Alt AS |- |Alt AS. This field can be changed at any time. However, if a peer is configured to use the peer group field and the field is changed while the peer is active, depending on the setting of the bgpPeergrResetPeerOnCfgChange field, the peer session may either be immediately reset, or the configuration change is not applied until the peer session is restarted.