Alcatel-Lucent 7750 SR OS Service Manual page 348

VPLS Features
Adding a SAP to a Chain
A SAP must meet all the following conditions to be chained in a VPLS BMU flooding list:
1. The SAP is successfully defined as an egress multicast group member
2. The SAP is not currently an egress mirror source
Further, a SAP must meet the following conditions to be chained in an egress IP multicast (s,g)
Flooding List:
1. The SAP is participating in IGMP snooping
2. A static or dynamic join to the (s,g) record exists for the SAP or the SAP is defined as a mul-
ticast router port
Note: While an operationally down SAP is placed into replication chains, the system ignores that
SAP while in the process of replication.
Based on the egress multicast group and the native or alien nature of the SAP in the list, a set of
chains are selected for the SAP. The IOM will search the chains for the first empty position in an
existing chain and place the SAP in that position. If an empty position is not found, the IOM will
create a new chain with that SAP in the first position and add the SAP to the flooding list to
represent the new chain.
Removing a SAP from a Chain
A SAP will be removed from a chain in a VPLS BMU flooding list or egress IP multicast (s,g)
flooding list for any of the following conditions:
1. The SAP is deleted from the VPLS instance
2. The SAP is removed from the egress multicast group of which it was a member
3. The SAP is defined as an egress mirror source
Further, a SAP will be removed from an egress IP multicast (s,g) flooding list for the following
conditions:
1. IGMP snooping removes the SAP as an (s,g) destination or the SAP is removed as a multi-
cast router port
When the SAP is only being removed from the efficient multicast replication function, it may still
need to be represented as a stand alone SAP in the flooding list. If the removed SAP is the first
SAP in the list, the second SAP in the list is added to the flooding list when the first SAP is de-
chained. If the removed SAP is not the first SAP, it is first de-chained and then added to the
flooding list. If the removed SAP is the only SAP in the chain, the chain is removed along with
removing the SAP from the flooding list.
Page 348 7750 SR OS Services Guide