Virtual Private LAN Services
7750 SR OS Services Guide Page 449
VPLS Broadcast/Multicast/Unknown Flooding List
The IOM includes all VPLS destinations in the egress VPLS Broadcast/Multicast/Unknown
(BMU) flooding list that exist on a single VPLS context. Whenever a broadcast, multicast or
unknown destination MAC is received in the VPLS, the BMU flooding list is used to flood the
packet to all destinations. For normal flooding, care is taken at egress to ensure that the packet is
not sent back to the source of the packet. Also, if the packet is associated with a split horizon
group (mesh or spoke/SAP) the egress forwarding plane will prevent the packet from reaching
destinations in the same split horizon context as the source SAP or SDP-binding.
The VPLS BMU flooding list may contain both egress multicast group SAPs and other SAPs or
SDP bindings as destinations. The egress IOM will separate the egress multicast group SAPs from
the other destinations to create one or more chains. Egress multicast group SAPs are placed into a
chain completely at the discretion of the IOM and the order of SAPs in the list will be
nondeterministic. When more SAPs exist on the VPLS context within the egress multicast group
then are allowed in a single chain, multiple SAP chains will be created. The IOM VPLS egress
BMU flooding list will then contain the first SAP in each chain plus all other VPLS destinations.
The SAPs in the same VPLS context must be in the same split horizon group to allow membership
into the egress multicast group. The split horizon context is not required to be the same between
VPLS contexts.
SAPs within the same VPLS context may be defined in different egress multicast groups, but
SAPs in different multicast groups cannot share the same chain.
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