H3C S6800 Series Configuration Manual page 10

•
The maximum number of TRILL distribution trees that the RB can compute (this number is fixed
at 15).
•
The number of TRILL distribution trees that the RB has computed.
•
The priority for the RB to be a TRILL distribution tree root.
Each RB can compute a maximum of m TRILL distribution trees. An RB determines the number of
TRILL distribution trees to compute (n) by selecting the lower value from the following values:
•
The number of TRILL distribution trees that the highest-priority RB wants all RBs to compute.
•
The smallest m value across the TRILL network.
The RB selects the first n nicknames from the nickname list advertised by the highest-priority RB.
The RB uses the selected nicknames as the root nicknames for computing distribution trees.
An ingress RB assigns a TRILL distribution tree to each forwarding VLAN (VLAN that uses the RB as
the AVF) for multidestination frame forwarding. As shown in
VLAN 10 enters the TRILL network, RB 1, which is an ingress RB, encapsulates the multicast frame
into a TRILL frame. In the frame, the egress RB is RB 2, which is the root bridge of the TRILL
distribution tree for VLAN 10, and the destination MAC address is multicast address
0180-C200-0040. When the frame arrives at the root bridge, it is distributed throughout the TRILL
distribution tree. Then, the TRILL frame is de-encapsulated by RB 3 and sent to the destination
station S2. Because the network segment where RB 4 resides does not have a receiver of this frame,
RB 4 drops the frame.
Figure 3 Layer 2 multicast frame forwarding flow
S1
RB 1
VLAN 10
Inner D-MAC = Multi
Inner S-MAC = S1
Inner VLAN = 10
Payload
Ethernet frame
Multicast frame
RB 4
VLAN 200
TRILL network
RB 2
Outer D-MAC = All RBs
Outer S-MAC = RB 1
Outer VLAN = 200
Egress RB = RB 2
Ingress RB = RB 1
Inner D-MAC = Multi
Inner S-MAC = S1
Inner VLAN = 10
Payload
TRILL frame
Distribution tree
of VLAN 10
4
Figure 3, when a multicast frame from
RB 3
Outer D-MAC = All RBs
Outer S-MAC = RB 2
Outer VLAN = 200
Egress RB = RB 2
Ingress RB = RB 1
Inner D-MAC = Multi
Inner S-MAC = S1
Inner VLAN = 10
Payload
TRILL frame
Root bridge of
distribution tree
S2
VLAN 10
Inner D-MAC = Multi
Inner S-MAC = S1
Inner VLAN = 10
Payload
Ethernet frame
Leaf of
distribution tree