Protocols And Standards; Configuration Restrictions And Guidelines - HP 6125XLG Trill Configuration Manual

Figure 4 Multicast ECMP
RB 1
TRILL distribution trees support Equal Cost Multiple Path (ECMP), also known as multicast ECMP. When
multicast ECMP is enabled, TRILL assigns equal-cost links to different TRILL distributions trees. This
improves the load sharing performance.
When N equal-cost links exist in the network, each TRILL distribution tree selects an equal-cost link for
forwarding packets through J mod N in root bridge priority order. J is the priority sequence number of a
TRILL distribution tree and starts from 0.
As shown in
• The link directly connecting RB 1 to RB 3 is assigned to the TRILL distribution tree rooted at RB 3.
The link RB 1-RB 2-RB 3 is assigned to the TRILL distribution tree rooted at RB 4.
•
TRILL distribution trees support fast switching the roots. When an RB finds that the root of a distribution
tree is unreachable based on the unicast route calculation, the RB actively ages out the LSPs of the root
in the LSDB, and triggers the TRILL network to recalculate the multicast route information. This feature
makes sure multicast, broadcast, and unknown unicast traffic can be fast switched to the newly calculated
distribution tree.

Protocols and standards

RFC 6325, Routing Bridges (RBridges): Base Protocol Specification
•
RFC 6326, Transparent Interconnection of Lots of Links (TRILL) Use of IS-IS
•
RFC 6327, Routing Bridges (RBridges): Adjacency
•
RFC 1 195, Use of OSI IS-IS for Routing in TCP/IP and Dual Environments
•

Configuration restrictions and guidelines

When you configure TRILL, follow these restrictions and guidelines:
Configuration in Layer 2 Ethernet interface view takes effect on only the current port. Configuration
•
in Layer 2 aggregate interface view takes effect on the current interface and its member ports.
Configuration on the member port of an aggregate interface takes effect after the member port
leaves the aggregation group.
To connect a common Layer 2 network to a TRILL network, enable the spanning tree protocol on the
•
common Layer 2 network and disable the spanning tree protocol on the TRILL network. For more
information about spanning tree protocols, see Layer 2—LAN Switching Configuration Guide.
RB 2
Cost = 1
Figure 4:
RB 3
5
RB 4