Alcatel-Lucent 9500 MXC User Manual page 157

3DB 23063 ADAA - Rev 004 July 2007
• Normally (default), the 16 LAKs are split evenly, or near-even for an
odd-number split, between the aggregated channels and/or ports. For
example where two channels are configured for link aggregation 8 LAKs are
assigned to each; for two channels and one port, 6 LAKs are assigned to the
port and 5 to each of the channels.
• CT provides a tool to customize this splitting of LAKs between channels and
ports, which has particular application where links of different capacities are
used. For example to provide even (near even) load balancing between a 300
Mbps link and a 150 Mbps link, 10 LAKs can be assigned to the 300 Mbps
link, and 6 to the 150 Mbps link. The number of LAKs assigned must always
total 16.
• In this way two, three, or four links may be link-aggregated to provide an
aggregated maximum up to1000 Mbps.
• L2 link aggregation is enabled within the DAC GE Operational Mode
settings.
• L1 link aggregation uses the circuit cross-connects on the INU/INUe backplane
bus to split DAC GE transport channel traffic between two separate links.
• Ethernet traffic is split equally between the link timeslots on a byte basis
(parallel bus) meaning data within an Ethernet frame is transported across
both links.
• Links do not need to be configured for equal capacity.
• Compared to L2 aggregation it provides optimum payload balance
regardless of the throughput demands of individual user connections.
Whether there is one, a few or many concurrent sessions, traffic is always
split between the links based on the configured capacity of the links.
• In the event one link is lost its traffic is assigned to the remaining link.
• One or both DAC GE transport channels can be configured for L1 link
aggregation.
L2 and L1 link aggregation can be deployed in tandem. For example where two
DAC GEs are used to support four co-path links, L1 aggregation can be used for
transport channel aggregation, and L2 for aggregating the traffic between the
DAC GEs.
For applications where just two physical links are to be aggregated L1
aggregation is recommended as it supports equitable loading (load balancing)
regardless of the number of data sessions in play. It also supports higher burst
speeds compared to L2 aggregation.
For more information on aggregation refer to Link Aggregation on page 7-76,
Volume IV, Chapter 7.
9500 MXC User Manual
Vol. II-3-63