Alcatel-Lucent 7750 Configuration Manual page 138

Mixed Port-Speed LAG Support
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Operators can add higher speed member ports to an existing LAG in service when all ports of the
lag have the speed as selected by port-weight-speed or when port-weight-speed is disabled (non-
mixed port-speed operation). To do so, first port-based thresholds related to that LAG should be
switched to weight-based thresholds, and then port-speed-weight should be set to the port speed of
the existing member ports. After that, operators can add higher speed ports adjusting weight-based
thresholds as required.
Similarly, operators can disable mixed port-speed operation in service if all ports have the same
port speed and port-weight-speed equals to member ports' speed. Note that weight-based
thresholds may remain to be in use for the LAG.
Feature limitations:
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to allow common operational model (each port has a weight of 1 to mimic port-threshold
and related configuration).
Similarly to the above, it is recommended that operators use weight-based thresholds for
other system configurations that react to operational change of LAG member ports, like
MCAC (see use-lag-port-weight) and VRRP (see weight-down)
When sub-groups are used, the following behavior should be noted for selection criteria:
→ highest-count – continues to operate on physical link counts. Therefore, a sub-group
with lower speed links will be selected even if its total bandwidth is lower. For
example: a 4 * 10GE subgroup will be selected over a 100GE + 1 GE sub-group).
→ highest-weight – continues to operate on operator-configured priorities. Therefore, it
is expected that configured weights take into account the proportional bandwidth
difference between member ports to achieve the desired behavior. For example, to
favor sub-groups with higher bandwidth capacity but lower link count in a 10GE/
100GE LAG, 100GE ports need to have their priority set to a value that is at least 10
times that of the 10GE ports priority value.
→ best-port – continues to operate on operator-configured priorities. Therefore, it is
expected that the configured weights will take into account proportional bandwidth
difference between member ports to achieve the desired behavior.
requires chassis mode D.
supported on network, access, and hybrid mode LAGs, including MC-LAG.
supported for standard-port LAGs and on 10GE WAN/100GE LAN port combinations.
PIM lag-usage-optimization is not supported and must not be configured.
LAG member links must have the default configuration for config port ethernet egress-
rate/ingress-rate.
not supported on 7450 ESS-6V and 7710 platforms.
not supported for ESM
not supported with weighted per-link-hash
7750 SR Interface Configuration Guide