Port Link Damping; Lacp - Alcatel-Lucent 7210 SAS M Interface Configuration Manual

Mbps. The advantage of this method over a scheme where the PIR is divided equally among all
the member ports of the LAG is that, a single flow can uses the entire SLA. The disadvantage is
that the overall SLA can be exceeded if the flows span multiple ports.

Port Link Damping

Hold time controls enable port link damping timers that reduce the number of link transitions
reported to upper layer protocols.
The 7210 SAS OS port link damping feature guards against excessive port transitions. Any initial
port transition is immediately advertised to upper layer protocols, but any subsequent port
transitions are not advertised to upper layer protocols until a configured timer has expired.
An "up" timer controls the dampening timer for link up transitions, and a "down" timer controls
the dampening timer for link down transitions.

LACP

Generally, link aggregation is used for two purposes: provide an increase in bandwidth and/or
provide redundancy. Both aspects are addressed by aggregating several Ethernet links in a single
LAG.
Under normal operation, all non-failing links in a given LAG will become active and traffic is load
balanced across all active links. In some circumstances, however, this is not desirable. Instead, it
desired that only some of the links are active and the other links be kept in stand-by condition.
LACP enhancements allow active lag-member selection based on particular constrains. The
mechanism is based on the IEEE 802.3ax standard so interoperability is ensured.
Active-Standby LAG Operation without LACP
Active/standby LAG is used to provide redundancy while keeping consistency of QOS
enforcement. Some devices do not support LACP and hence an alternative solution is required.
The active/standby decision for LAG member links is local decision driven by pre-configured
selection-criteria. This decision was communicated to remote system using LACP signalling.
As an alternative, the operator can disable the signal transmitted by using power-off option for
standby-signalling in the CLI command at the LAG level at the port member level. As a
consequence, the transmit laser will be switched off for all LAG members in standby mode. On
7210 SAS M, T, X, R6, R12, Mxp Interface Configuration Guide
Interface Configuration
Page 39