Lag; Lacp - Alcatel-Lucent 7750 Configuration Manual

LAG

LAG
Based on the IEEE 802.1ax standard (formerly 802.3ad), Link Aggregation Groups (LAGs) can be
configured to increase the bandwidth available between two network devices, depending on the
number of links installed. LAG also provides redundancy in the event that one or more links
participating in the LAG fail. All physical links in a given LAG links combine to form one logical
interface.
Packet sequencing must be maintained for any given session. The hashing algorithm deployed by
Alcatel-Lucent routers is based on the type of traffic transported to ensure that all traffic in a flow
remains in sequence while providing effective load sharing across the links in the LAG.
LAGs must be statically configured or formed dynamically with Link Aggregation Control
Protocol (LACP). The optional marker protocol described in IEEE 802.1ax is not implemented.
LAGs can be configured on network and access ports.
The LAG load sharing is executed in hardware, which provides line rate forwarding for all port
types.
SR OS LAG implementation supports LAG that with all member ports of the same speed and
LAG with mixed port-speed members (see later section for details).
SR OS LAG implementation is supported on access and network interfaces.

LACP

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 (for example, all links on the same IOM) 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 802.1ax standard so interoperability is ensured.
To use LACP on a given LAG, operator must enable LACP on the LAG including, if desired,
selecting non-default LACP mode: active/passive and configuring administrative key to be used
(configure lag lacp). IN addition an operator can configure desired LACP transmit interval
(configure lag lacp-xmit-interval).
When LACP is enabled, an operator can see LACP changes through traps/log messages logged
against the LAG. See TIMETRA-LAG-MIB.mib for more details.
Page 110 7750 SR Interface Configuration Guide