Design Reference

Table 16: Path cost for RSTP or MSTP mode
Link speed Recommended path cost
Less than or equal 100 Kbps 200 000 000
1 Mbps 20 000 000
10 Mbps 2 000 000
100 Mbps 200 000
1 Gbps 20 000
10 Gbps 2000
100 Gbps 200
1 Tbps 20
10 Tbps 2
802.3ad-based link aggregation
Link aggregation provides link layer redundancy. Use IEEE 802.3ad-based link aggregation (IEEE
802.3 2002 clause 43) to aggregate one or more links together to form LAGs to allow a MAC client
to treat the LAG as if it were a single link. Use link aggregation to increase aggregate throughput of
the interconnection between devices and provide link redundancy. LACP can dynamically add or
remove LAG ports, depending on their availability and states.
Although IEEE 802.3ad-based link aggregation and MLT provide similar services, MLT is statically
defined. By contrast, IEEE 802.3ad-based link aggregation is dynamic and provides additional
functionality.
LACP and MLT
When you configure standards-based link aggregation, you must enable the aggregatable
parameter. This configuration creates a one-to-one mapping between the LACP aggregator and the
specified MLT.
A newly created MLT or LAG adopts the VLAN membership of its member ports after the first port
attaches to the aggregator associated with this LAG. After a port detaches from an aggregator, the
port is deleted from the associated LAG port member list. After the last port member is deleted from
the LAG, the LAG is deleted from all VLANs.
After you configure the MLT as aggregatable, you cannot add or delete ports or VLANs manually.
To enable tagging on ports that belong to a LAG, first disable LACP on the port, enable tagging on
the port, and then enable LACP.
Important:
Enabling Intermediate System to Intermediate System (IS-IS) is not supported on LACP-based
MLT.
802.3ad-based link aggregation
December 2014 Network Design Reference for Avaya VSP 4000 Series 43
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