3Com 3C15500 - Network Director - PC, User Manual

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Misconfigurations and Optimizations Report 871
If a port connected to a single end station is set to disable , whenever the
attached end station is powered up, the Spanning Tree protocol will treat
this as a topology change event. This results in the Filtering Database
entries being flushed and temporary flooding of traffic occurs until the
addresses are re-learned.
XRN Fabric Setting up VLANS with Distributed Resilient Routing
Distributed Resilient Routing allows the switches in the XRN Distributed
Fabric to act as a single logical router. This provides router resiliency in the
event of failure in one of the interconnected switches.
The loss of a unit in a Distributed Fabric does not affect routing, provided
all units can communicate with each other on all VLANs.
All VLANs must be set up on the Distributed Fabric and surrounding
devices, to ensure that during an interconnect failure units can continue
to communicate with each other.
Configure aggregated links using LACP
Distributed Link Aggregation ensures that all member ports of an
aggregated link distribute the traffic flow across the XRN Distributed
Fabric. This provides resilience and enhanced performance.
If a switch within the Distributed Fabric fails, aggregated links will redirect
all traffic down the link(s) to the unit that is still operating.
The optimal solution is to use LACP aggregated links. The 802.3ad (LACP)
protocol can automatically resolve network loops and increase bandwidth
by automatically creating aggregated links when multiple connections are
detected between two devices. To use LACP, the device connected to the
XRN Distributed Fabric must support LACP, and must be manually
enabled.
Note that manually aggregated links or resilient links are not resilient in
the event of an XRN interconnect module failure. This is because the
device connected to the Distributed Fabric will not be aware that there is
no longer a connection between the units in the Distributed Fabric. The
device will continue to send traffic over both links, resulting in data loss.