Planning a Switched Network
2-16
893-878-B
Address Tables in Multiple Model 58000 Switches on the Same Network
As stated earlier, each Model 58000 switch can store 1024 addresses per virtual
LAN. Addresses are shared and distributed between connected Model 58000
switches across trunk links in a process called global address learning. When a
trunk link is used to connect the Model 58000 switches, global address learning
between the hubs is automatic.
Global address learning (where the station MAC addresses for all the devices
attached to the Model 58000 switch are shared between the switches) is
activated every time a trunk link to another Model 58000 switch is established.
The master switch in a switch community will, upon receipt of a LattisSpan
frame from the newly connected Model 58000 switch, begin the spanning tree
process to establish primary paths between all the switches in the community.
It will also redistribute all addresses learned by the switches throughout the
community. Once the switch completes the spanning tree process, it can
participate in the LattisSpan global address learning process.
If more than one trunk link exists between two Model 58000 switches, the
LattisSpan protocol automatically designates one trunk as active and the other
as standby. The active and standby links of a Model 58000 switch are
determined according to the speed of the trunk link and the priorities of the
ports that support the trunk links.
If trunk links are operating at different speeds, the trunk link operating at the
higher speed is designated the active link because faster links have priority over
slower links. If both trunk links are operating at the same speed, a full-duplex
link has priority over a half-duplex link. If the link speeds and duplex modes
are the same for each link, the link connected to the port with the highest
priority is designated the active link.
Under normal network conditions, standby trunk link connections are in
blocking state and only forward LattisSpan frames that are used as part of the
topology process.
CAUTION:
When the network topology changes (for example, when a new
switch is added to the community, a new trunk link is established, or a trunk
link is disconnected or fails), all the switches in a community transition from
an “operational” state to a “configuring” state for a time ranging from 20 to
120 seconds. During this time, the switch uses a topology reconfiguration
process (LattisSpan convergence process) to construct a loop-free topology
and share virtual LAN information. The Model 58000 switch does not forward
any frames during the LattisSpan convergence process.
893-878-B Book Page 16 Monday, May 12, 1997 2:06 PM
Summary of Contents for 58000
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