Bay Networks 58000, Installation And Reference Manual

Page: 74 / 158

Planning a Switched Network
2-36 893-878-B
The Model 58000 switch uses special multicast packets to execute the topology
management process. All Model 58000 switches within a community exchange
topology information using these LattisSpan multicast packets to establish
trunk ports, break loops, and construct topology databases. As router or bridge
connections to the Model 58000 switch are established (using the RJ-45 ports)
the new source addresses are learned and added to the port MAC Store Table
after the new devices send data to the switch.
If Model 58000 switches are connected so that LattisSpan packets from one
Model 58000 switch traverse the internetworking device and reach another
switch, the topology management software reconfigures the associated ports as
trunk ports if these ports are configured in the auto (default) mode.
Because trunk links between connected Model 58000 switches do not
participate in local address learning (only global address learning), the new
source addresses received from the internetworking device therefore are not
learned or stored.
LattisSpan multicast packets must be blocked from passing through
internetworking devices in configurations where devices (such as routers) have
bridging enabled and have multiple Ethernet interfaces. For example, one
interface attaches to one port of the first Model 58000 switch belonging to
community 1, and another interface attaches to a separate port of a second
Model 58000 switch belonging to community 2.
Without filtering the LattisSpan multicast packets across the auto mode ports,
the preceding configuration results in connectivity and communication
protocol-related problems and cannot be supported. However, most
internetworking devices allow you to add static entries to their address tables,
so you can update the tables to discard these LattisSpan multicast packet types
when necessary.
NOTE: Global learning is accomplished by the sharing of station MAC
addresses between connected Model 58000 switches. Local learning is
dynamic learning by an individual Model 58000 switch port of the source
addresses of the frames it receives on that port.
NOTE: The multicast addresses 010081000200 and 010081000201 must
always be discarded or blocked from traversing internetworking devices that
interconnect Model 58000 switch communities.
893-878-B Book Page 36 Monday, May 12, 1997 2:06 PM