LattisSpan Protocol
893-878-B
2-7
Address Learning in Communities with Multiple Virtual LANs
In networks where more than one virtual LAN exists, the following learning
scenarios apply:
•
If the Model 58000 switch receives a unicast frame for a destination end
station whose address has not yet been learned (but the source address of
the station from which the frame originated has been learned), the switch
broadcasts the frame to all other ports in the same virtual LAN as the
source address.
•
If the Model 58000 switch receives a unicast frame for a destination end
station whose address has not yet been learned and the source address of
the station where the frame originated is still unknown (that is, has not
been learned), the first frame(s) is dropped. However, the source address is
learned soon after the first frame is received; therefore, the frames that are
received after the first frame address is learned are not dropped.
LattisSpan Protocol
This section briefly discusses the LattisSpan switch topology management
protocol used by the Model 58000 switch and describes how the LattisSpan
protocol varies from the IEEE 802.1d Spanning Tree protocol.
LattisSpan, a Bay Networks protocol used between Model 58000 switches and
other Bay Networks switches, is a variation of the IEEE 802.1d Spanning Tree
algorithm used by many bridges. The LattisSpan Protocol differs from the
IEEE 802.1d Spanning Tree Protocol in the following ways:
•
LattisSpan extends 802.1d protocol to support virtual LANs.
•
LattisSpan provides information about network topology to the network
management station, including active and standby links, and distributes
virtual LAN information throughout the switch community.
•
LattisSpan packets, often called PDUs (protocol data units), use a different
multicast MAC address from spanning tree packets.
NOTE:
Multicast addresses 010081000200 and 010081000201 must always
be discarded or blocked from traversing internetworking devices that bridge
traffic between Model 58000 switch communities.
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Summary of Contents for 58000
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