Planning a Switched Network
2-18
893-878-B
Configurable Port Types
You can configure the ports of the MDAs installed in the Model 58000 switch
to operate in one of two modes: automatic (auto) mode or forced feeder
(feeder) mode. All ports are preconfigured, by default, to operate in auto mode.
Auto ports use the LattisSpan trunk detection process to configure the port
automatically as a LattisSpan trunk port or feeder port. These ports operate
differently, and it is important to understand the difference between the ports
before configuring them to operate in auto or feeder mode.
The Difference Between LattisSpan Trunk and Feeder Ports
The link that connects LattisSpan trunk ports is a LattisSpan trunk link. Such a
link carries traffic for multiple virtual LANs between Model 58000 switches
and shares station MAC addresses between connected switches. Trunk ports do
not learn addresses of the individual end stations connected to the port. In
addition, if an Ethernet segment is used as a trunk link between two switches,
the switches will not learn the addresses of any end stations attached to the
segment. This means there is no connectivity to those end stations on that
segment. A LattisSpan trunk link joins the switches at each end of the link into
a single switch community.
The link that connects LattisSpan feeder ports is a LattisSpan feeder link.
The feeder link carries traffic for a single virtual LAN. Feeder ports learn the
addresses of all end stations on the segment connected to the port; therefore,
connectivity is provided to the end stations on that segment.
When a feeder link is used to connect two switches, only the network traffic is
carried between the two switches (the connected switches do not share global
station MAC address information). A single switch community is not formed
when two switches are connected by a feeder link.
Auto Mode
In auto mode, a switch port uses the LattisSpan trunk detection process to
automatically configure the port as a trunk port or a feeder port. When a switch
is connected to another switch, the connecting ports are automatically
designated as trunk ports. A port that is connected to an end station or Ethernet
segment is automatically designated as an active feeder port (if there are no
additional switches connected to the segment).
893-878-B Book Page 18 Monday, May 12, 1997 2:06 PM
Summary of Contents for 58000
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