Information Technology Reference
In-Depth Information
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LAN Emulation Client (LEC)
—An entity such as a workstation, LAN switch, or router that
performs data forwarding and receiving, address resolution, and other control functions for a single
endpoint in a single emulated LAN. The LEC provides a standard LAN service to any higher layers
that interface to it. A router or switch can have multiple resident LECs, each connecting with
different emulated LANs. The LANE client registers its MAC and ATM address with the LES.
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LAN Emulation Server (LES)
—A server that provides a registration facility for clients to join the
emulated LAN. Among other things, the LES handles LAN Emulation Address Resolution Protocol
(LE_ARP) requests and maintains a list or lookup table of LAN destination MAC addresses. Each
emulated LAN must have a LES.
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Broadcast-and-Unknown Server (BUS)
—A server that floods unknown destination traffic and that
forwards multicast and broadcast traffic to clients within an emulated LAN. Each emulated LAN
(ELAN) must have a BUS.
In Cisco's LANE implementation, the LES and the BUS are combined.
Note
LAN Emulation Configuration Server (LECS)
—A server that assigns individual clients to
particular emulated LANs by directing them to the LES that corresponds to the emulated LAN. The
LECS can enforce security by restricting ELAN membership to certain LECs based on their MAC
addresses. The LECS component, however, is optional in LANE—a client can contact directly the
LES to join an emulated LAN.
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Troubleshooting a LAN Emulation Network
Though not very complex in theory, the different configurations necessary to implement a LANE
network include a lot of long ATM addresses. It becomes easy to insert a typo that will cause the whole
setup to fail. Very often, then, troubleshooting a LANE network simply means to have it work! For this
reason, this part is split in two sections:
The “Troubleshooting LECs Not Coming Up” section deals with initial configuration issues when
it is a matter of bringing up a LEC.
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When the initial connection of the LECs is established, the second part, Table 21-2, goes deeper into
the troubleshooting of the live network.
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Troubleshooting LECs Not Coming Up
The flowchart shown in Figure 21-1 explains which section to use in this section. Issue a
show lane
client
exec command on the device hosting the LEC. Use the field Last Fail Reason, and jump to the
corresponding section in next table (the
show lane client
command is fully described in the section
“Understanding the show lane client Output,” later in this chapter). If you could not solve your issue by
simply following the flowchart, refer to the entry “If None of This Works,” in Table 21-1.
