IBM ATM OC-3c - Manual (Page 35)

ATM Connections Within Your Network 4-3
■
Virtual circuits required.
■
MAC addresses that can be held in the device
LAN Emulation ARP Table.
When a LAN Emulation Client (LEC) joins an ELAN,
up to five control connections may be required
before any data is transferred over a separate data
connection (VCC). Each time a LEC connects to
another LEC a further connection is required. You
should keep this in mind when calculating the
number of connections you require.
The ATM Module provides the following resources:
■
Up to 16 LECs to extend VLANs into the ATM
network over ELANs.
■
512 Virtual Circuits to/from the ATM network.
■
1024 remote MAC Addresses.
The ATM Module supports only 16 LECs, but this does
not limit your network to 16 ELANs.
■ Are the LAN Emulation services configured
correctly?
Is the LAN Emulation service that the LAN Emulation
Client (LEC) is going to join configured correctly?
For example, if your network uses a LAN Emulation
Client Server (LECS), does the LECS know about
the LES, and is the LES active? Have you supplied a
valid ELAN name?
Configuring the LECS and LES is outside of the scope
of this user guide. Consult the user guide that
accompanies the device implementing the LECS or LES.
Alternatively, if your LEC will not be using a LECS
and is being configured manually, ensure that:
■
The LES address that the LEC is using has been
correctly entered via the local management
screens.
■
The LES is active.
For the ATM Module, you can enter these settings
using the Port Configuration screen described in
“Displaying an ATM Connection”, on page 8-10.
ATM Connections Within Your Network
ATM connections in your ATM network can be
established dynamically by the Signalling protocol
(Switched Virtual Circuit), or through management
(Permanent Virtual Circuit).
The ATM Module does not support PVC
connections. All ATM Module connections are SVCs.
This network concepts section includes PVC
configuration concepts for completeness.
■ Switched Virtual Circuits (SVC) — SVCs are set
up dynamically by the signalling protocol. SVCs
require very little configuration, and only use the
resources you need. For these reasons, SVCs are
commonly used in the LAN environment.
■ Permanent Virtual Circuits (PVC) — You may
need to use a PVC within your network when a
remote edge-device does not support Switched
Virtual Circuits. For example, remote edge-devices
in Wide Area Networks (WANs) often use PVCs.