Chapter 4 - Configuring Rfc 1483; Overview; Virtual Switch Ports (Vsp) - Avaya P550R User Manual

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Overview

Virtual Switch
Ports (VSP)
Avaya P550R/P580/P880/P882 Multiservice Switch ATM Uplink User Guide, Version 2.0.
Configuring RFC 1483
In an RFC1483 based solution, it is the responsibility of the device
attached to the network to replicate and distribute packets to each
remotely connected endpoint. In a LANE-based solution this
function is handled by the BUS. The absence of this element (in
RFC1483) means the following:
The ATM Uplink module must replicate flooded (broadcast/
unknown) packets to all VCs in a broadcast domain.
The ATM Uplink module can only learn the VC-relative
location of end stations through the receive path. In other
words, each learned MAC address is associated with the VC
it received the Ethernet frame on.
Ethernet considers every host on the same LAN segment to be in a
Broadcast Domain. When one host transmits a Frame, every other
host on in the Broadcast Domain receives and to some extent,
processes the Frame.
In an ATM network, devices pass traffic through point to point
connections (VCs) making the distributing of a single Frame to
every other destination cumbersome. To accomplish this Broadcast
capability, you can either configure a VC from every device to
every other device; hence creating a mesh topology. Or, as is the
case for LANE, provide a BUS that all devices can forward traffic to
if that traffic needs to go to all of the other devices in the Broadcast
Domain.
The RFC1483 solution eliminates the need for LANE services. As
such, you must configure at least one Permanent Virtual Circuit
(PVC) to each destination in the ATM network for your Broadcast
Domain. The collection of PVCs associated with the Broadcast
Domain leads to the concept of a Virtual Switch Port (VSP).
In the simple case where there are only two devices in the ATM
network, the VSP need only send one copy of a Frame to the other
device. Since the VSP does not need "replicate" the Frame for two
or more destinations, the VSP is said to be "Non-Replicating".
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