Chapter 4 Virtual Channel Management; About Virtual Channels - ZyXEL Communications ALC1224 User Manual

4.1 About Virtual Channels

Defining channels (also called Permanent Virtual Circuits or PVCs) allows you to set priorities for different
services or subscribers. You can define up to eight channels on each DSL port and use them for different services or
levels of service. You set the PVID that is assigned to untagged frames received on each channel. You also set an
IEEE 802.1p priority for each of the PVIDs. In this way you can assign different priorities to different channels
(and consequently the services that get carried on them or the subscribers that use them).
For example, you want to give high priority to voice service on one of the line card's ADSL ports.
Use the Edit Static VLAN screen to configure a static VLAN on the ALC1224 line card for voice on the port.
Use the ADSL Edit Port Channel Setup screen to:
Configure a channel on the port for voice service.
Set the channel to use the PVID of the static VLAN you configured.
Assign the channel a high priority.
4.1.1 Super Channel
The ALC1224 forwards frames belonging to VLAN groups that are not assigned to specific channels to the super
channel. Enable the super channel option to allow a channel forward frames belonging to multiple VLAN groups
(that are not assigned to other channels). The super channel functions in the same way as the channel in a single
channel environment. One port can have only one super channel.
4.1.2 LLC
LLC is a type of encapsulation where one VC (Virtual Circuit) carries multiple protocols with each packet header
containing protocol identifying information. Despite the extra bandwidth and processing overhead, this method may
be advantageous if it is not practical to have a separate VC for each carried protocol, for example, if charging
heavily depends on the number of simultaneous VCs.
4.1.3 VC Mux
VC Mux is a type of encapsulation where, by prior mutual agreement, each protocol is assigned to a specific virtual
circuit, for example, VC1 carries IP, VC2 carries IPX, and so on. VC-based multiplexing may be dominant in
environments where dynamic creation of large numbers of ATM VCs is fast and economical.
Virtual Channel Management
Virtual Channel Management
This chapter shows you how to configure virtual channels.
ALC1224 User's Guide
Chapter 4
4-1