Port Vlan Trunking; Bandwidth Control; Broadcast Storm Control - ZyXEL Communications MSC1024G Series User Manual

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The MSC uses IEEE 802.3x flow control in full duplex mode and back pressure flow control

in half duplex mode.

IEEE 802.3x flow control is used in full duplex mode to send a pause signal to the sending

port, causing it to temporarily stop sending signals when the receiving port memory buffers

Back pressure flow control is typically used in half duplex mode to send a "collision" signal to

the sending port (mimicking a state of packet collision) causing the sending port to

temporarily stop sending signals and resend later.

15.11.3 Port VLAN Trunking

VLAN Trunking allows frames belonging to unknown VLAN groups to pass through a port.

This is useful if you want to set up VLAN groups on end devices without having to configure

the same VLAN groups on intermediary devices.

Refer to the following figure. Suppose you want to create VLAN groups 1 and 2 (V1 and V2)

on devices A and B. Without VLAN Trunking, you must configure VLAN groups 1 and 2 on

all intermediary switches C, D and E; otherwise they will drop frames with unknown VLAN

group tags. However, with VLAN Trunking enabled on a port(s) in each intermediary switch

you only need to create VLAN groups in the end devices (A and B). C, D and E automatically

allow frames with VLAN group tags 1 and 2 (VLAN groups that are unknown to those

switches) to pass through their VLAN trunking port(s).

Figure 341 Port VLAN Trunking

Use bandwidth control to define a maximum allowable bandwidth for incoming and/or out-

going traffic flows on individual Gigabit Ethernet interfaces. This may be useful for limiting

backbone bandwidth usage and preventing viruses from using up all of the system's resources.

Broadcast storm control limits the number of broadcast, multicast and destination lookup

failure (DLF) packets the switch receives per second on the ports. When the maximum number

of allowable broadcast, multicast and/or DLF packets is reached per second, the subsequent

packets are discarded. Enable this feature to reduce broadcast, multicast and/or DLF packets in

your network. You can specify limits for each packet type on each port. DLF packets are also

known as unknown unicast packets.

MSC1000G/1024G/1224G Series User's Guide

Chapter 15 Switch Screens

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