ZyXEL Communications MSC1000G Series, Руководство пользователя

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Chapter 13 Switch Screens
Management Switch Card User’s Guide
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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 fill.
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.
13.13.3 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 366
Port VLAN Trunking
13.13.4 Bandwidth Control
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.
13.13.5 Broadcast Storm Control
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.