Allied Telesis AR400 Series Router - Manual (Page 78)

78 AR400 Series Router User Guide
Software Release 2.6.1
C613-02021-00 REV D
Once the system resource becomes available the switch transmission by the
link partner of the port can resume.
You can set the global retransmission time delay for all switch ports operating
in half duplex mode. When the port attempts to transmit a packet and
encounters a collision, the switch stops transmission and starts a short delay
(backoff) before attempting re-transmission. If AGGRESSIVE is specified, the
time delay is shorter. If NORMAL is specified, the time delay is standard. The
default is NORMAL.
SET SWITCH BACKOFF={AGGESSIVE|NORMAL}
By default, switch ports will repeat attempts to transmit a packet until they
succeed:
SET SWITCH EXCESSIVECOLLISION=RETRY
Packet buffers available in the buffer pool are shared by all switch ports. By
default, these are allocated automatically according to the amount of traffic at
each port (ADAPTIVE). To limit the number of buffers available for any port,
enter the command:
SET SWITCH BUFFERPOOL={EQUAL|ADAPTIVE}
By default, broadcast and multicast packets are discarded if they are in excess
of 25% the line rate:
SET SWITCH BROADCASTLIMIT=ON
For more information about limiting switch traffic, see the Switching on the
AR410 chapter in the AR400 Series Router Software Reference.
Packet Storm Protection (AR450 only)
Using the packet storm protection feature, you can set limits on the reception
rate of broadcast, multicast and destination lookup failure packets. Packet
storm protection limits are set on a per port basis, beyond which each of the
different packet types are discarded.
By default, packet storm protection is set to NONE, that is, disabled. Packet
storm protection can be enabled, and each of the limits set, using the command:
SET SWITCH PORT=port-list POLARITY={MDI|MDIX}
[BCLIMIT={NONE|limit}] [DLFLIMIT={NONE|limit}]
[MCLIMIT={NONE|limit}] [other-options...]
Three sets of options are allowed for packet storm protection:
■ broadcast limit only (BCLIMIT)
■ broadcast limit and multicast limit (BCLIMIT and MCLIMIT)
■ broadcast limit, multicast limit, and destination lookup failure limit
(BCLIMIT, MCLIMIT, and DLFLIMIT)
The limit specified for each option, i.e the number of kilobytes per second
(Kbps), must be the same for all modes of storm protection selected. The limit
is set to the most recent limit specified. For example:
SET SWI PORT=1 POLARITY=MDI BCLIMIT=256 MCLIMIT=256
DLFLIMIT=256
To display the packet storm protection settings, use the command:
SHOW SWITCH PORT[={port-list|ALL}]