IBM RackSwitch G8000, Application Manual

Page: 91 / 362

© Copyright IBM Corp. 2011 Chapter 7. Access Control Lists
89
VMap Example
In this example, EtherType 2 traffic from VLAN 3 server ports is mirrored to a
network monitor on port 4.
Using Storm Control Filters
The G8000 provides filters that can limit the number of the following packet types
transmitted by switch ports:
•
Broadcast packets
• Multicast packets
• Unknown unicast packets (destination lookup failure)
Broadcast Storms
Excessive transmission of broadcast or multicast traffic can result in a broadcast
storm. A broadcast storm can overwhelm your network with constant broadcast or
multicast traffic, and degrade network performance. Common symptoms of a
broadcast storm are slow network response times and network operations timing
out.
Unicast packets whose destination MAC address is not in the Forwarding Database
are unknown unicasts . When an unknown unicast is encountered, the switch
handles it like a broadcast packet and floods it to all other ports in the VLAN
(broadcast domain). A high rate of unknown unicast traffic can have the same
negative effects as a broadcast storm.
Configuring Storm Control
Configure broadcast filters on each port that requires broadcast storm control. Set a
threshold that defines the total number of broadcast packets transmitted
(0-2097151), in Megabits per second. When the threshold is reached, no more
packets of the specified type are transmitted.
To filter broadcast packets on a port, use the following commands:
To filter multicast packets on a port, use the following commands:
To filter unknown unicast packets on a port, use the following commands:
RS G8000(config)#
access-control vmap 21 packet-format ethernet
ethernet-type2
RS G8000(config)#
access-control vmap 21 mirror port 4
RS G8000(config)#
vlan 3
RS G8000(config-vlan)#
vmap 21 serverports
RS G8000(config)#
interface port 1
RS G8000(config-if)#
broadcast-threshold
<packet rate>
RS G8000(config-if)#
multicast-threshold
<packet rate>
RS G8000(config-if)#
dest-lookup-threshold
<packet rate>
RS G8000(config-if)#
exit