Allied Telesis Layer 3 Switches manual Bandwidth limiting

Protecting the network

Service providers need to prevent storms from disrupting services to customers. AlliedWare offers the following options for mitigating storms:

zlimiting broadcasts and multicasts on a port (“Bandwidth limiting” on page 4)

zdetecting a storm and disabling that port or VLAN (“Using QoS policy-based storm protection” on page 5)

Bandwidth limiting

ARP packets are the most frequent trigger for broadcast storms. One ARP packet is flooded around and around a network, crowding out all other traffic.

You can use a simple Quality of Service (QoS) configuration to match ARP packets and make sure that when a broadcast storm occurs, the effect is minimised.

Products

All switches listed on page 2

Software Versions

All

			ISP switch
When ISP switch has	misconfigured	flood of ARPs	port
no bandwidth control:	customer switch		48
			ISP switch
When ISP switch has	misconfigured	flood of ARPs	port
bandwidth limiting:	customer switch		48
			secure-switch-bandwidth.eps

Configuration To limit the bandwidth for ARPs:

1.Create a classifier to match ARP packets.

2.Create a QoS framework of policy, traffic class, and flow group. In the traffic class settings, specify the maximum bandwidth for ARP traffic.

3.Apply the policy—and therefore the bandwidth limit—to one or more ports.

Example The following configuration limits ARP packets to 100kbps on port 48.

create classifier=1 protocol=0806 ethformat=ethii-untagged create qos policy=1

create qos trafficclass=1 maxbandwidth=100 create qos flowgroup=1

add qos policy=1 trafficclass=1 add qos trafficclass=1 flowgroup=1 add qos flowgroup=1 classifier=1 set qos port=48 policy=1

Create A Secure Network With Allied Telesis Managed Layer 3 Switches 4