Cabletron Systems SmartSwitch manual Source Filtering and ACLs, Weighted-Fair Queueing

Chapter 22: WAN Configuration Guide

Source Filtering and ACLs

Source filtering and ACLs can be applied to a WAN interface; however, they affect the entire module, not an individual port.

For example, if you want to apply a source MAC address filter to a WAN serial card located in slot 5, port 2, your configuration command line would look like the following:

ssr(config)# filters add address-filter name wan1 source-mac 000102:030405 vlan 2 in-port-list se.5

Port se.5 is specified instead of se.5.2 because source filters affect the entire WAN module. Hence, in this example, source-mac 000102:030405 would be filtered from ports se.5.1, se.5.2, se.5.3, and se.5.4 (assuming that you are using a four-port serial card).

ACLs work in a similar fashion. For example, if you define an ACL to deny all http traffic on one of the WAN interfaces, it will apply to the other WAN interfaces on that module as well. In practice, by making your ACLs more specific, for example by specifying source and destination IP addresses with appropriate subnet masks, you can achieve your intended level of control.

Weighted-Fair Queueing

Through the use of Weighted-Fair Queueing QoS policies, WAN packets with the highest priority can be allotted a sizable percentage of the available bandwidth and “whisked through” WAN interface(s). Meanwhile, the remaining bandwidth is distributed for “lower-priority” WAN packets according to the user’s percentage-of-bandwidth specifications. Please refer to Chapter 35: “qos Commands” in the SmartSwitch Router Command Line Interface Reference Manual for more detailed configuration information.

Note: Weighted-Fair Queueing applies only to best-effort traffic on the WAN card. If you apply any of the WAN specific traffic shaping commands, then weighted fair queuing will no longer be applicable.

Congestion Management

One of the most important features of configuring the SSR to ensure Quality of Service is the obvious advantage gained when you are able to avoid network congestion. The following topics touch on a few of the most prominent aspects of congestion avoidance when configuring the SSR.

Random Early Discard (RED)

RED allows network operators to manage traffic during periods of congestion based on policies. Random Early Discard (RED) works with TCP to provide fair reductions in traffic proportional to the bandwidth being used. Weighted Random Early Discard (WRED)

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