Nortel Networks 2500 Series Other features, Asymmetric mode, Rate Limiting Configuration, RFCs

Other features 79

Asymmetric mode

This mode lets the link partner send flow control pause frames to the GBIC port. When a pause frame is received, the receiving port suspends transmission of frames for a number of slot times specified in the control frame or until a pause-release control frame is received.

In this mode, the GBIC port is disabled from transmitting pause frames to its link partner. Use this mode when the GBIC port is connected to a buffered repeater device.

You can choose a high speed flow control mode using CLI commands. For more information about the commands see "Enabling flow control" (page 240).

Rate Limiting Configuration

The Rate Limiting feature lets you configure the threshold limits for broadcast and multicast packets ingressing on a port for a given time interval. The Ethernet Routing Switch 2500 Series drops any packets received above the threshold value if the traffic ingressing on the port exceeds the threshold. The hardware restrictions on this platform do not allow you to determine if the traffic from a port is the cause of excess broadcast or multicast traffic. Consequently you cannot perform port specific actions such as disabling a port. You can generate a trap to detect the excess traffic or you can configure the switch to store a message in the system log when the traffic on the port exceeds the threshold value. This message in the system log conveys that some traffic to the switch is dropped.

When the volume of either packet type is high, placing severe strain on the network (often referred to as a "storm"), you can set the forwarding rate of those packet types to not exceed a specified percentage of the total available bandwidth. The pps (Packets Per Second) value you set is a small amount of the maximum value of pps for the maximum available bandwidth that is 262143 pps.

ATTENTION

All Rate Limiting configuration settings are applied across the entire unit. You cannot set some ports in the unit to limit broadcast traffic with a value of X pps and some other ports in the same to limit multicast traffic with a value of Y pps.

Other features

RFCs

For more information about networking concepts, protocols, and topologies, consult the following RFCs:

•RFC 1213 (MIB-II)

Nortel Ethernet Routing Switch 2500 Series

Overview — System Configuration

NN47215-500 (323162-B) 02.02 Standard

4.1 19 November 2007

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