Information masks, Spanning tree protocol, Broadcast storms and storm thresholds – HP ProCurve 520wl Wireless Access Point User Manual

Page 66: Information masks -17

Bridge Configuration Settings

4-17

Figure 4-18

Figure 4-18 Static MAC Filter Configuration Screen

Static MAC Filter Configuration Screen

information masks

The MAC Address combines with the Bit Mask to create a filter. Wired MAC Addresses and their associated masks, and

wireless MAC Addresses and their associated masks are known generically as “information masks” and are written in the

following format:

MAC Address:

00 02 10 12 34 56

Bit Mask:

FF FF FF FF 00 00

In this example, all MAC Addresses starting with 00 02 10 12 are filtered.

spanning tree protocol

A Spanning Tree is used to avoid redundant communication loops in networks with multiple bridging devices. Bridges do not

have any inherent mechanism to avoid loops, because having redundant systems is a necessity is certain networks. However,

redundant systems can cause Broadcast Storms, multiple frame copies, and MAC address table instability problems.
Complex network structures can create multiple loops within a network. The Spanning Tree configuration blocks certain ports

on WL520 devices to control the path of communication within the network, avoiding loops and following a spanning tree

structure.

NOTE:

For more information on Spanning Tree protocol, please see Section 8.0 of the IEEE 802.1d standard.

broadcast storms and storm thresholds

Storm Threshold is an advanced Bridge setup option that you can use to protect the network against data overload by:

Specifying a maximum number of frames per second as received from a single network device (identified by its MAC

address).

Specifying an absolute maximum number of messages per port.

The ‘Storm Threshold’ parameters allow you to specify a set of thresholds for each port of the WL520, identifying separate

values for the number of broadcast messages/second and Multicast messages/second.
When the number of frames for a port or identified station exceeds the maximum value per second, the WL520 will ignore all

subsequent messages issued by the particular network device, or ignore all messages of that type.
–

Address Threshold

. Enter the maximum allowed number of packets per second.

–

Ethernet Threshold

Enter the maximum allowed number of packets per second.

–

Wireless-Slot A Threshold

Enter the maximum allowed number of packets per second.

–

Wireless-Slot B Threshold

Enter the maximum allowed number of packets per second.