3Com PathBuilder S200 Series, Owner'S Manual

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Bridging 65
T0008-16F Release 5.2M
Bridge Filtering
MAC Wildcard Filtering
What Is It?
MAC wildcard filtering is an enhancement to the Motorola Network Access
Products MAC Filter table. MAC wildcard filtering lets you configure the MAC
filter tables and use wildcards “*” to designate numeric pieces of the MAC address.
The MAC Address filter lets you configure a table of MAC Address filters (each
filter contains a MAC address which is a string of 12 characters from the range 0-9,
A-F). The table is searched for each incoming and outgoing frame on the LAN/WAN
link to find a match in the table for the MAC address in the frame.
This enhancement lets you use the wildcard character “*” in any of the 12 character
positions while configuring a filter. The wildcard character matches any of the valid
characters allowed in a MAC address (0-9, A-F) when it is used to filter a given
MAC Address.
MAC wildcard filtering lets you configure a smaller MAC Address Filter table if you
configure MAC Address filters where one or more of the 12 character positions can
be allowed to take any value in the permissible range.
For example, with the existing functionality, if the Bridge had to be configured to
block all the frames with MAC addresses in the range 080004001F00 to
080004001FFF, you would have to configure 256 filters. Now you can simply
specify 080004001F**.
PathBuilder S200
Series Switch
Support
PathBuilder S200 series switches support the MAC wildcard feature on the Ethernet.
How MAC Wildcard
Filtering works
Figure 34 shows a typical MAC wildcard filtering application:
Figure 34. Example of How MAC Wildcard Filtering Works
With the old filtering system, if you do not want any of the devices shown on the
LAN on the left to access the WAN, you would need to configure all five entries.
With the MAC wildcard filtering, only one entry is required. For example, you can
specify 080004001F** to prevent all devices from accessing the WAN.
080004001F01
080004001F02
080004001F03
080004001F04
080004001F05
080004002F01