Cabletron Systems CSX1000 - Manual (Page 226)

USER’S GUIDE
226 CyberSWITCH
MAC address filters reference either the source or destination MAC address fields in a packet.
Protocol filters use the protocol Id field in a packet. Packet data filters reference data outside the
address and protocol fields in a packet. Each filter has a distribution list that identifies the potential
destinations for a filtered packet.
For each filter category, there are three filtering actions that the system can perform on a packet:
discard, forward, or connect.
P ROTOCOL D EFINITIONS
If you configure any protocol filters, you must first configure any needed protocol definitions. After
you define a protocol filter, it will automatically be assigned a protocol Id. The protocol Id is a
required field when configuring a protocol filter.
You can define up to 10 protocol definitions. These definitions represent the protocol Id tokens for
the protocol filter commands to use. Users specify the protocol name, and also the protocol Id value
for the Ethernet type field and/or the 802.3 LSAP field.
Inspecting the 13th and 14th bytes of the MAC frame determines the packet format. These bytes are
the length field in an 802.3 format frame, and are the Ethernet type field in an Ethernet format
frame. If the value of the byte is less than hexadecimal 600, the packet is 802.3 format and the LSAP
field is used for the protocol Id. If the value is greater than or equal to hexadecimal 600, the packet
is Ethernet format and the Ethernet type field is used for the protocol Id.
Two of the more common protocols used today are:
•
The IP Protocol Id, which identifies DOD Internet Protocol packets with Ethernet type equal to
hexadecimal 800, or 802.3 LSAP equal to hexadecimal 6060.
• The IPX Protocol Id, which identifies Novell (old) NetWare IPX packets with Ethernet type
equal to hexadecimal 8137, or 802.3 LSAP equal to hexadecimal E0E0.