3Com PathBuilder S200 Series Owner's Manual page 78

Bridge Filtering
DSAP Values
SNAP Protocol ID
74
The DSAP is a 1-byte ID found in the LLC field (see Figure 37). You set this value
in the Protocol Value parameter of the Protocol Filter Table. Examples of DSAPs
include:
• IBM (04, 08,...)
• Banyan Vines (BC)
• Novell IPX (E0)
• IBM NetBIOS (F0)
Figure 37. Protocol ID DSAP Located in LLC Field
The SNAP is five bytes and is also found in the LLC field. The first three bytes are
OUI and the last two bytes are the Protocol ID (Figure 38).
Figure 38. SNAP Protocol ID
The SNAP format is used to identify Ethernet and pre-IEEE 802 protocol IDs that do
not fit the 1-byte ID.
LLC Field
DSAP SSAP Control LLC Info
LLC Field
DSAP SSAP Control 5 Bytes
OUI
AA AA 03
00 00 00
AA = Indicates SNAP Format
03 = Unnumbered Information
OUI = Organizationally Unique Identifier
Type = 2-Byte Protocol ID
Type
2 Bytes
Bridging