Ethernet uses the type field to determine the packet protocol.
Since there are only 256 possible SAP values, they are fairly hard to get. This is the SNAP header which uses the same type field used by V2 Ethernet. Novell can be found as either Ethernet type 0x8137, or a raw 802.3 packet. There are only a few SAP values that you are likely to run across. Cisco Systems Inc. All rights reserved.