3Com WX3000 Procedure for the Switch to Judge Packet Protocol , Encapsulation Formats , Implementation of Protocol-Based VLAN

1-7
Procedure for the Switch to Judge Packet Protocol
Figure 1-9 Procedure for the switch to judge packet protocol
Receive
packets
Type(Length)
field
Ethernet II
encapsulation
Match the
type value
Invalid packets
that cannot be
matched
802.2/802.3
encapsulation
Control
field
Invalid packets
that cannot be
matched
dsap/ssap
value 802.2 SNAP encapsulation
Match the
dsap/ssapvalue
802.2 LLC
encapsulation Match the type value
802.3 raw
encapsulation
0x05DD to 0x05FF0x0600 to 0xFFFF
0 to 0x05DC
Value is not 3
Value is 3
Both are AABoth are FF
Other values
Receive
packets
Type(Length)
field
Ethernet II
encapsulation
Match the
type value
Invalid packets
that cannot be
matched
802.2/802.3
encapsulation
Control
field
Invalid packets
that cannot be
matched
dsap/ssap
value 802.2 SNAP encapsulation
Match the
dsap/ssapvalue
802.2 LLC
encapsulation Match the type value
802.3 raw
encapsulation
0x05DD to 0x05FF0x0600 to 0xFFFF
0 to 0x05DC
Value is not 3
Value is 3
Both are AABoth are FF
Other values
Encapsulation Formats
Table 1-1 lists the encapsulation formats supported by some protocols. In brackets are type values of
these protocols.
Table 1-1 Encapsulation formats
Encapsulation
Protocol Ethernet II 802.3 raw 802.2 LLC 802.2 SNAP
IP (0x0800) Supported Not supported Not supported Supported
IPX (0x8137) Supported Supported Supported Supported
AppleTalk
(0x809B) Supported Not supported Not supported Supported
Implementation of Protocol-Based VLAN
The switching engines of the devices assign the packet to the specific VLAN by matching the packet
with the protocol template.