H3C S7500 Series Ethernet Switches Operation Manual

Operation Manual – VLAN
H3C S7500 Series Ethernet Switches Chapter 1
VLAN Overview
1-8
DA&SA(12) Length(2) DSAP(1) SSAP(1) Control(1) OUI(3) DataPID(2)
t Figure 1-8 802.2 SNAP encapsulation forma
In 802.2 SNAP encapsulation format, the values of the DSAP field and the SSAP field
are always AA, and the value of the control field is always 3.
The switch differentiates between 802.2 LLC encapsulation and 802.2 SNAP
encapsulation according to the values of the DSAP field and the SSAP field.
 Note:
When the OUI is 00-00-00 in 802.2 SNAP encapsulation, the PID field has the same
meaning as the type field in Ethernet II encapsulation, which both refer to globally
unique protocol number. Such encapsulation is also known as SNAP RFC 1042
encapsulation, which is standard SNAP encapsulation. The SNAP encapsulation
mentioned in this chapter refers to SNAP RFC 1042 encapsulation.
1.3.3 Procedure for the Switch to Judge Packet Protocol
Both are AA
Both are FF
Dsap
ssap
snap
llc
Match dsap
and ssap value
Match
type
Other values
snap
llc
snap
llc
snap
llc
Receive packets
Type (length ) field
0x600
0 to 0x05DC
0x6000x6000x600
0x05DC to 0x0600
Inv
c
alid packets that
annot be matched
802.3 encapsulation
Control
field
Invalid pack
cannot be
Value is 3
Value is not 3
ets that
matched
snap
llc
Raw
encapsulation
snap
llc
snap
llc
snap
llc
snap
llc
snap
llc
snap
llc
snap
llc
snap
llc
snap
llc
snap
llc
snap encapsulation
llc encapsulation
0x6000x6000x600
Ethernet II
encapsulation
Match the
type value
0x600 to 0xFFF
Control
Both are AA
Both are FF
Dsap
ssap
snap
llc
Match dsap
and ssap value
Match
type
Other values
snap
llc
snap
llc
snap
llc
Both are AA
Both are FF
Dsap
ssap
snap
llc
Match dsap
and ssap value
Match
type
Other values
snap
llc
snap
llc
snap
llc
Dsap
ssap
snap
llc
Match dsap
and ssap value
Match
type
Other values
snap
llc
snap
llc
snap
llc
Receive packets
Type (length ) field
0x600
0 to 0x05DC
0x6000x6000x600
0x05DC to 0x0600
Inv
c
802.3 encapsulation802.3 encapsulation
alid packets that
annot be matched
Control
field
Invalid pack
cannot be
Value is 3
Value is not 3
ets that
matched
snap
llc
Raw
encapsulation
snap
llc
snap
llc
snap
llc
snap
llc
Raw
encapsulation
snap
llc
snap
llc
snap
llc
snap
llc
snap
llc
snap
llc
snap
llc
snap
llc
snap
llc
snap
llc
snap encapsulation
llc encapsulation
0x6000x6000x600
Ethernet II
encapsulation
Match the
type value
0x600 to 0xFFF
Control
Both are AA
Both are FF
Dsap
ssap
snap
llc
Match dsap
and ssap value
Match
type
Other values
snap
llc
snap
llc
snap
llc
Both are AA
Both are FF
Dsap
ssap
snap
llc
Match dsap
and ssap value
Match
type
Other values
snap
llc
snap
llc
snap
llc
Dsap
ssap
snap
llc
Match dsap
and ssap value
Match
type
Other values
snap
llc
snap
llc
snap
llc
Receive packets
Type (length ) field
0x600
0 to 0x05DC
0x6000x6000x600
0x05DC to 0x0600
Inv
c
alid packets that
annot be matched
802.3 encapsulation802.3 encapsulation
Control
field
Invalid pack
cannot be
Value is 3
Value is not 3
ets that
matched
snap
llc
Raw
encapsulation
snap
llc
snap
llc
snap
llc
snap
llc
Raw
encapsulation
snap
llc
snap
llc
snap
llc
snap
llc
snap
llc
snap
llc
snap
llc
snap
llc
snap
llc
snap
llc
snap encapsulation
llc encapsulation
0x6000x6000x600
Ethernet II
encapsulation
Match the
type value
0x600 to 0xFFF
Control
Both are AA
Both are FF
Dsap
ssap
snap
llc
Match dsap
and ssap value
Match
type
Other values
snap
llc
snap
llc
snap
llc
Dsap
ssap
snap
llc
Match dsap
and ssap value
Match
type
Other values
snap
llc
snap
llc
snap
llc
Both are AA
Both are FF
Dsap
ssap
snap
llc
Match dsap
and ssap value
Match
type
Other values
snap
llc
snap
llc
snap
llc
Dsap
ssap
snap
llc
Match dsap
and ssap value
Match
type
Other values
snap
llc
snap
llc
snap
llc
Receive packets
Type (length ) field
0x600
0 to 0x05DC
0x6000x6000x600
0x05DC to 0x0600
Inv
c
802.3 encapsulation802.3 encapsulation
alid packets that
annot be matched
Control
field
Invalid pack
cannot be
Value is 3
Value is not 3
ets that
matched
snap
llc
Raw
encapsulation
snap
llc
snap
llc
snap
llc
snap
llc
Raw
encapsulation
snap
llc
snap
llc
snap
llc
snap
llc
snap
llc
snap
llc
snap
llc
snap
llc
snap
llc
snap
llc
snap encapsulation
llc encapsulation
0x6000x6000x600
Ethernet II
encapsulation
Match the
type value
0x600 to 0xFFF
Control
Figure 1-9 Procedure for the switch to judge packet protocol