Operation Manual – VLAN
H3C S5600 Series Ethernet Switches
Chapter 1 VLAN Overview
1-8
802.2/802.3 packet:
Figure 1-5
802.2/802.3 encapsulation format
In the two figures, DA and SA refer to the destination MAC address and source MAC
address of the packet respectively. The number in the bracket indicates the field length
in bytes.
The maximum length of an Ethernet packet is 1500 bytes, that is, 0x05DC in
hexadecimal, so the length field in 802.2/802.3 encapsulation is in the range of 0x0000
to 0x05DC.
Whereas, the type field in Ethernet II encapsulation is in the range of 0x0600 to
0xFFFF.
Packets with the value of the type or length field being in the range 0x05DD to 0x05FF
are regarded as illegal packets and thus discarded directly.
The switch identifies whether a packet is an Ethernet II packet or an 802.2/802.3 packet
according to the ranges of the two fields.
Note:
The H3C S5600 series switches recognize packets with the value of the type field being
in the range 0x05DD to 0x05FF as 802.2/802.3 encapsulated packets.
II. Extended encapsulation formats of 802.2/802.3 packets
802.2/802.3 packets have the following three extended encapsulation formats:
z
802.3 raw encapsulation: only the length field is encapsulated after the source and
destination address field, followed by the upper layer data. No other fields are
included.
Figure 1-6
802.3 raw encapsulation format
Currently, only IPX supports 802.3 raw encapsulation, featuring with the value of the
two bytes after the length field being 0xFFFF.
z
802.2 Logical Link Control (LLC) encapsulation: the length field, the destination
service access point (DSAP) field, the source service access point (SSAP) field
and the control field are encapsulated after the source and destination address
field. The value of the control field is always 3.