3Com Switch 4500 Family, Руководство по настройке

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1-3
frame as needed. When doing that, you should set the same TPID on both the customer-side port and
the service provider-side port.
The TPID in an Ethernet frame has the same position with the protocol type field in a frame without a
VLAN tag. To avoid problems in packet forwarding and handling, you cannot set the TPID value to any
of the values in the table below.
Table 1-1
Commonly used protocol type values in Ethernet frames
Protocol type Value
ARP 0x0806
IP 0x0800
MPLS 0x8847/0x8848
IPX 0x8137
IS-IS 0x8000
LACP 0x8809
802.1x 0x888E
Inner-to-Outer Tag Priority Replicating and Mapping
As shown in Figure 1-3 , the user priority field is the 802.1p priority of the tag. The value of this 3-bit field
is in the range 0 to 7. By configuring inner-to-outer tag priority replicating or mapping for a
VLAN-VPN-enabled port, you can replicate the inner tag priority to the outer tag or assign outer tags of
different priorities to packets according to their inner tag priorities.
Refer to
QoS
part for information about priority.
Transparent IGMP Message Transmission on a VLAN-VPN Port
For detailed information about IGMP messages and how a switch processes IGMP messages of
different types, refer to the
Multicast
module in this manual.
For a VLAN-VPN-disabled port, the switch transparently transmits an IGMP message received on the
port within the VLAN that the IGMP message belongs to. For the switch to transparently transmit an
IGMP message received on a VLAN-VPN port in the outer VLAN, you must enable transparent IGMP
message transmission on the port.
VLAN-VPN Configuration
VLAN-VPN Configuration Task List
Complete the following tasks to configure VLAN-VPN: