3com S7906E 安装指导
3-11
Configuring the Link Type of an ONU Port
You can configure an ONU port as an access port or trunk port.
When a PC is directly connected to the ONU port, you can configure the ONU port as an access
port, which receives and transmits only untagged packets.
port, which receives and transmits only untagged packets.
When a home gateway or Layer-2 switch is connected to the ONU port, you can configure the ONU
port as a trunk port.
port as a trunk port.
Different from Ethernet ports describe in VLAN Operation, ONU ports process uplink/downlink packets
as described in
as described in
.
Table 3-2
The link type of an ONU port and how it processes packets
Port type
Traffic direction
Processing
Uplink packets
Allow only untagged packets to
pass through and tag these
packets with the default VLAN
tag.
pass through and tag these
packets with the default VLAN
tag.
Access
Downlink packets
Allow only packets with the
default VLAN tag to pass
through and remove the tag of
these packets.
default VLAN tag to pass
through and remove the tag of
these packets.
Uplink packets
For untagged packets, tag
them with the default VLAN
tag and forward them.
them with the default VLAN
tag and forward them.
For tagged packets, forward
them directly without any
processing
them directly without any
processing
Trunk
Downlink packets
Allow only tagged packets to
pass through.
pass through.
For how to configure the link type of an ONU port, refer to
and
. Note that:
The access ports described in
do not include ports in the default state, namely, the
access ports in VLAN 1.
The link type of the ONU ports under the same OLT port must be the same (access or trunk). Thus,
when an ONU port under an OLT port is configured as an access port in a VLAN other than VLAN
1, you can only configure the other ONU ports under the same OLT port as access ports or leave
them in the default state (that is, access ports in VLAN 1); when the ONU port is configured as a
trunk port, you can configure the other ONU ports as trunk ports or leave them in the default state.
when an ONU port under an OLT port is configured as an access port in a VLAN other than VLAN
1, you can only configure the other ONU ports under the same OLT port as access ports or leave
them in the default state (that is, access ports in VLAN 1); when the ONU port is configured as a
trunk port, you can configure the other ONU ports as trunk ports or leave them in the default state.
The ONU ports in the default state only allow untagged packets to pass through in the uplink
direction and tag these packets with VLAN 1 tag. In the downlink direction, they only allow the
packets with the VLAN 1 tag to pass through. Such ONU ports remove the VLAN tag of the
downlink packets if the other ONU ports under the same OLT are configured as access ports, and
do not remove the tag of the downlink packets if the other ONU ports under the same OLT port are
configured as trunk ports.
direction and tag these packets with VLAN 1 tag. In the downlink direction, they only allow the
packets with the VLAN 1 tag to pass through. Such ONU ports remove the VLAN tag of the
downlink packets if the other ONU ports under the same OLT are configured as access ports, and
do not remove the tag of the downlink packets if the other ONU ports under the same OLT port are
configured as trunk ports.
Setting the link type of an ONU port to access
Follow these steps to set the link type of an ONU port to access: