3Com 8800 Configuration Manual page 483

3Com Switch 8800 Configuration Guide Chapter 37 BGP/MPLS VPN Configuration
Note:
Cautions and configuration limitations in hybrid networking:
For a trunk port on the common interface card, you can configure to redirect MPLS
VPN of multiple VLANs to the same destination port.
In a VLAN you can configure only one source port to redirect MPLS VPN to the
destination port. It is unnecessary to make multiple redirection configurations in a
VLAN which is redirected to the same destination port, since the VLAN can contain
other ports (for Layer 2 forwarding).
In a VLAN you can configure only one destination port to which MPLS VPN is
redirected and the destination port must be in loopback state. Make sure before
redirection configuration that no other loopback port exists in the VLAN.
For a destination port on the enhanced interface card, you can make multiple
redirection configurations and just need to trunk one VLAN for each redirection
configuration. Loopback is set automatically on it after you make one redirection
configuration on such a destination port, and no more redirection configurations can
be made, so you must check that the destination port is not in manual shutdown
state (the shutdown command is used) before making another redirection
configuration.
You are recommended to bind the VLAN interface to the VPN after making MPLS
VPN redirection configuration, to enable your configuration.
You cannot configure MPLS VPN redirection and protocol VLAN on the same port.
That is, you cannot configure MPLS VPN redirection if you have enabled protocol
VLAN, and vice versa. MPLS VPN redirection configuration clears all protocol
VLANs on the destination port if there are any.
You cannot configure MPLS VPN redirection on the POS port or use the POS port
as the destination port for MPLS VPN redirection configuration.
You cannot configure MPLS VPN redirection on the aggregation port or use the
aggregation port as the destination port for MPLS VPN redirection configuration. If
redirection configuration is made on the destination port on the common interface
card or enhanced interface card, you cannot add it to any aggregation group.
If VRRP is enabled on the VLAN interface where the source port for MPLS VPN
redirection configuration belongs to, removing and inserting the enhanced interface
card triggers state transition of the VRRP group on the VLAN interface.
The trunk FE port can use only the VLAN of 1k for VPN access and MPLS
forwarding, but you can define the starting VLAN ID. Then the VLANs which can
pass the trunk FE port range from vlan-id to vlan-id+1023.
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