Indirect Connections - Avaya 8800 Planning And Engineering

Indirect connections

The following figure shows a switch using routable port-based VLANs for indirect connections.
When configured in this way:
• Port P1 provides a connection to the Layer 2 switch.
Port P1 is configured for tagging. All P1 ingress and egress packets are tagged (the packet
type can be either PPPoE or IP).
• Port P2 provides a connection to the ISP network.
Port P2 is configured for tagging. All P2 ingress and egress packets are tagged (the packet
type is PPPoE).
• Port P3 provides a connection to the routed network.
Port P3 can be configured for either tagging or nontagging (if untagged, the header does
not carry any VLAN tagging information). All P3 ingress and egress packets are untagged
(the packet type is IP).
• Ports P1 and P2 must be members of the same VLAN.
The VLAN must be configured as a routable VLAN. Routing must be disabled on Port P2.
VLAN tagging is preserved on P1 and P2 ingress and egress packets.
• Port P3 must be a member of a routable VLAN but cannot be a member of the same
VLAN as Ports P1 and P2. VLAN tagging is not preserved on P3 ingress and egress
packets.
For indirect user connections, you must disable routing on port P2. This allows the bridging of
traffic other than IP and routing of IP traffic outside of port number 2. In the latter case, port
1 has routing enabled and allows routing of IP traffic to port 3. By disabling IP routing on port
P2, no IP traffic flows to this port.
Planning and Engineering — Network Design
PPPoE-based VLAN design example
November 2010 129