Chapter 8 The VPN Transport Screens
User’s Guide
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8.3 Customer Interface
Customer interfaces connect data coming from your computers to Ethernet pseudowires,
according to the data’s VLAN (Virtual Local Area Network) information. One customer
interface is for traffic that has no tag; this is the default interface (rule 0) which cannot be
deleted in the GUI. All other customer interfaces are identified by their VLAN ID.
Once the WiMAX Modem has examined a frame’s VLAN tag, it is able to assign the frame to
a specified path. This is done using a customer interface. The customer interface is simply a
set of information that takes frames from a VLAN and put them on an Ethernet pseudowire,
and vice versa.
In this example, the WiMAX Modem takes frames tagged with two different VLAN IDs (10
and 20) and using the customer interfaces, assigns them to specific pseudowires (PW1 and
PW2).
Figure 42 Pseudowire Mapping
The WiMAX Modem has a default customer interface configured for frames that arrive at the
WiMAX Modem without VLAN tags.
8.3.1 Multi-Protocol Label Switching
The WiMAX Modem uses MPLS VPNs to create virtual private LANs. MPLS stands for
Multi-Protocol Label Switching, and is a packet-switching technology that allows packets
with different VLAN tags to be transported on different paths (known as LSPs, or Label
Switched Paths). Each packet is identified by its VLAN tag and sent to a specific LSP for
transport over the WiMAX network.
Each LSP has a defined start-point and end-point. Since MPLS creates mono-directional paths
(traffic flows in only one direction), each Ethernet pseudowire uses two LSPs so that traffic
can flow both ways. One LSP carries upstream traffic, and the other carries downstream
traffic.
VLAN 10 PW1
VLAN 20 PW2
10
20
PW1
PW2
1
2
WiMAX
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