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12-13
Cisco SCE 2000 and SCE 1000 Software Configuration Guide
OL-7827-12
Chapter 12 Value Added Services (VAS) Traffic Forwarding
VAS Traffic Forwarding Topologies
Figure 12-4
Single SCE Platform, Multiple VAS Servers
Data Flow
The data flow is:
•
A subscriber packet is received at port #1 (Subscriber).
•
The SCE platform opens a flow and classifies the flow as either a non-VAS (blue) flow or as a VAS
flow (red).
•
If the flow is non-VAS (blue), the SCE platform passes the packet to the network. The VAS server
is not involved in this case.
•
If the flow is a VAS flow (red), the SCE platform selects the VAS server to which the packet should
be sent, adds the server VLAN tag to the packet and transmits the packet on port #4 (Network).
•
The packet is routed by the Ethernet switch to the VAS server according to its VLAN tag (the port
towards the VAS server should be the only port with this VLAN tag allowed).
•
The VAS server processes the packet and either drops or forwards it without changing the VLAN
tag.
•
The packet is forwarded by the Ethernet switch to the SCE platform according to its VLAN tag (the
port towards the SCE platform should be the only port with this VLAN tag allowed).
•
The SCE platform receives the packet on port #3 (Subscriber), strips the VLAN tag and forwards
the packet to the network via port #2 (Network)
VLAN 505
3 (S)
S
N
S
N
S
N
1 (S)
2 (N)
VLAN 506
VLAN 306
VLAN 505
4 (N)
VLAN 506
VLAN 306
VAS server 1
VAS server 2
VAS server 3
Ethernet
switch
Ethernet
switch
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