White Papers

15 Using Policy Based Routing and Access Control Lists in a Virtualized Network
4 Example 3 – VLAN Traffic Redirection
Match packets on one VLAN, then route them to egress another VLAN to get to their destination.
Consider the following example where it is assumed traditional routing is already enabled and configured.
Remote servers X, Y, and Z are cached hourly to local servers A, B, and C. Users on VLAN 10 use the local
cache servers 99% of the time but periodically need to access the most current data from servers X, Y, and
Z located in another city (Figure 3). Traffic on the path between the local and remote servers is
oversubscribed and often uses 100% bandwidth. To minimize any delays in traffic between the user
workstations on VLAN 10 and the remote servers, a PBR is used to avoid the bottleneck depicted by the
red arrow in Figure 3.
N3048
(VLAN 10, 20)
VLAN 10
VLAN 20
Servers A, B, C
Servers X, Y, Z
VLAN traffic without PBR Figure 3.
A route-map is created to forward matching packets incoming on VLAN 10 with a destination of Servers X,
Y, or Z to egress VLAN 20. Traffic from VLAN 10 workstations to the remote servers is then rerouted over a
less utilized path as shown in Figure 4.