Service Manual

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Policy-based Routing (PBR)
Policy-based Routing (PBR) allows a switch to make routing decisions based on policies applied to an interface.
Overview
When a router receives a packet, the router normally decides where to forward the packet based on the destination address in the
packet, which is used to look up an entry in a routing table. However, in some cases, there may be a need to forward the packet
based on other criteria: size, source, protocol type, destination, and so forth. For example, a network administrator might want to
forward a packet that uses transmission control protocol (TCP) across a dierent next-hop than packets using Internet control
message protocol (ICMP). In these situations, you can congure switch route packets according to a policy applied to interfaces.
When the packet comes from this source and wants to go to that destination, you must route it to this next-hop or onto that
specic interface. This permits routing over dierent links or towards dierent networks when the destination is the same but the
packet origins are dierent.
To enable a PBR, create a redirect list. Redirect lists are dened by rules, or routing policies. You can dene following parameters in
routing policies or rules:
• IP address of the forwarding router (next-hop IP address)
• Protocol as dened in the header
• Source IP address and mask
• Destination IP address and mask
• Source port
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Policy-based Routing (PBR)