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Policy-based Routing
Policy-based Routing is supported on platforms: c e s
PBR is supported on the E-Series ExaScale platform with FTOS 8.1.1.0 and later.
PBR is supported on the E-Series TeraScale, C-Series, and S-Series platforms in FTOS 8.4.2.0 and later.
This chapter covers the following topics:
• Overview
• Implementing Policy-based Routing with FTOS on page 803
• Configuration Task List for Policy-based Routing on page 804
• Create a Redirect List on page 804
• Create a Rule for a Redirect-list on page 805
• Apply a Redirect-list to an Interface using a Redirect-group on page 808
• PBR Exceptions (Permit) on page 807
• Sample Configuration on page 810
Overview
Policy-based Routing (PBR) enables you to make routing decisions based on policies applied to a specific
interface. When a router receives a packet it normally decides where to forward it 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, etc.
For example, a network administrator might want to forward a packet that uses TCP across a
different next-hop than packets using ICMP.
Rules for PBR can also be a combination of things: when the packet comes from this source and wants
to go to that destination then route it to this next-hop or onto that specific interface.
This permits
routing over different links or towards different networks even while the destination is the same but
depending on where the packet originates.