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JUNOS Enterprise Routing by Harry Reynolds, Doug Marschke

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Routing Policy

This section details JUNOS software routing policy operation and configuration. The actual application of policy to solve some specific networking requirement is generally left to the protocol-specific coverage found in subsequent chapters. You configure policy-related options and statements at the [edit policy-options] hierarchy. Routing policy and firewall filters have a similar syntax in JUNOS software. The former deals with routes in the control plane, whereas the latter deals with packets in the data plane.

What Is a Routing Policy, and When Do I Need One?

Simply put, routing policy is used to:

  • Control what routes are installed into the route table for possible selection as an active route

  • Control what routes are exported from the route table, and into which protocols

  • Alter attributes of routes, either at reception or at the time of advertisement to other peers

Given that routing policy is used to control the reception and transmission of routing information and to alter route attributes, it’s safe to say that you need routing policy when the default policy does not meet your requirements.

The specifics of the various default policies are covered later, but to provide an example, consider that, by default, directly connected routes are not advertised into any routing protocol; in the case of RIP, not even when RIP is configured to run on those directly connected interfaces. If your goal is to get direct routes advertised into RIP, the default policy obviously does not ...

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