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Example: Rejecting Routes with Prefixes Longer than 24 Bits

Reject all prefixes longer than 24 bits. You would install this routing policy in a sequence of routing policies in an export statement. The first term in this filter passes on all routes with a prefix length of up to 24 bits. The second, unnamed term rejects everything else.



[edit policy-options]
policy-statement 24bit-filter {


term acl20 {


from {
route-filter 0.0.0.0/0 upto /24;
}


then next policy;
}


then reject;
}

If, in this example, you were to specify route-filter 0.0.0.0/0 upto /24 accept, matching prefixes would be accepted immediately and the next routing policy in the export statement would never get evaluated.

If you were to include the then reject statement in the term acl20, prefixes greater than 24 bits would never get rejected because the policy framework software, when evaluating the term, would move on to evaluating the next statement before reaching the then reject statement.

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