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How Prefix Order Affects Route List Evaluation

The order in which the prefixes are specified (from top to bottom) typically does not matter, because the policy framework software scans the route list looking for the longest prefix during evaluation. An exception to this rule is when you use the same destination prefix multiple times in a list. In this case, the order of the prefixes is important, because the list of identical prefixes is scanned from top to bottom, and the first match type that matches the route applies.

In the following example, different match types are specified for the same prefix. The route 0.0.0.0/0 would be rejected, the route 0.0.0.0/8 would be marked with next-hop self, and the route 0.0.0.0/25 would be rejected.



route-filter 0.0.0.0/0 upto /7 reject;
route-filter 0.0.0.0/0 upto /24 next-hop self;
route-filter 0.0.0.0/0 orlonger reject;

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