Prior to ExtremeXOS 15.7, routing protocol OSPFv2 applied routing policies with keyword “import-policy”, which can only be used to change the attributes of routes installed into the switch routing table. ExtremeXOS 15.7 provides the flexibility of using import policy to determine the routes to be added to or removed from the routing table.
To prevent a route being added to the routing table, the policy file must contain a matching rule with action “deny”. If there is no matching rule for a particular route, or the keyword “deny” is missing in the rule, the default action is “permit”, which means that route will be installed into the routing table. Refer to the following policy file example:
entry entry-one {
if {
nlri 11.22.0.0/16;
}
then {
cost 100;
}
}
entry entry-two {
if {
nlri 22.33.0.0/16;
}
then {
deny;
}
}
In the above policy example, entry-one is used to change the cost of any matching routes, and entry-two is used to remove those matching routes from the routing table.
Note
Only “Network Layer Reachability Information” (NLRI) and "route origin" can be used as matching criteria in policy rules; using "next_hop" as a matching criteria is not supported. Any other policy attribute is not recognized and is ignored.