Border gateway protocol inbound policy optimization
View Patent ↗A BGP capable packet network device is located at the boundary of an autonomous network and in communication with a peer BGP capable packet network device in a neighboring autonomous network. The BGP capable packet network device is comprised of one or more line cards for receiving and, processing and sending packets of information, and for receiving and forwarding routing update information to a route processor comprising the packet network device. The route processor runs a border gateway protocol which is configured with one or more policies that operate to filter the routing update information received from the line card. The routing update information filter is comprised of at least one variable length path attribute and the filter operates such that it only applies the variable length path attribute one time to the routing update information.
1. A method for filtering update messages received by a border gateway protocol (BGP) capable packet network device, comprising:
configuring a policy filter in the packet network device with a filter explicit path attribute, a filter explicit prefix attribute, and a route map including a filter implicit path attribute and a filter implicit prefix attribute;
receiving an update message that includes a plurality of message attributes;
applying the filter explicit path attribute to the update message prior to applying the route map to the update message;
in response to the filter explicit path attribute permitting at least one path in the plurality of message attributes, applying the filter implicit path attribute in the route map to the update message without applying the filter implicit prefix attribute in the route map to the update message; and
in response to the filter implicit path attribute in the route map not permitting at least one path in the plurality of message attributes, dropping the update message without applying the filter explicit prefix attribute to the update message.
2. The method of claim 1 , further comprising:
in response to the filter implicit path attribute in the route map permitting at least one path in the plurality of the message attributes, adding the filter implicit path attribute to a list.
3. The method of claim 2 , further comprising:
in response to adding the filter implicit path attribute to the list, applying the filter explicit prefix attribute to a first prefix in the plurality of message attributes.
4. The method of claim 3 , further comprising:
in response to the filter explicit prefix attribute not permitting the first prefix, discarding the first prefix and applying the filter explicit prefix attribute to a second prefix in the plurality of message attributes.
5. The method of claim 3 , further comprising:
in response to the filter explicit prefix attribute permitting the first prefix, applying the filter implicit prefix attribute in the route map to the first prefix.
6. The method of claim 5 , further comprising:
in response to the filter implicit prefix attribute in the route map not permitting the first prefix, discarding the first prefix.
7. The method of claim 5 , further comprising:
in response to the filter implicit prefix attribute in the route map permitting the first prefix, storing the first prefix.
8. A method for filtering update messages received by a border gateway protocol (BGP) capable packet network device, comprising:
configuring a policy filter in the packet network device with a plurality of filter explicit path attributes, a plurality of filter explicit prefix attributes, and a route map including a plurality of filter implicit path attributes;
receiving an update message including a plurality of message attributes;
applying each one of the plurality of filter explicit path attributes to the update message prior to applying the route map to the update message;
in response to each of the plurality of filter explicit path attributes permitting at least one path in the plurality of message attributes, applying the plurality of filter implicit path attributes in the route map to the update message; and
in response to the plurality of filter implicit path attributes in the route map not permitting at least one path in the plurality of message attributes, dropping the update message without applying the plurality of filter explicit path attributes to the update message.
9. The method of claim 8 , further comprising:
in response to a first filter implicit path attribute in the plurality of filter implicit path attributes in the route map permitting at least one path in the plurality of message attributes, adding the first filter implicit path attribute to a list.
10. The method of claim 9 , further comprising:
in response to adding the first filter implicit path attribute to the list, applying the plurality of filter explicit prefix attributes to a first prefix in the plurality of a message attributes.
11. The method of claim 10 , further comprising:
in response to the plurality of filter explicit prefix attributes not permitting the first prefix, discarding the first prefix and applying the plurality of filter explicit prefix attributes to a second prefix in the plurality of message attributes.
12. The method of claim 10 , further comprising:
in response to the plurality of filter explicit prefix attributes permitting the first prefix, determining whether the route map includes at least one filter implicit prefix attribute.
13. The method of claim 12 , further comprising:
in response to the route map including at least one filter implicit prefix attribute, applying the at least one filter implicit prefix attribute in the route map to the first prefix.
14. The method of claim 13 , further comprising:
in response to the at least one filter implicit prefix attribute in the route map not permitting the first prefix, discarding the first prefix.
15. The method of claim 13 , further comprising:
in response to the at least one filter implicit prefix attribute in the route map permitting the first prefix, storing the first prefix.
16. A border gateway protocol (BGP) capable packet network device, comprising:
a line card comprised of a packet processor, a memory, and a plurality of input/output ports all of which operate to receive update messages from a peer BGP capable packet network device; and
a route processor comprised of a BGP process and a memory, wherein the BGP process includes a policy filter including a filter explicit path attribute, a filter explicit prefix attribute, and a route map including a filter implicit path attribute, and wherein the route processor is configured to:
receive an update message that includes a plurality of message attributes;
apply the filter explicit path attribute in the policy filter to the update message prior to applying the route map to the update message;
in response to the filter explicit path attribute permitting at least one path in the plurality of message attributes, applying the filter implicit path attribute in the route map in the policy filter to the update message; and
in response to the filter implicit path attribute in the route map not permitting at least one path in the plurality of message attributes, dropping the update message without applying the filter explicit prefix attribute to the update message.
17. The BGP capable packet network device of claim 16 , wherein the route processor is configured to:
in response to the filter implicit path attribute in the route map permitting at least one path in the plurality of message attributes, applying the filter explicit prefix attribute to a first prefix in the plurality of message attributes.
18. The BGP capable packet network device of claim 17 , wherein the route processor is configured to:
in response to the filter explicit prefix attribute not permitting the first prefix, discarding the first prefix and applying the filter explicit prefix attribute to a second prefix in the plurality of message attributes.
19. The BGP capable packet network device of claim 18 , wherein the route processor is configured to:
in response to the filter explicit prefix attribute permitting the first prefix, determining that that the route map includes a filter implicit prefix attribute and applying the filter implicit prefix attribute in the route map to the first prefix.
20. The BGP capable packet network device of claim 19 , wherein the route processor is configured to:
discard the first prefix in response to the filter implicit prefix attribute in the route map not permitting the first prefix; and
store the first prefix in response to the filter implicit prefix attribute in the route map permitting the first prefix.