System and method for abstracting an IGP zone
Various systems and methods for migrating a zone to a pseudo node are described herein including a method performed by a zone edge node. In an embodiment, the method includes receiving, by the zone edge node, an execution request to initiate migration from the zone to the pseudo node. The method also includes sending, by the zone edge node, at least one Hello packet to a zone external node adjacent to the zone edge node for requesting the zone external node to create an adjacency between the pseudo node and the zone external node on the zone external node. The method further includes creating, by the zone edge node, the adjacency between the pseudo node and the zone external node on the zone edge node.
1 . A zone edge node comprising:
a memory configured to store instructions; and
a processor coupled to the memory and configured to execute the instructions to cause the zone edge node to:
receive an execution request to migrate a zone to a pseudo node;
send a Hello packet to a zone external node adjacent to the zone edge node for requesting the zone external node to create an adjacency between the pseudo node and the zone external node on the zone external node, wherein the Hello packet comprises a pseudo node identifier (ID) as a source ID of the Hello packet and an Adjacency to Abstracted Node bit (AN-bit) that is set to a value that indicates to the zone external node to create the adjacency between the pseudo node and the zone external node on the zone external node; and
create the adjacency between the pseudo node and the zone external node on the zone edge node.
2 . The zone edge node of claim 1 , wherein the Hello packet comprises an Extended Options and Flag-Type/Length/Value (EOF-TLV) comprising the AN-bit.
3 . The zone edge node of claim 1 , wherein the instructions when executed by the processor further causes the zone edge node to establish a normal adjacency between the zone edge node and the zone external node when there is not an existing adjacency between the zone edge node and the zone external node.
4 . The zone edge node of claim 1 , wherein the instructions when executed by the processor further causes the zone edge node to terminate an existing adjacency between the zone edge node and the zone external node.
5 . The zone edge node of claim 1 , wherein the instructions when executed by the processor further causes the zone edge node to:
receive a link state (LS) packet for the pseudo node, the LS packet comprising all links connecting zone external nodes to any zone edge node of the zone.
6 . The zone edge node of claim 1 , wherein the instructions when executed by the processor further causes the zone edge node to:
compute internal routes within the zone based on a topology of the zone; and
compute external routes outside the zone based on the topology of the zone and a topology outside of the zone without the pseudo node.
7 . The zone edge node of claim 1 , wherein the instructions when executed by the processor further causes the zone edge node to: advertise a zone edge node link state (LS) packet to the zone external node, wherein the zone edge node LS packet excludes all links inside the zone.
8 . The zone edge node of claim 1 , wherein the instructions when executed by the processor further causes the zone edge node to:
receive a zone external node link state (LS) packet from the zone external node; and
flood the zone external node LS packet to neighbor nodes of the zone edge node both inside and outside of the zone.
9 . A method performed by a zone leader node of a zone, the method comprising:
receiving updated link state packets originated by all zone external nodes having adjacencies with zone edge nodes of the zone;
originating a link state (LS) packet for the zone as a pseudo node;
advertising the LS packet to neighbor nodes of the zone leader node for migrating the zone to the pseudo node, wherein the LS packet comprises all links connecting the zone external nodes to any of the zone edge nodes of the zone;
receiving a command to migrate the pseudo node back to the zone;
updating the LS packet by changing every link metric for the pseudo node to a maximum metric in the LS packet to obtain an updated LS packet; and
advertising the updated LS packet to the neighbor nodes for migrating the pseudo node back to the zone.
10 . The method of claim 9 , wherein at least one of a source identifier (ID) and advertising node/router ID of the LS packet is an ID of the pseudo node for the zone.
11 . The method of claim 9 , wherein the LS packet includes stub links for routes inside the zone accessible by zone external nodes.
12 . A zone external node comprising:
a memory configured to store instructions; and
a processor coupled to the memory and configured to execute the instructions to cause the zone external node to:
receive a Hello packet requesting the zone external node create an adjacency between a pseudo node and the zone external node on the zone external node, wherein the Hello packet comprises a pseudo node identifier (ID) as a source ID of the Hello packet and an Adjacency to Abstracted Node bit (AN-bit) that is set to a value that indicates to the zone external node to create the adjacency between the pseudo node and the zone external node on the zone external node;
create the adjacency between the pseudo node and the zone external node; and
add the adjacency into a link state (LS) database of the zone external node.
13 . The zone external node of claim 12 , wherein the instructions when executed by the processor further causes the zone external node to:
generate an LS packet comprising the adjacency between the pseudo node and the zone external node; and
flood the LS packet to a zone leader node of a zone.
14 . The zone external node of claim 12 , wherein the instructions when executed by the processor further causes the zone external node to advertise a router link state advertisement (LSA).
15 . A method performed by a zone edge node for transitioning a pseudo node back to a zone, the method comprising:
receiving, from a network management system, a command to initiate migration from the pseudo node to the zone;
determining, in response to the command, whether link state (LS) packets inside the zone were advertised to zone external nodes before the zone was abstracted as the pseudo node;
sending the LS packets to the zone external nodes having connections to the zone edge node when the LS packets were advertised to the zone external nodes before the zone was abstracted as the pseudo node; and
initiating removal of an adjacency between the pseudo node and at least one of the zone external nodes by sending a Hello packet to the at least one of the zone external nodes, wherein the Hello packet comprise an Adjacency to Abstracted Node bit (AN-bit) that is set to a value that indicates a request to the at least one of the zone external nodes to remove the adjacency between the at least one of the zone external nodes and the pseudo node.
16 . The method of claim 15 , wherein initiating removal of the adjacency between the pseudo node and at least one of the zone external nodes comprises sending, by the zone edge node, a normal Hello packet to each of the zone external nodes, the normal Hello packet comprising an identifier (ID) of the zone edge node as a source ID of the normal Hello packet.
17 . The method of claim 15 , wherein initiating removal of the adjacency between the pseudo node and at least one of the zone external nodes comprises terminating sending of Hello packets for the adjacency to the at least one of the zone external nodes.
18 . The method of claim 15 , wherein the Hello packet comprises an Extended Options and Flag-Type/Length/Value (EOF-TLV) comprising the AN-bit.