Method and an Apparatus for Routing Data Packets in a Network Topology

• US 20200136956A1
• Filed: 10/16/2019
• Published: 04/30/2020
• Est. Priority Date: 10/29/2018
• Status: Active Grant

• Current Assignee: Telia Company AB
• Original Assignee: Telia Company AB
• Inventors: Neshat, Reza
• Granted Patent: US 11,159,418 B2
• Time in Patent Office: Days
• CPC Class Codes: H04L 45/04 Interdomain routing, e.g. hierarchical routing
• CPC Class Codes: H04L 45/22 Alternate routing
• CPC Class Codes: H04L 45/24 Multipath
• CPC Class Codes: H04L 45/28 using route fault recovery
• CPC Class Codes: H04L 45/54 Organization of routing tables

Abstract

The embodiments relate to a method and a routing device. The method comprises introducing a logical hierarchy by defining a plurality of transit layers wherein to each transit layer a transit layer address is assigned and a transit router and wherein each transit router has a unique network address; the layers are organized in a descending order of subnet masks; for each interface between a router and said transit routers, defining, in a routing table of said router, a static route based on the transit layer address and the subnet mask of the transit router interfacing with the router; and if a connection that carries traffic between the router and any of the transit routers fails, selecting a static route in said routing table as a redundant route for carrying said traffic towards its destination.

Claims

1. A routing method in a network topology, the method comprising:

introducing in the network topology, a logical hierarchy by defining a plurality of transit layers wherein to each transit layer a transit layer address is assigned and a transit router is assigned, each transit router having a unique network address;

organizing the transit layers in a descending order of subnet masks so that the transit layer address assigned to a highest transit layer in said descending order is a subnet of each transit layer address assigned to lower transit layers in said descending order;

for each interface between a router and said transit routers, defining, in a routing table of said router, a static route based on the transit layer address and the subnet mask of the transit router interfacing with the router; and

if a connection that carries traffic between the router and any of the transit routers fails, selecting a static route in said routing table as a redundant route for carrying said traffic towards its destination.

2. The method according to claim 1, wherein, if the connection that carries traffic between the router and any of the transit routers fails, and the transit router is that of a subnet having a lower transit layer address, further comprising selecting the static route corresponding to that of the transit router of the highest transit layer as a redundant route for carrying said traffic.

3. The method according to claim 2, wherein the transit router associated with the highest transit layer has the highest subnet mask in said descending order, and the transit router associated with the lowest transit layer in said descending order has the lowest subnet mask in said descending order.

4. The method according to claim 1, wherein, for each interface between the router and any of the transit routers, the routing table of the router further includes the transit layer address and the network address of the transit layer associated with the transit router interfacing with said router.

5. The method according to claim 4, wherein if said connection that carries traffic between the router and any of the transit routers fails, further comprising removing, from the routing table of the router, the network address and the static route associated with the failed connection.

6. A routing device comprising a processor and a memory, said memory containing instructions executable by said processor, the routing device being in a network topology wherein a logical hierarchy is introduced by defining a plurality of transit layers wherein to each transit layer a transit layer address is assigned and a transit router is assigned, and wherein each transit router has a unique network address, the transit layers are organized in a descending order of subnet masks so that the transit layer address assigned to the highest transit layer in said descending order is a subnet of each transit layer address assigned to lower transit layers in said descending order;

said routing device is operative to;

for each interface between the routing device and said transit routers, define, in a routing table of said router or routing device, a static route based on the transit layer address and the subnet mask of the transit router interfacing with the routing device;

if a connection that carries traffic between the routing device and any of the transit routers fails, select a static route in said routing table as redundant route for carrying said traffic towards its destination; and

if a connection that carries traffic between the router or routing device and any of the transit routers fails, select a static route in said routing table as a redundant route for carrying said traffic towards its destination.

7. The routing device according to claim 6, wherein, if the connection that carries traffic between the router or routing device and any of the transit routers fails, and the transit router is that of a subnet having a lower transit layer address, the routing device is further operative to select the static route corresponding to that of the transit router of the highest transit layer as a redundant route for carrying said traffic.

8. The routing device according to claim 7, wherein the transit router associated with the highest transit layer has the highest subnet mask in said descending order, and the transit router associated with the lowest transit layer in said descending order has the lowest subnet mask in said descending order.

9. The routing device according to claim 6, wherein, for each interface between the router and any of the transit routers, the routing table of the router or routing device further includes the transit layer address and the network address of the transit layer associated with the transit router interfacing with said routing device or router.

10. The routing device according to claim 9, wherein, if said connection that carries traffic between the routing device or router and any of the transit routers fails, the routing device is further operative to remove from the routing table of the router or routing device the network address and the static route associated with the failed connection.