Designated forwarder selection for multihomed hosts in an ethernet virtual private network

Patent metadata

Field	Value
Publication number	US-11895028-B2
Application number	US-202217817870-A
Country	US
Kind code	B2
Filing date	Aug 5, 2022
Priority date	May 11, 2020
Publication date	Feb 6, 2024
Grant date	Feb 6, 2024

Abstract

Embodiments for handling multidestination traffic in a network are described. The multidestination traffic includes packets that are in transit to a multihomed destination in the network. Upon determining the destination is multihomed, a network switch determines a hash value from a selection of header values in the network traffic and uses the hash value to determine if the network switch is a designated forwarder for the multihomed destination. The network switch handles the network traffic according to a designated forwarder status.

First claim

We claim:

1. A method comprising:
receiving an indication of updated network settings for a network at a network switch;
storing a shadow hash forwarding table at the network switch by storing a hash forwarding table in current use at a time of the indication as the shadow hash forwarding table; and
forwarding a multidestination packet to a destination in the network using the shadow hash forwarding table.

2. The method of claim 1 , further comprising:
receiving an updated hash forwarding table; and
using the shadow hash forwarding table to forward the multidestination packet until the updated hash forwarding table is converged on the network switch.

3. The method of claim 1 further comprising:
determining a hash value from a selection of header values of the multidestination packet using a hash function;
determining, using the hash value, a designated forwarding status for the network switch from a hash forwarding table; and
when the network switch is a designated forwarder for the multidestination packet according to the designated forwarding status, forwarding the multidestination packet to the destination.

4. The method of claim 3 , wherein the hash value is determined using a same hash function by each edge device connected to the destination, and wherein the hash value is an 8-bit value calculated based on a 5-tuple flow information and a VLAN for the multidestination packet.

5. The method of claim 3 , wherein the hash forwarding table provides load balancing for a network by load balancing between network switches connected to the destination.

6. The method of claim 1 , further comprising:
determining a link for the destination is down;
updating a hash forwarding table to remove the down link; and
transmitting an indication of the down link to a controller.

7. A computer program product, the computer program product comprising:
a computer-readable storage medium having computer-readable program code embodied therewith, the computer-readable program code executable by one or more computer processors to perform an operation, the operation comprising:
receiving an indication of updated network settings for a network at a network switch;
storing a shadow hash forwarding table at the network switch by storing a hash forwarding table in current use at a time of the indication as the shadow hash forwarding table; and
forwarding a multidestination packet to a destination in the network using the shadow hash forwarding table.

8. The computer program product of claim 7 , wherein the operation further comprises:
receiving an updated hash forwarding table; and
using the shadow hash forwarding table to forward the multidestination packet until the updated hash forwarding table is converged on the network switch.

9. The computer program product of claim 7 , wherein the operation further comprises:
determining a hash value from a selection of header values of the multidestination packet using a hash function;
determining, using the hash value, a designated forwarding status for the network switch from a hash forwarding table; and
when the network switch is a designated forwarder for the multidestination packet according to the designated forwarding status, forwarding the multidestination packet to the destination.

10. The computer program product of claim 9 , wherein the hash value is determined using a same hash function by each edge device connected to the destination, and wherein the hash value is an 8-bit value calculated based on a 5-tuple flow information and a VLAN for the multidestination packet.

11. The computer program product of claim 9 , wherein the hash forwarding table provides load balancing for a network by load balancing between network switches connected to the destination.

12. The computer program product of claim 7 , wherein the operation further comprises:
determining a link for the destination is down;
updating a hash forwarding table to remove the down link; and
transmitting an indication of the down link to a controller.

13. A system comprising:
a processor; and
a memory comprising instructions which, when executed on the processor, performs an operation, the operation comprising:
receiving an indication of updated network settings for a network at a network switch;
storing a shadow hash forwarding table at the network switch by storing a hash forwarding table in current use at a time of the indication as the shadow hash forwarding table; and
forwarding a multidestination packet to a destination in the network using the shadow hash forwarding table.

14. The system of claim 13 , wherein the operation further comprises:
receiving an updated hash forwarding table; and
using the shadow hash forwarding table to forward the multidestination packet until the updated hash forwarding table is converged on the network switch.

15. The system of claim 13 , wherein the operation further comprises:
determining a hash value from a selection of header values of the multidestination packet using a hash function;
determining, using the hash value, a designated forwarding status for the network switch from a hash forwarding table; and
when the network switch is a designated forwarder for the multidestination packet according to the designated forwarding status, forwarding the multidestination packet to the destination.

16. The system of claim 15 , wherein the hash value is determined using a same hash function by each edge device connected to the destination, and wherein the hash value is an 8-bit value calculated based on a 5-tuple flow information and a VLAN for the multidestination packet.

17. The system of claim 15 , wherein the hash forwarding table provides load balancing for a network by load balancing between network switches connected to the destination.

Assignees

• Cisco Tech Inc

Inventors

• Subagio Putu H
• Nasika Ravikanth
• Bhattacharya Saikat
• Huang Chih-Tsung

Classifications

• G06F16/90

  Details of database functions independent of the retrieved data types · CPC title

• H04L45/7453 Primary

  using hashing · CPC title

• H04L12/4641

  Virtual LANs, VLANs, e.g. virtual private networks [VPN] (LAN interconnection over a bridge based backbone H04L12/462; encapsulation techniques H04L12/4633; routing of packets H04L45/00; packet switches H04L49/00; virtual private networks for security H04L63/0272) · CPC title

• H04L47/125

  by balancing the load, e.g. traffic engineering · CPC title

• H04L49/3009

  Header conversion, routing tables or routing tags · CPC title