Networking system having multiple components with multiple loci of control

Patent metadata

Field	Value
Publication number	US-11588756-B2
Application number	US-202217579812-A
Country	US
Kind code	B2
Filing date	Jan 20, 2022
Priority date	Mar 2, 2020
Publication date	Feb 21, 2023
Grant date	Feb 21, 2023

Abstract

Each switch unit in a networking system shares its local state information among other switch units in the networking system, collectively referred to as the shared forwarding state. Each switch unit creates a respective set of output queues that correspond to ports on other switch unites based on the shared forwarding state. A received packet on an ingress switch unit operating in accordance with a first routing protocol instance can be enqueued on an output queue in the ingress switch; the packet is subsequently processed by the egress switch unit, operating in accordance with a second routing protocol instance that corresponds to the output queue.

First claim

What is claimed is:

1. A method in a switching module, the method comprising:
a first switch unit in the switching module receiving a packet;
the first switch unit performing a forwarding lookup operation using addressing information in the received packet to identify a next hop address and an egress port, wherein the egress port is on a second switch unit in the switching module;
the first switch unit identifying a virtual output queue (VOQ) that corresponds to the egress port on the second switch unit and a rewrite index based on the next hop address;
the first switch unit enqueuing the received packet and the rewrite index on the identified VOQ;
the second switch unit dequeuing the received packet and the rewrite index from the identified VOQ;
the second switch unit modifying the packet according to the rewrite index; and
the second switch unit transmitting the modified packet on the port that is associated with the identified VOQ, without performing a forwarding lookup operation in the second switch unit.

2. The method of claim 1 , wherein the rewrite index identifies a set of rewrite actions that the second switch unit uses to modify the received packet.

3. The method of claim 1 , further comprising a central source collecting local forwarding information from the first and second switch units and sharing the collected local forwarding information among the first and second switch units, wherein the first switch unit performs the forwarding lookup operation using the collected local forwarding information received from the central source.

4. The method of claim 1 , the method further comprising:
the second switch unit identifying a set of rewrite actions using the rewrite index; and
modifying the packet using the identified set of rewrite actions.

5. The method of claim 4 , wherein the rewrite actions are stored in the second switch unit.

6. The method of claim 1 , wherein the egress port is a member port of a link aggregate group (LAG) defined on the second switch unit, the method further comprising the first switch unit identifying all member ports of the LAG and selecting one of the member ports of the LAG as a new egress port.

7. A modular chassis comprising:
a first switch unit comprising a first processor operable as a first controller; and
a second switch unit comprising a second processor operable as a second controller,
the first controller in the first switch unit configured to:
receive packets;
perform a forwarding lookup operation using addressing information contained in a packet received on a port of the first switch unit to determine a next hop address and an egress port on which to egress the received packet; and
when the egress port is a port on the second switch unit:
identify a rewrite index and a virtual output queue (VOQ) that is associated with the next hop address; and
enqueue the received packet and the rewrite index on the VOQ,

the second controller in the second switch unit configured to:
dequeue the received packet and rewrite index from the VOQ;
modify the received packet according to the rewrite index; and
transmit the modified packet on a port on the second switch unit that is associated with the VOQ, without performing a forwarding lookup operation in the second switch unit.

8. The modular chassis of claim 7 , wherein when the egress port is a member port of a LAG defined on the second switch unit, then the first switch unit identifies all member ports of the LAG and selects as a new egress port one of the member ports of the LAG.

9. The modular chassis of claim 7 , wherein the first switch unit has stored therein a local copy of shared forwarding information that is used to identify the virtual output queue (VOQ) and the rewrite index.

10. The modular chassis of claim 9 , wherein the shared forwarding information comprises:
rewrite indices generated by each of a plurality of switch units in the modular chassis, including the first and second switch units, each rewrite index identifying a set of rewrite actions in one of the plurality of switch units; and
a plurality of VOQ identifiers, each VOQ identifier uniquely identifying a port on one of the plurality of switch units.

11. The modular chassis of claim 9 , wherein each of a plurality of switch units in the modular chassis, including the first and second switch units, is configured to provide its respective forwarding information to a central server, wherein the shared forwarding information is an aggregation of the respective forwarding information received from the plurality of switch units, wherein each of the plurality of switch units stores a local copy of the shared forwarding information.

12. A distributed switch fabric comprising:
a first switch unit comprising a first processor operable as a first controller; and
a second switch unit comprising a second processor operable as a second controller,
the first controller in the first switch unit configured to process a first packet received on a port of the first switch unit when the first packet is destined for egress on another port of the first switch unit;
the first controller in the first switch unit configured to enqueue a second packet and a rewrite index on a virtual output queue (VOQ) associated with the second switch unit when the second packet is destined for egress on a port of the second switch unit,
wherein the second controller of the second switch unit:
dequeues the second packet and rewrite index from the virtual output queue;
modifies the second packet in accordance with rewrite actions identified by the rewrite index; and
transmits the modified second packet on a port on the second switch unit that corresponds to the virtual output queue.

13. The distributed switch fabric of claim 12 , wherein the modified second packet is transmitted by the second switch unit without the second switch unit performing a forwarding lookup operation.

14. The distributed switch fabric of claim 12 , wherein the first switch unit stores a local copy of shared forwarding information and uses the shared forwarding information to identify the virtual output queue and the rewrite index.

15. The distributed switch fabric of claim 14 , wherein the shared forwarding information comprises:
rewrite indices generated by each of a plurality of switch units, each rewrite index identifying a set of rewrite actions in one of the plurality of switch units; and
a plurality of VOQ identifiers, each VOQ identifier uniquely identifying a port on one of the plurality of switch units.

16. The distributed switch fabric of claim 12 , further comprising a modular chassis wherein a plurality of switch units, including the first and second switch units, is installed in the modular chassis and interconnected by a communication fabric, wherein the modular chassis is configurable to add switch units and to remove switch units.

17. The distributed switch fabric of claim 12 , further comprising a plurality modular chassis interconnected by a communication fabric, each modular chassis comprising at least some of the plurality of switch units installed therein, each modular chassis being configurable to add switch units and to remove switch units.

18. The distributed switch fabric of claim 12 , further comprising a plurality of fixed-configuration chassis, each fixed-configuration chassis comprising a fixed number of the plurality of switches.

Assignees

• Arista Networks Inc

Inventors

• Labonte Francois
• Chandran Kartik
• Baskaran Eswaran
• Holbrook Hugh Weber

Classifications

• H04L12/66

  Arrangements for connecting between networks having differing types of switching systems, e.g. gateways · CPC title

• H04L49/252

  Store and forward routing · CPC title

• H04L49/3045 Primary

  Virtual queuing · CPC title