US 9,866,401 B2Granted

Dynamic protection of shared memory and packet descriptors used by output queues in a network device

AssigneeCisco Technology, Inc.

InventorsMohammadreza Alizadeh Attar, Sha Ma, Vinod Mitulal, Krishnan Subramani, Georges Akis, Peter Newman

Life of this patent

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Abstract

A network switch includes a buffer to store network packets and packet descriptors (PDs) used to link the packets into queues for output ports. The buffer and PDs are shared among the multiple traffic pools. The switch receives a multicast packet for queues in a given pool. The switch determines if there is unused buffer space available for packets in the given pool based on a pool dynamic threshold, if there is unused buffer space available for packets in each queue based on a queue dynamic threshold for the queue, if there are unused PDs available to the given pool based on a pool dynamic threshold for PDs, and if there are unused PDs available for each queue based on a queue dynamic threshold for PDs for the queue. The network switch admits the packet only into the queues for which all of the determining operations pass.

Claims20

Dependent claims

A method comprising:

at a network switch including a buffer having buffer space to store network packets, and a store of packet descriptors (PDs) that are used to link the network packets into queues that feed the packets to output ports of the switch, wherein the buffer space is shared among multiple traffic pools and the PDs are shared among the multiple traffic pools:
receiving a multicast packet destined for multiple queues associated with a given pool;
determining if there is unused buffer space available for packets in the given pool based on a pool dynamic threshold;
determining, for each queue, if there is unused buffer space available for packets in that queue based on a queue dynamic threshold for that queue;
determining if there are unused PDs available to the given pool based on a pool dynamic threshold for PDs;
determining, for each queue, a queue dynamic threshold for PDs so as to define a maximum number of PDs available to the queue that is based on a number of unused PDs available to the given pool, wherein the queue dynamic threshold for PDs is determined based on an average fanout of packets in the given pool, the average fanout being a ratio of (i) a number of PDs used by the given pool, and (ii) a pool occupancy for the given pool;
determining, for each queue, if there are unused PDs available for that queue based on the queue dynamic threshold for PDs for that queue;
and
admitting the packet only into the queues for which all of the determining operations pass.

6 more elements

An apparatus comprising:

network ports to receive and send network packets from and to a network;
and
a controller coupled to the network ports, the controller including a buffer having buffer space to store network packets, and a store of packet descriptors (PDs) that are used to link the network packets into queues that feed the packets to output ports of the apparatus, wherein the buffer space is shared among multiple traffic pools and the PDs are shared among the multiple traffic pools, the controller configured to:
receive a multicast packet destined for multiple queues associated with a given pool;
determine if there is unused buffer space available for packets in the given pool based on a pool dynamic threshold;
determine, for each queue, if there is unused buffer space available for packets in that queue based on a queue dynamic threshold for that queue;
determine if there are unused PDs available to the given pool based on a pool dynamic threshold for PDs;
determine, for each queue, a queue dynamic threshold for PDs so as to define a maximum number of PDs available to the queue that is based on a number of unused PDs available to the given pool, wherein the queue dynamic threshold for PDs is determined based on an average fanout of packets in the given pool, the average fanout being a ratio of (i) a number of PDs used by the given pool, and (ii) a pool occupancy for the given pool;
determine, for each queue, if there are unused PDs available for that queue based on the queue dynamic threshold for PDs for that queue;
and
admit the packet only into the queues for which all of the determining operations pass.

8 more elements

A non-transitory computer readable storage media encoded with instructions that, when executed by a controller of a network device that includes a buffer having buffer space to store network packets, and a store of packet descriptors (PDs) that are used to link the network packets into queues that feed the packets to output ports of the network device, wherein the buffer space is shared among multiple traffic pools and the PDs are shared among the multiple traffic pools, cause the controller to:

receive a multicast packet destined for multiple queues associated with a given pool;
determine if there is unused buffer space available for packets in the given pool based on a pool dynamic threshold;
determine, for each queue, if there is unused buffer space available for packets in that queue based on a queue dynamic threshold for that queue;
determine if there are unused PDs available to the given pool based on a pool dynamic threshold for PDs;
determine, for each queue, a queue dynamic threshold for PDs so as to define a maximum number of PDs available to the queue that is based on a number of unused PDs available to the given pool, wherein the queue dynamic threshold for PDs is determined based on an average fanout of packets in the given pool, the average fanout being a ratio of (i) a number of PDs used by the given pool, and (ii) a pool occupancy for the given pool;
determine, for each queue, if there are unused PDs available for that queue based on the queue dynamic threshold for PDs for that queue;
and
admit the packet only into the queues for which all of the determining operations pass.

5 more elements

Dependencies are inferred from the claim text.

Facts

Application: 14/710,974Filed 13 May 2015
Published: US 2016/0337142 A117 Nov 2016
Granted: 9 Jan 2018
Term ends: Not estimatedThe source records don’t support an estimate.

Classification6 codes

H04L 12/1881
For broadcast or conference , e.g. multicast: with schedule organisation, e.g. priority, sequence management
H04L 47/6255
For service slots or service orders: queue load conditions, e.g. longest queue first
H04L 47/6275
For service slots or service orders: based on priority
H04L 49/901
Buffering arrangements: using storage descriptor, e.g. read or write pointers