Traffic generator and monitor
A switch in a data communications network for performing traffic generation in addition to standard switching and routing operations is disclosed. The switch uses a fixed number of test packets retained in a conventional switch buffer to produce one or more infinite packet streams transmitted to a router under test (RUT). The switching device enqueues packets in the priority queues, dequeues the packets from the priority queues, transmits the dequeued packets to the RUT, and re-enqueues a copy of the dequeued packets into the priority queues from which they were dequeued. The enqueued packets and associated pointers to packets are organized into linked lists. By re-writing a copy of each dequeued packet to the tail of a linked list and updating the pointers, the switch produces repeatable streams of test packets. The priority buffers, without the re-write operation, may also be used for conventional egress traffic.
1. A data communications switching device for performing traffic generation in a data communications network comprising equipment under test (EUT), the switching device comprising:
at least one port configured to receive a first plurality of protocol data units (PDUs);
a routing engine configured to execute forwarding operations on the first plurality of PDUs;
a traffic generator configured to produce a second plurality of PDUs; and a plurality of priority queues; wherein the switching device is configured to:
enqueue the first plurality of PDUs and second plurality of PDUs in the plurality of priority queues, selectively associate the second plurality of PDUs using at least one linked list;
repeatedly dequeue the second plurality of PDUs from the plurality of priority queues using the at least one linked list, wherein the switching device further includes a scheduler configured to dequeue the first plurality of PDUs and second plurality of PDUs dequeued from the plurality of priority queues, wherein the scheduler dequeues the first plurality of PDUs and second plurality of PDUs using a bandwidth allocation scheme selected from the group consisting of: strict priority, round robin, and weighted fair queuing, wherein the rate at which the second plurality of PDUs are transmitted from data communications switching device is programmable, and disassociating the first plurality of PDUs from the first set of pointers; and
a traffic monitor configured to receive the second plurality of PDUs from EUT and compile traffic generation statistics that are usable by the switching device if the switching device evaluates the forwarding operability of the EUT.
2. The data communications switching device of claim 1 , wherein the first plurality of PDUs are associated with a first set of pointers to the plurality of priority queues, and the second plurality of PDUs are associated with a second set of pointers to the plurality of priority queues.
3. The data communications switching device of claim 2 , wherein the at least one linked list comprises the second set of pointers.
4. The data communications switching device of claim 2 , wherein the switching device is configured to: dequeue the first plurality of PDUs from the plurality of priority queues; and disassociate the first plurality of PDUs from the first set of pointers.
5. The data communications switching device of claim 2 , wherein the switching device further includes a scheduler for transmitting PDUs from the plurality of priority queues.
6. The data communications switching device of claim 2 , wherein the switching device is further configured to dequeue the first plurality of PDUs from the plurality of priority queues.
7. A method of performing traffic generation in a data communications switching device within a network comprising equipment under test (EUT), the switching device comprising:
receiving a first plurality of protocol data units (PDUs) addressed to one or more destination nodes reachable through the switching device;
preparing the first plurality of PDUs for forwarding to one or more destination nodes;
generating at a traffic generator a second plurality of test PDUs;
enqueuing the first plurality of PDUs and second plurality of test PDUs in a plurality of priority queues;
associating the second plurality of test PDUs; and
dequeuing the second plurality of test PDUs from the plurality of priority queues, wherein the second plurality of test PDUs are associated with at least one linked list, and the second plurality of test PDUs dequeued from the plurality of priority queues with the at least one linked list, wherein the first plurality of PDUs are associated with a first set of pointers to the plurality of priority queues, and the second plurality of test PDUs are associated with a second set of pointers to the plurality of priority queues,
wherein the method further comprises the steps of: dequeuing the first plurality of PDUs from the plurality of priority queues; and disassociating the first plurality of PDUs from the first set of pointers and dequeuing the second plurality of test PDUs from the associated priority queues comprises the steps of: releasing one of the second plurality of test PDUs for transmission to the EUT; and retrieving a linked list pointer to a next test PDU to be released, wherein the linked list pointer selected from the second set of pointers using the linked list.
8. The data method of performing traffic generation of claim 7 , wherein the second plurality of test PDUs are associated with at least one linked list, and the second plurality of test PDUs dequeued from the plurality of priority queues with the at least one linked list.
9. The data method of performing traffic generation of claim 8 , wherein the first plurality of PDUs are associated with a first set of pointers to the plurality of priority queues, and the second plurality of test PDUs are associated with a second set of pointers to the plurality of priority queues.
10. A data communications switching device for performing traffic generation in a data communications network comprising equipment under test (EUT), the switching device comprising:
a first set of at least one priority queue;
a queue manager configured to:
enqueue a plurality of protocol data units (PDUs) in each of the at least one priority queue, dequeue the plurality of PDUs from each of the at least one priority queue, and re-enqueue the plurality of dequeued PDUs in the at least one priority queue, wherein the switching device further comprises a second set of at least one priority queue for buffering one or more egress PDUs, wherein the switching device is configured to concurrently dequeue egress PDUs from the second set of at least one priority queue and dequeue the plurality of PDUs from each of at least one priority queue of the first set, and wherein the first plurality of PDUs is disassociated from the first set of pointers; and
a traffic monitor configured to receive the plurality of PDUs in each of the at least one priority queue from the EUT and compile traffic generation statistics that are usable by the switching device if the switching device evaluates the forwarding operability of the EUT.
11. The switching device of claim 10 , wherein each of the at least one priority queue comprises a linked list, each linked list comprising a plurality of pointer, each pointer being associated with one of the plurality of enqueued PDUs.
12. The switching device of claim 10 , wherein the at least one priority queue is a first in first out (FIFO) memory.
13. The switching device of claim 10 , wherein the switching device is a multi-layer switch configured to perform switching and routing operations in accordance with Layer 1 and Layer 2 of the Open Systems Interconnect (OSI) reference model.