PROBES FOR PREDICTIVE DETERMINATION OF CONGESTION BASED ON REMARKING/DOWNGRADING OF PACKETS

• US 20080225704A1
• Filed: 03/16/2007
• Published: 09/18/2008
• Est. Priority Date: 03/16/2007
• Status: Active Grant

• Current Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Original Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Inventors: Ballantyne, Andrew John, SHEINFELD, GIL MATI
• Granted Patent: US 8,018,862 B2
• Time in Patent Office: Days
• US Class Current: 370/229
• CPC Class Codes: H04L 41/0213 Standardised network management protocols, e.g. simple network management protocol [SNMP]
• CPC Class Codes: H04L 43/12 Network monitoring probes

Abstract

In one embodiment, a technique for detecting the re-marking of a parameter in a network packet is provided. The technique involves sending a request packet that contains a first value of a type of service parameter effecting how the packet is to be handled relative to other packets and receiving a response packet to the request packet, the response packet containing an indication of a second value of the type of service parameter in the request packet as received by a network device that sent the response packet. The first and second values of the type of service parameter are compared. A determination that the request packet was re-marked is made if the first and second values of the type of service parameter do not match.

Claims

1. A method comprising:

sending a request packet that contains a first value of a type of service parameter effecting how the packet is to be handled relative to other packets;

receiving a response packet to the request packet, the response packet containing an indication of a second value of the type of service parameter in the request packet as received by a network device that sent the response packet;

comparing the first and second values of the type of service parameter; and

determining the request packet was re-marked if the first and second values of the type of service parameter do not match.

2. The method of claim 1, further comprising sending a notice to a network management system if the first and second values do not match.

3. The method of claim 1, further comprising performing one or more operations to identify a network device that re-marked the request packet.

4. The method of claim 3, wherein performing one or more operations to identify a network device that re-marked the request packet comprises:

sending a first request with a first value of a time to live parameter to a first intermediate network device;

comparing a type of service value sent with the first request to a type of service value as received in the first request by the first intermediate device; and

determining the packet was re-marked prior to receipt by the first intermediate device if the type of service value sent with the first request does not match the type of service value as received in the first request by the first intermediate device.

5. The method of claim 4, further comprising, in response to determining the type of service value sent with the first request matches the type of service value as received in the first request by the first intermediate device:

sending a second request with a second value of a time to live parameter different than the first time to live parameter to a second intermediate network device;

comparing a type of service value sent with the second request to a type of service value as received in the second request by the first intermediate device; and

determining the packet was re-marked prior to receipt by the second intermediate device if the type of service value sent with the second request does not match the type of service value as received in the second request by the second intermediate device.

6. The method of claim 1, wherein the request is designed to elicit the error response by targeting an invalid port of the network device that sends the error response.

7. The method of claim 1, further comprising creating a probe on a network device to send the request packet, receive the response packet and compare the first and second values of the type of service parameter.

8. The method of claim 1, wherein the request packet targets members of a multicast group.

9. The method of claim 1, further comprising storing information regarding re-marking of packets in a management information base (MIB).

10. The method of claim 9, further comprising sending information regarding re-marking of packets stored in the MIB to a network management system in response to a polling request from the network management system.

11. An apparatus, comprising:

an interface for establishing communication with a network; and

a controller configured to send a ping request targeting a destination device on the network and to compare a first value of a type of service parameter as sent in the ping request to a second value of the type of service parameter as received in the ping request by the destination device.

12. The apparatus of claim 11, wherein the controller is configured to send results of the comparing to a network management system in response to detecting the first value of the type of service parameter as sent in the ping request does not match the second value of the type of service parameter as received in the ping request by the destination device.

13. The apparatus of claim 11, wherein the controller is configured to send ping requests targeting devices belonging to different multicast groups.

14. The apparatus of claim 11, wherein the controller is further configured to perform one or more operations to identify a network device that re-marked the request packet.

15. The apparatus of claim 14, wherein the one or more operations comprise:

sending a first request with a first value of a time to live parameter to a first intermediate network device;

comparing a type of service value sent with the first request to a type of service value as received in the first request by the first intermediate device; and

determining the packet was re-marked prior to receipt by the first intermediate device if the type of service value sent with the first request does not match the type of service value as received in the first request by the first intermediate device.

16. The apparatus of claim 11, wherein the request is designed to elicit the error response by targeting an invalid port of the destination device.

17. The apparatus of claim 11, further comprising:

a management information base; and

wherein the controller is further configured to store information regarding re-marking of packets in a management information base (MIB).

18. A system, comprising:

at least one probe deployed on at least one network device in a network, the probe configured to detect re-marking of network packets by comparing a value of a type of service parameter sent in a ping request targeting a destination device to a value of a type of service parameter in the ping request as received by the destination device; and

a network management component configured to obtain an indication of re-marking of packets by one or more devices in the network based on information received from the probe.

19. The system of claim 18, wherein the network management component is configured to poll the probe for the information.

20. The system of claim 18, wherein the probe is configured to automatically send the information.

21. The system of claim 18, wherein the network management component is configured to notify an administrator of the network in response to obtaining the indication of re-marking of packets.

22. The system of claim 21, wherein the network management component is configured to notify the administrator by providing the administrator with a location in the network where the re-marking occurred.

23. The system of claim 18, wherein the information provides an indication of a network device that is re-marking packets.

24. An apparatus, comprising:

means for establishing communication with a network; and

means for sending a ping request targeting a destination device on the network and comparing a first value of a type of service parameter as sent in the ping request to a second value of the type of service parameter as received in the ping request by the destination device.