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Use of a Programmable Network Processor to Measure Packet Flow Characteristics Using Precision Packet Insertion and De-insertion

IP.com Disclosure Number: IPCOM000015946D
Original Publication Date: 2002-May-28
Included in the Prior Art Database: 2003-Jun-21
Document File: 6 page(s) / 83K

Publishing Venue

IBM

Abstract

For precise measurement of traffic flow characteristics, one needs to measure the latency of a packet across a network. Often this measurement needs to be repeated multiple times to obtain an "averaged" result and to obtain jitter and other information. With the advent of high speed networks, this becomes difficult. The network processor can be used to precisely insert "marked" packets into a data stream and to remove them from a data stream, resulting in highly accurate network characteristic measurements in a very high-speed environment. Figure 1, illustrates this with a network of Network Processor Systems, 3 of which are measuring the latency and jitter characteristics of two given flows. By using the functions of a Network Processor, a "marker packet" can be precisely inserted by a Network Processor into a flow at the beginning observation node and removed by the network processor at the ending observation node (Figure 1). By use of time stamps, the transit time of the packet and the interpacket arrival time can be obtained. Given this information, for example, latency and jitter for a particular virtual path or flow can be derived. Note that either or both a path (all the packets leaving a port) or a flow (a subset of packets leaving a port that have been identified as part of a logical flow) can be measured. As Figure 2 illustrates, the beginning observation node precisely inserts (e.g., after the Nth packet) a "marker packet" into the data stream. A "marker packet" is a packet generated by the NP acting as the beginning observation node that contains a time stamp of when the packet was enqueued, a correlator that associates the packet with a particular measurement, and an address or marker that allows identification of the "marker packet" by a ending observation node. The endpoint can be identified in one off three methods, the NP IP address itself,

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  Use of a Programmable Network Processor to Measure Packet Flow Characteristics Using Precision Packet Insertion and De-insertion

    For precise measurement of traffic flow characteristics, one needs to measure the latency of a packet across a network. Often this measurement needs to be repeated multiple times to obtain an "averaged" result and to obtain jitter and other information. With the advent of high speed networks, this becomes difficult.

The network processor can be used to precisely insert "marked" packets into a data stream and to remove them from a data stream, resulting in highly accurate network characteristic measurements in a very high-speed environment. Figure 1, illustrates this with a network of Network Processor Systems, 3 of which are measuring the latency and jitter characteristics of two given flows.

By using the functions of a Network Processor, a "marker packet" can be precisely inserted by a Network Processor into a flow at the beginning observation node and removed by the network processor at the ending observation node(Figure 1). By use of time stamps, the transit time of the packet and the interpacket arrival time can be obtained. Given this information, for example, latency and jitter for a particular virtual path or flow can be derived. Note that either or both a path (all the packets leaving a port) or a flow (a subset of packets leaving a port that have been identified as part of a logical flow) can be measured.

As Figure 2 illustrates, the beginning observation node precisely inserts (e.g., after the Nth packet) a "marker packet" into the data stream. A "marker packet" is a packet generated by the NP acting as the beginning observation node that contains a time stamp of when the packet was enqueued, a correlator that associates the packet with a particular measurement, and an address or marker that allows identification of the "marker packet" by a ending observation node. The endpoint can be identified in one off three methods, the NP IP address itself,

the IP address associated with the NP's physical egress port

the IP address of the ultimate destination.


A.


B.


C. When method C is configured, a unique source & destination port number is also required (so that the Ending Observation Point can detect the "marker packet" and remove it from the flow).

1

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NP

Beginning Observing Node for Flow A

NP

NP

NP

Ending Observing Node for Flow B

Figure 1: Typical Network with Two Network Flow Characterizations

The IBM PowerNP Network Processor hardware, for example, can maintain precise counters that are decremented (or incremented) with each frame that is forwarded for a particular session, physical or logical port, or data stream. The PowerNP can also generate new packets as needed, such as the marker packet described here.

The network administrator defines the following:

Marked Packet Beginning Observation Node (IP Address)

Sending "marked packet" mode (pick one of following)


C. Marked Packet Ending Ob...