RTP monitoring with IPFIX

1
RTP monitoring with IPFIX

• Hyeongu Son
• jeongil9_at_cnu.ac.kr
• Data Networks Laboratory
• Dept. of Computer Science and Engineering
• Chungnam National University

2
Introduction

• Traffic Monitoring
• Account user traffic
• Check QoS (Packet loss, Delay, etc)
• Flow-based traffic monitoring
• popular, easy, cheap and reduced data
• Whats the purpose?
• to provide QoS of multimedia streaming traffic
  by monitoring RTP
• to measure QoS metrics such as delay, jitter,
  packet loss
• to develop RTP monitoring tools supporting IPFIX
  in IPv6 networks

3
RTP Header
allow synchronization and jitter calculations

• increase number by one for every RTP packet
• be able to check dropped packet (packet loss)
• determine sequence of packet
• generate random number for the initial number

Version be usually set 2
payload type ( DV 123, MPEG2 33)
padding
CSRC Count
extension
Marker
0
31
18
Timestamp
Synchronization Source (SSRC) Identifier
4
MPEG 2 DV(IEC 61834) Traffic

• The character of MPEG2 traffic in RTP
• timestamp 1) somewhat different
• 2) estimate and reduce any network-induced
  jitter
• 3) synchronize relative time
  drift
• payload contain an integral number of MPEG
  transport packets
• Header extension

• The Character of DV traffic in RTP
• Dynamically assign the payload type
• All packets have the same timestamp (within the
  same video frame)
• Frame change based on a difference in the RTP
  timestamp
• Not necessary additional payload-format-specific
  header

5
RTP Plugin Flow Format in nProbe (1)

• Already defined field type for RTP monitoring

6
RTP Plugin Flow Format in nProbe (2)

• add 4 field type such as next table

7
RTP Monitoring Method (1)
8
RTP Monitoring Method (2)

• Flow Classifier
• processes incoming packets with five-tuples
  (source/destination IP address and port number,
  protocol)
• Flow Exporter
• send flow-exporting pakcets to the flow
  collector that contains flow information
• Flow Collector
• receives IPFIX message and save the template and
  data record
• Flow Analyzer
• classifies only one flow which is the same
  5-tuples with the RTP as well as
• typical port numbers
• Flow Visualizer
• show the analyzed data by graph and table

9
Experiments Test Environment
10
Experiments Test Environment
11
Experiments Test Environment
12
Experiments Monitoring Tool

• Java program for RTP monitoring

13
Experiments Delay (1)

• delay (current packet timestamp previous
  packet timestamp)
• In case of DV, use NTP timestamp
• calculated at just one flow
• Originally, nProbe just has MAX delay value
• added MIN and Average delay value in rtp plugin
• look for MAX, MIN, Average delay between
  consecutive packets in nProbe
• Ex) A flow has 1,000 packets. This flow has 999
  delay values.
• This monitoring represent minimum, maximum
  and average delay value
• between those values

14
Experiments Delay (4)
15
Experiments Delay (5)
16
Experiments Inter-arrival Jitter (1)

• An estimate of the statistical variance of RTP
  data packet inter-arrival time
• defined to be the mean deviation of the
  difference in packet spacing at
• the receiver compared to the sender for a pair
  of packets
• the method of calculating inter-arrival jitter
  (Referenced by RFC 1889)
• 1) transit current time last time
• 2) jitter sample(d) transit last transit
• 3) d lt 0 ? d -d
• 4) new jitter (d last jitter) / 16

17
Experiments Inter-arrival Jitter (2)
18
Experiments packet loss (1)

• derived from sequence number
• sequence number incremented for every RTP
  packet
• Be able to know whether packet is dropped
  through sequence number
• The method of packet loss calculation
• temp current sequence number initial
  sequence number
• packet loss temp amount of packets
• if(packet loss lt 0) ? packet loss 0

19
Experiments packet loss (2)
20
Experiments Bit Rate and Packet Rate
21
Conclusion

• A RTP traffic monitoring method
• based on the IPFIX standard
• through IPFIX information, we can get some data
• Maximum, Minimum, Average Delay
• inter-arrival jitter
• packet loss, packet rate, bit rate
• Future Work
• measure DV traffic between Korea (Chungnam
  National University) and
• Japan (Kyushu University)

22

Thank you Do you have any question?