Title: RTP monitoring with IPFIX
1RTP monitoring with IPFIX
- Hyeongu Son
- jeongil9_at_cnu.ac.kr
- Data Networks Laboratory
- Dept. of Computer Science and Engineering
- Chungnam National University
2Introduction
- 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
3RTP 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
4MPEG 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
5RTP Plugin Flow Format in nProbe (1)
- Already defined field type for RTP monitoring
6RTP Plugin Flow Format in nProbe (2)
- add 4 field type such as next table
7RTP Monitoring Method (1)
8RTP 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
9Experiments Test Environment
10Experiments Test Environment
11Experiments Test Environment
12Experiments Monitoring Tool
- Java program for RTP monitoring
13Experiments 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
14Experiments Delay (4)
15Experiments Delay (5)
16Experiments 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
17Experiments Inter-arrival Jitter (2)
18Experiments 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
19Experiments packet loss (2)
20Experiments Bit Rate and Packet Rate
21Conclusion
- 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?