RTP T esting Strategies Colin P erkins < c.p - PowerPoint PPT Presentation

RTP T esting Strategies Colin P erkins < c.p erkins@cs.ucl.ac.uk > Depa rtment of Computer Science Universit y College London Go w er Street London W C1E 6BT

Objectives A new draft (draft-ietf-avt-rtptest-00.txt) suggests means b y which RTP implementations ma y b e tested, to help demonstrate interop erabilit y � illustrate common implementation erro rs � This is a set of confo rmance tests! not Colin P erkins/RTP T esting Strategies/1

F unctions tested End systems � Media transp o rt { Basic RTCP including SR/RR, reaction to loss { RTCP SDES, BYE, APP { T ranslato rs � Mixers � Colin P erkins/RTP T esting Strategies/2

Media T ransp o rt { T est Scena rio +------- --- -- --- -- + +-------+ Test instrumen t +-----+ | +------- --- -- --- -- + | | | +------- -+- -- -- --+ +-------+ --- -- --- + | First RTP | | Second RTP | | implement at io n | | implementa ti on | +------- --- -- -- --+ +-------- --- -- --- + T est instrument can dela y o r drop pack ets passing � b et w een the t w o implementations T est instrument can reco rd pack et contents fo r analysis � Colin P erkins/RTP T esting Strategies/3

Media T ransp o rt { RTP T ests T est instrument fo rw a rds pack ets with no loss o r dela y . V erify exchange of media with a va riet y of co decs, including the follo wing edge conditions: Timestamp & sequence numb er wrapa round � P adding, ma rk er bit, header extension � Sequence numb er increment, random sta rt value � Timestamp increment and, random sta rt value � Random choice of SSRC � Colin P erkins/RTP T esting Strategies/4

Media T ransp o rt { Basic RTCP T ests T est instrument fo rw a rds pack ets with no loss o r dela y . V erify the follo wing: Structure of comp ound RTCP pack ets � Consistency of SR/RR headers with the data pack ets � b eing sent RR pack ets sho w lo w jitter and no loss � SDES pack ets { esp ecially CNAME { and their � co rrectness BYE pack ets { including `reason fo r leaving' text � Colin P erkins/RTP T esting Strategies/5

Media T ransp o rt { Advanced RTCP T ests T est instrument va riously inserts dela y and/o r loss. V erify the follo wing: Loss fraction in RR matches loss generated � Jitter in RR va ries with dela y generated � V erify pla y out of media streams subject to small amount of dela y/loss. Colin P erkins/RTP T esting Strategies/6

T ranslato rs { T est Scena rio +------- --- -- --- -- + +-------+ RTP Translator +-----+ | +------- --- -- --- -- + | | | +------- -+- -- -- --+ +-------+ --- -- --- + | First RTP | | Second RTP | | implement at io n | | implementa ti on | +------- --- -- -- --+ +-------- --- -- --- + Simil a r to p revious tests, but with the translato r fo rw a rding pack ets b et w een the implementations. Colin P erkins/RTP T esting Strategies/7

T ranslato rs { T ests Pla y out of translated stream � F o rw a rding of RTCP pack ets � Check that translated SR/RR match the translation � Details dep end on the translation, so ha rd to give exact tests. Colin P erkins/RTP T esting Strategies/8

Mixers { T est Scena rio +------- --- -- -- --+ | Second RTP | | implement at io n | +------- -+- -- -- --+ | | +------- --- -+ +-------+ RTP Mixer +-----+ | +------- --- -+ | | | +------- -+- -- -- --+ +------- +- --- -- --+ | First RTP | | Third RTP | | implement at io n | | implemen tat io n | +------- --- -- -- --+ +------- -- --- -- --+ Colin P erkins/RTP T esting Strategies/9

Mixers { T ests Pla y out of mixed stream � CC is set to 2 and CSRC list is p resent in RTP pack ets � RTP pack ets have SSRC of the mixer � RR pack ets generated to w a rds sender � SR pack ets generated to w a rds receivers � F o rw a rding of SDES pack ets � F o rw a rding of BYEs, generation of BYE when mixer quits � Colin P erkins/RTP T esting Strategies/10

T o do... T ests fo r lo op detection algo rithm � T ests fo r encrypted media � Merge with the RTCP testing draft? � Colin P erkins/RTP T esting Strategies/11

F utures... Is this so rt of do cument a go o d idea? � Mak e an info rmational RF C giving testing strategies fo r � RTP implementations? Colin P erkins/RTP T esting Strategies/12