2009/8/21 Ingemar Johansson S <[email protected]>: > Hi > > Tried with an MS-Windows version of tracert (ftrace), it was supposed to be > able to set the ToS field. However it seems like when I run wireshark that > the modified ToS field does not stick, it could be some Windows specific > feature that simply clears the ToS field. I will try some traceroute tests on > our Linux boxes next week when I really start working. It could be that this > will do. > > I also tried http://www.microsoft.com/windows/using/tools/igd/default.mspx as > it claimed that my homelaptop is indeed ECN capable. The test seems however > to be a bit limited and perhaps a bit faulty. The SYN packet sets ECE and CWR > according to RFC3168, the ECE flag is however not set in the SYN-ACK packet, > still the ECN test is marked as passe!. Also the ECN bits are never set in > any subsequent data traffic which means that AFAIK nothing is really tested. > If your home laptop is Vista then it will support ECN for TCP but it needs to be enabled using netsh: netsh interface tcp set global ecncapability=enabled
See: http://technet.microsoft.com/en-us/library/bb726965.aspx#ctl00_MTContentSelector1_mainContentContainer_ctl05 > I have not looked at PlanetLab earlier, will have a look at it, thanks for > the tip. > Sure. Piers. > Regards > /Ingemar > >> -----Original Message----- >> From: [email protected] [mailto:[email protected]] On >> Behalf Of Piers O'Hanlon >> Sent: den 20 augusti 2009 18:38 >> To: Ingemar Johansson S >> Cc: iccrg; tsv-area; carlberg; Colin Perkins; Magnus Westerlund >> Subject: Re: Testing ECN support for UDP flows >> >> Hi Ingmar, >> >> I found that one could do some quite useful tests using (on >> Linux) traceroute -t <tos> hostname. Linux machines seem to >> reflect the TOS byte contents even in ICMP error responses >> and ICMP echos. Though DSCP bits are usually reset the the >> ECN bits are more resilient... Since traceroute uses UDP as >> default it's quite a neat test. And it seems that ICMP time >> exceeded responses are more likely to get thru router filters >> than plain ICMP responses - and the can carry ECN markings. >> Though it seems that that there maybe some bugs in certain >> routers as I've seen the TOS byte reversed in some replies?! >> >> As ken mentioned - I was thinking that wide area testing >> could be most easily done using PlanetLab - though as far as >> I'm aware it doesn't tunnel packets - though packet timings >> can get skewed by the vserver implementation. Also the >> network sharing system in use on Planetlab can make things >> tricky if someone else on that machine using the same ports. >> >> Additionally it may be worth checking with the methodology >> used by Floyd et al when they did their [tcp] tbit testing: >> http://www.icir.org/tbit/ecn-tbit.html >> >> Piers. >> >> 2009/8/20 Ingemar Johansson S <[email protected]>: >> > Hi >> > >> > Sorry for the cross-post, I would believe that it is best >> to reply to tsv-area only. >> > >> > I have previously asked people regarding the support of ECN >> especially >> > for UDP flows.. There seems to be a lot of uncertanities >> around this and in general it is difficult to get any clear >> view (if there is any ?) So... how do I best test this on a >> larger scale ? >> > >> > 1) UDP port 7: The idea is to ping other host with UDP >> packets on port 7, some of the packets are ECT(0)/(1) marked, >> some are not. If I get things right, port 7 is not genarally >> enabled these days, are there any host around that are known >> to leave port 7 open. >> > >> > 2) Modified STUN client: The idea is to do STUN requests to >> a number of STUN servers. Some of the STUN requests are ECT. >> > >> > 3) Setup a mesh of volountary hosts that installs a >> software that agrees to communicate via a specific port, the >> hack would need to implement some means to communicate NAT'ed >> addresses etc. This would require some logistic effort to >> gather up volounteers for the test-fest. >> > >> > Ideally the test should be able to tell if possible ECN >> issues are located close to the user (e.g firewalls, WLAN >> routers etc) or in the core-networks. Also I believe that >> running UDP would be beneficial even though I know some >> people have already tried with ICMP. >> > >> > Which would be the best alternative in order to do such a >> test ?, comments/suggestions are welcome. >> > >> > Regards >> > Ingemar >> > >> > ******************************************* >> > Ingemar Johansson >> > Senior Research Engineer, IETF "nethead" >> > EAB/TVK - Multimedia Technologies >> > Ericsson Research Ericsson AB >> > Box 920 S-971 28 Luleå, Sweden >> > Tel: +46 (0)10 7143042 >> > ECN: 852-43042 >> > ECC: 852-19042 >> > Mobile: +46 (0)730 783289 >> > Visit http://labs.ericsson.com ! >> > ******************************************* >> > >> >
