Hi, I have came across an odd issue that has gone against what I thought was "normal" UDP behaviour.
I have set up a network as follows: 1 2 O----O I set up Node 1 to be a UDP source and Node 2 to be a UDP Sink. I then created an 80Mb CBR stream with a packet size of 1472B that would start at time = 0s and end at time = 20s. The link has a bandwidth of 100Mb with a link delay of 0.01ms, and the queue is a DropTail with a queue size of 100,000. Now, when I set up an ErrorModel across link 1-2 of 0.01 the queue size at Node 1 starts to increase, and will keep increasing until it reaches 100,000 (if the scenario was run for a long enough period of time). Why, when UDP has no flow control, is there a queue build up at Node 2? If UDP has no flow control I would expect there to be no queue build up because an 80Mb stream should have no issue going across a 100Mb link! The fact that some of the packets are dropped going across the link shouldn't have an effect on the queue size - or am I mistaken? I have searched Google and through the mail archives and I have been unable to find any mention of this issue anywhere! Your help with this issue would be greatly appreciated. Kind Regards, Chris PS The system I am using is: Fedora Core 5, Kernel 2.6.15-1.2054 NS-2 2.31 The information contained in this E-Mail and any subsequent correspondence is private and is intended solely for the intended recipient(s). The information in this communication may be confidential and/or legally privileged. Nothing in this e-mail is intended to conclude a contract on behalf of QinetiQ or make QinetiQ subject to any other legally binding commitments, unless the e-mail contains an express statement to the contrary or incorporates a formal Purchase Order. For those other than the recipient any disclosure, copying, distribution, or any action taken or omitted to be taken in reliance on such information is prohibited and may be unlawful. Emails and other electronic communication with QinetiQ may be monitored and recorded for business purposes including security, audit and archival purposes. Any response to this email indicates consent to this. Telephone calls to QinetiQ may be monitored or recorded for quality control, security and other business purposes. QinetiQ Limited Registered in England & Wales: Company Number:3796233 Registered office: 85 Buckingham Gate, London SW1E 6PD, United Kingdom Trading address: Cody Technology Park, Cody Building, Ively Road, Farnborough, Hampshire, GU14 0LX, United Kingdom http://www.QinetiQ.com/home/legal.html
