Topic: 回顾一下，星期一又把system搞down了。and True-or-False questions to gurus @佛州华人论坛:佛州枫下论坛 The Rolia Forum of Florida

工作学习 / 专业技术讨论 / 回顾一下，星期一又把system搞down了。and True-or-False questions to gurus -647i(流浪的步行万里); 2006-6-15 {854} (#3030171@0)

TCP protocol it self does not queue traffic <--- wrong. -iwantcar(流浪的EnjoyStudying); 2006-6-15 (#3030587@0)

Queue has special meaning in network layer. Queued packets are stored as individuals so it can be reordered. TCP buffers incoming traffic only. Bufferred traffic is a single flow of bytes so it cannot be reordered. -diresu(手气不错); 2006-6-15 (#3030657@0)

TCP buffer outgoing data too. not for the purpose of reordering. but for the purpose of device driving and resent....etc. -iwantcar(流浪的EnjoyStudying); 2006-6-15 (#3030706@0)

Outbound traffic sent by write() is not buffered for sending.It does put into TCP window for retransmit purpose. But write() will wait for TCP pass the data to lower SAP then return. If the lower SAP rejects the packets, write() will return error immediately. On otherhand, inbound traffic will not sent to application unless PUSH, read() or window full. -diresu(手气不错); 2006-6-15 {293} (#3030911@0)

between IP package and NIC, there is queue, buffer is at connection level. -647i(流浪的步行万里); 2006-6-15 {699} (#3030705@0)
by my understanding, the data in received queue for application is safe, it be read when appliction call read().what I am thinging is if the queue is full and the traffic control package can't be send from the localhost (or, can't be received by remote sender), the rest incoming package received by NIC will lost? or not

Or it will be just discard? -647i(流浪的步行万里); 2006-6-15 {242} (#3030718@0)
I don't think we are talking about the queue in the same termI am talking about queueing on the network switch/router, it is not done by TCP protocol. and I think lz's production network environment should be able handle rcp file transimission, even though it is a big file. -buma(buma); 2006-6-15 {214} (#3030732@0)

h1. the TCP stack buffer for transmitting data.
2. good enough. -buma(buma); 2006-6-15 {63} (#3030728@0)

when the buffer is empty, the appliction should keep waiting for the block I/O on read() call to socket. it shouldn't have error. the tcp connection is as "keep-alive" option.Need to find out how long is the timeout for "keep-alive". -647i(流浪的步行万里); 2006-6-15 {60} (#3030735@0)

That is the darkest part of TCP/IP protocol. timeout can never be a reasonable value because lack of QOS. -iwantcar(流浪的EnjoyStudying); 2006-6-15 (#3030747@0)

what kind of Qos? let Ack, and small package to through the NIC in higher priority? the fact is the rcp runs very well(that means Send, recieve, ACK) in 10MB/s on 100Mbps NIC. -647i(流浪的步行万里); 2006-6-15 (#3030770@0)

Forget it. That topic is out of your topic. In fact, I didn't read your post carefully. I just pick out some sentence that catched my eye. timeout is possible in TCP/IP. And it is quite application specific. -iwantcar(流浪的EnjoyStudying); 2006-6-15 (#3030786@0)
Next time please write in Chinese. Too much English will kill me. -iwantcar(流浪的EnjoyStudying); 2006-6-15 (#3030795@0)

will look into it, thanks. A question, both ftp, scp are protocal/application based on TCP, the flow control is build in TCP level. unless rcp is not based on TCP(IP, UDP). -647i(流浪的步行万里); 2006-6-15 (#3030846@0)

TCP doesn't do keep-alive.It does use a derived value RTO to control retransmitting. The Idle-timeout is application timmer to savage TCP resource after unexpected termination without FIN. It should be set to long enough to cover any possible silence period of the application. The timmer of 14400 is in seconds, or 4 hours make sense. (You definately don't want to lose your connection of telnet for 15 seconds of idle). -diresu(手气不错); 2006-6-15 {396} (#3031021@0)

Any packets can be queued and dropped -diresu(手气不错); 2006-6-15 {940} (#3030391@0)

That's the AIX in our environment, Before file system parameter tunned, rcp will cause swap disk 100% busy. Now, it can cause tcp time-out.以后干活都要在晚上偷偷摸摸地了 -647i(流浪的步行万里); 2006-6-15 (#3030517@0)

thanks alot to all reply. Talked to unix admin, he said he will check system parameter. Will post feedback from him later. -647i(流浪的步行万里); 2006-6-15 (#3031285@0)

@Florida