Effect of routing on RTTs to 2 sites in Hangzhou, ChinaLes Cottrell. Page created: January 8, 2004.
Central Computer Access | Computer Networking | Network Group | More case studies
1cottrell@flora04:~>date Thu Jan 8 09:16:21 PST 2004 1cottrell@flora04:~>ping -s www.hz.zj.cn PING www.hz.zj.cn: 56 data bytes 64 bytes from 188.8.131.52: icmp_seq=0. time=570. ms 64 bytes from 184.108.40.206: icmp_seq=1. time=566. ms ... 64 bytes from 220.127.116.11: icmp_seq=437. time=588. ms ^C ----www.hz.zj.cn PING Statistics---- 439 packets transmitted, 438 packets received, 0% packet loss round-trip (ms) min/avg/max = 551/588/647 1cottrell@flora04:~>ping -s cad.zju.edu.cn PING cad.zju.edu.cn: 56 data bytes 64 bytes from cad.zju.edu.cn (18.104.22.168): icmp_seq=0. time=320. ms 64 bytes from cad.zju.edu.cn (22.214.171.124): icmp_seq=1. time=303. ms ... 64 bytes from cad.zju.edu.cn (126.96.36.199): icmp_seq=383. time=252. ms ^C ----cad.zju.edu.cn PING Statistics---- 386 packets transmitted, 346 packets received, 10% packet loss round-trip (ms) min/avg/max = 249/292/372It is seen that the RTT to cad.zhj.edu.cn is much better than that to www.hz.zj.cn, despite the latter's apparently better connectivity to the Internet. However the packet loss is lower for www.hz.zj.cn.
The reverse routes (from Hangzhou to SLAC) are also different from each other as well as being asymmetric with the forward routes. Cad.zju.edu.cn goes via CERnet (188.8.131.52 thru 184.108.40.206 and 220.127.116.11 thru 18.104.22.168 ERX-CERNET-BKB) through STARTAP in Chicago (22.214.171.124 through 126.96.36.199) to ESnet. www.hz.zj.cn goes via CERnet to Cable & Wireless in LA and thence to PAIX in Palo Alto and on to ESnet and SLAC.
We used pingroute to see where the losses occurred on the forward routes. There appears to be about 2% packet loss on the end-to-end path between SLAC and cad.zju.edu.cn. It is difficult to see where this loss occurs since many routers along the path lose packets addressed to them. It is possible that the losses start occurring at the exchange between APAN and CERnet since from then onwards the losses are of the order of 2%. There appears to be < 0.1% loss on the www.hz.zj.cn route, even though some of the routers on the path lose pings directed at them.
I recheck the report from CNNIC and find out that the exact bandwidth provisioned for interconnecting China to the world is: ( By Sep. 30, 2003 ) CERNet -- U.S. 310Mbps CERNet -- Japan 10Mbps CERNet -- UK 45Mbps ChinaNet -- U.S. 5935Mbps ChinaNet -- Japan 1219Mbps ( CERNet: China Education and Research Network, ZJU located connects to it; ChinaNet: China Telecom, the bigest commercial Network Service Provider of China, www.hz.zj.cn the homepage for its division in HangZhou; above data could be found at http://www.cnnic.net.cn/resource/mapinfo/200302/20031125.swf ).