I have a following network topology: T60[eth0] <-> [Fa0/2]WS-C2950C-24[Fa0/1] <-> [eth0]PE860
eth0 interface of T60 has autonegotiation enabled and comes up in 100BASE-TX/Full mode: root@martin-ThinkPad-T60:~# mii-tool eth0 eth0: negotiated 100baseTx-FD, link ok root@martin-ThinkPad-T60:~# Fa0/2 interface of WS-C2950C-24 is configured to "speed auto"/"duplex auto" and thus comes up in 100BASE-TX/Full as well: Fa0/2 -> T60 connected 1 a-full a-100 10/100BaseTX WS-C2950C-24 port Fa0/1 is configured to "speed 100" and "duplex full": Fa0/1 -> PE860 connected 1 full 100 10/100BaseTX ..and as PE860 eth0 interface is configured to autonegotiate it's speed, there is a duplex mismatch between the switch and PE860 machine. I configured IP address 10.10.10.1 to eth0 of T60 and 10.10.10.2 to eth0 of PE860. There is no packet loss between the T60 and PE860 if there is no traffic other than ICMP "echo requests" and "echo replies" between the hosts: root@martin-ThinkPad-T60:~# ping -qc1000 -i 0.1 10.10.10.2 PING 10.10.10.2 (10.10.10.2) 56(84) bytes of data. --- 10.10.10.2 ping statistics --- 1000 packets transmitted, 1000 received, 0% packet loss, time 100039ms rtt min/avg/max/mdev = 0.190/0.595/1.207/0.253 ms root@martin-ThinkPad-T60:~# Now if I set up an Iperf server in TCP mode in PE860 machine(iperf -s -fm) and execute Iperf client in T60: iperf -c 10.10.10.2 -fm -d -t20 ..I get rather poor results: [ 5] local 10.10.10.1 port 51381 connected with 10.10.10.2 port 5001 [ 4] local 10.10.10.1 port 5001 connected with 10.10.10.2 port 46702 [ ID] Interval Transfer Bandwidth [ 5] 0.0-20.0 sec 190 MBytes 79.4 Mbits/sec [ 4] 0.0-20.1 sec 2.84 MBytes 1.18 Mbits/sec ..and there are hundreds of CRC errors on switch Fa0/1 interface and PE860 eth0 interface. Now if I execute Iperf server in UDP mode(iperf -s -fm -u) and Iperf client with following settings: iperf -c 10.10.10.2 -fm -d -t20 -u -b 100m [ 4] local 10.10.10.1 port 54559 connected with 10.10.10.2 port 5001 [ 3] local 10.10.10.1 port 5001 connected with 10.10.10.2 port 34610 [ ID] Interval Transfer Bandwidth [ 4] 0.0-20.0 sec 229 MBytes 95.9 Mbits/sec [ 4] Sent 163099 datagrams [ 3] 0.0-12.1 sec 1.33 MBytes 0.93 Mbits/sec 40.014 ms 925/ 1876 (49%) [ 3] 0.0-12.1 sec 1 datagrams received out-of-order [ 4] Server Report: [ 4] 0.0-20.0 sec 228 MBytes 95.5 Mbits/sec 0.009 ms 604/163098 (0.37%) [ 4] 0.0-20.0 sec 1 datagrams received out-of-order So I guess duplex mismatch does affect UDP traffic as well? And why are upload/download so unequal? regards, martin _______________________________________________ cisco-nsp mailing list [email protected] https://puck.nether.net/mailman/listinfo/cisco-nsp archive at http://puck.nether.net/pipermail/cisco-nsp/
