I'm trying to replay captured UDP multicast packets at a rate of a couple of hundreds of Mbps, but it maxes out at about 86 Mbps. (For some strange reason, at other times during the day it consistently maxes out at one tenth of that rate, about 8.8 Mbps)
tcpreplay on eth0
Yields only about 86Mbps:
> tcpreplay -ieth0 --topspeed x.pcap
sending out eth0
processing file: x.pcap
Actual: 459424 packets (137973257 bytes) sent in 12.23 seconds.
Rated: 11281542.0 bps, 86.07 Mbps, 37565.33 pps
iperf on eth0
iperf on the other hand goes up to about 800Mbps. Note that this is true even during those times when tcpreplay only yields about 8.x Mbps)
iperf -c 192.168.20.55 -u -T 1 -t 5 -i 1 -b10000M
------------------------------------------------------------
Client connecting to 192.168.20.55, UDP port 5001
Sending 1470 byte datagrams
UDP buffer size: 208 KByte (default)
------------------------------------------------------------
[ 3] local 192.168.20.55 port 50238 connected with 192.168.20.55 port 5001
[ ID] Interval Transfer Bandwidth
[ 3] 0.0- 1.0 sec 96.9 MBytes 813 Mbits/sec
[ 3] 1.0- 2.0 sec 96.9 MBytes 813 Mbits/sec
[ 3] 2.0- 3.0 sec 97.8 MBytes 820 Mbits/sec
[ 3] 3.0- 4.0 sec 96.4 MBytes 809 Mbits/sec
[ 3] 4.0- 5.0 sec 96.4 MBytes 809 Mbits/sec
[ 3] 0.0- 5.0 sec 484 MBytes 812 Mbits/sec
[ 3] Sent 345538 datagrams
[ 3] Server Report:
[ 3] 0.0- 5.0 sec 400 MBytes 671 Mbits/sec 0.071 ms 60212/345537 (17%)
[ 3] 0.0- 5.0 sec 1 datagrams received out-of-order
tcpreplay on lo
Just to make sure tcpreplay isn't waiting on my disk:
> tcpreplay -ilo --topspeed x.pcap
Warning in sendpacket.c:sendpacket_open_pf() line 669:
Unsupported physical layer type 0x0304 on lo. Maybe it works, maybe it wont.
See tickets #123/318
sending out lo
processing file: x.pcap
Actual: 459424 packets (137973257 bytes) sent in 0.56 seconds.
Rated: 246380816.0 bps, 1879.74 Mbps, 820400.00 pps
What explains tcpreplay being slow on eth0 and is there a way to improve on that?
Best Answer
What version of tcpreplay? Newer versions are faster then older versions. You really want to run the latest 4.x which supports injection via NETMAP.
Also, are you sure you're on a 1Gbps or better interface? Are you connected to a 100Mbps switch port or for some reason negotiated 100Mbps? Look in /var/log/messages or dmesg to see how your interface negotiated.