5.4. Auto-negotiation and duplex issues

As discussed before, the interface speed and duplex settings for all Ethernet links on the path between the two Steelhead appliances should configured and negotiated correctly.

The symptoms for an incorrect configured or negotiation can be determined via various ways:

5.4.1. Ping times

Under normal conditions, the response times for the ping command should be constant. With problems in the interface speed and duplex settings, this response time will fluctuate wildly because of constant problems on this link in the network.

Figure 5.31. Ping through a clean network

SH # ping 192.168.1.1
PING 192.168.1.1 (192.168.1.1): 56 data bytes
64 bytes from 192.168.1.1: icmp_seq=0 ttl=63 time=147.372 ms
64 bytes from 192.168.1.1: icmp_seq=1 ttl=63 time=140.338 ms
64 bytes from 192.168.1.1: icmp_seq=2 ttl=63 time=137.355 ms
64 bytes from 192.168.1.1: icmp_seq=3 ttl=63 time=137.144 ms
64 bytes from 192.168.1.1: icmp_seq=4 ttl=63 time=137.219 ms

Figure 5.32. Ping through a network with speed/duplex setting issues

SH # ping 192.168.1.1
PING 192.168.1.1 (192.168.1.1): 56 data bytes
64 bytes from 192.168.1.1: icmp_seq=0 ttl=63 time=303.304 ms
64 bytes from 192.168.1.1: icmp_seq=1 ttl=63 time=253.271 ms
64 bytes from 192.168.1.1: icmp_seq=2 ttl=63 time=312.912 ms
64 bytes from 192.168.1.1: icmp_seq=3 ttl=63 time=264.712 ms
64 bytes from 192.168.1.1: icmp_seq=4 ttl=63 time=248.469 ms

5.4.2. Throughput tests

This can be done on the Steelhead appliances but also on a client and server behind the Steelhead appliances.

These tests should only be done if the data stream is not affected by QoS.

Be aware that this determines the end-to-end packet-loss, not the packet-loss on individual links in the path.

5.4.2.1. Ping flood

A ping flood consists of the client sending out lots of ICMP Echo Request packets and measuring the amount of received ICMP Echo Response packets, making it possible to determine the packet-loss on a link in the network.

Figure 5.33. Ping flood on a relative clean path in the network

SH # ping -f -s 1400 -c 1000 192.168.1.1
PING 192.168.1.1 (192.168.1.1) 1400(1428) bytes of data.

--- 192.168.1.1 ping statistics ---
1000 packets transmitted, 1000 received, 0% packet loss, time 13951ms
rtt min/avg/max/mdev = 131.142/133.056/134.008/0.561 ms, pipe 13, ipg/ewma 13.965/133.019  \
    ms

Figure 5.34. Ping flood on a path with duplex configuration or negotiation issues.

SH # ping -f -s 1400 -c 1000 192.168.1.1
PING 192.168.1.1 (192.168.1.1) 1400(1428) bytes of data.
.......................................................................................... \
    ...................................................................................... \
    ...................................................................................... \
    .............................................
--- 192.168.1.1 ping statistics ---
1000 packets transmitted, 753 received, 24.7% packet loss, time 16701ms
rtt min/avg/max/mdev = 166.241/184.156/208.234/18.631 ms, pipe 13, ipg/ewma 16.701/160.190 \
     ms