Customer Troubleshooting Cases

Trunk Interface Saturation

This is an example of a customer who was complaining of retransmissions (packet drops).

Captures were extracted from the box at the time the customer gave, which was a time 3 days previously from when the customer alerted us.
A single box was monitoring the trunk (shared) interface and the capture was also filtered for the specific servers traffic.

Analysis clearly shows a trunk interface on an internal device was overloaded.

The interface is 1Gbps and you can clearly see the grouping of retransmissions around the 1Gpbs at 1mS microburst window.
The interface buffers would be in the order if 1mS and lower.

With all other equipment the limit is 25mS or 10mS microbursts and historic packet data is not retained so only MONI is capable of showing this.

Below is a graph during a quieter period as a benchmark

This is a linear graph showing 1000mS, 100mS, 10mS amd 1mS microburst windows

As you can see even the 10mS would not show the problem peaking at around 800Mbps (for a 1Gbps interface)

This was solved by selling the customer their own dedicated connection,
which was quite straight forward once the data clearly showed the problem.

Policer/Shaper on Vendor Circuit Dropping Traffic

Here we can see the traffic is flattened indicating there is a policer or shaper in the circuit around 100Mbps.

Checking the feed at the exchange we can see it is not the same shape and goes much higher.

This was solved by selling an increase in the vendor circuit.
Again quite straight forward once the data clearly shown.