Appendix H. Constant Quality Monitoring - technical details

Table of Contents

The FireBrick provides constant quality monitoring. The main purpose of this is to provide a graphical representation of the performance of an interface or traffic shaper .

100 second interval statistics available graphically as svg or png and in text as csv covering at least the last 25 hours (one day)
Loss latency stats where available including minimum, average, and maximum latency for the 100 second sample, and percentage packet loss.
Throughput stats where available (e.g. interfaces, shapers ) including average tx and rx rate for 100 second sample

Graphs can be loss/latency or throughput of both. A ping only system would only have loss/latency. An interface or shaper normally has only throughput data.

H.1. Access to graphs and csvs

Graphs can be accessed via HTTP using the normal web management interface. This can be used as a direct link from a web browser, or using common tools such as curl and wget.

The web management interface (services/http) defines the port, allowed user list and also a trusted IP access list. The CQM config defines a secret which is used to authorise untrusted access using an SHA1 hash in the URL.

All CQM URLs are in the /cqm/ path.

H.1.1. Trusted access

To access a graph you simply need to request the URL that is the graph name, followed by the file extension. E.g. http://host:port/cqm/circuit.png.

Table H.1. File types

Extn	Format
svg	SVG image
png	PNG image
csv	COMMA separated values list
tsv	TAB separated values list
txt	SPACE separated values list
xml	XML data

H.1.2. Dated information

Without any date the data returned is the latest. This includes the last 24 to 25 hours.

You can display data for a specific date. This only makes sense for today, and during the first couple of hours of the day you can get yesterday in full.

The syntax is that of a date first in the form YYYY-MM-DD/, e.g. http://host:port/cqm/YYYY-MM-DD/circuit.png.

H.1.3. Authenticated access

Authenticated access requires a prefix of a hex SHA1 string. e.g. http://host:port/cqm/longhexsha1/circuit.png or http://host:port/cqm/longhexsha1/YYYY-MM-DD/circuit.png.

The SHA1 is 40 character hex of the SHA1 hash made from the graph name, the date, and the http-secret. The date is in the form YYYY-MM-DD, and is today's date for undated access (based on local time).

This means a graph URL can be composed that is valid for a specific graph name for a specific day.

Note that an MD5 hash (32 character hex) can also be used instead, but SHA1 is the preferred method.


G.3. Advanced commands		H.2. Graph display options