Saturday 29 November 2014

A Whole School Down the Wire

Another common objection raised to the adoption of SaaS technologies is the opinion that a single broadband connection is insufficient to support an entire school and that the quality of service will degrade as the number of students accessing external services increases.

Under normal circumstances it can be difficult to see how a school of 500 students might operate over a single broadband connection especially when networks appear to be slow and overloaded running across 1Gbs switches. Without closer examination it does seem counter intuitive to believe that placing all the services on the end of a slower connection could actually result in a more responsive system.

In support of this case, and to allow the bandwidth demands to be estimated with some degree of accuracy it's assumed that school will use Google G Suite for Education (GSfE) and the the primary file format is Google Docs.

Evidence suggests allowing 150Kbs for each GSfE editing session.  Using these figures it is conceivable that a significant number of users could be accommodated on a broadband connection.

Collecting information from a number of schools backs up this assumption. One example is from school that supports 800 students and 70 teachers on a full 1:1 Chromebook program with heavy GSfE usage. They record 40% bandwidth usage on average peaking to 70% 2-3 times a week on a 100Mbs circuit.

In fact schools report that the major factor affecting the user experience is not the number of active GSfE sessions but bandwidth being utilised by multimedia and data download streams during peak times. In a SAS/GSfE school this traffic needs to be closely managed because it could adversely effect how the user perceives the responsiveness of all the SaaS applications they have adopted.

The type of bandwidth controls available to schools include strict limitations on guest wireless, blacklisting of non-curriculum download sites and enabling educational filtering on multimedia sites. (for example: YouTube for Schools).

More sophisticated methods make of the traffic shaping features present on some of the more advanced firewalls by creating a bandwidth reservation for or by blocking or throttling specific application data streams (for example: BitTorrent, Spotify).

With bandwidth controls in place a 100Mbs connection would be sufficient to support a school of 500+ active GSfE users even allowing for additional services.

The relationship is between bandwidth requirements and number of users is fairly linear but as you trend towards the lower end of you can see some remarkable figures.

Perhaps even more surprising than the 800 user school is a smaller school in Guatemala that runs 125 users with 60 being heavy GSfE users on ‘laggy’ 4Mbs synchronous link.

This is not a recommendation but does give you some idea of what's possible.

No comments:

Post a Comment