Saturday, 7 January 2017
Traffic management in A&A
This was somewhat brought home recently when someone tried to sell Alex some DPI / traffic management system over linked-in seeming to think A&A would need some.
What he was selling was DPI (Deep Packet Inspection) systems that can "manage" various types of traffic. As he explained, this could "throttle" peer to peer traffic.
What was amusing is Alex tried to explain that we don't need that - one would only need such things to manage a congested link. We aim not to be the bottleneck and so not have congested links. This is hard work and there are always occasional exceptions from time to time, but the plan is that we have enough back-haul to carriers, core network, and links to peers and transit that normally we are not the bottleneck. Basically, we should not slow down at peak times.
Alex's tweet (here) showed the exchange, where the salesman did not quite understand how we work. I am pleased at the number of comments and retweets appreciating our stance on this.
From the discussion it is worth mentioning a couple of exceptions to the rule.
1. Denial of service attacks are where so much data is sent to a customer they have an unusable Internet link anyway. We take action in such cases not only to help the end user in question but everyone else on our network that could be affected. Such traffic is far from "normal" usage and not something our customer has asked for. We always reserve the right to protect the network as a whole. Thankfully this is rare.
2. Where the link to the customer is congested because of the capacity of that link to their line - here we do do some extremely "light" traffic management in that larger packets are dropped before smaller ones. We have to drop packets if the link is full! This is a very simple metric and needs no DPI. Large packets are a feature of bulk data transfer like TCP, which can adapt and slow down, but smaller packets are more likely interactive or VoIP or DNS which cannot adapt. This level of management, which we allow customers to control, allows VoIP to work in the face of large downloads. We offer customer options to manage this, so you have control.
Basically, that is it.
We have no need for Deep Packet Inspection traffic management. If someone wants to P2P filling links, then they can. Our tariffs all have some level of usage cap, even if in the terabytes, so if someone is "taking the piss" they will hit limits. Even so, with 1TB and 2TB monthly usage packages now, we are pretty accomodating even with non stop streaming video.
At the end of the day we should not care what you are doing and do not need DPI based traffic management systems! Well done Alex for explaining this.