Saturday, 29 January 2011
Determining Maximum Transmission Unit (MTU) size
Not regarding myself as a 'techie', by any stretch of the imagination, I classify anything like transmission units, as requiring help from the 'powers of the blogosphere', and I rate my mate, Chuck, as one, and he's approachable.
When problems occur, you get frustrated, perhaps, or even flustered. One thing you must remember, or three things, really, is to remain calm. If I have a problem which drives me nuts, like, for instance, sites not loading, or blank screens, or possibly sites timing-out, or 404s, I think about it, I discuss the symptoms, possibly with Chuck, try and find a reason, and then, generally, I refer to, what I call, 'Chuck's techie bible' - PChuck's Network, for my answers. It covers a huge range of technical and testing information, not just about general blogging, like The Real Blogger Status blog. I may not always be given an answer, but, 99% of the time, I find out how to help myself !1
Such was the case with MTU. I wrote a small post on MTU some time ago, when I had a previous problem with packet size, and briefly touched on testing for packet loss.
The above mentioned article by Chuck, attends to the matter of testing in far more depth. Packet size can be tricky, and time consuming, to pinpoint accurately, but Chuck runs you through it clearly.
Once you have determined the data bytes size, as Chuck 1 suggests: "...The maximum that anybody can use is 1500, which includes a 28 byte header. You specify the amount of data, not including the header, in the ping command. Start with a data size of 1472...", then it's time for DrTCP. Scary, eh? Well, it is, and it isn't - as long as you add your information in the correct 'box' and don't go touching things you don't need to, it's a gentle lamb.