Re: MTU Sizes

In article <f6e8f6$ekq$(E-Mail Removed)>, Geoff Lane says...
> Owing to an erratic internet connection my ISP has suggested I try the
> following MTU settings;
>
> 1458, 1478 and 1500
>
> My Linksys router's manual has the following suggestions;
>
> Try this list of values, one value at a time, in this order, until your
> problem is solved:
> 1462
> 1400
> 1362
> 1300
>
> Microsoft apparently say do not go below 1400
>
> None of these suggestions appear to match up, what do the numbers
> represent, I am baffled.
>
The size of the Maximum Transmittion Unit. It refers to the largest
size in bytes that a network protocol can send.

What happens is that if the value is too high and over what the ISP
uses, it fragments the packet which can lead to high latency and data
loss.

The values the ISP gave are what are widely used for ADSL in the UK.
The values on the router are "should work" no matter where you are.


--
Conor

Light travels faster than sound. This is why some people appear bright
until you hear them speak.........


Conor

Conor wrote:
> In article <f6e8f6$ekq$(E-Mail Removed)>, Geoff Lane says...
>> Owing to an erratic internet connection my ISP has suggested I try the
>> following MTU settings;

>> None of these suggestions appear to match up, what do the numbers
>> represent, I am baffled.
>>
> The size of the Maximum Transmittion Unit. It refers to the largest
> size in bytes that a network protocol can send.

That bit I understand, what was puzzling me was the actual numbers, most
computer related figures are some relation to 8, 32 or 64. I couldn't
see a pattern to the numbers.

Geoff Lane

In article <f6jd7h$gtq$(E-Mail Removed)>,
Geoff Lane <(E-Mail Removed)> wrote:
>Conor wrote:
>> In article <f6e8f6$ekq$(E-Mail Removed)>, Geoff Lane says...
>>> Owing to an erratic internet connection my ISP has suggested I try the
>>> following MTU settings;
>
>>> None of these suggestions appear to match up, what do the numbers
>>> represent, I am baffled.
>>>
>> The size of the Maximum Transmittion Unit. It refers to the largest
>> size in bytes that a network protocol can send.
>
>That bit I understand, what was puzzling me was the actual numbers, most
>computer related figures are some relation to 8, 32 or 64. I couldn't
>see a pattern to the numbers.

The 1500 number goes back many many years to the days of co-ax
Ethernet. That was the maximum number of bytes you could throw out onto
the wire while keeping to the CSMA-CD principles.

http://en.wikipedia.org/wiki/CSMA-CD

Gordon