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Can I get faster than half a meg?

I have asked around and some smaller ISPs have said they don't mind but don't support it. Which means you would have to unbond them to find the problems. I was also told that you need both connections to be on the same Dslam and BT don't support this. I do know it is used and some companies use bonded ADSL.
 
It looks like I am stuck with my 512 connection until there is some kind of change at my exchange or technology in my area!!

Changing the subject slightly, I have seen some stuff about MTU settings and DRTCP?

Will changing my MTU settings give me a little performance boost?
What else can I use to make use of this 512k connection to its maxiumum?

Thanks for all your help.
 
Scorpio said:
It looks like I am stuck with my 512 connection until there is some kind of change at my exchange or technology in my area!!

Changing the subject slightly, I have seen some stuff about MTU settings and DRTCP?

Will changing my MTU settings give me a little performance boost?
What else can I use to make use of this 512k connection to its maxiumum?

Thanks for all your help.

I changed my router's MTU setting and got a small performance boost, on average about 30Kbps faster down (maybe 3% faster) and 5Kbps faster upstream on our 1Mbps service based on several runs of adslguide's speed test at an off peak time. We're on an IPStream service and an MTU of 1478 seems to give the best results, with an MTU of 1430 giving almost identical results.

Apparently the ideal settings avoid any unused space in the ATM cells.
 
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The best is roughtly 1458 due to the header and tail of the packet going on and keeping it under the 1500 mark where BT's network will fragment the packets if it is over that.
 
ManOfMeans said:
The best is roughtly 1458 due to the header and tail of the packet going on and keeping it under the 1500 mark where BT's network will fragment the packets if it is over that.

I think bt may have resolved this issue see http://www.sinet.bt.com/374v1p3.pdf - I seem to recall reading it was a limitation caused by sending encapsulated IP datagrams over "fast ethernet" which has a max MTU of 1500. The encapsulation uses 42 bytes of additional headers, leaving your 1458 as the maximum recomended value. If I understand it correctly their new equipment supports an MTU of 1542 to allow for the headers.

2.2 Transport IP Layer
This layer must conform to RFC 791|7].
There is no requirement for a routing protocol to be used - static routes are configured instead.

The MTU size associated with this layer needs to be at least 1542 to allow 1500 byte packets to be sent un-fragmented to the BT-RAS and hence improve the performance of the BT IPStream service received by End Users. The use of an MTU size of at least 1542 bytes on this interface will be mandatory from the middle of 2003. BT, however, recommends Customers use a MTU size of 1600 bytes on this interface to allow for future enhancements. BT will use an MTU size of 1600 bytes on this interface.


The ATM cells are a fixed length (53 bytes including 5 byte header) - ie 48 bytes of data. I read 10 bytes are added to your IP datagram in headers, So the most efficient IP packet size should be 10 bytes less than a whole multiple of 48 and as close to 1500 as possible.


(1478 + 10) / 48 = 31 ATM cells exactly ie zero waste.

(1430 is exactly 48 bytes less == 1 ATM packet less)

Increasing the MTU by one ie 1431 or 1479 should give consistantly noticably poorer results in a speed test as a whole extra ATM cell will be required to carry just one single byte.

On my connection with an MTU of 1430, I got speeds of 958 - 962 Kbps, increasing the MTU to 1431 produced speeds of 930 - 931 KBps.

With MTU of 1478 I got speeds on average of 961 Kbps from the ADSLGuide site, while tests with an MTU of 1458 gave 951 Kbps.
 
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I probably should have added that I set the router's MTU and MRU to the same value and its MSS to the MTU - 40.
 
I have changed the MTU to 1478 using DRTCP but I dont know how to change the MTU on my router??

Any ideas?

I have a Belkin F5D7633 Modem/Router

Thanks
 
Don't have a Belkin, but on my router it is under WAN configuration.

I believe your connection will use the lowest overall figure, so changing it on your PC
could have the same result, this test :- http://broadbandreports.com/tweak will report the MTU and MSS figures used for your connection.

I prefered to change the settings on my router and left Windows' MTU setting at its default so that traffic remaining within my LAN continues to use an MTU of 1500.
 
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