I have no idea what exchange I am on, I am afraid (I am in St Albans).
Setting an MRU of greater than 1500 is one way of getting Orange to deal with fragmentation needed requests correctly. Since a MRU greater than 1500 exceeds the MTU I agree it should not make any difference but it does - it is just an artifact of Orange's (mis)configuration of their routers. On ppp negotiation I request a MTU of 1500 but, since I was converted to LLU, after negotiation the MTU is always set at 1492, even when using PPPoATM, which is the original source of the problem - and hence the need for packet size fragmentation.
I do not know what the MWIN is but I would guess it is around 8k.
This is the complete story arising from the solutions I have tried, for those interested.
1. The issue arises because the Orange LLU ppp remote server on 91.104.0.1 refuses to agree a MTU request of 1500. It will only negotiate a MTU of 1492, which is the normal size for PPPoE. PPPoA normally uses a MTU of 1500, so why Orange do this is not clear - perhaps they want to leave open changing to PPPoE later, or perhaps they just haven't set it up correctly.
2. This of itself would not be problematic, except that the upstream Orange router does not properly send, receive and/or deal with fragmentation requests arising from the MTU of 1492 established from the default MTU/MRU negotiation.
3. I have verified that I can successfully deal with the problem by changing the ethernet MTU for all the windows computers on my home network to 1492. They will then negotiate that as the packet size (instead of the usual Windows/ethernet size of 1500 bytes) when the user establishes connections to internet web sites.
4. However, I have also found that if the local ppp connection has its MRU set at higher than 1500, then that will cause Orange to defragment packets correctly. 1501 will do, but I have set mine to 1600. I cannot explain why this works, but it does.
5. I believe it can also be done by MSS clamping in the NATing router (where the router can do MSS clamping, as it can with my iptables NATing), but since either 3 or 4 above work, I have not tried this out.
In summary: if you set the MRU to 1501 or higher with Orange LLU, then things seem to work OK.
Chris
Changing my MTU to 1492 did the trick as I had changed it from 1486 to 1500 then I got the strangest of problems. Firstly I noticed MSN (or windows live messenger as it is thesedays) wouldnt sign in (since I upgraded to Vista not long ago I knew there was a problem with the netgear DG834Gv2 routers unless you had firmare 3.01.25) so I checked my router firmware which was fine, I tried flashing this with the newest and back down to 3.01.25 which was the only one I had found to work. Then I noticed I couldn't open any myspace pages, then I tried killing the firewalls and openeing all ports on the router and even disabling the NAT. This all failed so I tried going to some microsoft pages and guess what it didnt want to load any of their pages either... no problem with 99% of other sites I tried. Couldn't log on to hotmail directly or through Outlook 2007.
Finally stumbled across this forum and hey presto you solved the mystery.
I'm very interested in understanding everything that is going on here. Firstly I have had Orange broadband unlimited for a year now (£5 through my Orange phone contract) and it took them over 2 months to originally get me online. When they did I had full 8meg connection for about 7 month... then it went off and back on a week later at only 6meg... I rang them up and they said it was due to my distance from the exchange. Now The exchange hasn't somehow moved further from me all of a sudden and I argued this point quite strongly but they just couldn't grasp that I had the full speed prior and now I don't. No hardware or any other changes had took place. Can anyone explain this?
Oh and also I am unable to set my MTU on my router above 1500 which I see you have suggested, any reason why I can't do this?
line has been acivated and trained
IN Sunny Weston-super-mare
I am 500 yards away from the main exchange
I am getting 5600kbs down speed
and 288 upstream
UPstream should be 488kbps for 8meg
MTU settings un the Whole of the uk should be 1492 as this is the packet length of the equipment in the exhange it will work higher but you will get allot of crc errors.
ORANGE HAVE ADMITED A PROBLEM BETWEEN Orange AND LAZY BT WHOLESALE ENGINEERS CONECTING Orange CUSTOMERS WITH NAFF CONNECTIONS Orange HAVE SAID THEY HAVE RECOGNISED THE PROBLEM AND WILL GET BT TO SORT MY SPEED OUT IN 5 DAYS.DONT GIVE UP ON INDIA PESTER THEM
Chris your attenuation is 37 is this for your up stream or down either way this is good i only have an attenuation of 5 down and 10 up and they connected me at 5600kps NOT HAPPY.
People Orange say to use PPPoa(ATM) it will connect but you wont get a stable connection it will appear that site just will not respond.
Use PPPoe(Ethernet) and all will be fine.
MTU = 1492 for the UK(BT)
dont forget 228kbps upstream is not good enought.
is should be 448kbps for 8 meg even if you are 20 miles away from the exchange.
again DONT GIVE UP ON INDIA PESTER THEM
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