Murphx/C&W LLU

Hi All,

I have 2 ADSL lines at the moment, one is BE and the other is C&W LLU via a Murphx reseller.

Both lines sync ~20Mbit/s (The BE line is slightly slower due to Annex M)

However the problem I'm having is dispite the C&W/Murphx line being in Sync at 21276 kbps on the downstream I can never seem to get above 15Mbit/s in actual throughput.

At first I thought it was my router as I have a setup that uses PBR (policy based routing) to direct certain machines to a specific line, however I disconnected my usual router and tried a standalone ADSL modem/router configured for PPPoA (I usually use PPPoE from a ALIX2d3 running routerOS via a bridged modem) and then connected a Laptop Directly to this router and tried again.

I still was unable to get more than 15Mbit/s even then.

Is there likely to be some kind of profiling/rate limiting going on somewhere or is something broken?

Not that I know of. I know of C&W lines syncing above 15Mb and achieving the maximum. Has another laptop/machine been tried? Also, it could be CRC/HEC errors causing some minor data loss on that particular line.

Tried this? http://www.dslreports.com/tweaks

In reply to a post by Adsl24:

Not that I know of. I know of C&W lines syncing above 15Mb and achieving the maximum. Has another laptop/machine been tried? Also, it could be CRC/HEC errors causing some minor data loss on that particular line.

I wouldn't have thought it was Excessive CRC errors as previously I had both lines on BE and was able to pull close to the maximum throughput on that line also.

Decided to move one of them so that they're on different ISP's

Edit:

The laptop was used to test in order to rule out my desktop as the problem

Edited by dragon2611 (Wed 10-Aug-11 21:11:24)

Not really relevant because 2 lines fed from the same incoming drop wire can take different routes back to the exchange or one pair may be slightly unbalanced or noisy causing errors. Your router should show you the error counts etc. It's unlikely, but I'm struggling to think of any other reason as C&W don't do any throttling or profiling etc.

In reply to a post by Adsl24:

Not really relevant because 2 lines fed from the same incoming drop wire can take different routes back to the exchange or one pair may be slightly unbalanced or noisy causing errors. Your router should show you the error counts etc. It's unlikely, but I'm struggling to think of any other reason as C&W don't do any throttling or profiling etc.

No i meant the Line that's on C&W now was previously on BE, it got migrated over Yesterday.

I used to have 2 lines on BE, I now have one on BE and one on C&W


When it was on BE the throughput was consistent with what I would expect for a line syncing within the 20Mbit/s reigon.

Apart from possibly the routing within the exchange it's unlikely the routing of the line has changed since Monday.


I suppose it could be Crosstalk, particularly as the other line is Annex M and therefore it's upstream will overlap some of the downstream frequencies of the C&W line.

Can I just confirm what the MTU should be set at for a C&W LLU line, I've got 1492 set on the router but I'm not 100% sure that's correct.

I've now tested again with the modem unplugged on the BE line (To eliminate possible crosstalk from the other line)

Still can't get more than 16Mbit/s, In fact My router shows 14.2Mbit/s incoming speed on it's PPPoE interface.

Suspect it's probably something setup slightly wrong somewhere, either on my end or at the ISP end.

I've spoken with the ISP and they're going to look into it for me.

Edited by dragon2611 (Wed 10-Aug-11 22:32:57)

Update for anyone who's reading this.

Murphx responded back to the ISP claiming it was probably my equipment.

Tried with a different modem (DG834GT) in the test socket with PPPoA turned off my BE DSL line to ensure no crosstalk

Wired a laptop directly into the Netgear and disabled the wireless, laptop running on mains power and the only device connected to the router

The laptop was a different machine to the one I tested with originally (Core i5, 6gb ram 120GB SSD win7 x64, Antivirus and firewall disabled).

Also tried with a segmented download manager just in case, doesn't make any difference

So that's 3 different computers, 3 Different DSL modems
Tested with both PPPoE and PPPoA doesn't make any noticeable difference

Still doesn't get more than 16Mbit/s throughput despite a 20Mbit/s sync, sustained throughput is ~14.2Mbit/s

As far as I can tell this is not a DSL fault but rather it feels like a rate-limit being applied somewhere, probably on the RAS / BNG.

Edited by dragon2611 (Sat 13-Aug-11 16:10:39)

When I had Bulldog via C&W, it was an 8Megs offering originally and then they doubled it to 16Megs. Maybe they never upgraded your exchange to 24Megs?

Maybe,

Although I'd expect Murphx to know that and to tell my provider accordingly.

It was sold to me as an up to 24Mbit/s line so as far as I'm concerned either something is wrong and needs to be fixed or someone made a mistake somewhere and I've been missold.

That's true, but it's always hard when you have to deal with so many layers standing between you and the underlying ISP. You know what I'd do...

In the opening post you said "Sync at 21276 kbps on the downstream I can never seem to get above 15Mbit/s in actual throughput".

Now you say "Still doesn't get more than 16Mbit/s throughput despite a 20Mbit/s sync", which is perfectly normal. The maximum possible throughput is 82%-87% of sync, depending on the way the individual ISP has things set up, as the ATM and TCP/IP overheads are between 13% and 18%.

In reply to a post by RobertoS:

In the opening post you said "Sync at 21276 kbps on the downstream I can never seem to get above 15Mbit/s in actual throughput".

Now you say "Still doesn't get more than 16Mbit/s throughput despite a 20Mbit/s sync", which is perfectly normal. The maximum possible throughput is 82%-87% of sync, depending on the way the individual ISP has things set up, as the ATM and TCP/IP overheads are between 13% and 18%.

Interesting, could be that I suppose although it would put the overheads for that line at ~20% which seems a tad high, i'd have expected closer to 17Mbit/s throughput on a 21Mbit/s sync

Note the 20Mbit/s was on a broadcom based modem, not sure what chipset the other modem is but it usually syncs at 21Mbit/s

Edited by dragon2611 (Sat 13-Aug-11 20:33:20)

C&W equipment is capped to 16mbit/s, I know this from my own personal experience, I was with bethere and sync'ed at 22mbit/s, Full 24mbit/s with fastpath on, Then around 6 months ago i left be to join surfanytime LLU, Which is C&W, I was syncing the same on C&W 22mbit/s, But i never could get above 16mbit/s, For a few weeks i was in ticket support with surfanytime about it, Eventually surfanytime partially refunded me 25% of each of my monthly payments, Because they offered and upto 24mbit/s and i wasen't getting what they offered, So i got my MAC and wen't back to bethere.