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[BridgeTap]

Hi all,

Hope this is the correct sub to use, apologies if not.

I'm away at the minute and am having to make do with a very mediocre dsl line from T Com. Naturally I had a poke around and sure enough default logins got me modem access. What's confusing me is the stats v speed.

Code: [Select]

Downstream rate: 6272 kbps
Upstream rate: 767 kbps
PPPoE pass-through: Disabled
ADSL Line
 
Status: Cable connected
Line mode: ADSL2+
Maximum line rate: 7760 kbps (downstream) / 859 kbps (upstream)
Noise margin: 8.9 dB (downstream) / 11.3 dB (upstream)
Line attenuation: 35.9 dB (downstream) / 21.3 dB (upstream)
Output power: 17.8 dBm (downstream) / 12.6 dBm (upstream)
Throughput peaks at 3.93Mb consistently, indicating a 4Mb line but the link to their RAS is over 6Mb so effective rates should be 5.9Mb+. It doesn't look like congestion, no fluctuations.

At home "packages" are applied to the DSLAM, eg an 8Mb package limits the sync to 8Mb, but is this rate limiting at the RAS itself? If so is that the norm?

Thanks,
Tap

[kitz]

Hi tap and welcome

Im not familar with dsl in Croatia, but here in the UK, rate limiting of throughput can occur at several places.

- The RAS for line profiles
- The ISP for product profiles
- Max sync rate can also be applied at the DSLAM/MSAN (ie 8Mbps)

>> At home "packages" are applied to the DSLAM, eg an 8Mb package limits the sync to 8Mb, but is this rate limiting at the RAS itself?

Im not quite sure if I understand what you mean, but in the UK 8128 is the limit at the DSLAM. This is more of a limitation of the technology ie ADSL1.   

BT Wholesale also apply an IPprofile at the bRAS which is in line with your sync speed.  This is to ensure that the backhaul (exchange <-> RAS) isn't flooded and helps avoid congestion and dropped packets.  Other UK ISPs such as TT, Sky etc dont use this on their networks.

The ISP then rate limits the line depending on the product they sell, so for example if they wished they could apply a product/package profile of 4Mbps at this point.   In the UK ISPs such as plusnet purchase a product from BTWholesale and there would be not much point them rate limiting to 4Mb as they are paying BTw for 8Mbps, but if they wanted to they could.

If the network wholesaler uses DLM then those profiles are applied at the DSLAM.

Hope this info helps.

[BridgeTap]

Thanks Kitz,

Shoulda been clearer, home is Ireland. The 8Mb example was in regards to a 24Mb 2+ DSLAM. Eircom operate in a similar fashion to BT(they copy in many areas), the wholesale bitstream products are 1,3,7/8,12 & 24Mb, the resellers then just use these. So its weird to me that the line rare would be different to the effective rate.

Thanks for the info