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Standard User flipdee
(newbie) Mon 03-Feb-14 13:21:54
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DLM - The Big Question


[link to this post]
 
Hello again,
I know it has been talked about before, and kitz.co.uk have some older details on it.
But my question is, Is there any published information available on DLM and does it really vary between ISP, i.e. BT Retail and Sky for example.

I'm mainly interested in DLM in relation to FTTC but any solid details on BT's / UK based implementations would be very useful!

Cheers,

flipdee
Standard User Chrysalis
(legend) Mon 03-Feb-14 14:45:12
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Re: DLM - The Big Question


[re: flipdee] [link to this post]
 
its managed by openreach so shouldnt vary across isp's unless they choose different DLM profiles. As there is 3 DLM profiles.

Administrator MrSaffron
(staff) Mon 03-Feb-14 15:19:34
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Re: DLM - The Big Question


[re: Chrysalis] [link to this post]
 
http://www.thinkbroadband.com/news/5929-reminder-abo...

Andrew Ferguson, andrew@thinkbroadband.com
www.thinkbroadband.com - formerly known as ADSLguide.org.uk
The author of the above post is a thinkbroadband staff member. It may not constitute an official statement on behalf of thinkbroadband.


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Standard User flipdee
(newbie) Mon 03-Feb-14 21:06:42
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Re: DLM - The Big Question


[re: MrSaffron] [link to this post]
 
Wow, Must have missed that article, thanks a lot MrSaffron!
Is there a definitive answer on vdsl modem reboots/power cycles?
Can the DSLAM definitely not distinguish between "issues" and modem reboots?
For example, if high latency and packet loss occur when upstream is maxed out, will DLM intervene?

Cheers,
flipdee
Standard User jchamier
(eat-sleep-adslguide) Mon 03-Feb-14 22:03:26
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Re: DLM - The Big Question


[re: flipdee] [link to this post]
 
In reply to a post by flipdee:
For example, if high latency and packet loss occur when upstream is maxed out, will DLM intervene?

Thats an effect on TCP/IP caused by a saturated link. Its nothing to do with the physical layer (ADSL or VDSL) that your line is working at. DLM only looks at the physical layer.

James BT Infinity 2 19/09/2012 - Sold 42/6 - Getting 49/8.5 - Sync 53 / 9.5 Mbps @ 470m approx
14 years of broadband (ntl: cable to BT FTTC) - Router: Asus RT-N66U - Modem: Huawei HG612 speedtest
Standard User flipdee
(learned) Mon 03-Feb-14 22:35:06
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Re: DLM - The Big Question


[re: jchamier] [link to this post]
 
Hi jchamier,
Thanks for your reply.
When the downstream is maxed out the ping doubles to around 120ms but no packet loss.
Is there a situation where DLM will not ensure a "robust" connection, is the packet loss described something the ISP is responsible for?
I'll have to check line stats during the packet loss.

Cheers,
flipdee
Administrator MrSaffron
(staff) Mon 03-Feb-14 23:00:19
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Re: DLM - The Big Question


[re: flipdee] [link to this post]
 
The DLM will not be worried about you saturating your line and delaying the TCP packets

Andrew Ferguson, andrew@thinkbroadband.com
www.thinkbroadband.com - formerly known as ADSLguide.org.uk
The author of the above post is a thinkbroadband staff member. It may not constitute an official statement on behalf of thinkbroadband.
Administrator MrSaffron
(staff) Mon 03-Feb-14 23:01:53
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Re: DLM - The Big Question


[re: flipdee] [link to this post]
 
Is there a definitive answer on vdsl modem reboots/power cycles? NO
Can the DSLAM definitely not distinguish between "issues" and modem reboots? Varied feedback from end-users
For example, if high latency and packet loss occur when upstream is maxed out, will DLM intervene? No, it will only intervene if it sees packet loss over the VDSL2 layer i.e. a packet it knew it had capacity to send did not reach the other end. TCP congestion is at a different layer.

Andrew Ferguson, andrew@thinkbroadband.com
www.thinkbroadband.com - formerly known as ADSLguide.org.uk
The author of the above post is a thinkbroadband staff member. It may not constitute an official statement on behalf of thinkbroadband.
Standard User Ripley
(committed) Mon 03-Feb-14 23:04:23
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Re: DLM - The Big Question


[re: MrSaffron] [link to this post]
 
Could that just be the processor in your router struggling to deal with the ping requests when your line is maxed out?

Assuming you are noticing the difference in ping by looking at the TTB broadband quality monitor?

Freeserve Dial-Up --> BTopenworld --> <n>ildram -->Talk Talk LLU --> ZeN
ASUS RT-AC66U
Standard User Andrue
(knowledge is power) Tue 04-Feb-14 10:13:54
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Re: DLM - The Big Question


[re: Ripley] [link to this post]
 
In reply to a post by Ripley:
Could that just be the processor in your router struggling to deal with the ping requests when your line is maxed out?
Or just leaving them at the bottom of the list of things to worry about. I would assume any half-way decent router would prioritise its tasks and responding to ICMP requests (especially Echo Reply) ought to be one of the least important things on its list.

---
Andrue Cope
Brackley, UK
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