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Author Topic: Increased latency when using ECI modems  (Read 1564 times)

bill888

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Increased latency when using ECI modems
« on: February 23, 2017, 10:10:34 AM »

hi

I wonder if anyone can explain why I suddenly see increased latency when using my main ECI B-Focus V-2Fub/r Rev.B modems?   

When I ping websites such as www.bbc.co.uk and others, it used to return around 9-10ms for many years.  Now it is around 18ms since the weekend.

When I use an unlocked HG612 or HH5a (Lantiq chipset) running LEDE 17.01.0, the ping times are back to normal, around 10ms.

I'm connected to a Huawei cabinet.  LEDE on HH5a reports System Vendor ID is 'Broadcom 164 140'.

I thought my ECI modem was perhaps faulty, so I tested a brand new 2016 ECI modem with same results, circa 18ms ping times.   I prefer to use the ECI because it runs a lot cooler than HG612.

I should add, last week, I was swapping out routers very frequently but I did take care to close the PPP session before unplugging anything.

If DLM has kicked in and applied interleaving, shouldn't I see 18ms ping times regardless of what modem router I use?

Any ideas what's going on?
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ejs

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Re: Increased latency when using ECI modems
« Reply #1 on: February 23, 2017, 10:16:44 AM »

It's possibly due to the Lantiq modem firmware and drivers within the ECI modem not supporting upstream retransmission (G.INP), so you might get upstream interleaving instead.

The unlocked HG612, and the HH5a with LEDE, using more up-to-date Lantiq firmware and drivers, will support upstream retransmission.
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bill888

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Re: Increased latency when using ECI modems
« Reply #2 on: February 23, 2017, 10:58:23 AM »

Thanks for the explanation. 

I previously thought G.INP only applied to downstream connections.

So it does look like my modem swapping antics, has perhaps caused DLM to kick in, resulting in interleaving being enabled on upstream when using ECI modems. 

Update: DLM caused a resync shortly before 9am.  Looks like interleaving has been removed on upstream.  Everything back to 'normal'.  According to logs, a previous resync occurred 15 days ago around same time which corresponded to when I first noticed interleaving must have been turned on.



« Last Edit: March 07, 2017, 09:09:24 AM by bill888 »
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