Weird. Maybe overflow from the dedicated bearer falls into the default
bearer? I also have to wonder if it's a bug in the UE. It seems like
it must fall on the UE to ultimately enforce the rate limit.
In our uplink throughput issue, I might have tripped over something of
interest. I originally reported to Telrad that I was getting about half
of what I expect for UL throughput. Now I think we actually do get the
expected throughput, but only for a moment. Five seconds later there's
next to nothing, then 5 seconds later back to full speed, and so on. I
see it when looking at the realtime traffic display on our switch port,
but on your typical chart with a 5 minute average it just looks like
you're getting half speed.
Weird thing is that it's not happening all the time. I started iPerf on
6 UE at one site at 4am the other day and when looking at traffic at the
switch port I saw a perfect sine wave with 10 seconds peak to peak.
Later that day I repeated the test to show one of my co-workers and the
damn thing wouldn't do it.
I don't know what to make of it yet.
------ Original Message ------
From: "Nathan Anderson" <[email protected]>
To: "[email protected]" <[email protected]>; "'Adam Moffett'"
<[email protected]>
Sent: 2/10/2017 3:59:40 PM
Subject: RE: [Telrad] Uplink throughput again
So last night, I re-ran this test again, and captured the whole thing
not just at the edge of the LTE network coming out of the EPC, but
between the EPC and eNB, so that I could grab the user traffic together
with the encapsulating GTP headers.
What I found was that when traffic comes from behind the UE with the
proper DSCP value set, it DOES get transmitted by the UE on the
dedicated bearer, but the MBR is still not being enforced. I had a
10Mbit/s UL AMBR configured and a 256Kbit/s UL MBR set on the dedicated
bearer, and when I ran an upload test on the dedicated bearer, it hit
10 megs. (Download test on the dedicated bearer was limited to the
configured 256Kbit/s DL MBR.)
What makes this so bizarre is that even if there is a bug that causes
the system (which part?) to not enforce the configured rate limit for
the dedicated bearer on the uplink, the UE AMBR should not be taken
into account for GBR bearers, as discussed before. But it sure seems
like what is happening is that whatever is supposed to be policing the
uplink is mistakenly enforcing the UE UL AMBR on the dedicated bearer
instead of the UL MBR.
Ticket opened with Telrad.
-- Nathan
From:[email protected] [mailto:[email protected]] On
Behalf Of Nathan Anderson
Sent: Monday, February 06, 2017 3:56 PM
To: 'Adam Moffett'; [email protected]
Subject: Re: [Telrad] Uplink throughput again
Then maybe the problem is not that the properly-marked upload traffic
isn't getting transmitted on the right bearer, but rather that the UL
GBR/MBR are not being enforced?
Whose responsibility is enforcement of bitrates on uplink? The UE's?
The eNB? The EPC? A little of columns A, B, and C?
-- Nathan
From:[email protected] [mailto:[email protected]] On
Behalf Of Adam Moffett
Sent: Monday, February 06, 2017 2:50 PM
To:[email protected]
Subject: Re: [Telrad] Uplink throughput again
Somewhere there must be traffic counters for each QCI, or for
individual bearers, or something. Without seeing them it's hard to say
for sure.
On a busy eNB (50+ UE), I tried changing the mgmt DSCP value on an
individual UE from 6 to 5 and testing before and after.
With the UE set to DSCP 5 for mgmt, I get 0.1 mbps upload and 7% packet
loss (500 byte pings, 0.1 second interval)
On DSCP 6 I get 0.5mbps and 0% packet loss.
That's not scientific rigor, but it seems like it's working.
On a lighter loaded eNB I was actually getting slightly more UL
throughput with the UE Mgmt DSCP set to 5. I don't know why.
-Adam
------ Original Message ------
From: "Nathan Anderson" <[email protected]>
To: "[email protected]" <[email protected]>; "'Adam Moffett'"
<[email protected]>
Sent: 2/6/2017 5:11:49 PM
Subject: RE: [Telrad] Uplink throughput again
...also, I still remain unconvinced that the UEs are transmitting any
upload traffic -- even when properly marked with the right DSCP -- on
the dedicated bearer. Until it is proven beyond a doubt that this
works, testing upload capacity using dedicated bearers is probably a
waste of time because it isn't doing what you think it is doing.
I have tested both CPE7000 and CPE8000 at this point, and have the
same issue on both, so I don't think it is a CPE firmware bug (that
would be a freaky coincidence, given that both CPEs are
contract-manufactured by different companies). So I don't know if
this is me being stupid and not configuring my EPCs correctly, or
what. But something is not working here.
-- Nathan
From:[email protected] [mailto:[email protected]] On
Behalf Of Nathan Anderson
Sent: Monday, February 06, 2017 2:06 PM
To: 'Adam Moffett'; [email protected]
Subject: Re: [Telrad] Uplink throughput again
Something that I learned that I should point out:
A dedicated bearer with a higher priority should take precedence over
default bearer traffic, yes. But from what I can tell, LTE spec. does
not have a way of putting a total speed cap on the entire UE across
any and all bearers. The UE AMBRs only restrict all non-GBR bearers
(default or not, even across multiple APNs) but does NOT take into
account GBR bearers, and QCI 1 is GBR.
What this means is that, for example, if you have a default bearer
with QCI 6, and dedicated bearer with QCI 1, and the UE DL and UL
AMBRs are set to 10 and 1 Mbit/s respectively, and your dedicated
bearer's MBRs are set to 5 and 0.5 (half of the UE AMBRs, for the sake
of this example), you haven't actually set up things such that up to
half of the subscriber's AMBRs are given priority on the dedicated
bearer, leaving that user half of his total bandwidth if you end up
filling the dedicated bearer up to its MBR in both directions. No,
instead because the GBR QCIs are not accounted for within the AMBR,
the user can move up to 5x0.5 on the dedicated bearer and
*simultaneously* also move up to 10x1 (assuming there is enough sector
capacity at the time) on the default bearer.
Maybe in some cases, this is desireable. If you use QCI 1 for VoIP,
for example, then you are effectively providing the customer with a
separate channel for their voice calls that does not dip into their
configured speed package, but is instead additive. But it is
something to keep in mind as you are planning and building your
network as well as running tests.
-- Nathan
From:[email protected] [mailto:[email protected]] On
Behalf Of Adam Moffett
Sent: Monday, February 06, 2017 1:48 PM
To:[email protected]
Subject: Re: [Telrad] Uplink throughput again
The EPC and most of the eNB are running the latest general release
available on Zendesk.
A couple of eNB are running some kind of maintenance release that
support wanted us to try.
I'm making sure to run iPerf on the dedicated bearer to eliminate
other user traffic from weaker UE as a factor. At QCI 1 it should
take precedence over the default bearer traffic.
I would definitely take the time to set one up, not necessarily for
this purpose, but rather to ensure you always have access to your UE.
If the default bearer is hosed with a torrent and you don't have a
dedicated bearer for management access then you can be completely
locked out of the unit. Monitoring, management access, and firmware
updates all work more reliably with the dedicated bearer and I'd
strongly recommend it. There's a knowledge base article in Zendesk
about it. Use DSCP 6 because that's tagged by default in the UE.
------ Original Message ------
From: "Jeremy Austin" <[email protected]>
To: "Adam Moffett" <[email protected]>; [email protected]
Sent: 2/6/2017 4:30:43 PM
Subject: Re: [Telrad] Uplink throughput again
On Mon, Feb 6, 2017 at 12:20 PM, Adam Moffett
<[email protected]> wrote:
Can somebody tell me if they're getting expected uplink throughput?
What ENB and EPC revisions are you at, Adam?
We're investigating this same issue ourselves, although we haven't
tried a dedicated bearer.
--
Jeremy Austin
(907) 895-2311
(907) 803-5422
[email protected]
Heritage NetWorks
Whitestone Power & Communications
Vertical Broadband, LLC
Schedule a meeting: http://doodle.com/jermudgeon
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