Re: [Apn] Regarding APN Usecase in Mobile Core

Hi David,

Many excellent points below w.r.t GTP-u and the Access Point Name (APN)
which defines the network path for all cellular data connectivity.

However, I presume Robin was referring to a different APN -
https://datatracker.ietf.org/wg/apn/about/

--
Uma C.

On Mon, Jan 18, 2021 at 12:10 PM David Lake <[email protected]> wrote:

> The APN provides the linkage between the application profile and the radio
> bearers.  GTP-u is manner by which the traffic is tunnelled to the anchor
> point and you MAY end up with different end points for each of the GTP
> bearers.
>
>
>
> Traffic at both the UE and the PGW (in LTE – UPF in 5G) are directed to
> the correct APN by a Traffic Flow Template (TFT).  This is to ensure that
> traffic goes across both the correct radio bearer and is marked correctly
> in the IP network.
>
>
>
> Users will often be unaware of multiple APNs on their UE; the most common
> hidden APN is one for VoLTE which, with the use of the TFT, will ensure
> that the VoIP frames (media) are put across the QCI 9 radio bearer and into
> the correct class on the IP network.  QCI 9 maps to a specific numerology
> on the Air Interface so that quality can be maintained for the voice call.
>
>
>
> In theory, multiple APNs all with their own TFT rules and potentially
> multiple GTP-u tunnels could be used but this is very rarely done.
>
>
>
> David
>
>
>
> *From:* Apn <[email protected]> *On Behalf Of *Uma Chunduri
> *Sent:* 18 January 2021 19:17
> *To:* Lizhenbin <[email protected]>
> *Cc:* [email protected]; dmm <[email protected]>
> *Subject:* Re: [Apn] [DMM] Regarding APN Usecase in Mobile Core
>
>
>
> Hi Robin,
>
>
>
> In-line..
>
>
>
> Cheers!
> --
>
> Uma C.
>
>
>
> On Mon, Jan 18, 2021 at 5:25 AM Lizhenbin <[email protected]> wrote:
>
> Hi APNers and DMMers,
>
> I remember that in the mobile core scenarios the GTP-u tunnel can be set
> up according to the user and application requirements, but I do not
> understand the details.
>
>
>
> [Uma]: Obviously, the best reference for GTP-U is TS 29.281. However, uou
> should look into
> https://datatracker.ietf.org/doc/draft-ietf-dmm-5g-uplane-analysis/
> <https://eur02.safelinks.protection.outlook.com/?url=https%3A%2F%2Fdatatracker.ietf.org%2Fdoc%2Fdraft-ietf-dmm-5g-uplane-analysis%2F&data=04%7C01%7Cd.lake%40surrey.ac.uk%7C984c8fa55bbf4ea5b98908d8bbe5aa2d%7C6b902693107440aa9e21d89446a2ebb5%7C0%7C0%7C637465942368442430%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C1000&sdata=namC6OofWdMQvTEjFwNkZT0ornR2gx1Q%2BV8SXxIHUis%3D&reserved=0>
> where lot more details and other references related this topic was analyzed
> (primarily started after/during REL-15, when  any other use plane other
> than GTP-U is worthwhile is debated for 5G N9 interface).
>
>
>
> I think when the packet tunneled by GTP-u traverses the APN-based
> transport network, it may be mapped to the corresponding tunnel according
> to the user and application requirements to implement the uniform service.
> If you are familiar with the principle of GTP-u in the mobile core, please
> help provide some details.
>
>
>
>
>
> Best Regards,
>
> Zhenbin (Robin)
>
>
>
>
>
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