multiple apn per UE

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hello we have a brand new lte network and we have defined 4 different apn's in core. our problem: vendor saying with current EPC settings we should be able to use all 4 apn with single UE, but in UE there is no option to have multiple APN it only selects one at a time. can someone help?

[Nyquist]

Hi.
I am not expert on Core (you should check), but this is what I know.
You are right, the UE interface only knows one APN. This is the main access point to the network (Core).
When an operator says that UE should support up to 4 APN that means that the UE should support 4 different network services, for example, voice, Interactive RAB, conversational RAB and streaming RAB, all at the same time. Each network service has its own APN, but this APN is not known by the UE.
In summary, the UE only knows an access point to access the network. The UE should support multiRAB features in order to support several services simultaneously. Core network should know the different APN for different services and manage them in order to provide the different services.
I hope it helps
Nyquist

[Nyquist]

Hi.
Additional info, in order to clarify this issue.
The different APN are related to the different QCI within the QoS mapping. That info is managed in the Base Stations.

[Nyquist]

Hi.
More info sorry.

QoS at Subscriber level
----------------------
The HSS subscription profile contains the information that defines the service that must be provided to the LTE users.
The information in the EPS subscription profile includes the Quality of Service (QoS) per APN.
The LTE/EPC uses a class-based QoS concept where each EPS bearer is assigned a QCI. This QCI is a number and the numerical value in itself does not represent any QoS property. The QCI is just a pointer, or reference, to node specific parameters which defines what packet forwarding treatment a particular bearer should receive when processed in a node (e.g. scheduling weights, admission thresholds, queue management thresholds, link layer protocol configuration, etc.).


An Example:




HSS QCI Configuration





APN


QCI Value


Description




Internet


8


Internet traffic





mms


6


MMS traffic




xxx.corp



6


Operator’s corporative traffic

[auto_art]

Yes like you put above, we have 4 APNS..say A, B, C, D having QCI 4,5,6,7 repectively. each apn has one QCI.

In HSS I see I have assigned specif IMSI all 4 APN's but only one can be defaulted to be assigned when UE dont have reqest.

now in UE again I can select one at a time and network is indeed sending only one IP to it during attach accept according to what is selected in UE. I don't know what to do ahead, still researching someway to have two simulatneous APN operational.

[Nyquist]

Hi.
Please, bear in mind that the APN's associated to different QCI and the APN configured inside the UE by the user are not the same. They are different things.
That is the answer to your question when open this thread.
As told you I am not expert on Core, so I cannot help you according to your last message, sorry.

Regards

[NathanA]

QCIs and APNs have nothing to do with each other. You don't need multiple APNs to support different services with different QCIs. You have a single APN and a single IP address assigned to UE with multiple bearers, and with each bearer set to a different QCI.

To use Ethernet as an analogy: an APN is like a VLAN ID, and a QCI is like a CoS value within the VLAN tag. (The analogy isn't perfect, and like all analogies it breaks down at some point, but I think it works pretty well overall.)

You can absolutely have multiple APNs defined within a core, and you can even have a single UE bring up multiple PDN sessions (each to different APN). Each PDN session will have at least one default bearer (set to whatever QCI you want for the default bearer on that APN) and have a separate, unique IP address. You can then bring up additional dedicated bearers on top of each PDN with a different QCI, but sharing the same IP as the default bearer for that PDN.

The core has nothing to do with the features that the UE supports, though. If you can't figure out how to make a given UE bring up more than one PDN via more than one APN, that's a UE problem, not a core problem. Some UEs simply don't support bringing up connections to more than one APN at a time. If a specific UE doesn't support it, how is that a problem with your core?

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Thanks for your reply NathanA,

No, I am not saying core has an issue. i am just exploring the the on how to use it. as you said APN is like VLAN that is what we are trying to exploit here so we can route traffic based on APN.
in our network we have 4 different MEC, our goal is to have each APN tied to MEC's. so in field one UE is capable of sending traffic for specific applications to respectively MEC.
today we need 4 UE to accomplish that, which is not practical due to logistic.

[Nyquist]

Maybe you have it.
Just in case

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I would like to update further on this issue.

findings:-
1. Our network is different from 99.9% of the networks as it is a private network supporting enterprise activity.
2. we found multuple ways to satisfy out need of QCI and PDN usage.
3. Connection to more than one pdn can be initiated by UE as well as Core. also There could be more than One APN per PDN
4. COtS UE do not let you have more than APN as NathanA said. we worked with our UE vendor and found a way to establish three different APN in one go.
5. Now UE know using TFT what apn to use for what subnet of traffic

thanks all for their insight.