I have a question. A MS station is moving through 2 areas, these 2 areas are served by different SGSN, and each SGSN is connected to 2 differents GGSN. How PDP Modification/Update work in this case?

GGSN area can not be changed without dropping the data session. If both the SGSN serving two different area were connected to single GGSN, then RAU will followed by PDP update request would have happened.

Could you please tell me as per feature multiple pdp context for one subscriber, what is the maximum no. of pdp context for one subscriber and can we limit as per our requirement?

could anyone please make me understand about the maximum 11 pdp context????like is one pdp context for on website or what??I am not understanding the use of multiple pdp context...when do we need a second pdp context and a third one and so on???

For all websites we need one pdp. secondary pdp is used only when QOS is different from previous one.

there are three layers of connectivity between UE and GGSN 1- is PDP session (one UE IP address and one APN) so that one session can used for one PDN like internet for example 2- inside PDP session we have default bearer and if you need you can create a secondary bearer for different QoS, but both primary and secondary bearer share the same IP&APN (one UE can have up to 11 PDP context active concurrently) 2- inside primary bearer we have a service flow so any website use one service flow and the service flow is unlimited

Good Question Hayato.. for that possible enviroment you can read more about the Gc interface that is very rare to set up for any mobile operator. Basically, the GGSN get the SM context at the beginning and the to activate the PDP , this node needs to send a Paging request to activate the PDP creation . The key point is the Gc interface between the GGSN and the HLR. If there is no context at all. Paging is the answer to set up an MM context and then the PDP context.

Hi Tomeci85,

Could you please tell me as per feature multiple pdp context for one subscriber, what is the maximum no. of pdp context for one subscriber and can we limit as per our requirement?

the maximum number of PDP context is 11 because the length of bearer id is 4 bits (from 0to15) and the 16 id is divided like this: 0to4 reserved by 3GPP for future's use, (5to8) for 4G VoLTE QCI, (9to15) for 2G/3G/4G CSFB QCI

16 pdp at the max, however n/w does imposed restriction.

Number of PDP depends on NSAPI range. NSAPI value varies from 0-15, so 16 values we have. However, NSAPI values 0-4 are reserved and therefore we have 11 values of NSAPI and hence a maximum of 11 PDP context can be supported.

Hi Anand,
Thanks for the precise and spot on answer; appreciate.

What is the relation between GGSN and APN?
How can I choose a particular APN for activating a PDP?

to connect internet user need a path from UE to GGSN called user plane this path needed IP address form user side and APN from GGSN side.
to choose a particular APN for activate a PDP context: if there are one bearer (1st one called default bearer) and user want to use internet the UE select APN (created for internet) that setup in UE by operator the same APN is created in GGSN then from GGSN to internet

I have question about Figure 7.20.
When an external network wants to send IP PUD to UE but if the external network does not know an IP address of target UE, how the external network to get it?
I've confirmed TS23.060 but I could not find answer.

From DNS by using DNS query?
But usually, UE does not have FQDN and does not perform to register own IP address to DNS.

From HSS/HLR by using 3GPP specific I/F?
I think HSS/HLR holds UE's IP address as subscriber data but I don't think there is standardized I/F between HSS/HLR and external network.

I need urgent answer.

GGSN initiated PDP activation can only be supported with an optional Interface Gc between GGSN and HLR.

If the PDP address was requested by the MS during the PDP context
activation procedure, the GGSN releases this PDP address in order to
keep it free for a subsequent PDP context activation.

shouldn't it be "during the PDP context *de*activation procedure"?

Hi, I have the following scenario, maybe you can help me out here. I'm working with Huawei E3372 (NDIS/ECM with Serial port PCUI control). Once plugged in with a SIM card it works on a default PDP context with a dynamic address on this APN setting. The SIM has another subscription to a Static IP APN (Global) which I'm trying to set via the serial PCUI port. For this to work I'm creating a new PDP context (+CGDCONT) and connect thorugh the NDIS interface (+NDISDUP). on (+CGACT) I see they are both connected, and (+CGPADDR) shows both IP's are set (dynamic and global). however, when I try to go to the Internet I get that my IP address is dynamic while I would like to route all the traffic through the Static Global PDP context. My question is: how can I route the traffic and makes it pass through the second APN ? I can't remote the primary APN (+CGACT=0,1) because it refuses to do it. I can't set the second APN alone. Notice this dongle has a Web interface control which affects the first primary APN, so I guess my only solution is a route one. thanks in advance.

hi, what is secondary pdp ? and what is multiple pdp? is it the same?

I have a question about secondary pdp context activation. What does the MS do if i configure my GGSN to reject secondary PDP context activation? Will the MS notify the user that an error has ocurred and afect his/her service? Or will the MS use the primary PDP which is currently active to serve the requested service?

A subscriber has pdp context active and receives a new attach request. What does the sgsn?

There is mistake in Chapter 7.2.6.1 PDP Context Activation Procedure "Initiated by GGSN":
Then GGSN have incoming PDU, there is incoming paging from SGSN side to MS, after what MS establish PDP Context.

How the GGSN will find the address of the Packet Data Network (PDN) to connect to?

Question to whom wrote this article.

Which 3GPP version of TS did you quote for this?
At the above description in "Initiated by MS" in "7.2.6.1 PDP Context Activation Procedure", there is following description.

"A PDP address is provided only if the MS already has a static address."

I don't think this accords with current 3GPP specification at least for 3GPP release 4 or later release.

According to 1) in "9.2.2.1 PDP Context Activation Procedure" of 3GPP TS 23.060 V4.11.0 (this is newest TS23.060 release 4), there is following description.

"The MS sends an Activate
PDP Context Request (NSAPI, TI, PDP Type, PDP Address, Access Point Name, QoS
Requested, PDP Configuration Options) message to the SGSN. The MS shall use PDP
Address to indicate whether it requires the use of a static PDP address or
whether it requires the use of a dynamic PDP address."

This means MS shall indicate whether static PDP address or dynamic PDP address.
I think this is depending on subscriber data in HLR. When HLR has PDP address of UE, this calls "static PDP address" but when HLR does not have PDP address of UE, dynamic PDP addressing should be used.

Also in "9.2.1 Static and Dynamic PDP Addresses" of TS23.060, there is "Only static PDP addressing
is applicable in the network-requested PDP context activation case."

So I think that description (A PDP address is provided only if the MS already has a static address.) should be for "Initiated by GGSN", not for "Initiated by MS".

We have a feature to define APN with Static IP pool. In such case, devices are assigned an IP statically from the APN IP Pool at the time of provisioning. So, PDP address is initiated by MS in such cases but address allocation is done by HSS/HLR.

In case MS request static IP address but HLR subscription is set to dynamic allocation how should SGSN react?
1. Reject the PDP with cause 33: service/option not subscribed
2. Allow the PDP request by sending PDP Context Request to GGSN using dynamic address allocation

Can vendors decide themselves how to handle this or is there a 3GPP rule to follow?

Nicely explained article..Is it possible to allow only selective URLs/ servers corresponding to a particular APN. i.e. the user should only be allowed to use these selected URLs only. 

Hi Tomeci85,
Thank you for your answer but still it is not enough because you wrote about Gc and HLR which could be necessary after GGSN receives PDP PDU from external network.
My question is before GGSN receives PDP PDU.
Interface between external network and GGSN is Gi which is generic IP interface so before sending of PDP PDU, external network should know a target UE's IP address. Therefore if external network does not know the IP address of target UE, it cannot send PDP PDU to GGSN.

This is one damn good info on what is APN. Many people uses 3G router/modem but do not know what the APN etc is for. This provides a good balanced discussion between tech and semi-tech stuff. I have asked many telecom vendor(I come from one), no one can tell me what APN "links" to.
 

what do you want to know? I can help. 

what are the causes for the Activate Pdp Ctxt Decrease???

well explained

Hi All

I would like to know how single APN get selected from multiple APN's configured in handset. For example i have APN configured for browsing , streaming ,mms and i initiate the youtube.com from my handset then how handset will select only streaming APN not any other APN. On the basis of what APN will get selected before sending PDP request to the SGSN?????

THANKS in Advance!!!!!!

Hi sumit,
Each APN has a QOS values and depending on this the handset select the APN most suitable to the service requested.

Hi Sumit,
In handset there are multiple APNs but a default APN is set for each service. If you can check APN setting in you handset you will find different default APNs there for different services like Internet, WAP and MMS. And depending upon the service you try to use, default APN configured for that service is sent in Activate PDP request.

I have one query which is came in live network:
Home subscriber itself unable to browse in 3G mode (we are seeker from other Operator) , and observing R symbol in HS and then data getting stopped-this is observing multiple locations which covers in one RNC -
as per live Home GGSN found UE itself

1. Configuring EPLMN in the seeker SGSN should solve the R symbol issue.
2. Check "Data Roaming" option in handset. It should be allowed to access data in roaming network.