Gopala Namburi
Solutions Marketing Manager
Blog

GTP Session: The ABCs of Network Visibility

July 26, 2017 by Gopala Namburi

For mobile carriers, network service dependability and customer experience are critical to success. A GTP session controller helps mobile carriers and service providers maximize network probes and capacity while improving visibility into cellular core networks.

What is a GTP Session Controller (GSC)?

A GTP session stands for GRE tunneling protocol session. GPRS Tunneling Protocol (GTP) is a group of IP-based communications protocols used to carry general packet radio service (GPRS) within 5G, 2G (GSM), 3G (UMTS/CDMA/WCDMA) and 4G (LTE) networks.

Typical Use Cases

In summary GTP helps cellular and wireless core networks to allow end users to move from place to place. GTP in high technology years is considered as old as the Intel’s Pentium processor. But, what has changed is that GTP will now be transporting new types of application traffic associated with IoT, AR and VR, HD movies, and connected cars. 1G supported voice, 2G delivered text and voice, 3G brought us online and 4G gave us the speeds.

The volume of the traffic increased in the telecommunications cloud from 1G to 10G, 40G, and 100G, and will soon be crossing 400G with 5G deployments going live. In the hands-free driving of the future, a vehicle interior can be used as a mini-conference room, a study center or an entertainment suite that is talking to the 5G network.

List of scenarios where GTP helps:

GPRS Core Network - GTP is the primary protocol used in the GPRS core network. It is the protocol that allows end users of a GSM or UMTS network to move from place to place whilst continuing to connect to the Internet as if from one location at the GGSN. It does this by carrying the subscriber's data from the subscriber's current SGSN to the GGSN which is handling the subscriber's session. GTP helps carry General Packet Radio Service (GPRS) within 3G/4G/5G networks.

5G Evolved Packet Core (EPC) - The EPC is a multi - access core network based on the Internet Protocol (IP) that enables operators to deploy and operate one common packet core network for 3GPP radio access (5G, 4G, 3G, and 2G), non - 3GPP radio access (HRPD, WLAN, and WiMAX), and fixed access (Ethernet, DSL, cable, and fiber). The core network could transport IP based traffic between subscriber and the datacenter due to GTP among other things.

Mobility Management –  GTP helps in handing off a subscriber session between two base stations and across 3G/4G for 3GPP mobility. GTP also helps maintain states for all UE’s (a technical term for a cell phone) to support paging, roaming and handover.

Due to the volume and nature of the traffic, packet routing and transfer, and mobility management are harder to implement without loss of quality of experience (QoE). QoE is key for customer retention and for selling new services to increase average revenue per user (ARPU) and for maintaining SLA’s.

Considerations

Almost all carriers would like to improve QoE for increasing ARPU.  The best way to improve QoE is to have visibility into the mobile core networks and a GSC would help collect the data from mobile core networks via network probes and feed it to the APM and NPM monitoring tools like Splunk for detailed insights. Before you deploy a GSC with probes, consider the following options.

 

  • GTP Session Correlation – Understand if you need to correlate sessions among a family of users or subscribers across state lines, as their calls must be handed over from cell tower to cell tower as they roam. However, consider a GSC that can still put all the control and user data back together by subscriber and deliver it to the same monitoring probe. So, when the probe generates a KPI (key performance indicator), an operator knows the stats for that account.
  • GTP Load Balancing – Figure out which subscribers from a region will generate tons of data across any given region. A GSC that can divide this traffic up into smaller manageable chunks, in a subscriber-aware fashion and give each probe one chunk to process might be a clever idea. So, the probe has what it can manage and does not get overloaded.
  • Subscriber Filtering – As a mobile operator all subscribers may not be equal-size or equal-value to you. You can optimize monitoring costs by selectively tracking subscribers via IMSI list., Choose a GSC that can further help optimize costs by allowing operators like yourself to only track high-value customers, by specifying IMSI list. This is done, because some subscribers are more sensitive to service disturbances considering the volume of their accounts. In some cases, subscribers have paid for a higher level of service, so operators need to ensure they are meeting SLAs.

Ixia’s GSC and subscriber aware visibility solutions help gain visibility into your mobile core networks, while giving you the insights needed to improve QoE, track SLA's and help provision new services to increase average revenue per user (ARPU).