Private Network Traffic Management

PRIVATE NETWORK TRAFFIC MANAGEMENT

1. Introduction

This white paper provides an overview of the Verizon Wireless Private Network Traffic Management solution to meet business and government needs to receive Quality of Service (QoS) for 4G Long Term Evolution (LTE) Private Network subscribers.

1.1 Audiences

This white paper has been developed for business and government customers, IT administrators, technical decision makers and Verizon sales associates and solution engineers. It is assumed that the reader has an understanding of wireless technologies, as well as of computers and networks.

2. Executive summary

The evolution of LTE technology and Third Generation Partnership Project (3GPP) standards serve as the enablers to provide QoS for the Verizon 4G LTE Private Network subscribers. Verizon Private Network Traffic Management is an enhancement to the 4G LTE Private Network that provides a premium and differentiated network experience. It allows you to create IP traffic preferences for business critical applications and to achieve more predictable application performance during times of peak network demand. With Private Network Traffic Management, businesses can manage the user experience during peak network demand through:

• More control. When the wireless 4G LTE Private Network becomes congested, Private Network Traffic Management gives you the ability to prioritize your applications for high performance.
• High productivity. With more predictable application performance during high–traffic periods, you can use business–critical applications when and where you need them.
• Increased flexibility. Private Network Traffic Management lets you map your applications into the Business Critical Class of Service (CoS) based on the applications’ requirements.
• New potential. Private Network Traffic Management extends QoS policies traditionally provided on fixed WAN to the 4G LTE Private Network, giving you expanded 4G LTE Private Network control.
   

3. Private Network Traffic Management

Private Network Traffic Management relies on three core LTE network pillars to provide more predictable application performance during heavy network utilization: Traffic Priority, Admission Priority and Access Priority.

• Traffic Priority. Provides the supporting structure on how packets are treated within the 4G LTE Private Network. This core network pillar applies to all the Private Network Traffic Management service options.
• Admission Priority. Provides the framework to allocate and retain network resources during heavy network utilization. This core network pillar applies to all the Private Network Traffic Management service options.
• Access Priority. Provides the network mechanism to allocate radio resources to a subscriber during heavy network utilization. This core network pillar applies only to the Public Safety service option.

Private Network Traffic Management provides the following subscription options:

• Enhanced is the Private Network Traffic Management entry level available to enterprise and government customers. Enhanced allows mapping of business-critical applications into a maximum of 0.5 Mbps service class, with the remaining best-effort applications mapped into the Best Effort service class, utilizing the outstanding (leftover) bandwidth available.
• Premium is the highest Private Network Traffic Management level available to enterprise and government customers. Premium allows mapping of business-critical applications into a maximum of 2 Mbps service class, with the remaining best-effort applications mapped into the Best Effort service class, utilizing the outstanding (leftover) bandwidth available.
• Public Safety is the highest level of Private Network Traffic Management, reserved for qualified public safety customers. Public Safety allows mapping of business-critical applications into a maximum of 2 Mbps service class, with the remaining best-effort applications mapped into the Best Effort service class, utilizing the outstanding (leftover) bandwidth available. Public Safety is also prioritized on the access network during heavy network utilization.
   

4. How does Private Network Traffic Management work?

4.1 Traffic Priority

In the 4G LTE Private Network, QoS is implemented between user equipment (UE) and the Private Network gateway, and in the IP core network connecting to the customer IP network (e.g., Private IP—Verizon MultiProtocol Label Switching [MPLS] services). There is a set of bearers between the UE and the enterprise gateway (ExGW). This set of bearers carries user-data IP flows and receives specific IP traffic treatment discussed in this section.

4.1.1 Private Network Traffic Management bearer types

Default bearer: When the UE attaches to the 4G LTE Private Network, it will be assigned a default bearer, which remains as long as the UE is attached. The default bearer transports IP traffic that does not require any specific QoS treatment, such as best-effort IP flows (e.g., email, web, etc.). The default bearer IP flows are carried on the Best Effort class over the 4G LTE Private Network.

Dedicated bearer: When the UE attaches to the 4G LTE Private Network, an additional bearer on the top of the default bearer remains as long as the UE is attached. The dedicated bearer transports more specific IP flows that need the specific QoS treatment (e.g., enterprise VoIP). Business-critical applications are mapped to the dedicated bearer utilizing applications IP marking; please see section 4.1.3 for additional details.

4.1.2 Private Network Traffic Management bearer properties

Non-guaranteed bit rate (non-GBR): Bearer does not have a fixed bandwidth allocated and there is no guarantee as to how much traffic it can carry. Default and dedicated bearers are non-GBR. Maximum bit rate (MBR): Maximum guaranteed bit rate for the dedicated bearer. The specified MBR is applied to the uplink and downlink dedicated bearer. The ExGW is responsible for enforcing the MBR for the uplink and downlink dedicated bearer. The dedicated bearer carries the business-critical applications, and, depending on the Private Network Traffic Management subscription level, the MBR is 2 Mbps (Public Safety/ Premium) or 0.5 Mbps (Enhanced). The applications’ bandwidth requirements should be carefully considered before placing them in the Business Critical class. IP packets with bit rates exceeding the applicable MBR will be discarded.

4.1.3 Private Network Traffic Management IP flow classifications

Private Network Traffic Management relies on customers’ applications’ (VoIP, video, etc.) IP marking in order for the IP flows to be prioritized over the 4G LTE Private Network. The customers’ applications’ IP markings are preserved and passed across the 4G LTE Private Network. The 4G LTE Private Network utilizes IP rules based on the application’s IP marking on the UE and network to determine which IP packet should be placed on the dedicated or default bearer. Each Private Network Traffic Management bearer is associated with a traffic flow template (TFT), which is basically the IP filter for the uplink IP flows. Private Network Traffic Management TFT utilizes the type of service (ToS) of the IP header to classify the IP flow into the dedicated or default bearer. Similar IP rules are applied on the downlink IP flows on the Private Network gateway.

Private Network Traffic Management is designed to be Differentiated-Service (DiffServ) aware. The IP DiffServ Code Point (DSCP) value carried in the original IP packet header TOS is used to map business-critical applications into the correct bearer. The table below provides the mapping for DSCP values required for the Business Critical and Best Effort classes. Business Critical class will carry the customer’s IP flows with the following DSCP values: Expedited Forwarding (class selector [CS] 5) and Assurance Forwarding classes 4 and 3 (CS4 and CS3). The remaining DSCP values will be placed into the Best Effort class. Business Critical class is recommended for video, VoIP, interactive services and other business-critical applications that need the priority treatment. Best Effort class is suitable to best-effort applications (e.g., email, web browsing, etc.).

Each PNTM bearer has a QoS class identifier (QCI) associated. QCI determines the IP packet treatment that customers’ IP flows transported on a given bearer should receive. Private Network Traffic Management default bearer is assigned to QCI 8, and dedicated bearer is assigned to QCI 7. The eNB utilizes a scheduling algorithm to forward uplink and downlink IP packets to the respective bearers. The eNB has a higher scheduling weight for QCI 7 than the QCI 8 bearer. During congestion, this translates into prioritizing of QCI 7 IP flows on the dedicated bearer on the air interface (eNB) against the QCI 8 default bearer IP flows.

4.1.4 IP backbone

The IP backbone refers to the Verizon IP core infrastructure that transports Private Network Traffic Management IP flows to (and from) the Private Network gateway, across the IP core network into the customer access option (i.e., Private IP). The Verizon IP core is designed with high redundancy and resiliency, and the IP backbone is engineered to limit congestion due to circuit or hardware failures. Although we do not expect to see congestion in the IP backbone, we have implemented common QoS techniques; some of these are Class-Based Weighted Fair Queuing (CBWFQ) and Priority Queuing. Private Network Traffic Management Business Critical IP flows (dedicated bearer) are also prioritized on the IP core.

4.2 Admission Priority

Admission Priority manages the allocation and retention of Private Network Traffic Management bearers, which, in turn, control admission of traffic into the network. This is performed by using allocation and retention priority (ARP). ARP is used for deciding whether new bearer modification or establishment requests should be accepted, considering the current resource situation. The lower the ARP priority, the higher the probability of getting bearer establishment. Public Safety class has the lowest ARP priority, followed by the Premium and Enhanced classes.

4.3 Access Priority

Access class barring (ACB) is one of the LTE access control mechanisms that prioritizes the radio resources for emergency service subscribers during overload network conditions caused by state of emergency, national disasters and the like. During these situations, ACB prevents UE users from gaining access to radio resources based on their access classes. The Enhanced and Premium subscribers are members of 1 out of 10 randomly allocated mobile populations, defined as access classes 0 to 9. The Private Network Traffic Management Public Safety subscribers belong to high-priority access classes 11 to 15. The high-priority access classes are exempt from ACB. During these overload network conditions, the eNB performs ACB, allowing the high-priority access classes to obtain access to the radio resources, while Enhanced and Premium in the lower class keep attempting the access request. ACB is automated on the Verizon access network during peak network utilization.

4.4 End-to-end Quality of Service

LTE Private Network with the Private IP access option allows extending Private Network Traffic Management CoS into Private IP CoS. The Private IP wireless gateway (PWG) is provisioned with Private IP Enhanced Traffic Management (ETM). Customers utilizing EF on the 4G LTE Private Network will be required to order through the PWG port, under Private IP EF/ Real-Time bandwidth. This design allows mapping Private Network Traffic Management CoS to Private IP CoS. Dedicated physical circuits such as point-to-point (T1/DS3) are supported access options.

5. LTE Private Network Traffic Management device

Private Network Traffic Management requires eligible 4G LTE devices provisioned on the 4G LTE Private Network. The 4G LTE device is capable of performing Private Network Traffic Management functionality only on the LTE access technology; previous access technologies (e.g., 3G) are not capable of supporting it. The LTE device should support network-initiated QoS for both default and dedicated bearers, including the creation of new dedicated bearer(s) using the 3GPP standard. The LTE device should support changes to the QoS for the default or dedicated bearer using the 3GPP standard. The device shall support the removal of a dedicated bearer using the 3GPP standard. The LTE device should route IP packets to the dedicated bearer based on TFT information provided by the Verizon Wireless network. Please reach out to your Verizon contact for the latest list of eligible devices for Private Network Traffic Management. Private Network Traffic Management capability will not be available when roaming off the Verizon Wireless network, since roaming carriers’ networks can’t establish the dedicated bearer used for Private Network Traffic Management.

6. LTE roaming

Private Network Traffic Management capability will not be in service when roaming off the Verizon Wireless network, since roaming carriers’ networks can’t establish the Private Network Traffic Management dedicated bearer.

7. Conclusion

Verizon allows you to extend QoS policies traditionally provided over fixed WAN (MPLS) to prioritize traffic over the Verizon 4G LTE Private Network. Private Network Traffic Management helps maintain mission-critical services so you can connect, collaborate, communicate and deliver a better customer experience when it matters most.

Learn more about Private Network Traffic Management at
http://www.verizonenterprise.com/products/networking/private-network/