Cisco Systems 4 Monitoring System Architecture Evolution Networks (SAE-GW)

25-42

Cisco Prime Network 4.0 User Guide

OL-29343-01

Chapter 25 Monitoring Mobile Technologies

LTE Networks

• Viewing the Local Mobility Anchor Configuration (LMA), page 25-106

Monitoring System Architecture Evolution Networks (SAE-GW)

Systems Architecture Evolution (SAE) has a flat all-IP architecture with separation of control plane and

user plane traffic. The main component of SAE architecture is the Evolved Packet Core (EPC), also

known as SAE Core. The EPC serves as an equivalent to GPRS networks by using its subcom pone nts

Mobility Management Entities (MMEs), Serving Gateway (S-GW), and PDN Gateway (P-GW).

Mobility Management Entity (MME)

MME is the key control node for a Long Term Evolution (LTE) access network. It is responsible for idle

mode User Equipment (UE) tracking and paging procedure inc lud ing r etr an smission s. It i s involved in

the bearer activation/deactivation pr o cess a nd i s also r es p ons ib le f or c ho o sing the S-GW for a UE at the

initial attach and at time of intra-LTE handover involving Core Network (CN) node relocation. The

MME also provides the control plane function for mobility between LTE and 2G/3G access networks

with the S3 interface terminating at the MME from the SGSN. See

Serving Gateway (S-GW)

The S-GW routes and forwards user data packets, while also acting as the mobility anchor for the user

plane during inter-eNodeB handovers and as the anchor for mobility between LTE and other 3GPP

technologies. For idle state UEs, the S-GW terminates the downlink data path and triggers paging wh en

downlink data arrives for the UE. It manages and stores UE contexts, such as paramet ers of the IP bearer

service, network internal routing information, and so on. It a lso p er fo rms re pli cat ion of the u ser t raffic

in case of lawful interception. For more information, see Working with Serving Gateway (S-GW),

page 25-46.

PDN Gateway (P-GW)

The P-GW provides connectivity from the UE to external packet data networks by being the point of exit

and entry of traffic for the UE. A UE may have simultaneous connecti vity with more th an one P-GW f or

accessing multiple PDNs. The P-GW performs policy enforcement, packet filtering for each user,

charging support, lawful interception, and packet screening. Another key role of the P-GW is to act as

the anchor for mobility between 3GPP and non-3GPP technologies such as WiMAX and 3GPP2. For

more information, see Working with PDN-Gateways (P-GW), page 25-44.

Running S-GW and P-GW services together as a SAE-GW provides the following benefits:

• Higher capacity—For a UE with one PDN connection that is passing throug h standalone S-GW and

P-GW services consumes 2 license units because both S-GW and P-GW services account for it

separately. SAE-GW as a single node consumes only one license unit for the same, thus increasing

the capacity.

• Cohesive configuration—Configuration and management of SAE-GW as a node is simpler to follow

and logical to explain.

See Viewing SAE-GW Properties, page 25-42 for details on how to view SAE-GW properties in Prime

Network Vision.

Prime Network Vision displays the SAE-GWs in a SAE-GW container under the Mobile node in the

logical inventory. The icon used for representing SAE-GW in the logical inventory is explained in

Logical Inventory Icons, page A-7.

To view SAE-GW properties: