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Session & Bearer

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From netmanias. In my understanding, - EPS session = PDN connection - An EPS session can have single or multiple EPS bearers - EPS bearer is transmission path between UE and P-GW to deliver user traffic (IP flows) with specficied QoS - An EPS bearer can have single or multiple IP flows 1 EPS Session IP connection between a UE and a PDN is called PDN connection or EPS session. Each PDN connection (or EPS session) is represented by an IP address of the UE and a PDN ID (in other words, Access Point Name (APN)). It has more than one EPS bearer to deliver user traffic (IP packets), and applies the service quality (QoS) policy obtained from a PCRF to the EPS bearers. The minimum fundamental bearer that an EPS session has for a PDN is called a default EPS bearer. 2. EPS Bearer A UE can have multiple EPS bearers concurrently. So, different EPS bearers are identified by their EPS bearer ID, which is allocated by an MME. EPS bearer actually is a concatenation o
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TEID 2

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Bearer Building and Tunnel Timing from ; http://lteuniversity.com/get_trained/expert_opinion1/b/donhanley/archive/2012/01/30/bearer-building-and-tunnel-timing.aspx By now, you should be familiar with the concept of an EPS bearer, which transports user traffic between the User Equipment (UE) and the PDN Gateway (P-GW) in LTE networks. If you’ve taken just about any Award Solutions course on LTE, you’ve learned that an EPS bearer is comprised of 3 parts: the Data Radio Bearer (DRB) over the air interface between the UE and the evolved Node B (eNB); the S1-U bearer between the eNB and the Serving Gateway (S-GW); and the S5 bearer between the S-GW and the P-GW. You will also recall that the S1-U and S5 bearers make use of GPRS Tunneling Protocol (GTP) to identify the individual bearers connecting two nodes. Since each eNB, S-GW and P-GW may be supporting hundreds of active bearers, the GTP Tunnel Endpoint Identifiers (TEIDs) assigned to each bearer allows each node to determine
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LTE : Tracking Area Update with SGW Change

LTE : Tracking Area Update with SGW Change After an hour of Metallica rock and few shots of Espresso I sat down on the saturday afternoon to understand the another handover scenario in LTE. Some time back I wrote about  Tracking Area Update Procedure without SGW change . In this post I would like to explore Tracking Area Update procedure  WITH  SGW change. Ref : 3GPP TS 23.401 5.3.3.1. Before we dive into the post a quick note. Tracking Area is the area/cell being tracked by an eNB. TAI change may indicate a change in eNB. Routing Area is the area/cells tracked by a SGW. So a SGW can track multiple tracking areas. The title of the post is little confusing. I say Tracking area update with SGW change and also say tracking area is taken care by eNB. Well if a eNB changes and the corresponding MME changes which may also lead to a SGW change. This is the scenario we are dealing below. The below picture should be of some help. When UE detects that it has entered a new Cell then it
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VoLTE: Using TCP parameters in packet analysis The TCP is used to transfer a continuous stream of octets in each direction between users by packaging some number of octets into segments for transmission through the internet system[RFC793]. In SIP realm, the TCP is one of the most commonly used protocol along with UDP to transfer user data. The above diagram shows an example of the protocol map for LTE user plane. The backhaul is placed between eNB and the EPC in the operator's network in general. The IPv4 packet sent by the UE over the air is wrapped by the eNB using GTP and IPv6 headers. The eNB sends the IPv6 packet through the GTP tunnel and the PGW at the end of GTP tunnel unwraps the IPv6 and GTP headers. The retrieved IPv4 packet at PGW is forwarded to the P-CSCF over SGi interface. I. TCP header The following shows the TCP headers and parameter descriptions as specified in RFC793 Sequence Number(32bits): The sequence number of the first data octet in th
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teid

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VoLTE: Understanding of GTP TEID to use in LTE trouble shooting The GTP(GPRS Tunneling Protocol) is a communication protocol used by the LTE to deliver IP packets within the EPC. The GTP-C is used to deliver the controlling signals over S11 and S5, whereas the GTP-U is used to deliver application payload over S1 and S5.  I. TEID exchanges The TEID(Tunnel Endpoint IDentifier) is generated by each node during the initial attach procedure. The Create Session Request includes the S11 MME DL TEID and the S5 SGW DL TEID, which are generated and included by MME and Serving GW respectively. The Create Session Response includes the S5 PGW UL TEID and the S11 SGW UL TEID, which are generated and included by PGW and Serving GW respectively. The following diagram shows the actual call flow and depicts how the TEID is exchanged between NEs. Upon receiving the Create Session Request, the Serving GW establishes the downlink GTP-C tunnel towards the MME using the received S11 MME
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