205583569 gb-interface-detailed-planning-final
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205583569 gb-interface-detailed-planning-final
- 1. 1 © NOKIA 2000 Gb interface detailed planning Core Network Planning Gb Interface Detailed Planning
- 2. 2 © NOKIA 2000 Gb interface detailed planning Agenda • Gb interface introduction • Gb review ( protocol stack / ntw layers ) • Gb in detail ( NSE / logical connections ) • Frame relay interface planning • BSC dimensioning • Frame relay dimensioning • SGSN dimensioning • Gb Detail planning ( e.g. Topology ) • Exercise 1: case study Nortel BSS – Nokia SGSN • Exercise 2: detailed planning
- 3. 3 © NOKIA 2000 Gb interface detailed planning Gb Interface BSC PCU BSS SGSN PAPU GPRS F ra m e R e la y Gb interface
- 4. 4 © NOKIA 2000 Gb interface detailed planning Gb Interface Review other PLMN MSC/VLR HLR EIR SGSN GGSN GGSN SGSN PDN TE SMS-GMSC SMS-IWMSC MS BSS GiGn Gn Gp Gb Gd Um GcGr Gs Gf CE D A Signalling & Data Transfer Signalling GPRS Interfaces
- 5. 5 © NOKIA 2000 Gb interface detailed planning Gb Interface Review GPRS Protocol Stack / transmission plane SGSNBSS SNDCP APP TCP/UDP IP MAC GSM RF RLC LLC MS MAC NS GSM RF L1 RLC BSSGP GTP UDP IP SNDCP LLC BSSGP NS L1 L1 LLC/SNAP MAC Radio interface Um Gb Gn Gi G703 Frame Relay 100 Mbps Ethernet GGSN USER PAYLOAD GTP UDP IP L1 LLC/SNAP MAC APP TCP/UDP IP L2 L1Relay Relay GPRS IP Backbone Internet •SNDCP: Sub-Network Dependent Convergence Protocol The primary function of BSSGP is to provide the radio-related, QoS, and routing information that is required to transmit user data between a BSS and an SGSN. A secondary function is to enable two physically distinct nodes, the SGSN and BSS, to operate node management control function . •BSSGP: Base Station System GPRS Protocol •NS: Network Service •SNAP: Subnetwork access protocol
- 6. 7 © NOKIA 2000 Gb interface detailed planning Gb Interface Review Network Layers GPRS TCP/IP ATM & FR Transport/SDH BSC SGSN SGSN BSC Gb Intra-site Gn Inter-site Gn Gb GPRS IP Backbone Network
- 7. 8 © NOKIA 2000 Gb interface detailed planning Gb Interface Review Gb Interface BSC PCU SGSN Frame Relay Gb PAPU BSS GPRS
- 8. 9 © NOKIA 2000 Gb interface detailed planning Gb Interface; planning issues 2 Mbps Channelised E1 link2 Mbps Channelised E1 link NS-VC capacity: 16 kbps…1.92NS-VC capacity: 16 kbps…1.92 MbpsMbps FR Bearer channel: 64 kbps… 1.92FR Bearer channel: 64 kbps… 1.92 MbpsMbps
- 9. 10 © NOKIA 2000 Gb interface detailed planning NSE = (PCU) NSE Gb Interface Review Network Service Entity (NSE) BSCSGSN NS-VC NS-VC NS-VC NS-VC BVC 0 for signalling Own BVC for each cell Own BVC for each cell BVC 0 for signalling Own BVC for each cell Own BVC for each cell BVC = BSSGP Virtual Connection BSSGP = Base Station Subsystem GPRS Protocol NSE = Network Service Entity NS-VC = Network Service Virtual Connection FR = Frame Relay FR Bearer Channel Physical Link (= PCM TSL) DLCI Data Link Connection Identifier (FR address) NS-VC DLCI Data Link Connection Identifier (FR address) Load Sharing FR Bearer Channel Physical Link (= PCM TSL)
- 10. 12 © NOKIA 2000 Gb interface detailed planning SGSN BSS 1 Bearer Channel_1 Bearer Channel_2 DLCI_16 DLCI_17 DLCI_16 DLCI_17 DLCI_18 Bearer Channel_3 DLCI_16 Bearer Channel_5 Bearer Channel_6 DLCI_16 DLCI_17 PAPU 3 PAPU 2 PAPU 1 PCU 1 PCU 2 PCU 3 LA RA 1 BTS_6 BTS_3 RA 2 BTS_8 BTS_22 Bearer Channel_4 DLCI_16 DLCI_17 BSS 2 PCU 3 LA RA BTS_22 NSEI_7 NS-VCI_6 NS-VCI_9 NSEI_3NS-VCI_4 NS-VCI_1 NS-VCI_11 NSEI_2NS-VCI_5 NS-VCI_8 NS-VCI_3 NSEI_1 NS-VCI_7 NS-VCI_2 NSEI_7 NS-VCI_6 NS-VCI_9 NSEI_3NS-VCI_4 NS-VCI_1 NS-VCI_11 NSEI_2NS-VCI_5 NS-VCI_8 NS-VCI_3 BSSGP NS FR Signal Data Data & Signal NSEI_1 BVCI_22 BVCI_0 BVCI_22 BVCI_0 BVCI_8 BVCI_8 BVCI_6 BVCI_0 BVCI_0 BVCI_22 BVCI_6 BVCI_0 BVCI_0 BVCI_3 BVCI_22 BVCI_0 NS-VCI_7 NS-VCI_2BVCI_3 BVCI_0 Gb Interface Review Logical Structure Id Unique in NSE own BVC for each cell Id Unique in bearer NS_VCI unique in SGSN
- 11. 13 © NOKIA 2000 Gb interface detailed planning FR bearer channels, 1…31 TSL NS-VCs, CIR=16…1.984 Mbit/s BVCs • FR bearer channels run on PCM links (64…1984 kbit/s) • Max. 4 NS-VCs configured on FR bearers (CIR of each 16…1984 kbit/s) •CIR doesn‘t stand in relation to subscriber datarate / cell • Max. 4 NS-VCs per NSE (PCU), and 256 NS-VCs per PAPU PCM Link 32 TSL PCU Gb Interface Review Logical Channels in Physical Link
- 12. 14 © NOKIA 2000 Gb interface detailed planning Frame Relay Link Parameters - 1 • BVC - 1 BVC (BVCI) for each CELL - unique within an NSE - 1 BVC (BVCI) can be mapped into 2 NS-VC (load sharing) - 1 or MORE BVCs (BVCI's) are mapped into 1 or more NS-VC - 1 SIGNALING BVC per PCU, BVCI = 0000HEX • NS-VC - NS-VCI = DLCI and FR BEARER CHANNEL IDENTIFIER - 1…4 NS-VCs per NSE (=PCU) - up to 256 per PAPU - 1 NS-VC supports several BVC - capacity controlled by CIR in steps of 16 Kbps up to the BEARER CHANNEL capacity - NS-VCI is unique within a SGSN, identical on BOTH ENDS (end to end) ; range 0…65535 • PCU - 1 PCU = 1 NSE (NSEI) - 1 PCU handles maximum 64 cells
- 13. 15 © NOKIA 2000 Gb interface detailed planning Frame Relay Link Parameters - 2 • NSE - NSEI is unique within a BSC, identical on BOTH ENDS (end to end) range 0…65535 - on BOTH ENDS are connected by 1 or MORE NS-VC - within 1 NSE, NS-VCs are shared by all BVCs • DLCI - up to 124 DLCI on 1 BEARER CHANNEL - unique within 1 BEARER CHANNEL, identical on BOTH SIDES - range 16…991 • BEARER CHANNEL - capacity from 64 to 1984 Kbps (1 to 31 TS of an E1) in multiples of 64Kbps • PAPU - supports up to 64 PCU per PAPU • SGSN - number of NS-VCs in SGSN = number of DLCI (up to 256 per PAPU)
- 14. 16 © NOKIA 2000 Gb interface detailed planning Gb Inteface Planning • BSC Planning - defining the number of active PCUs • Frame Relay Link Planning – Topology Planning – Frame Relay Link Dimensioning • SGSN Dimensioning - defining the number of PAPU & SGSN equipments and extension units 3 Sections of Gb Inteface Planning
- 15. 17 © NOKIA 2000 Gb interface detailed planning Gb Inteface Planning Selecting the Protocol Overhead Gb I/F Protocol Stack Percentage of Overhead in GPRS Traffic at the Gb Interface Protocol Min Header size (oct.) Max Header size (oct.) Reference SNDCP 3 4 GSM 04.65 LLC 5 40 GSM 04.64 BSSGP 12 54 GSM 08.18 NS 4 4 GSM 08.16 FR 6 6 GSM 03.60 Total 30 108 Packet size Min OH % Max OH % 50 60.00 216.00 60 50.00 180.00 100 30.00 108.00 150 20.00 72.00 200 15.00 54.00 256 11.72 42.19 300 10.00 36.00 400 7.50 27.00 512 5.86 21.09 750 4.00 14.40 1000 3.00 10.80 1250 2.40 8.64 1500 2.00 7.20 216 180 108 4.0 3.0 2.4 2.0 15.0 20.0 50.0 30.0 11.7 10.0 7.5 5.9 60.0 72 54 42 36 27 79111421 0 50 100 150 200 250 300 100 150 200 256 300 400 512 750 1000 1250 1500 Packet length (octets) Overhead(%) Ohmax OHmi n
- 16. 18 © NOKIA 2000 Gb interface detailed planning Gb Inteface Planning Selecting the Burst Margin Actual traffic load, X % Burst Margin, 100 - X % Discarded data Throughput time • Packet data traffic is bursty in nature • Nokia PCU implements a Static Frame Relay • Data above the CIR is discarded (EIR = 0) • CIR calculation should include burst margin CIR EIR=0
- 17. 19 © NOKIA 2000 Gb interface detailed planning ET5C ET5C ET5C BCSUBCSU BCSU BCSU BCSUBCSU BCSU WDDC CLOC CLAC ET5C ET5C PSA20 PSFP PSA20 PSFP OMUMCMU MCMU SW1C SW1C BCSU ET5C WDDC BCSU ET5C • All BSC's BCSU units must be fully equipped with PCUs (max. 8+1 per BSC) • GSWB expanded from 128 to 192 PCMs (if not already done) • BSC2E/A: Extra ET5C Cartridges to increase PCMs from 80 to 112 • PCU controls cells, not TRXs like BCSU ⇒ PCU does not handle the same TRXs as the BCSU where it is located PCU HW in every BCSU BSC Dimensioning Packet Control Unit - PCU 3rd SW64B cartridges ET5C cartridges
- 18. 20 © NOKIA 2000 Gb interface detailed planning BSC Dimensioning Defining the active number of PCUs • Dimensioning Criteria for the number of active PCUs: 1. Each BSC in GPRS coverage area has to contain at least one active PCU (minimum requirement) 2. PCU can supports 256 TCHs 3. PCU Data processing capacity is 2 Mbit/s 4. PCU can support up to 64 cells 5. PCU can supports 128 TRX's
- 19. 21 © NOKIA 2000 Gb interface detailed planning Input BSC Dimensioning Simple Dimensioning Example (PCU) • 3 BSC (with capacity of 128 TRXs ) • Coverage area contains 60 BTS sites, each having 2+2+2 cell/TRX configuration • 4 TCHs/cell used by GPRS on average • Estimated GPRS traffic: 15 Mbit/s + 19% Overhead = 18.5 Mbit/s • Packet size of 400 bytes assumed 1. Minimum requirement: 3 BSC => 3 PCUs required (each for 128 TRX) 2. 60 x 3 cells = 180 cells, 180/64=2.8 => 3 PCUs required 3. 12 TCH/BTS x 60 BTS=720 TCH, 720/256 => 3 PCUs required 4. GPRS traffic: 18.5 Mbit/s / 2 Mbit/s = 9.3 =>10 PCUs required CalculationsResult • Take the biggest of the results above, I.e. 10 active PCUs required in total
- 20. 22 © NOKIA 2000 Gb interface detailed planning Frame Relay Link Planning Link Dimensioning • Frame Relay traffic is carried in logical 64 kbit/s PCM time slots. • Each active PCU has its own separate Gb interface connection, I.e. FR connection • Capacity: n * 64 kbit/s, where n = 1… 31. • 64 kbit/s … 1.984 Mbit/s (E1 speed) • At least one 64 kbit/s PCM TSL is required per active PCU
- 21. 23 © NOKIA 2000 Gb interface detailed planning Frame Relay Link Planning Link Dimensioning • Dimensioning criteria for the number of 64kbit/s links: 1. At least two 64 kbit/s channels per BSC is recommended (due to bursty nature of data) 2. At least one 64 kbit/s channel per active PCU 3. Dimensioning is based on estimated GPRS traffic during the Busy Hour, + the estimated protocol overhead on the Gb interface traffic + margin for bursting
- 22. 24 © NOKIA 2000 Gb interface detailed planning Gb Link Dimensioning Simple Dimensioning Example (Gb links) • Total number of PCUs in 3 BSCs: 10 PCUs • Estimated total GPRS traffic during the BH: 15 Mbit/s • Overhead correction: + 19% • Packet size of 400 bytes assumed • 15 Mbit/s * 19% = 18.5 Mbit/s Input 1. Two 64 kbit/s links per PCU (10 * 2) => 20 links 2. GPRS traffic: 18.5 Mbit/s / 64 kbit/s = 289.1 => 290 links Calculations • Take the bigger of the results above, I.e. 290 links (á 64 kbit/s) required in total (equals to 10 E1 PCM links) Result
- 23. 25 © NOKIA 2000 Gb interface detailed planning SGSN Dimensioning DX 200 SGSN SGAC SGBC CL SU PAPU 1 PAPU 2 PAPU 9 PAPU 10 GSW 0 GSW 1 PAPU 3 PAPU 4 MCHU 0 MCHU 1 PAPU 0 ET 0 ( 32 * ET2E/A) 0 1 2 3 4 5 6 7 8 9 SD MCHU 0 SD MCHU 1 PDFU 0 PDFU 1 SD OMU 0 SD OMU 1 OMU 1 OMU 0 PAPU 11 PAPU 12 ET 1 ( 28 * ET2E/A) PDFU 0 PDFU 1 CL BU 1 PAPU 6 PAPU 7 PAPU 5 PAPU 16 SMMU 0 SMMU 1 SMMU 2 SMMU 3 SMMU 4 PAPU 8 PAPU 13 PAPU 14 PAPU 15 10 CL BU 0 One fully equipped SGSN element has the following design targets concerning connectivity: • 120 physical 2Mbps E1-PCMs • PCMs are freely selectable between Gb- interface and SS7 based interfaces (Gs, Gr, Gd, Gf) • 96 SS7 signalling links (24 per SMMU) • 1024 64kbps Frame Relay links for Gb- interface use (64 in each PAPU) • E.g 100 BSCs each having 8x64kbps Gb- interface connection could be connected into one SGSN • 16 100-baseTX Ethernet connections for Gn-interface use (one in each PAPU) • Maximum of 16 000 Routing Areas, 2 000 Location Areas
- 24. 27 © NOKIA 2000 Gb interface detailed planning SGSN Dimensioning SGSN Configuration Levels 4 PAPUs, 1 SMMU 4 PAPUs, 1 SMMU 4 PAPUs, 1 SMMU 4 PAPUs, 1 SMMU SGSN 12 Mbit/s 30 000 subscr. 256 Gb IF (64kbit/s) 24 Mbit/s 60 000 subscr. 512 Gb IF (64kbit/s) 36 Mbit/s 90 000 subscr. 768 Gb IF (64kbit/s) 48 Mbit/s 120 000 subscr. 1024 Gb IF (64kbit/s) Basic Unit Extension Units Capacities: SGSN can be configured in four steps. The right configuration level for each case is determined by the dimensioning rules.
- 25. 28 © NOKIA 2000 Gb interface detailed planning Gb Interface Dimensioning Simple Dimensioning Example (Summary) 4 PAPUs, 1 SMMU 4 PAPUs, 1 SMMU 4 PAPUs, 1 SMMU SGS N 1 Basic Unit & 2 Extension Units in the SGSN 290 links (64kibt/s) in 10 E1 PCM links BSC 10 active PCUs in 3 BSCs BSC BSC
- 26. 29 © NOKIA 2000 Gb interface detailed planning Gb INTERFACE DETAILED PLANNING
- 27. 30 © NOKIA 2000 Gb interface detailed planning GPRS Dimensioning Considerations • FUTURE SCENARIOS - Operator's short and long term plans concerning the network expansions and evolution to new technologies • CAPACITY DEMAND - Subscriber volume - GPRS traffic estimation - GPRS coverage area • EXISTING NETWORK INFRASTRUCTURE - Existing Transmission, Data Communication backbone and GSM network infrastructures
- 28. 31 © NOKIA 2000 Gb interface detailed planning Topology and Dimensioning Requirements • BSC Distribution • PCU Distribution among MSC sites • Network Topology • Network Architecture • Subscriber Distribution • GPRS Traffic Distribution • Overhead % Requirement • Burst Margin • Future Network Expansion
- 29. 32 © NOKIA 2000 Gb interface detailed planning GPRS Coverage Planning From the requirements stated on the previous slide we can determine the following : - GPRS coverage areas - Topology and Capacity of the Frame relay links in a GPRS service area - GPRS network dimension per coverage areas
- 30. 33 © NOKIA 2000 Gb interface detailed planning BSC & PCU Distribution Among MSC Sites BSC Distribution Among MSC Sites Number of BSCs in year Subscriber Percentage of regional BSCs 2000 2001 2002 2003 2004 1 City A 13.9% 89.4% 55 70 70 70 70 2 City B 1.7% 10.6% 6 8 8 8 8 REGIONS 3 City C 14.0% 75.3% 50 65 65 65 65 South 4 City D 4.6% 24.7% 17 21 21 21 21 East 5 City E 11.2% 40.3% 33 43 43 43 43 Mid 6 City F 8.0% 28.9% 24 31 31 31 31 South 7 City G 10.8% 74.4% 37 48 48 48 48 West 8 City H 8.6% 36.4% 33 42 42 42 42 9 City I 8.5% 30.8% 26 33 33 33 33 10 City J 9.6% 40.6% 37 47 47 47 47 11 City K 5.4% 23.0% 21 27 27 27 27 12 City L 3.7% 25.6% 13 16 16 16 16 Total 100.0% 352 451 451 451 451 PCU Distribution Among MSC Sites Number of PCUs in year Subscriber Percentage of regional PCUs 2000 2001 2002 2003 2004 1 City A 13.9% 89.4% 110 140 140 140 140 2 City B 1.7% 10.6% 12 16 16 16 16 3 City C 14.0% 75.3% 100 130 130 130 130 REGIONS 4 City D 4.6% 24.7% 34 42 42 42 42 South 5 City E 11.2% 40.3% 10 12 12 13 13 East 6 City F 8.0% 28.9% 7 9 9 9 9 Mid 7 City G 10.8% 74.4% 74 96 96 96 96 South 8 City H 8.6% 36.4% 66 84 84 84 84 West 9 City I 8.5% 30.8% 7 10 10 10 10 10 City J 9.6% 40.6% 74 94 94 94 94 11 City K 5.4% 23.0% 42 54 54 54 54 12 City L 3.7% 25.6% 26 32 32 32 32 Total 100.0% 562 719 719 720 720
- 31. 34 © NOKIA 2000 Gb interface detailed planning GPRS Service Areas SGSN Areas GPRS Subs Attached GPRS Subs Active GPRS Subs Active PDP Contexts GPRS Traffic (Mbps) 2001 AREA 1 19 500 19 500 9 750 14 625 1.39 2001 AREA 2 28 850 28 850 14 425 21 638 2.05 2001 AREA 3 33 750 33 750 16 875 25 313 2.40 2001 AREA 4 14 750 14 750 7 375 11 063 1.05 2001 AREA 5 19 250 19 250 9 625 14 438 1.37 2002 AREA 1 49 200 49 200 24 600 36 900 3.50 2002 AREA 2 52 440 52 440 26 220 39 330 3.73 2002 AREA 3 57 600 57 600 28 800 43 200 4.10 2002 AREA 4 49 800 49 800 24 900 37 350 3.54 2002 AREA 5 55 800 55 800 27 900 41 850 3.97 Attached Subs 100% Active Subs 50% 2 PDP Contexts 50% 1 PDP Context 50% Mean PDP / sub 1.5 PDCH per cell 3 CS2 (Kbps) 13.4 thru per cell (Kbps) 40.2 traf_sub (KBytes BH) 50 Overhead 25% thru_sub (Kbytes BH) 62.5 thru_sub (Kbps) 142.22 SGSN fill rate 70% Coding Schemes CS1 9.05 CS2 13.4 CS3 15.6 CS4 21.4 SGSN area 1 City 1 SGSN area 2 Cities 2 and 3 SGSN area 3 Cities 4, 5, 6, 7 and 8 SGSN area 4 Cities 9, 10, 11 and 12 SGSN area 5 Cities 13 and 14
- 32. 35 © NOKIA 2000 Gb interface detailed planning SGSN AREA CALCULATIONS Initial Dimensioning Figures Covered Regions Number of Subscribers Number of Cells Min. No. of PDCH (during BHT) SGSN area 1 19 500 1 115 3 345 City 1 Radio Network Estimates Covered Regions Number of Cells Min. No. of PDCH (during BHT) SGSNarea 1 1 115 3 345 City 1 GPRS Traffic (Mbps) 2001 1.39 2002 3.50 GPRS Attached Subscribers 2001 19 500 2002 49 200 GPRS Active subscribers Active PDP Contexts 2001 9'750 14'625 2002 24'600 36'900 Nokia BSC's 18 Nokia BCSU's 162 Non-Nokia PCU 0 Non-Nokia Gb Interface 0 Total Gb Interfaces 80 CALCULATION RESULTS 2001 2002 PCU(Active) 18 PCU(Hardware) 162 Gb Interface Functionality 22 57 SGSN 1 PAPU(Active) 4 10 PAPU(Hardware) 4 12 SMMU 1 3
- 33. 36 © NOKIA 2000 Gb interface detailed planning Ater TIMESLOT ALLOCATION Bits TS 1 2 3 4 5 6 7 8 00 TS 0 01 LAPD 1 2 3 02 4 5 6 7 03 8 9 10 11 04 12 13 14 15 Channels of 05 16 17 18 19 ET2E 0, 06 20 21 22 23 interface 1 07 24 25 26 27 08 28 29 30 31 09 - 1 2 3 10 4 5 6 7 11 8 9 10 11 12 12 13 14 15 Channels of 13 16 17 18 19 ET2E 1, 14 20 21 22 23 interface 0 15 24 25 26 27 16 28 29 30 31 17 - 1 2 3 18 4 5 6 7 19 8 9 10 11 Channels of 20 12 13 14 15 ET2E 1, 21 16 17 18 19 interface 1 22 20 21 22 23 23 24 25 26 27 24 28 29 30 31 25 64 kbit/s 26 64 kbit/s 27 64 kbit/s Channels of 28 64 kbit/s ET2E 2, 29 64 kbit/s interface 0 30 64 kbit/s 31 64 kbit/s TSs 25-31 can carry Frame Relay traffic (to the Gb interface). Ater Time Slot Allocation •Existing E1 lines are utilized for Frame Relay traffic •Voice Traffic and Frame Relay Traffic combined •Throughgoing 64Kbps TS for Frame Relay traffic
- 34. 37 © NOKIA 2000 Gb interface detailed planning DEDICATED PCM SIGNAL •Time Slot allocation of a dedicated E1 signal for carrying the Gb / Frame Relay traffic to the SGSN.
- 35. 38 © NOKIA 2000 Gb interface detailed planning DN2 DXC EQUIPMENT OVERVIEW 1 - Cross-connection Node - 2 Mbit/s - 64 kbits - nx8 kbit/s - up to 40 2 Mbit/s interfaces (G.703) 2 - Drop-and-Insert equipment (“in-built” DB 2) 3 - Primary Multiplexing Equipment (“in- built” DM 2) Three cartridge sizes: 20 T (four units) 40 T (eight units) 19” Subrack (sixteen units) 40-port DN 2 uses two subracks and interconnecting cables 2 Mbit/s DN 2 D DCH CH 2 Mbit/s
- 36. 39 © NOKIA 2000 Gb interface detailed planning PHYSICAL TOPOLOGY - 1 Ethernet Switch GGSN #1 GGSN #2 MSC SGSN Transcoders MSC/SGSN site BSC Frame Relay Gb-int. Ater E1 PCM (Ater + Frame Relay) Abis Abis Abis MUX MUX BSC BSC •Voice and Data Traffic are multiplexed on the same physical connection as used for the GSM traffic on the Ater interface
- 37. 40 © NOKIA 2000 Gb interface detailed planning PHYSICAL TOPOLOGY - 2 Ethernet Switch GGSN #1 GGSN #2 MSC SGSN Transcoders MSC/SGSN site Frame Relay Gb-int. AterMUX BSC E1 PCM for Ater traffic Abis Abis Abis MUX BSC BSC Dedicated E1/ PCM for Frame Relay traffic •Voice and Data Traffic are allocated on separate E1 / PCM signal
- 38. 41 © NOKIA 2000 Gb interface detailed planning Ethernet Switch GGSN #1 GGSN #2 MSC SGSN Transcoders MSC/SGSN Site 1 Frame Relay Gb-int. Ethernet Switch GGSN #1 GGSN #2 MSC SGSN Transcoders MSC/SGSN Site 2 Frame Relay Gb-int. PHYSICAL TOPOLOGY - 3 Abis Abis Abis MUX MUX BSC BSC SGSN 1 SERVICE AREA SGSN 2 SERVICE AREA Ater Ater E1 PCM for Ater traffic Dedicated E1/ PCM for Frame Relay traffic •Voice and Data Traffic are allocated on different E1s BSC
- 39. 42 © NOKIA 2000 Gb interface detailed planning PHYSICAL TOPOLOGY - 4 • For large capacity networks such as SDH networks • Separate E1s for Ater and Frame Relay traffic Abis Abis Abis MUX BSC BSC SGSN 1 SERVICE AREA SGSN 2 SERVICE AREA Ethernet Switch GGSN #1 GGSN #2 MSC SGSN Transcoders MSC/SGSN Site 1 Frame Relay Gb-int. Ater Ethernet Switch GGSN #1 GGSN #2 MSC SGSN Transcoders MSC/SGSN Site 2 Frame Relay Gb-int. Ater MUX TRANSPORT NETWORK BSC E1/PCM for FR Ater E1/PCM for FR Ater E1/PCM for FR Ater ADM ADM ADM
- 40. 43 © NOKIA 2000 Gb interface detailed planning PHYSICAL TOPOLOGY - 5 • GPRS traffic is concentrated and carried e.g. in a packet data network over the Gb interface Ethernet Switch GGSN #1 GGSN #2 MSC SGSN Transcoders MSC/SGSN site Abis Gb Interface Packet Data Network (FR, ATM, etc.) FR Switch FR Switch BSC BSC BSC
- 41. 44 © NOKIA 2000 Gb interface detailed planning EXAMPLE BSC / PCU CONFIGURATION
- 42. 45 © NOKIA 2000 Gb interface detailed planning EXAMPLE SGSN/PAPU Configuration
- 43. 46 © NOKIA 2000 Gb interface detailed planning Nortel BSS - Nokia SGSN Exercise 1 - Case Study
- 44. 47 © NOKIA 2000 Gb interface detailed planning Tasks for Exercise • Make a draft of 2 BSCs connected to Nortel PCU • Nortel PCU interfaces Nokia SGSN • You can assume 10 timeslots of traffic in E1 frame per BSC (10 x 64kbps) • Allocate bearer channels, NS-VCs, DLCIs, SGSN, PAPUs • Show some redundancy options
- 45. 48 © NOKIA 2000 Gb interface detailed planning Background to Encountered Problems Frame Relay over E1 must be used • Timeslots reserved for FR bearer channels are specified in SGSN • Nokia assumes that channelised FR is supported by Nortel PCU, as it is a standard FR feature and normally supported by Nortel Passport. Nortel BSS - Nokia SGSN interoperability tests not complete enough • Tests were carried out with one NSE/bearer channel so the full capability of Nokia SGSN was not tested Nokia SGSN supports several NSEs per bearer channel • Blu in Italy, upto 5 NSEs/bearer channel • Depending in the FR capabilities of the PCU in question, Nokia may deploy different FR solutions
- 46. 49 © NOKIA 2000 Gb interface detailed planning Solution Nokia and Nortel together implement the technical solutions proposed in the following slides in the Dutchtone network • Both vendors will document the test results for Dutchtone and for their own interoperability documentation Nokia proposes to take an action point to • Carry out the interoperability test with Nortel in the Dutchtone network • Fully document the SGSN Frame Relay capabilities • Changes to SGSN software or Change Deliveries would not de- activate the solution in future
- 47. 50 © NOKIA 2000 Gb interface detailed planning
- 48. 51 © NOKIA 2000 Gb interface detailed planning NSE2 NS-VC2 NSE1 NS-VC1 BSC 1 BSC 2 BSC 2 BSC 1 NORTEL PCU SGSN E1 E1 DLCI_16 PAPU_1 NSE1 NSVC_1 DLCI_17 2 BSCs terminated into same PAPU NSE2 NSVC_2 BEARER CH. 1 CIR n x64 kbps CIR (31 - n) x64 kbps Remarks: • A Bearer channel can be associated to several NSEs, channel rate n x 64 Kbps • Bearer channel minimum rate = 64 Kbps • EIR set to null • Maximum 50 NS-VCs/bearer channel • If NS-VCs are terminated into same PAPU, they can be carried over same bearer channels
- 49. 52 © NOKIA 2000 Gb interface detailed planning NSE2 NS-VC1 NSE1 NS-VC1 BSC 1 BSC 2 BSC 2 BSC 1 NORTEL PCU SGSN E1 E1 BEARER CH. 1 DLCI_16 PAPU_1 PAPU_2 CIR n x64 kbps, n=1..31 CIR DLCI_17 Remarks: • A Bearer channel can be associated to several NSEs, channel rate n x 64 Kbps • Bearer channel minimum rate = 64 Kbps • EIR set to null • Maximum 50 NS-VCs/bearer channel • If NS-VCs are terminated into different PAPUs, they have to be carried over separate bearer channels 2 BSCs terminated into different PAPUs BEARER CH. 2 (31 - n) x64 kbps IF 50% of E1 per BSC, FULL E1 REQUIRED NSE1 NSVC_1 NSE2 NSVC_1
- 50. 53 © NOKIA 2000 Gb interface detailed planning Typical Gb NSE2 NS-VC2 NSE1 NS-VC1 BSC 1 BSC 2 BSC 2 BSC 1 NORTEL PCU SGSN E1 E1 DLCI_16 PAPU_1 NSE1 NSVC_1 DLCI_17 BEARER CH. 1 CIR n x64 kbps CIR (31 - n) x64 kbps NSE3 NS-VC3 BSC 3 BSC 3 DLCI_18 BEARER CH. 2 NSE2 NSVC_2 PAPU_3 E1 E1 NSE5 NS-VC5 NSE4 NS-VC4 BSC 4 BSC 5 BSC 5 BSC 4 NSE6 NS-VC6 BSC 6 BSC 6 E1 E1 DLCI_20 DLCI_21 BEARER CH. 3 DLCI_19 CIR n x64 kbps NSE5 NSVC_5 NSE6 NSVC_6 PAPU_2 NSE3 NSVC_3 NSE4 NSVC_4 REMARKS: • About 1/2 E1 required per BSC • PAPU processing capacity 3 Mbps -> 1 BSC can be connected into same PAPU, each occupying 15 x 64 k FR
- 51. 54 © NOKIA 2000 Gb interface detailed planning Gb with Redundancy NSE 1 BSC 1 BSC 1 NORTEL PCU SGSN E1 E1 DLCI_16 PAPU_1 DLCI_17 BEARER CH. 1 DLCI_18 BEARER CH. 2E1 E1 DLCI_19 NSVC_1 NSVC_2 NSVC_1 NSVC_2 NSE 1 NSE 2 BSC 2 BSC 2 NSVC_3 NSVC_4 NSVC_3 NSVC_4 NSE 2
- 52. 55 © NOKIA 2000 Gb interface detailed planning Detailed planning exercise Exercise 2
- 53. 56 © NOKIA 2000 Gb interface detailed planning Input for exercise BSC • 2 BSCs (geographically split) 1. BSC ( 16 sites connected – each 2 cells) 2 BCSUs 8 x 64k TS GPRS traffic for 8 sites on each PCU 2. BSC (6 sites connected – each 2 cells) 1 BCSUs 6 x 64k TS GPRS traffic for 6 sites SGSN • One PAPU FR links • BSC BSC1 is connected with 2 FR links while BSC2 has one FR link connection
- 54. 57 © NOKIA 2000 Gb interface detailed planning Considerations for the planning • Prepare an overview of the network • Dimension FR links (Bearer channels) • Allocated all ids‘ : NSEI,BVCIs, NS-VCIs, DLCIs, and define the capacity of all Bearer channels and DLCs. Also include some examples of load sharing or protection • This is a freestyle exercise – so there is no really a right solution of this exercise.
- 55. 58 © NOKIA 2000 Gb interface detailed planning Overview of the network - output BSC 1 2 BCSUs SGSN PAPU_1 NSE3 NSVC_3/4 E1(1) E1(1) DLCI_1 6 DLCI_17 BEARER CH. 1 CIR 4 x64 kbps CIR 3 x64 kbps BSC 2 1 BSCU DLCI_16 DLCI_17 BEARER CH.3 PCU-1 PCU-2 DLCI_16 DLCI_17 16 TS = 16*64kbps 6 TS = 6*64kbps 22 TS = 22*64kbps BEARER CH. 2 NSE2 NSVC_5/6 E1(2) E1(2) E1(1) E1(1) PCU- 1 NSE1 NSVC_1/2
- 56. 59 © NOKIA 2000 Gb interface detailed planning Overview of the network – output BC BSC 1 2 BCSUs SGSN PAPU_1 NSE1 NSVC_1 /2 NSE2 NSVC_3/4 DLCI_1 6 DLCI_17 BEARER CH. 1 BSC 2 1 BSCU DLCI_16 DLCI_17 BEARER CH.3 DLCI_16 DLCI_17 Bearer channel = 6*64kbps = 384kbps BEARER CH. 2 NSE3 NSVC_5/6 Bearer channel = 8 TS = 8*64kbps = 512kbps Bearer channel = 8 TS = 8*64kbps = 512kbps Data link connection = 2x 3*64kbps = 2 x 128kbps E1(1) E1(1) E1(2) E1(2) E1(1) E1(1) CIR 4 x64 kbps CIR 3 x64 kbps PCU- 1 PCU-2 PCU-1
- 57. 60 © NOKIA 2000 Gb interface detailed planning Overview of the network – output NSEI/NS-VCI BSC 1 2 BCSUs SGSN PAPU_1 NSE1 NSVC_1 /2 NSE2 NSVC_3/4 DLCI_1 6 DLCI_17 BEARER CH. 1 CIR (31 - n) x64 kbps BSC 2 1 BSCU E1(1) E1(1) DLCI_16 DLCI_17 BEARER CH.3 DLCI_16 DLCI_17 BEARER CH. 2 NSE3 NSVC_5/6 NSE1 NSVC_1 /2 NSE2 NSVC_3/4 NSE3 NSVC_5/6 E1(1) E1(1) E1(2) E1(2) CIR 4 x64 kbps CIR 3 x64 kbps PCU-1 PCU-2 PCU- 1
- 58. 61 © NOKIA 2000 Gb interface detailed planning Overview of the network – output BVCI BSC 1 2 BCSUs BSC 2 1 BSCU PCU-1 PCU-2 PCU- 1 BSC PCU 1 - 8 sites site cell BVCI 1 1 1 1 2 2 2 3 3 2 4 4 3 5 5 3 6 6 4 7 7 4 8 8 5 9 9 5 10 10 6 11 11 6 12 12 7 13 13 7 14 14 8 15 15 8 16 16 BSC PCU 2 - 8 sites site cell BVCI 1 1 1 1 2 2 2 3 3 2 4 4 3 5 5 3 6 6 4 7 7 4 8 8 5 9 9 5 10 10 6 11 11 6 12 12 7 13 13 7 14 14 8 15 15 8 16 16
- 59. 62 © NOKIA 2000 Gb interface detailed planning Thank you !!!
- 60. 63 © NOKIA 2000 Gb interface detailed planning BSC HLR/ AC/ EIR TCSM MSC/VLR BTS Abis Interface Ater Interface A Interface Air Interface TC Ater’ Interface GSM architecture BSS NSS O&M Interface NMS
Editor's Notes
- 1 Brief overview of Interfaces in GPSR / GSM 2 Gb interface Review ( Protocol stack / NW Layers) 3 Channelisation of 2Mbps 4 Network service entity 5 Logical structure 6 Logical channels in Physical Link 7 Frame relay Link Parameters 8 Gb interface planning - BSC dim - FR link planning - SGSN dim Gb INTERFACE DETAILED PLANNING CASE STUDY
- The Gb interface shall allow many users to be multiplexed over the same physical resource. Resources are given to a user upon activity (when data is sent or received) and are reallocated immediately thereafter. This is in contrast to the A interface where a single user has the sole use of a dedicated physical resource throughout the lifetime of a call irrespective of activity. GPRS signaling and user data are sent in the same transmission plane. No dedicated physical resources are required to be allocated for signaling purposes.
- GPRS is logically implemented on the GSM structure through the addition of two network nodes, the Serving GPRS Support Node and the Gateway GPRS Support Node. It is necessary to name a number of new interfaces. No inference should be drawn about the physical configuration on an interface from the figure. What we see here is the logical network overview showing all different network interfaces. In this module we‘ll focus on the Gb interface which you can find between the BSS and the SGSN. BSS stands for Base station subsystem and SGSN for Serving GPRS suport node. So, what is now the BSS and the SGSN ..... The BSS is the whole access network (BTS,BSC, TCSM) The Serving GPRS Support Node (SGSN), which is at the same hierarchical level as the MSC, keeps track of the individual MSs' location and performs security functions and access control. The SGSN is connected to the base station system with Frame Relay. GPRS security functionality is equivalent to the existing GSM security. The SGSN performs authentication and cipher setting procedures based on the same algorithms, keys, and criteria as in existing GSM. GPRS uses a ciphering algorithm optimised for packet data transmission. The Serving GPRS Support Node (SGSN) is the node that is serving the MS (i.e., the Gb interface is supported by the SGSN). At GPRS attach, the SGSN establishes a mobility management context ( = MMF are used to keep track of the current location of an MS within the PLMN or within another PLMN) containing information pertaining to e.g., mobility and security for the MS. At PDP Context Activation, the SGSN establishes a PDP context, to be used for routeing purposes, with the GGSN that the GPRS subscriber will be using.
- GSM 03.60! The transmission plane consists of a layered protocol structure providing user information transfer, along with associated information transfer control procedures (e.g., flow control, error detection, error correction and error recovery). The transmission plane independence of the Network Subsystem (NSS) platform from the underlying radio interface is preserved via the Gb interface. - GPRS Tunnelling Protocol (GTP): This protocol tunnels user data and signalling between GPRS Support Nodes in the GPRS backbone network. All PDP PDUs shall be encapsulated by the GPRS Tunnelling Protocol. GTP is specified in GSM 09.60 [25]. - TCP carries GTP PDUs in the GPRS backbone network for protocols that need a reliable data link (e.g., X.25), and UDP carries GTP PDUs for protocols that do not need a reliable data link (e.g., IP). TCP provides flow control and protection against lost and corrupted GTP PDUs. UDP provides protection against corrupted GTP PDUs. TCP is defined in RFC 793 [42]. UDP is defined in RFC 768 [39]. - IP: This is the GPRS backbone network protocol used for routeing user data and control signalling. The GPRS backbone network may initially be based on the IP version 4 protocol. Ultimately, IP version 6 shall be used. IP version 4 is defined in RFC 791. - Subnetwork Dependent Convergence Protocol (SNDCP): This transmission functionality maps network-level characteristics onto the characteristics of the underlying network. SNDCP is specified in GSM 04.65 [14]. - Logical Link Control (LLC): This layer provides a highly reliable ciphered logical link. LLC shall be independent of the underlying radio interface protocols in order to allow introduction of alternative GPRS radio solutions with minimum changes to the NSS. LLC is specified in GSM 04.64. - Relay: In the BSS, this function relays LLC PDUs between the Um and Gb interfaces. In the SGSN, this function relays PDP PDUs between the Gb and Gn interfaces. - Base Station System GPRS Protocol (BSSGP): This layer conveys routeing- and QoS-related information between BSS and SGSN. BSSGP does not perform error correction. BSSGP is specified in GSM 08.18 [20]. - Network Service (NS): This layer transports BSSGP PDUs. NS is based on the Frame Relay connection between BSS and SGSN, and may be multi-hop and traverse a network of Frame Relay switching nodes. NS is specified in GSM 08.16 [19]. - RLC/MAC: This layer contains two functions: The Radio Link Control function provides a radio-solution-dependent reliable link. The Medium Access Control function controls the access signalling (request and grant) procedures for the radio channel, and the mapping of LLC frames onto the GSM physical channel. RLC/MAC is defined in GSM 04.60 [12]. GSM RF: As defined in GSM 05 series.
- The signalling plane consists of protocols for control and support of the transmission plane functions: - controlling the GPRS network access connections, such as attaching to and detaching from the GPRS network; - controlling the attributes of an established network access connection, such as activation of a PDP address; - controlling the routeing path of an established network connection in order to support user mobility; and - controlling the assignment of network resources to meet changing user demands. Legend: GPRS Mobility Management and Session Management (GMM/SM): This protocol supports mobility management functionality such as GPRS attach, GPRS detach, security, routeing area update, location update, PDP context activation, and PDP context deactivation, as described in subclauses "Mobility Management Functionality" and "PDP Context Activation, Modification, and Deactivation Functions".
- The grafic presents different network layers, which may serve the GPRS system. Which network layers are utilised to serve GPRS in each network planning case is highly dependent on the suitability and availability of existing network layer solutions. Gb Interface The connection over the Gb interface is based on Frame Relay protocol logical connections. In practice, the Gb interface connection will be implemented using SDH transport network on top which the FR traffic is transported. Traditionally, also in GSM, the speech traffic over the Ater interface (analogous to Gb) is carried in SDH network. In addition, pure Frame Relay or ATM backbone networks could be utilised to carry the FR traffic (2nd layer in Figure 1). In such a case, the underlying SDH network wouldn't be utilised. Comment left / right Gb connection: Left BSC is connected via and FR network layer to the SGSN, while the right BSC is connected via an FR connection running FR over SDH....
- The Gb interface connects the BSS and the SGSN, allowing the exchange of signaling information and user data as shown in the grafic. The Gb interface shall allow many users to be multiplexed over the same physical resource. Resources are given to a user upon activity (when data is sent or received) and are reallocated immediately thereafter. This is in contrast to the A interface (BSC_MSC) where a single user has the sole use of a dedicated physical resource throughout the lifetime of a call irrespective of activity. GPRS signaling and user data are sent in the same transmission plane. No dedicated physical resources are required to be allocated for signaling purposes. Access rates per user may vary without restriction from zero data to the maximum possible line rate (e.g., 1 984 kbit/s for the available bit rate of an E1 trunk).
- Frame relay provides bearer channels (BC) to its users. Frame relay supports logical connections called data link connections (DLC). Each DLC has an identifier, the DLCI. There can be a maximum of 124 DLCIs on one bearer channel and the DLCI must be unique within one bearer channel. The frame relay network does not support flow control, but the rate at which users may send frames is restricted. Also, a FR network does not support error correction. Flow control and error correction are performed by higher layer protocols. The Frame Relay Bearer channels can range from 1 to 31 PCM time slots. In the ETSI environment the maximum combined Access Rate of Frame Relay Bearer channels can be configured from 64 kbit/s to 1984 Mbit/s in 64 kbit/s steps. In the ANSI environment the range is from 64 kbit/s to 1472 Mbit/s in 64 kbit/s steps. The Committed Information Rate of Network Service Virtual Connections can be configured from 16 kbit/s up to the Access Rate of the Bearer channel in 16 kbit/s steps. In Nokia Implementation each PCU represents one and only one Network Service Entity (NSE).
- Network Service control layer On both sides of the Gb interface, there is a logical entity called network service entity (NSE). NSEs are identified by their identifiers called NSEIs. An NSEI must be identical and unique at both sides, because there is a direct relationship between the two NSEs. NSEs at the BSS and the SGSN are connected with one or more network service virtual connections (NS-VC). The NSEI is used by the SGSN to determine the NS_VCs that provide service to a BVC. One NSE is configured between two peer NS entities. This grouping is performed by administrative means. At each side of the Gb interface, there is a one-to-one correspondence between a group of NS_VCs and an NSEI. The NSEI has an end-to-end significance across the Gb interface. NS_VC is the FR PVC and corresponds to the FR DLCI together with the bearer channel identifier. NS_VCs are permanently established by means of administrative procedures. Each NS_VC is identified by means of an NS_VCI. The number of the NS-VCs in the SGSN is equal to the number of DLCs. The network service control layer is responsible for the NS SDU transmission, load sharing, NS-VC management and GPRS-specific addressing, which maps cells to virtual connections.
- BSSGP is a layer 3 protocol for delivering data packets and associated control information. BSSGP also includes procedures for downlink flow control, paging, virtual circuit management, and so on. BSSGP supports the BSSGP virtual connections (BVC) so that each cell always has one BVC over the Gb interface. The BVC identifier, BVCI, is only unique within an NSE. One NS-VC supports several BVCs. Within one NSE, the NS-VCs are shared by all BVCs. Before the system creates any BVCs, the location area codes (LAC) served by the SGSN must be configured. The two types of BVCs are a signalling BVC and a PTP BVC. The system automatically creates a signalling BVC when the user creates the first NS-VC to an NSE. Similarly, when the user deletes the last NS-VC of an NSE, the system automatically deletes the signalling BVC for that NSE. The creation of PTP BVCs is dynamic, meaning that the BVCs are configured in the BSS and the SGSN receives the BVCI in a message.
- As it is mentioned in the previous sections, frame relay supports logical connections called data link connections (DLC) and each DLC has an identifier called DLCI. One important thing is that DLCI is unique within one bearer channel. DLCI is identical in both ends only in case of point-to-point FR connections- if FR network with permanent virtual circuits (PVC) is used between the SGSN and the BSC, the DLCI has only local significance. There can be two types of frame relay connections, point-to-point or intermediate frame relay network connection. In point-to-point FR connections, the BSS is considered to be the user side of the User-to-Network Interface (UNI), the SGSN being the network side. In an intermediate FR network, both the BSS and the SGSN are considered to be a user side. Basically, each Packet Control Unit (PCU) in the BSC supports one NSE. Since up to 64 PCUs can be served by one PAPU, PAPU also supports several NSEs. The number of the NS_VCs in the SGSN is equal to the number of the DLCIs. In other words, each NS_VC in the network service control layer, maps one-to-one onto the DLCs of the frame relay layer. BVC 0 for signalling used!
- Because one bearer channel supports several DLCs, it can also be shared by several NS_VCs. Load sharing can be applied so that the traffic of one cell can be routed via several, evenly loaded NS_VCs. The NS_VC capacity can be controlled with the Committed Information Rate (CIR) parameter in steps of 16 kbps. In this way, flow control is also performed although it is not supported by the frame relay. In contrast to the DLCI, the NS_VCI must always be identical at both sides. The NS_VCI is also unique in the whole SGSN. Also BVCI has an end-to-end significance. In this way, both the BSC and the SGSN can identify cells with the BVCI. The BVCI is unique only within an NSE. BVCI=0 is reserved for signalling purposes. One NS_VC supports several BVCs. Within one NSE, the NS_VCs are shared by all BVCs. BSSGP supports both cell-specific (BVC) and MS-specific flow control.
- NS-VC: because of load sharing possibilities when planning and defining size of a NS-VCs, also consider possible traffic prodection when on NS-VC goes down. The link as physical connection could work, while a logical connection between 2 NSEs could be down. This means if i send the data from on BVC on two NS-VCs, might just loose the half of the traffic of one cell (one cell has its own BVC).... – also refer to page 11 and show again what‘s possible....
- DL-CI: 124 ids because you can have per TS 4. When you multiply 4 DL-CIs with a maximum of 31 TS, you get 124!
- It is not necessary to equipe the BSC with 8+1 BCSUs and 8+1 PCU in order to be GPRS capable. If BSC has only 6 BCSUs (5+1) then the only requisite is to equipe them qith 6 PCUs (5+1) and using dimensioning rules determine how many of this PCU will be active.
- RA definition is an input from Radio Planning. Cells are related to certain PAPUs, one RA cannot be split by two or more PAPUs
- Nokia BSC limits the number of NS-VCs to 4 per bearer channel, SGSN can handle more. Nokia PCUs cannot share the same bearer channel, Nortel implementation DOES it. For customer discussions, ask some official statement from GPRS Business Program for BSC FR limitations (no burst margin supported)
- SUPPORT SLIDE