Bremen Institute of Industrial Technology and Applied Work Science ATM in TCP/IP environment: Adaptations and Effectiveness Dipl.-Ing. Kai-Oliver Detken, BIBA ATM Traffic Symposium, Mykonos, Greece, September the 17th, 1997
Content Introduction of the European ACTS project EIES (European Information Exchange Service) IP-over-ATM difficulty IP-over-ATM possibilities: Classical IP, LAN Emulation (LANE), and MPOA IP effectiveness: protocol overhead, TCP throughput obstacles, sender and receiver buffers, RTT and MTU deadlocks, UDP and Client performance Performance Improvements and further developments 17.09.97 IP-over-ATM (EXPERT).ppt Folie 2/28
The ACTS project EIES Definition, implementation, and experimentation of advanced telecommunication services Support routine and non-routine communication between different maritime players Define and transpose the user requirements for the service development of EIES Build-up a pre-commercial global EIES service Establish an ATM link between the different harbour sites (Bordeaux, Bremen, Brest, Santander) to use the prototypes in real life 17.09.97 IP-over-ATM (EXPERT).ppt Folie 3/28
EIES services Computer Supported Cooperative Work (CSCW) Distribution of multimedia information about different databases (BluePages and Port Entry Guide) Integration of Electronic Data Interchange (EDI) and Electronic Mail (Email) Mobile communication (DSRR, DECT, and Inmarsat) for the mobile access to the services. Fixed networks: ATM, ISDN, and Internet (IP) 17.09.97 IP-over-ATM (EXPERT).ppt Folie 4/28
EIES platform Mobile Access Mobile Access ATM Communications Server Communications Server LAN Client LAN Client LAN 1 LAN 2 Internet Server IP Router Internet IP Router Internet Server Remote Client Remote Client 17.09.97 IP-over-ATM (EXPERT).ppt Folie 5/28
IP features Internet Protocol works connectionless (hop-byhop-transmission) No acknowledgements, error- and duplicate detection with IP Data packets are variable: 20 byte - 65 kbyte; destination address identified the other client Lost data packets have to repeat requested by higher layer protocols (TCP) Multicast/broadcast functions Type-of-Service (TOS) 17.09.97 IP-over-ATM (EXPERT).ppt Folie 6/28
ATM features Connection-oriented technologie: virtual connections will establish for the cell transport (PVC/SVC) ATM has its own address structur and routing funktions 53 byte cells with fixed size contain payload and control data Point-to-point connections Quality-of-Service (QoS) 17.09.97 IP-over-ATM (EXPERT).ppt Folie 7/28
IP-over over-atm Adaptations Classical-IP - IETF: RFC-1577 - ATM clients use IP LAN-Emulation (LANE) -ATM-Forum - Traditional networks use ATM Multiprotocol over ATM (MPOA) - ATM-Forum and IETF protocols - Routing mechanisms will be implemented 17.09.97 IP-over-ATM (EXPERT).ppt Folie 8/28
Classical-IP (RFC-1577) RFC-1577: Classical-IP and ARP over ATM Logical Link Control Encapsulation: Multiple protocols can be transported over a single connection (RFC-1483) VC-Based Multiplexing: Single protocol is transported over an ATM connection (RFC-1483) D-MTU: 9180 Byte PVC/SVC connections Transport over the AAL-5 layer Point-to-point connections Address resolution by central ATMARP server 17.09.97 IP-over-ATM (EXPERT).ppt Folie 9/28
Classical-IP architecture ATMARP- Server 1 ATM ATMARP- Server 2 LIS 1 LIS 2 Client 1 Router Client 1 Client 2 Control Connection Data Connection Ethernet 17.09.97 IP-over-ATM (EXPERT).ppt Folie 10/28
Encapsulation (RFC-1483) IP header IP payload IP packet 20 byte 0-9160 byte LLC 0xAAAA03 3 byte OUI 0x000000 PID 0x0800 3 byte 2 byte IP packet 20-9180 byte LLC/SNAP packet 8 byte IP packet with LLC-SNAP header PAD CPI + CPCS-UU Length Detection CRC-32 AAL-5 packet header 28-9188 byte header 0-47 byte PT 0 SAR-PDU payload 1-192 cells PT 0 SAR-PDU payload SAR sublayer ATM header ATM payload ATM header ATM payload ATM cells 5 byte 48 byte 5 byte 48 byte 17.09.97 IP-over-ATM (EXPERT).ppt Folie 11/28
RFC-1577 conclusions Advantages: - high data throughput by high MTU (9180 byte) - simple and stabile standard Disadvantages: - only IP unicast is supported - high manual configuration effort - no multicast/broadcast support - no redundant ATMARP server - direct connections to other LIS subnets is not possible - no QoS 17.09.97 IP-over-ATM (EXPERT).ppt Folie 12/28
LAN Emulation (LANE) Migration of traditional LANs to ATM: Ethernet switch (layer 2) und router (layer 3) coupling Universal implementation (MAC layer is emulated): arbitrary LAN protocols Using of the application layer without ATM configuration Support of PVC/SVC connections IP multicasting D-MTU: 1500 byte 17.09.97 IP-over-ATM (EXPERT).ppt Folie 13/28
LANE architecture Configuration Control Connection LAN Emulation Service LAN Emulation Configuration Server (LECS) Configuration Control Connection Control Connection LAN Emulation Server (LES) Control Connection Distributed Control Connection Multicast Control Connection LEC Send Unicast Broadcast and Unknown Server (BUS) Send Multicast LEC Distributed Data Connection Multicast Data Connection Direct Data Exchange 17.09.97 IP-over-ATM (EXPERT).ppt Folie 14/28
LANE encapsulation IP header IP payload 20 Byte 0-1472 byte IP packet LLC AA AA 03 3 byte OUI 00 00 00 PID 0800 3 byte 2 byte IP packet 20-1492 byte LLC/SNAP packet LEheader Destination Address 2 byte 6 byte Source Type/ LANE packet Address Length IP packet with LLC/SNAP encapsulation 6 byte 2 byte 8 byte 28-1500 byte IP packet with LLC/SNAP- and additional LAN encapsulation PAD CPI + CPCS-UU Lenght Detection CRC-32 AAL-Typ5 packe header 44-1516 byte header 0-47 byte PT 0 SAR-PDU payload 2-32 cells PT 0 SAR-PDU payload SAR Sublayer ATM payload ATM- header ATMheader ATM payload ATM cell 5 byte 48 byte 5 byte 48 byte 17.09.97 IP-over-ATM (EXPERT).ppt Folie 15/28
LANE conclusions Advantages: - integration of traditional networks - transparency for arbitrary network protocols - multicast/broadcast support - automatic configuration Disadvantages: - high functionality (layer 2 emulation) - MTU and older network boards limitated throughput - bad scalability - no redundant BUS (overload) - no QoS 17.09.97 IP-over-ATM (EXPERT).ppt Folie 16/28
MPOA capacity Support multiple protocols effective over ATM networks Distribute the routing functions between route servers Separate routing from switching functions Leverage performance and QoS capabilities of ATM network Direct connections between ELANs rather than passing through traditional routers Direct Virtual Channel Connections (VCC) between data forwarding devices Interworking with unified routers Enables subnet members to be distributed across the network Efficient scalability of the ATM network 17.09.97 IP-over-ATM (EXPERT).ppt Folie 17/28
MPOA architecture Control Connection Control Connection Default Forwarder Functional Group Data Connection IASG Coordination Functional Group ATM network ATM-Host Control Connection Data Connection Kontrollverbindung Edge Device Shortcut Data Connection ATM-Host Token Ring Workstation 17.09.97 IP-over-ATM (EXPERT).ppt Folie 18/28
Extensions for MPOA attempts Multicast Address Resolution Server (MARS) - support of multicasting by additional MARS server Next-Hop Resolution Protocol (NHRP) - direct connection between subnets possible Resource Reservation Protocol (RSVP) - QoS parameter at connectionsless packets - similar to the UNI signaling Private Network-to-Network-Interface (P-NNI) - control data exchange between ATM systems - transparency pass on the virtual connection 17.09.97 IP-over-ATM (EXPERT).ppt Folie 19/28
Advantages: - QoS is supported for the first time - router bottlenecks are eliminated - management of large networks - build up of VLANs Disadvantages: MPOA conclusions - MPOA is not a full defined spezification (1998) - IETF protocols must further developed - scalability is an extremely complex issue - MPOA does not provide a stable network yet 17.09.97 IP-over-ATM (EXPERT).ppt Folie 20/28
IPoverATM-Overhead STM-1-Frame (OC-3): 155,52 Mbps ATM Layer: 149,76 Mbps Adaptation Layer AAL-5: 135,632 Mbps LLC/SNAP encapsulation: - MTU: 576 byte 126,937 Mbps - MTU: 9180 byte 135,22 Mbps - MTU: 65527 byte 135,563 Mbps Internet Protocol (IP): 125,2/135,1/135,6 Mbps Transport Layer: 120,9/134,8/135,5 Mbps Application Layer via TCP: 116,5/134,5/135,5 Mbps Application Layer via UDP: 119,1/134,7/135,5 Mbps 17.09.97 IP-over-ATM (EXPERT).ppt Folie 21/28
Socket buffer size at sender/receiver Network: Maximum Transport Unit (MTU) Protocol: Maximum Segment Size (MSS) Sender: using of the Nagle s algorithm Round-Trip-Time (RTT) TCP-Throughput Throughput Obstacles Receiver: delayed acknowledegements Sender: Silly Window Syndrom (SWS) Copy strategy at the socket interface Network congestion and lost packet notice 17.09.97 IP-over-ATM (EXPERT).ppt Folie 22/28
Sender and Receiver buffer S/E 16 kbyte 20 kbyte 24 kbyte 28 kbyte 32 kbyte 36 kbyte 40 kbyte 44 kbyte 48 kbyte 52 kbyte 16 kbyte 15,05 13,60 0,322 0,319 0,319 0,467 0,469 0,466 0,469 0,469 20 kbyte 15,99 14,60 15,07 14,87 15,40 14,24 1,095 1,095 0,548 0,549 24 kbyte 17,71 16,79 16,74 16,32 17,40 17,31 17,42 17,12 0,760 0,740 28 kbyte 16,57 17,69 17,93 18,13 18,36 19,20 19,74 19,78 18,38 18,20 32 kbyte 14,63 18,96 18,42 19,23 19,14 19,74 19,96 20,31 19,69 19,17 36 kbyte 14,33 19,22 18,12 19,82 19,77 19,92 20,56 20,49 20,13 20,20 40 kbyte 15,16 19,34 18,85 19,73 20,11 20,41 20,81 20,74 20,69 20,57 44 kbyte 14,80 19,40 18,27 20,39 20,16 20,74 20,99 20,87 20,89 20,70 48 kbyte 14,62 19,46 18,34 20,48 20,26 20,41 20,85 20,83 20,93 20,83 52 kbyte 13,92 19,41 18,26 20,50 20,06 20,21 20,88 20,91 21,21 21,06 17.09.97 IP-over-ATM (EXPERT).ppt Folie 23/28
RTT and MTU deadlocks MTU of 9180 byte has the best performance if the RTT is low MTU of 1500 byte has the best performance if the RTT is high If the MTU is smaller as the used packet size: fragmentation and reassembling is necessary! Throughput [Mbps] 60 50 40 30 20 10 0 0 5 10 15 20 25 30 RTT [10^-3 s] MTU 576 byte MTU 1500 byte MTU 9180 byte TCP-Window-Limit 17.09.97 IP-over-ATM (EXPERT).ppt Folie 24/28
UDP performance Connectionless structure UDP has no acknowledgements, no end-to-end control and no duplicate detection Less locking effects for protect shared protocol state and data Locking Effects limits the data throughput. 10-Mbps-Ethernet [kbyte] 4000 3000 2000 1000 0 0 10 20 Processor numbers UDP/IP TCP/IP 17.09.97 IP-over-ATM (EXPERT).ppt Folie 25/28
Client performance Operation system (interprocess communication) Data processing CPU performance Memory speed I/O bus bandwidth ATM adapter implementation Latency Time [µs] 450 400 350 300 250 200 150 100 50 0 1 2 3 4 5 6 Sender (1-3) and Receiver site (4-6) Single-Copy + Checksum LANs (1,4 Ethernet / 2,5 FDDI / 3,6 ATM) 17.09.97 IP-over-ATM (EXPERT).ppt Folie 26/28
Client Tuning Using of the D-MTU value Path-MTU: max. possible packet size should be switch on (none fragmentation) MSS value: 1436 byte for high speed networks Sender and receiver buffer at least 2 times bigger than MTU value Window Scale Option (RFC-1323) higher Window-Size Classical-IP: LAN-Emulation, test 1: LAN-Emulation, test 2: Throughput of 134,01 Mbps (Sun20-Ultra) Throughput of 76,30 Mbps (Sun20-Ultra) Throughput of 117,63 Mbps (Ultra-Ultra) 17.09.97 IP-over-ATM (EXPERT).ppt Folie 27/28
...further developments Classical-IP, Version 2 - distributed ATMARP server LANE, Version 2 - L-UNI: QoS, multicast, ELAN multiplexing - L-NNI: distributed LES/BUS IP-Switching (Ipsilon) - none standard - other proposal Tag-Switching from CISCO 17.09.97 IP-over-ATM (EXPERT).ppt Folie 28/28