1. SUPPORTING MULTIMEDIA COMMUNICATION OVER A GIGABIT ETHERNET NETWORK
- BERNARD DAINES, JONATHAN C.L. LIU AND K.SIVALINGAM
presented by: Sainath Morpoju ( )
Srinivas Medapati ( )

3. WHY GIGABIT ETHERNET ?
Streaming multimedia, VR, high-performance distributed computing, distance learning
National backbone network speed is 155 – 622 Mbps
A typical video server generates 2.88 Gbps traffic from the storage subsystem
Most of the information available on the internet is multimedia traffic
Information is shared among people using multimedia applications on their mobile phone.
Paper leverages the exsisting CDMA protocol used for wireless communication and extends it to include multimedia support as well.
Due to the exponential increase in Internet traffic there is now a fair amount of unpredictability on the performance and efficient multimedia networking is not a trivial task. There are many challenges

4. GIGABIT NETWORK COMPONENTS
Gigabit Network Interface Card ( GNIC )
Buffered Hub / full-duplex repeater ( FDR )
Gigabit Routing Switch ( GRS )
is the amount of digital data that is moved from one place to another in a given time.
The BER is calculated by comparing the transmitted sequence of bits to the received bits and counting the number of errors.

5. GNIC (Gigabit Network Interface Card)

6. IEEE 802.3z MAC frame format for gigabit speed ethernet
Interframe gap is 0.16 microseconds
Mobile phones use this technology called CDMA
Concept here is that ..
This allows several users to share a band of frequencies (see bandwidth). To permit this without undue interference between the users, CDMA uses a special coding scheme (where each transmitter is assigned a code).
Responsible to produce interferences between different users’ signals.

7. GNIC DESIGN ISSUES IEEE 802.3z frame compatibility
Operating at line speeds
Reducing host CPU utilization

8. GNIC ARCHITECTURE
Descriptor based DMAs (direct memory access) to reduce host CPU utilization
Dual burst FIFOs for operating at line speeds
GMAC implements IEEE 802.3z standard
Packet buffer to avoid lost packets

10. FDR (full duplex repeater)

11. Need for FDR ? In a typical Ethernet, MAC layer implements CSMA/CD
Collision detection and retransmissions are inefficient
Hub is a simple repeater (one to all), no processing of link layer data
Switches are intelligent (one to one) but use specialized hardware so cost is high
FDR uses a simple design without any ASICs

12. FDR Architecture Every port has an input buffer and an output buffer
A 1000 Mbps forwarder bus
A frame forwarder which picks a port to transmit, in a round robin fashion for fair allocation of bandwidth
Full duplex transmission possible without collisions
Allows congestion control using IEEE 802.3x protocol to notify sender if port buffer is full

15. GRS (Gigabit Routing Switch)

16. PE-4884 Architecture
It has 14 slots, 12 for interface / channel cards and 2 for EMMs (enterprise management module)
4884 backplane has a 52 Gbps capacity
Every channel card is connected to central memory through two non-blocking full duplex gigabit channels

17. Cross-bar Architecture Issues
Port-based memory : Inefficient use of available memory, even inactive ports have memory allocated
Head-of-line blocking : Packets destined for a busy receive port will block packets in queue
Difficult to provide reliable QoS support : Limited abilities to provide traffic based on priority

18. Shared Memory Architecture
Typically used for 10 Mbps and 100 Mbps switches
All ports access a shared memory pool
Access to the central memory is granted by an arbitration device
For Gigabit speeds arbitration device cannot run fast enough to be non-blocking

19. Parallel Access Shared Memory
All ports have simultaneous full-duplex gigabit access to the centralized memory pool
No need to replicate and store multicast traffic on multiple egress ports
Provides the ability to pull outbound traffic from dedicated port based priority queues

20. EXPERIMENTS 3 experiments were conducted to test the gigabit ethernet
The experiments were based on an echo server, a file server, and a video server

21. EXPERIMENT 1

22. Experiment 1 : Echo Server
Both machines are fitted with GNIC and use a special device driver ( yellowfin.c )
Netperf and netserver were used to measure peak performance.
Custom code was written to do accurate benchmarking ( used TCP_NODELAY to turn off nagle’s algorithm which groups smaller packets )
Linux and NT systems were tested

23. Results
For Linux platforms a max throughput of 180 – 200 Mbps is achieved
For NT platforms the performance is lower at 90 Mbps and equals that of linux machines with a faster processor ( DEC alpha )
PCI interaction and internal protocol stack are believed to be the main reasons for lower performance

24. EXPERIMENT 2 : File Server
Pentium Pro 2 ( 266 Mhz ) running NT Server 4.0 was setup as the file server
Clients request the fileserver for files and measure throughput
The sum of throughputs of all clients is recorded using NetBench
All machines were connected using FDR

26. Experiment 3 : Video on demand
Designed to measure concurrent accesses for on-demand video titles
Implemented the two-buffer scheme
Maintaining QoS ( < 1% jitter ) with maximum concurrent accesses

27. Results
32 concurrent streams could be maintained at 4Mbps ( throughput 128 Mbps )
19 concurrent streams were supported at 8Mbps
9 concurrent streams were supported at 16Mbps
Only 3 concurrent streams could be supported at 32 Mbps ( very high end video )

28. Conclusions
From the performance results it was observed that gigabit speeds at the interface card level can be achieved
High-end workstations like SUN UltraSPARC and DEC Alpha chips are able to achieve Mbps at TCP level
In the near future processing latency can be further reduced through simplified transport protocols, faster processors and increased bus widths

29. References https://www.cise.ufl.edu/class/cnt6885fa18/spaper01.pdf

30. Q/A

31. THANK YOU