CIS 725 High Speed Networks. High-speed networks High bandwidth, high latency Low error rates...
-
Upload
esmond-allison -
Category
Documents
-
view
215 -
download
0
Transcript of CIS 725 High Speed Networks. High-speed networks High bandwidth, high latency Low error rates...
![Page 1: CIS 725 High Speed Networks. High-speed networks High bandwidth, high latency Low error rates Message loss mainly due to congestion.](https://reader031.fdocuments.in/reader031/viewer/2022032612/56649ef15503460f94c02852/html5/thumbnails/1.jpg)
CIS 725
High Speed Networks
![Page 2: CIS 725 High Speed Networks. High-speed networks High bandwidth, high latency Low error rates Message loss mainly due to congestion.](https://reader031.fdocuments.in/reader031/viewer/2022032612/56649ef15503460f94c02852/html5/thumbnails/2.jpg)
High-speed networks
• High bandwidth, high latency• Low error rates• Message loss mainly due to congestion
![Page 3: CIS 725 High Speed Networks. High-speed networks High bandwidth, high latency Low error rates Message loss mainly due to congestion.](https://reader031.fdocuments.in/reader031/viewer/2022032612/56649ef15503460f94c02852/html5/thumbnails/3.jpg)
• Example:
A and B connected via a 1 Gps link
RTD = 60ms
![Page 4: CIS 725 High Speed Networks. High-speed networks High bandwidth, high latency Low error rates Message loss mainly due to congestion.](https://reader031.fdocuments.in/reader031/viewer/2022032612/56649ef15503460f94c02852/html5/thumbnails/4.jpg)
• Go Back N• Selective repeat
![Page 5: CIS 725 High Speed Networks. High-speed networks High bandwidth, high latency Low error rates Message loss mainly due to congestion.](https://reader031.fdocuments.in/reader031/viewer/2022032612/56649ef15503460f94c02852/html5/thumbnails/5.jpg)
Parallelism
• Thread models
- thread per layer
- thread per module
- thread per message
- thread per connection
![Page 6: CIS 725 High Speed Networks. High-speed networks High bandwidth, high latency Low error rates Message loss mainly due to congestion.](https://reader031.fdocuments.in/reader031/viewer/2022032612/56649ef15503460f94c02852/html5/thumbnails/6.jpg)
T3
T4
T1
T2
m1 m2 m3Thread per layer
- One thread for each layer- Pipelining
![Page 7: CIS 725 High Speed Networks. High-speed networks High bandwidth, high latency Low error rates Message loss mainly due to congestion.](https://reader031.fdocuments.in/reader031/viewer/2022032612/56649ef15503460f94c02852/html5/thumbnails/7.jpg)
Thread per function
- One thread for each function- More than one function may be possible in a layer
Send function
Receive function
![Page 8: CIS 725 High Speed Networks. High-speed networks High bandwidth, high latency Low error rates Message loss mainly due to congestion.](https://reader031.fdocuments.in/reader031/viewer/2022032612/56649ef15503460f94c02852/html5/thumbnails/8.jpg)
Thread per message
m1 m2
reordering
- Synchronization overhead
Thread pool
- Interface* recv_msg()
![Page 9: CIS 725 High Speed Networks. High-speed networks High bandwidth, high latency Low error rates Message loss mainly due to congestion.](https://reader031.fdocuments.in/reader031/viewer/2022032612/56649ef15503460f94c02852/html5/thumbnails/9.jpg)
![Page 10: CIS 725 High Speed Networks. High-speed networks High bandwidth, high latency Low error rates Message loss mainly due to congestion.](https://reader031.fdocuments.in/reader031/viewer/2022032612/56649ef15503460f94c02852/html5/thumbnails/10.jpg)
Thread per connection
• A separate thread is created for each connection• All messages for a connection are processed by the same thread
![Page 11: CIS 725 High Speed Networks. High-speed networks High bandwidth, high latency Low error rates Message loss mainly due to congestion.](https://reader031.fdocuments.in/reader031/viewer/2022032612/56649ef15503460f94c02852/html5/thumbnails/11.jpg)
![Page 12: CIS 725 High Speed Networks. High-speed networks High bandwidth, high latency Low error rates Message loss mainly due to congestion.](https://reader031.fdocuments.in/reader031/viewer/2022032612/56649ef15503460f94c02852/html5/thumbnails/12.jpg)
Blast Protocol
• Transmission occurs in blasts• Optimistic Assumption:
- Next packet to arrive is the expected one
- A blast is not interrupted by other packets
- Location of a data packet is known
![Page 13: CIS 725 High Speed Networks. High-speed networks High bandwidth, high latency Low error rates Message loss mainly due to congestion.](https://reader031.fdocuments.in/reader031/viewer/2022032612/56649ef15503460f94c02852/html5/thumbnails/13.jpg)
DLL
APP
• Normal Path
- copy data packets into temp buffer
check header
copy into final location• Optimistic path
- copy data packet into final location
check header
if incorrect then do recovery
tempDLL
APP
header
data
![Page 14: CIS 725 High Speed Networks. High-speed networks High bandwidth, high latency Low error rates Message loss mainly due to congestion.](https://reader031.fdocuments.in/reader031/viewer/2022032612/56649ef15503460f94c02852/html5/thumbnails/14.jpg)
• Selective retransmission based protocol
window = blast size
selective ack sent at end of blast
![Page 15: CIS 725 High Speed Networks. High-speed networks High bandwidth, high latency Low error rates Message loss mainly due to congestion.](https://reader031.fdocuments.in/reader031/viewer/2022032612/56649ef15503460f94c02852/html5/thumbnails/15.jpg)
• If unexpected packet is received
- wait until end of blast
recopy items
send nack
![Page 16: CIS 725 High Speed Networks. High-speed networks High bandwidth, high latency Low error rates Message loss mainly due to congestion.](https://reader031.fdocuments.in/reader031/viewer/2022032612/56649ef15503460f94c02852/html5/thumbnails/16.jpg)
Performance results
• Blast size = 32k• raw data rate = 9.4Mbs• Using normal processing = 63%• Best case optimistic = 85%• Worst case optimistic = 53%
![Page 17: CIS 725 High Speed Networks. High-speed networks High bandwidth, high latency Low error rates Message loss mainly due to congestion.](https://reader031.fdocuments.in/reader031/viewer/2022032612/56649ef15503460f94c02852/html5/thumbnails/17.jpg)
Image Transfer Protocol
• Purpose = transfer of stored images• Many images itself have certain degree of
uncertainty• Most images have spatial redundancy• Neighboring pixels are highly correlated
![Page 18: CIS 725 High Speed Networks. High-speed networks High bandwidth, high latency Low error rates Message loss mainly due to congestion.](https://reader031.fdocuments.in/reader031/viewer/2022032612/56649ef15503460f94c02852/html5/thumbnails/18.jpg)
• No retransmissions
- a message should not contain any two neighboring pixels
![Page 19: CIS 725 High Speed Networks. High-speed networks High bandwidth, high latency Low error rates Message loss mainly due to congestion.](https://reader031.fdocuments.in/reader031/viewer/2022032612/56649ef15503460f94c02852/html5/thumbnails/19.jpg)
• Protocol must handle packets out of order and in parallel
• The source image is decomposed into messages, each containing info to deduce the position of the pixels
• Image is pre-processed and stored as exact messages to be transferred
![Page 20: CIS 725 High Speed Networks. High-speed networks High bandwidth, high latency Low error rates Message loss mainly due to congestion.](https://reader031.fdocuments.in/reader031/viewer/2022032612/56649ef15503460f94c02852/html5/thumbnails/20.jpg)
• Congestion control:
- increases the transfer rate until the maximum acceptable loss rate is achieved