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Jose Saldana, Julian Fernandez-Navajas, Jose Ruiz-Mas, Eduardo Viruete Navarro, Luis Casadesus, "The Utility of Characterizing Packet Loss as a Function of Packet Size in Commercial Routers," in Proc. CCNC 2012, Work in progress papers, pp. 362-363, Las Vegas. Jan 2012. ISBN 9781457720697
Citation preview
The Utility of Characterizing Packet Loss as a Function of Packet Size in
Commercial Routers
Jose Saldana
Julián Fernández-Navajas
José Ruiz-Mas
Eduardo Viruete Navarro
Luis Casadesus
Communication Technologies Group (GTC)
Aragon Institute of Engineering Research (I3A)
University of Zaragoza, Spain
INDEX
I. Introduction and Related Works
II. Tests and Results
III. Conclusions
INDEX
I. Introduction and Related Works
II. Tests and Results
III. Conclusions
CCNC 2012. Las Vegas, 15 Jan 2011
Introduction and Related Works
- The Internet was designed as a best-effort
network
- The first deployed services were e-mail, ftp, etc.,
which did not have critical delay requirements.
- So they used big packets in order to have a good
bandwidth efficiency.
CCNC 2012. Las Vegas, 15 Jan 2011
Introduction and Related Works
- Nowadays, real-time services have very critical
delay requirements
- So they require a high rate of packets, which
implies small sizes
CCNC 2012. Las Vegas, 15 Jan 2011
Introduction and Related Works
- Efficiency problem
One IPv4/TCP packet 1500 bytes
η=1460/1500=97%
One IPv4/UDP/RTP packet of VoIP with two samples of 10 bytes
η=20/60=33%
CCNC 2012. Las Vegas, 15 Jan 2011
Introduction and Related Works
- Packet loss: one of the main impairments in
current networks
- Wireless: The radio link is the critical one
- Wired: Dropping in router queues
- TCP-based services can recover lost packets
- UDP-based services: interactive applications can
be seriously affected, as there is no time for
retransmission
CCNC 2012. Las Vegas, 15 Jan 2011
Introduction and Related Works
- ¿Is there a relationship Packet loss vs. Packet
size?
- Wireless environment: YES. The bigger the packet,
the bigger the probability of a corrupted bit.
- Wired environment: The main cause of packet loss is
dropping in router queues, so we have to study the
behavior of the queues.
- Many routers were designed for “classical”
services, so they are not prepared to deal with
small packets
CCNC 2012. Las Vegas, 15 Jan 2011
Introduction and Related Works
- Buffers of commercial routers have different
implementations
- Buffers can be measured in bytes, packets, or
maximum queuing delay
- Bandwidth is not the only limit: packets per second
limit is also present
- drop-tail, RED, etc
- The implementation may not strongly affect
delay and jitter, but may affect packet loss
CCNC 2012. Las Vegas, 15 Jan 2011
Introduction and Related Works
- Characterization of packet loss vs packet size
packet loss
packet size
CCNC 2012. Las Vegas, 15 Jan 2011
Introduction and Related Works
- Useful to make some decisions:
- Multiplexing or not
- Samples per packet
- Number of TS (Transport Stream) included in a packet
probability
packet size
One TS per packet
CCNC 2012. Las Vegas, 15 Jan 2011
Introduction and Related Works
- Useful to make some decisions:
- Multiplexing or not
- Samples per packet
- Number of TS (Transport Stream) included in a packet
probability
packet size
Five TS per packet
CCNC 2012. Las Vegas, 15 Jan 2011
Introduction and Related Works
What is better?
More TS per packet increases efficiency
But if it increases packet loss…
probability
packet size
Five TS per packet
CCNC 2012. Las Vegas, 15 Jan 2011
Introduction and Related Works
- So
- Let’s study packet loss vs. packet size
behavior of the router (and the Internet, as
future work)
- Help when making decisions
- Give us an idea of the internal (and non-
publicly available) router implementation
- The interest is the shape of the graphs
CCNC 2012. Las Vegas, 15 Jan 2011
Introduction and Related Works
“Sizogram”
packet loss
packet size
INDEX
I. Introduction and Related Works
II. Tests and Results
III. Conclusions
CCNC 2012. Las Vegas, 15 Jan 2011
Tests and Results
- Definition of a test able to reflect this
- An “empirical” test, suitable to be performed
with different routers and networks
- The router will be considered a “black box”
- We do not know its internal structure
CCNC 2012. Las Vegas, 15 Jan 2011
Tests and Results
- Background traffic: 100% of the capacity
- 50 % packets 40 bytes
- 10% packets 576 bytes
- 40% packets 1,500 bytes
CCNC 2012. Las Vegas, 15 Jan 2011
Tests and Results
0
2000
4000
6000
8000
10000
100 200 300 400 500 600 700 800 900 1000 1100 1200 1300 1400 1500
kb
ps
Packet size
Offered traffic
variable size
1500 bytes
576 bytes
40 bytes
Background
10Mbps
CCNC 2012. Las Vegas, 15 Jan 2011
Tests and Results
0
2000
4000
6000
8000
10000
100 200 300 400 500 600 700 800 900 1000 1100 1200 1300 1400 1500
kb
ps
Packet size
Offered traffic
variable size
1500 bytes
576 bytes
40 bytes
Variable size
100kbps
CCNC 2012. Las Vegas, 15 Jan 2011
Tests and Results
- Test traffic: two orders of magnitude smaller
0
2000
4000
6000
8000
10000
100 200 300 400 500 600 700 800 900 1000 1100 1200 1300 1400 1500
kb
ps
Packet size
Offered traffic
variable size
1500 bytes
576 bytes
40 bytes
CCNC 2012. Las Vegas, 15 Jan 2011
Tests and Results
- Duration of each test:
- From 200 to 3,000 seconds for each point, in order to
have 25,000 packets of variable size traffic
- Matlab simulations
CCNC 2012. Las Vegas, 15 Jan 2011
Tests and Results
- Two buffer implementations:
- byte-sized: 10kB, 20kB, 50kB, 100kB
- packet-sized: 16, 33, 83, 166 packets
- Can be considered “tiny buffers”
CCNC 2012. Las Vegas, 15 Jan 2011
Tests and Results: Byte-sized
0%
1%
2%
3%
4%
5%
6%
7%
8%
9%
10%
100 200 300 400 500 600 700 800 900 1000 1100 1200 1300 1400 1500
packet
loss
packet size (bytes)
packet loss, buffer byte-sized
10kB
20kB
50kB
100kB
CCNC 2012. Las Vegas, 15 Jan 2011
Tests and Results: Byte-sized
0%
1%
2%
3%
4%
5%
6%
7%
8%
9%
10%
100 200 300 400 500 600 700 800 900 1000 1100 1200 1300 1400 1500
packet
loss
packet size (bytes)
packet loss, buffer byte-sized
10kB
20kB
50kB
100kB
Monotonically
increasing
CCNC 2012. Las Vegas, 15 Jan 2011
Tests and Results: Byte-sized
0%
1%
2%
3%
4%
5%
6%
7%
8%
9%
10%
100 200 300 400 500 600 700 800 900 1000 1100 1200 1300 1400 1500
packet
loss
packet size (bytes)
packet loss, buffer byte-sized
10kB
20kB
50kB
100kB
Bigger packet –
Bigger packet loss
CCNC 2012. Las Vegas, 15 Jan 2011
Tests and Results: Byte-sized
0%
1%
2%
3%
4%
5%
6%
7%
8%
9%
10%
100 200 300 400 500 600 700 800 900 1000 1100 1200 1300 1400 1500
packet
loss
packet size (bytes)
packet loss, buffer byte-sized
10kB
20kB
50kB
100kB
The slope grows as the
buffer gets smaller
CCNC 2012. Las Vegas, 15 Jan 2011
0%
1%
2%
3%
4%
5%
6%
7%
8%
9%
10%
100 200 300 400 500 600 700 800 900 1000 1100 1200 1300 1400 1500
packet
loss
packet size (bytes)
packet loss, buffer packet-sized
16packets
33packets
83packets
166packets
Tests and Results: Packet-sized
No variation with packet
size, as expected
CCNC 2012. Las Vegas, 15 Jan 2011
Tests and Results: pps limit
0%
5%
10%
15%
20%
25%
30%
35%
40%
45%
50%
100 200 300 400 500 600 700 800 900 1000 1100 1200 1300 1400 1500
packet
loss
packet size (bytes)
packet loss, buffer byte-sized
10 kb
10kB, 2000pps
10kB, 2500pps
10kB, 3000 pps
10kB, 3500pps
CCNC 2012. Las Vegas, 15 Jan 2011
0%
5%
10%
15%
20%
25%
30%
35%
40%
45%
50%
100 200 300 400 500 600 700 800 900 1000 1100 1200 1300 1400 1500
packet
loss
packet size (bytes)
packet loss, buffer byte-sized
10 kb
10kB, 2000pps
10kB, 2500pps
10kB, 3000 pps
10kB, 3500pps
Tests and Results: pps limit
Offered 1,970 pps
CCNC 2012. Las Vegas, 15 Jan 2011
0%
5%
10%
15%
20%
25%
30%
35%
40%
45%
50%
100 200 300 400 500 600 700 800 900 1000 1100 1200 1300 1400 1500
packet
loss
packet size (bytes)
packet loss, buffer byte-sized
10 kb
10kB, 2000pps
10kB, 2500pps
10kB, 3000 pps
10kB, 3500pps
Tests and Results: pps limit
Increases significantly
with respect to no pps
limitation
CCNC 2012. Las Vegas, 15 Jan 2011
0%
2%
4%
6%
8%
10%
12%
14%
16%
18%
20%
100 200 300 400 500 600 700 800 900 1000 1100 1200 1300 1400 1500
packet
loss
packet size (bytes)
packet loss, buffer byte-sized
10kB
10kB, tproc=20us
10kB, tproc=40us
10kB, tproc=60us
10kB, tproc=80us
10kB, tproc=100us
Tests and Results: processing time
CCNC 2012. Las Vegas, 15 Jan 2011
0%
2%
4%
6%
8%
10%
12%
14%
16%
18%
20%
100 200 300 400 500 600 700 800 900 1000 1100 1200 1300 1400 1500
packet
loss
packet size (bytes)
packet loss, buffer byte-sized
10kB
10kB, tproc=20us
10kB, tproc=40us
10kB, tproc=60us
10kB, tproc=80us
10kB, tproc=100us
Tests and Results: processing time
Graphs have the same
shape
CCNC 2012. Las Vegas, 15 Jan 2011
0%
2%
4%
6%
8%
10%
12%
14%
16%
18%
20%
100 200 300 400 500 600 700 800 900 1000 1100 1200 1300 1400 1500
packet
loss
packet size (bytes)
packet loss, buffer byte-sized
10kB
10kB, tproc=20us
10kB, tproc=40us
10kB, tproc=60us
10kB, tproc=80us
10kB, tproc=100us
Tests and Results: processing time
Packet loss increase is
not so severe
INDEX
I. Introduction and Related Works
II. Tests and Results
III. Conclusions
CCNC 2012. Las Vegas, 15 Jan 2011
Conclusions
- We have studied the relationship between packet
size and packet loss in routers
- Depends on buffer implementation
- A methodology has been defined to find the
packet loss histogram as a function of packet
size
- This can give us an idea of the internal
implementation of the router, and help us when
making some decisions
CCNC 2012. Las Vegas, 15 Jan 2011
Conclusions
- Byte-sized buffers increase loss with size
- Packet-sized buffers do not vary
- Extension of this to Internet paths and
commercial routers
Thank you