Diffserv deployment in the wide area: network design and testing

1
Diffserv deployment in the wide area network
design and testing

• Tiziana Ferrari
• Italian National Institute for Nuclear Physics
• ferrari_at_cnaf.infn.it
• TF-TANT task force
• http//www.dante.net/tf-tant/

2
Overview

• Why diffserv?
• Test programme
• testbed
• interim results
• classification and marking
• policing
• scheduling
• QoS measurement
• services
• VLL

3
Motivation

• Why diffserv?
• independent of layer 2 technologies
• interoperability
• diffserv domains ? National Research Networks
  (NRN)
• diffserv region NRN 1 diffserv core domain
• independent diffserv implementation in each
  diffserv domain
• traffic aggregation
• scalability
• transparency to the application

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Motivation (cont)

• (some) benefits
• network layer
• VLL service, a potential replacement of ATM
  permanent connections
• resource allocation on congested links
• QoS support in/to NRN which are not ATM based
• application layer
• QoS support for mission critical applications
  (RSVP - diffserv)
• e.g. good QoS support to client-server
  distributed applications thanks to traffic
  aggregation

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Diffserv and the European network model
DS domain
DS domain
MPLS
NRN
NRN
Non DS capable domain
NRN
Marking policing
scheduling
TEN-155
DS domain
NRN
(marking)
shaping
NRN
DS domain
DS domain
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Overview of test programme

• Diffserv
• DSCP class selectors, EF, AF
• test of basic QoS features in diffserv platforms
• parameter tuning
• interoperability
• services definition, implementation, validation
  through test applications (video streaming, IP
  telephony, distributed applications)
• diffserv and intserv (end-to-end QoS)
• diffserv and MPLS
• QoS measurement
• Policy management

7
Work accomplished (June 99-Oct 99)

• network configuration
• baseline performance testing
• marking
• policing
• functionality, token bucket parameter tuning
  (normal and exceed burst size) with TCP traffic
• CB-WFQ (Class Based WFQ) traffic isolation
• scheduling
• CB-WFQ traffic isolation, VLL service in the
  wide area
• SCFQ (Self Clocked Fair Queuing) EF, AF and
  best-effort

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Work accomplished (cont)

• QoS measurement (ongoing)
• parameters one-way delay and one-way delay
  variation
• LAN and WAN (VLL service implementation and
  validation)
• traffic generators with GPS antennas
• NTP
• definition of test services
• point to point virtual leased line
• one-to-many virtual leased line
• resource allocation on congested links
• better than best-effort
• services for remote instrumentation control (AF)

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Diffserv test network
Uni. Bologna
CSELT
EPFL
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LAN layout (example)
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Equipment

• Test workstations (ATM, Ethernet, Fast Ethernet,
  Giga Ethernet interfaces)
• traffic generators (3 SmartBits, Netcom Systems)
  connected to GPS rx
• ATM switch(es) in each test sites
• 2 Cabletron Ethernet switches
• DS capable routers
• CISCO C7200 and/or C7500
• IBM 2212 and IBM 2216 (in 5 sites, 2 routers per
  site)

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Interim Results
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Classification, marking and policing

• Multi-field classification OK
• packet marking OK
• testing of different exceed actions OK
• policing (at a configurable rate)
• token bucket parameter tuning for TCP traffic
  performance optimisation
• normal burst
• exceed burst

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Policing test of exceed actions
drop
precedence 0
Throughput SWITCH 1.20 Mbps DANTE 0.38
Mbps (drop effect)
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Policing TCP burst tolerance

• Normal and exceed burst tuning with TCP traffic
• single and multiple TCP streams
• optimum values are functions of the rate R at
  which
• traffic is policed, in particular
• normal burst 0.5 sec R
• independently of the platform
• exceed burst 2 normal burst

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Policing TCP burst tolerance (cont)

• CISCO platforms
• Target rate 1.25 Mbps

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Policing TCP burst tolerance (cont)

• IBM platforms (IBM 2212)
• Small TCP burst tolerance in a policer can
  completely starve a TCP stream.
• Token bucket depth is function of the rate at
  which traffic is policed
• ? tuning needed

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Policing TCP burst tolerance (cont)
EF behaviour aggregate of TCP traffic, target
rate 163 Kbps
(IBM 2212)
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Policing, two-parameter TBoptimum burst size
for different traffic rates
IBM 2212

• Small TCP burst tolerance it can completely
  starve a TCP stream
• optimum token bucket size function of the
  policing rate

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Scheduling and policingtwo-parameter TB and
premium buffer size
Recommendation token bucket size lt premium
buffer size (for low packet loss probability)
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Scheduling CB-WFQ

• Scheduling implementation to provide minimum
  bandwidth
• guarantees to classes
• tested on CISCO platforms - C7200, IOS 12.0(5)T -
• class definition based on class selectors for
  aggregation ? OK
• bandwidth allocation no starvation, dynamic
  allocation in case of classes which are not fully
  deploying the capacity guaranteed to them ? OK
• traffic isolation between EF BA and best-effort
• several combinations of TCP and UDP traffic
• variable number of TCP streams (different
  aggregation degrees)

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CB-WFQ set-up
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CB-WFQ traffic isolation, 1 TCP stream

• Inconsistent results, for some sites TCP
  throughput lt 1.25 Mbps
• different ATM burst tolerances on the WAN
  connections seem seem to be
• the cause ? traffic isolation on WAN
  connections can be an issue

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CB-WFQ traffic isolation, multiple TCP streams

• Overall TCP performance of the behaviour
  aggregate improves when the
• aggregation degree increases
• TCP performance of a single connection still low
  
• ? problem under investigation

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Scheduling Self Clocked Fair Queuing

• IBM 2212
• Policy (traffic profile, validity period,
  diffserv action)
• Diffserv action (type of marking, queue type,
  bandwidth)
• optimum traffic isolation (tests only with UDP)

Premium 163.8 Kbps guaranteed (8 PPP link
bw) Assured 819.2 Kbps (40 PPP bw)
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QoS measurement

• Resource allocation monitoring
• for resource allocation and network dimensioning
• performance measurement
• passive
• active (invasive traffic)
• for service validation
• to understand the effect on end-to-end
  performance of buffering in one router or in a
  chain

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Parameters

• parameters of interest
• one-way delay, requirements clock
  synchronisation
• GPS based synchronisation
• SmartBits (Netcom Systems)
• NTP (Network Time Protocol)
• NTP client / server hierarchy
• one-way delay variation
• deployment of inter packet gap at rx and tx
• packet loss probability
• throughput

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QoS measurement 1-way delay and instantaneous
delay variation (LAN)
Goal VLL service implementation and
validation Metric Type-P-One-way-Delay (RFC
2679), type-P-one-way-ipdv Variables

• WFQ/SCFQ EF queue depth
• packet size
• EF queue weight
• traffic volume

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One-way delay average vs packet size
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Latency in time
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ipdv (without best-effort)
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ipdv (with best-effort)
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Services

• Virtual leased line
• point to point
• one to many
• capacity allocation on congested links (e.g. US
  links)
• better-than-best-effort (qualitative definition)

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VLL
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VLL implementation
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Future work

• Weighted Random Early Discard (WRED) testing
• completion of IBM testing
• study of TCP related issues ACK colouring, TCP
  and UDP aggregations with AF
• interoperability testing (other future platforms
  NORTEL, TELEBIT, TORRENT, Linux)
• service implementation and validation
• diffserv and MPLS
• diffserv and intserv
• policy management and bandwidth brokerage

37
To know more

• Activities of the TF-TANT task force
• http//www.dante.net/tf-tant
• Diffserv test programme and interim test results
• http//www.cnaf.infn.it/ferrari/tfng/ds
• QoS measurement test programme
• http//www.cnaf.infn.it/ferrari/tfng/qosmon