ipv6 qos tests in grnet2 network - terena...tf-ngn meeting - athens, november 2005 6 qos services in...

IPv6 QoS tests in GRNET2 Network

Athanassios LiakopoulosGreek Research & Technology Network

TF – NGN Meeting, Athens, November 4th,2005

TF-NGN Meeting - Athens, November 2005 2

Outline

ObjectivesBasic QoS mechanisms in DiffServIPv6 header and QoSQoS servicesGRNET2 NetworkTest results & AnalysisConclusions


Objectives

Validate the performance of basic QoS mechanisms with IPv6 traffic.Perform diverse set of tests

Hardware-based and software-based routersEthernet and PoS cardsPhysical and logical interfaces

Identify missing functionality or unexpected performance.Provide guidelines for the deployment of QoS services in an IPv6 production environment.


Basic QoS mechanisms in DiffServClassificationMeteringPolicing / ShapingQueue managementQueue scheduling

ClassifyClassify

GoldGold Scheduling

Router queues

OtherOtherBEBE GoldGold

GoldGoldGoldGold

OtherOther

BEBE

GoldGoldOtherOtherBEBE GoldGold

ClassifyClassify

GoldGoldGoldGold SchedulingScheduling

Router queues

OtherOtherOtherOtherBEBEBEBE GoldGoldGoldGold

GoldGoldGoldGoldGoldGoldGoldGold

OtherOtherOtherOther

BEBEBEBE

GoldGoldGoldGoldOtherOtherOtherOtherBEBEBEBE GoldGoldGoldGold

AverageRate

Bursts

MaximumBurst

QoS is much more than

the activation of some mechanism

s!


IPv6 header and QoS

Fragment OffsetFlags

Total LengthType of Service

IHL

PaddingOptions

Destination Address

Source Address

Header ChecksumProtocolTime to Live

Identification

Version

Next Header Hop Limit

Flow LabelTraffic Class

Destination Address

Source Address

Payload Length

Version

IPv4 HeaderIPv4 Header IPv6 HeaderHeader

- Field’s name kept from IPv4 to IPv6

- Fields removed in IPv6

- Name & position changed in IPv6

- New field in IPv6

IPv6 and IPv4 headers are not interoperable while IPv6 header is not a superset of IPv4 counterpart.The IPv6 header has two fields that are related to QoS; the traffic class and flow label fields. There is no difference among traffic class (IPv6) and type of service (IPv4) fields.The flow label field consists of 20 consecutive bits

Selected by the source and never modified in the network.In the IPv4 world, flow classification is based on the 5 tuples consisted of the source and destination addresses, ports, and the transport protocol type. These fields may be unavailable due to fragmentation or encryption.


QoS Services in GRNET2

Premium IP (PIP)Based on Expedited Forwarding PHB (EF-PHB)Gives absolute priority over any other class and provides low delay/jitter plus negligible packet loss guarantees. Suitable for real-time applications.Flavors: PIP Virtual Wire (source & destination aware), PIP VoIP(destination unaware) and PIP Transparent.

Best Effort (BE)Less than Best Effort (LBE)

Exploits network resources without (negative) impact other traffic classes. Suited for specific scavenger applications.


GRNET2 NetworkGRNET is the Greek National Research and Educational Network (NREN).Interconnects ~90 educational and research institutes.Technical specifications

12 PoPs in major citiesSTM-16 core links, up to 1Gbps access linksCisco GSR12400 series with 4xGE (Eng3) and 10xGE (Eng4+) line cards5Gbps connection to upstream provider (GÉANT)Dual stack network since December 2003.


GRNET2 Testbed

Hardware-based traffic generators – Smartbit 600Collect accurate time-related statistics.

traffic generator

Traffic flows

QoS interface (Eng4+)

QoS interface (Eng3)

traffic generator

AthensPatra Ilissos

GRNET

traffic generator

STM-64/PoSGigE

Cisco 12400 series

Thessaloniki

Larisa

Smartbit 600

FECisco 7200 series

Patra-2

QoS interface (FE)


CPU ImpactGenerate IP traffic at 2Gbps for a 30min period.

Use IPv4, IPv6, and mixture of IPv4/6 traffic.500Mbps IPv4 production traffic – 12% average load

ResultsNo impact with IPv4 traffic.7% absolute increase with mixture of IPv4 & IPv6 traffic.11%(26%) absolute increase for 5min (1min) intervals for IPv6-only traffic. Severe ISIS problem impacted network connectivity.


Basic tests with QoS mechanisms

ValidateInput and output classification based on ACLs

Physical and logical GigEthernet port (Eng3 card)Physical STM-16/PoS port

Input and output policingLogical GigEthernet port (Eng3 card)


Packet loss for BE traffic

0

20

40

60

80

10% 25% 40% 55% 70% 85% 100%

Load (% of 1Gbps)

Pack

et lo

ss (%

)

IPv6: 1 -> 2 IPv4: 1 -> 2 IPv6: 2 -> 1 IPv4: 2 -> 1 Total

Create bidirectional IPv6 and IPv4 flows. Increase load gradually.Results

IPv6 packet loss in Eng4+ GigEthernet cards (direction 2 ->1) is much higher than in Eng3 GigEthernet cards (direction 1->2)Different IPv6 switching capabilities for Eng3 and Eng4+ GigEthernet cards.IPv6 and IPv4 traffic experience the same packet loss in direction 1->2.IPv4 packet loss for traffic entering the Eng4+ cards


Latency for BE traffic

0

5000

10000

15000

20000

10% 25% 40% 55% 70% 85% 100%

Load (% of 1Gbps)

Late

ncy

(use

c)

IPv6: 1 -> 2 IPv4: 1 -> 2 IPv6: 2 -> 1 IPv4: 2 -> 1

Create bidirectional IPv6 and IPv4 flows. Increase load gradually.Results

IPv6 and IPv4 latency in Eng3 card is the same. Latency for IPv6 traffic is extremely low (provided zero packet loss).IPv6 latency in Eng4+ card is always higher than IPv4 even if there is no packet loss. Max latency values exhibit similar trends with average latency.Latency distribution is narrow.


Latency and packet loss for Premium IP (PIP) traffic

0

5,000

10,000

15,000

20,000

10% 25% 40% 55% 70% 85% 100%

Load (% of 1Gbps)

Late

ncy

(use

c)

PIP IPv6: 1 -> 2 PIP IPv4: 1 -> 2 PIP IPv6: 2 -> 1 PIP IPv4: 2 -> 1IPv6: 1 -> 2 IPv4: 1 -> 2 IPv6: 2 -> 1 IPv4: 2 -> 1

30

35

40

45

10% 25% 40% 55% 70% 85% 100%

Load (% of 1Gbps)

Late

ncy

(use

c)

PIP IPv6: 1 -> 2 PIP IPv4: 1 -> 2 IPv6: 1 -> 2 IPv4: 1 -> 2

Create bidirectional IPv6 and IPv4 flows. 2% of load is PIP traffic. Increase load gradually.Results

Latency for PIP traffic in Eng3 card is very low provided zero packet loss (<85% load). When there is packet loss (100% load), PIP latency is increased (~20 times) but still remains thousand times smaller than (IPv4/6) BE latency. PIP traffic experiences no packet loss.PIP IPv6 experiences higher latency than PIP IPv4 in Eng4+ card. Probably, PIP IPv6 traffic is handled as BE. Latency remains constant for most traffic loads. For 100% load, latency is ~1000 times higher than IPv6 PIP latency in Eng3 card.


CPU impact in a software-based platform

Create unidirectional IPv4, IPv6 and mix of IPv4/6 traffic

Switch traffic through a Cisco 7200 router (FE/GigEinterfaces). Traffic rate up to 130Mbps.Activate output QoS mechanisms at FE interface.

ResultsCPU load is higher when IPv6 traffic is present. Increase is 5-9% approximately. CPU load for mixture of IPv4/IPv6 traffic is similar with the IPv6-only traffic test.Measurement accuracy is coarse. Data collected via router CLI.

25

50

75

100

70 85 100 115 130

Traffic load (%)CP

U lo

ad (%

)

IPv4 IPv6 IPv4/6 IPv4/6 + QoS


ConclusionsIPv6 QoS is not an exotic feature! Routers under test do not lack functionality regarding QoS mechanisms and similar services are provided to IPv6 and IPv4 traffic. However, tests revealed that “obsolete” hardware lacks some pieces of functionality or provide lower level services to IPv6 compared to IPv4 traffic.

A common QoS model could be supported for both protocols in a production networks provided that hardware restrictions are overcome.

Today, IPv6 in terms of QoS support is neither superior nor inferior to IPv4 counterpart. However, the flow label field in the IPv6 header may be a valuable tool in the future for the easing provision of future services.


Thank you!

ipv6 qos tests in grnet2 network - terena...tf-ngn meeting - athens, november 2005 6 qos services in...

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