QoS in PPPoE

QoS in PPPoE

Quality of Service in the Point-to-Point Protocol over Ethernet

Master’s Thesis

Patrik LahtiKTH, Telia Research AB

25/10/2000 QoS in PPPoE 2

Outline

• Introduction– Quality of Service

– Point-to-Point Protocol over Ethernet

• Background and Model

• Problem Definition

• QoS in the PPPoE-based Broadband IP Access.

• Stability and Performance of PPPoE

• Summary, Questions & Credits


Quality of Service

• Enhance the network with the intelligence to treat traffic according to application requirements.– Delay

– Delay variation

– Loss

– Others...

• IP– Differentiated Services

– Integrated Services

• Ethernet– Priorities (802.1p)

– Subnet Bandwidth Manager


Point-to-Point Protocol over Ethernet

• Purpose– To set up Client to Access Concentrator relationship

– Encapsulate PPP, and multiplex multiple PPPoE sessions

• Operation– Simple Active discovery

– Session


PPP/PPPoE

t

Mulitcast PADI, w Service-Name

Unicast PADR, w Service-Name

Unicast PADO, w Service-Name(s)& AC-Name

Unicast PADS, w Service-Name& Session ID

Unicast PADO, w Service-Name(s)& AC-Name *)

*) There may be multiple ACs answering with a PADO**) May be sent by either side

PPP session Stage

Unicast PADT, w Session ID **)

Client AC

LCP

Auth

IPCP

IP data

ACClient


Outline









Background& Model

• CPN

• VLAN

• IP Access Node

• New Services => QoS

• NSP selection

• Protocols ATM

STB

PC

IPT

Ethernet Sw

Ethernet Sw

Ethernet Sw

IP-accessNode

AAA

IP Network

100Mbps Ethernet

10Mbps Ethernet

1Gbps Ethernet

ADSLmod.

STB

PC

IPT10Mbps Ethernet

ADSL

DS

LA

M

Ethernet

PPPoE

Physical

PPP

IP

Ethernet

Physical

Ethernet

Physical

Ethernet

Physical

Ethernet

Physical

Ethernet

PPPoE

Physical

PPP

IP

Sw Sw

?

IP

CustomerEquipment

EthernetSwitch

EthernetSwitch

IP-accessNode


Why PPP/PPPoE?

+ NSP selection

+ IP address allocation

+ Reuse of Legacy Equipment

+ Unified Model (Bridged ADSL)

+ Familiar to users

+ Per user access control and billing

- Overhead and Connection delay(?)

- Software update for Clients

- QoS issues unresolved (?)


Outline








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Problem Definition

• With what methods can QoS be support be introduced in PPPoE?

• Can services with different QoS requirements be multiplexed in one PPPoE session?

• Does PPP/PPPoE cope with loss, delay, reordering, and duplication?

• How is performance affected by PPP/PPPoE?• What issues have to be addressed in the IP access?

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Outline








25/10/2000 QoS in PPPoE 12

QoS in the PPPoE-based Broadband IP Access.

• IP Differentiated Services

– Guaranteed Service

– Low Delay

– Low Loss

– Best Effort

• Ethernet User Priorities, 802.1p– 7 Traffic types: NC, Voice, Video, Controlled Load, Excellent

Effort, BE, Background

• PPP/PPPoE?

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QoS

• PPPoE

– Service Name Tag, request certain DS or Service.• Allows CAC

• Integrate with/similar to SBM?

• One session/service or DSCP

• PPP

– DiffServ SLA negotiation• Allows CAC

– Fragmentation (slow link)

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QoS• QoS scope

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QoS

• Mapping DS to 802.1p– Static

– Hint in DS field

– SBM

• Recommendation:– Static

– Proposed mapping

– No change to PPP/PPPoE

Ethernet Traffic Class Service Class

7 Network Control Guaranteed Service

6 Voice Low Delay (-jitter)

5 Video

4 Controlled Load Low Loss

3 Excellent Effort

0 Best Effort Best Effort

1 Background

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Multiplexing QoS

• Alternatives– One PPPoE session/NSP

– One PPPoE session/DS class

– One PPP session/DS class

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Outline








25/10/2000 QoS in PPPoE 18

Stability and Performance of PPPoE

• Stability– Loss– Delay– Reorder– Duplication

• Performance– Connection delay– Maximum throughput

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Stability

• Lab

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Stability

• Result– PADS, PAP Authentication sensitive to loss

– Old LCP, IPCP packet Ids not ignored

– TCP segment size smaller than necessary

– Termination and Link maintenance

– Delays < 3s

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Performance

• Lab– 10Mbps FD

– 1Mbps HD

– 9 Mbps Load w/wo VLAN

– Connection Delay

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Performance

• Results– No significant

difference

– Except on1Mbps HD

– ConnectionDelay ~7s

– Can be optimised to ~1s

0

100

200

300

400

500

600

700

800

900

1000

1 5 9 13 17 21 25 29 33 37 41 45 49 53 57 61 65

Time [s]

Th

rou

gh

pu

t [k

bp

s]

Serie1

Throughput [kbps] (variance) IP PPPoE Difference

10Mbps Full-Duplex 7955 (208) 7520 (242) -5.5%

1Mbps Bottleneck 853 (60.0) 767 (170) -10.1%

9 Mbps Load 4760 (12.3) 4644 (14.4) -2.4%

9 Mbps Load VLAN sep. 4759 (18.3) 4646 (16.1) -2.4%

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Outline








25/10/2000 QoS in PPPoE 24

Summary

• QoS can be incorporated in the PPPoE architecture without changes to protocol standards.

• PPPoE implementation to set Ethernet user priorities according to IP DS.

• Simple multiplexing should be used, one PPPoE session/NSP.

• PPP/PPPoE is reasonably stable and performs well. Some issues to be further investigated and improved.

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Opposition

• ...

25/10/2000 QoS in PPPoE 26

Questions

• ?

25/10/2000 QoS in PPPoE 27

Thank you!

• Tack till Fredrik Roos, Stefan Sandell

• Alla på Bredbandsnät, Telia Research AB

• Tack till Björn Pehrson och Mikael Lind

• Tack till alla som kom.

25/10/2000 QoS in PPPoE 28

Information

• http://www.e.kth.se/~e95_pla/exjobb

• Still have my opposition to do.

• I am currently working at Nortel Networks’ Routing Architecture Lab:[email protected]

Documents

QoS in PPPoE