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
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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
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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
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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
25/10/2000 QoS in PPPoE 6
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
25/10/2000 QoS in PPPoE 7
Background& Model
• CPN
• VLAN
• IP Access Node
• New Services => QoS
• NSP selection
• ProtocolsATM
STB
PC
IPT
Ethernet Sw
Ethernet Sw
Ethernet Sw
IP-accessNode
AAA
IP Network
100Mbps Ethernet
10Mbps Ethernet
1Gbps Ethernet
ADSL.
STB
PC
IPT10Mbps Ethernet
ADSL
DSL
AM
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
25/10/2000 QoS in PPPoE 8
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 (?)
25/10/2000 QoS in PPPoE 9
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
25/10/2000 QoS in PPPoE 10
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?
25/10/2000 QoS in PPPoE 11
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
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?
25/10/2000 QoS in PPPoE 13
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)
25/10/2000 QoS in PPPoE 14
QoS• QoS scope
25/10/2000 QoS in PPPoE 15
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
25/10/2000 QoS in PPPoE 16
Multiplexing QoS
• Alternatives– One PPPoE session/NSP
– One PPPoE session/DS class
– One PPP session/DS class
25/10/2000 QoS in PPPoE 17
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
25/10/2000 QoS in PPPoE 18
Stability and Performance of PPPoE
• Stability– Loss– Delay– Reorder– Duplication
• Performance– Connection delay– Maximum throughput
25/10/2000 QoS in PPPoE 19
Stability
• Lab
25/10/2000 QoS in PPPoE 20
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
25/10/2000 QoS in PPPoE 21
Performance
• Lab– 10Mbps FD
– 1Mbps HD
– 9 Mbps Load w/wo VLAN
– Connection Delay
25/10/2000 QoS in PPPoE 22
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]
Thro
ughp
ut [k
bps]
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%
25/10/2000 QoS in PPPoE 23
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
25/10/2000 QoS in PPPoE 24
Summary
• QoS can be incorporated in the PPPoEarchitecture without changes to protocol standards.
• PPPoE implementation to set Ethernet user priorities according to IP DS.
• Simple multiplexing should be used, one PPPoEsession/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]