PPPoE Principles and Configuration

Principles and Configuration Principles and Configuration of PPPoEof PPPoE

V1.0

Data Customer Service Dept.

For Internal Use Only▲

<Confidential and Proprietary Information of ZTE Corporation ><Confidential and Proprietary Information of ZTE CORPORATION>

Internal Use Only▲

Course Objectives• Have a general knowledge about why PPPoE

came into use

• Grasp the principles of PPPoE protocol

• Grasp the workflow of PPPoE protocol

• Have a general knowledge of PPPoE basic configuration




Course Outline

• Chapter 1 PPPoE Protocol Principles

• Chapter 2 Typical Configuration




Course Content


Section 1 PPPoE Protocol Overview

Section 2 PPPoE Discovery Phase

Section 3 PPPoE Session Phase


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Definition

PPPoE ： Point-to-Point Protocol over Ethernet PPP protocol requires P2P relationship for the two communicating

parties, not suitable for broadcast in LAN or other PTMP type of networks. Thus PPPoE generated.

With PPPoE, multiple hosts on sharing Ethernet are able to perform multiple PPP sessions with Access Concentrator via one or several Bridges.



Flow

PPPoE Contains two phases: Discovery and PPP Session

In Discovery phase, based upon network topology, host is able to

discover several access concentrator and permit user to select one.

Discovery phase is stateless Client/Server, aiming to obtain Ethernet

MAC address of PPPoE terminator and establish a unique PPPOE

SESSION_ID.

After Discovery phase, enter standard PPP Session phase.




Course Content







PPP Discovery Phase

Discovery phase: to establish P2P connection on Ethernet, it has to

know the Ethernet address of peer end and establish a unique

Session ID

User’s host broadcasts to find all access concentrators ( or switches) and

obtain Ethernet MAC address thereof.

Select one AC needs to be connected and confirm PPP session-id.



Datagram Types

PPPOE_Client PPPOE_Server

PADI

PADR

PADO

PADS

There are four steps in Discovery phase, using following four type

s of datagram:

After Discovery phase, both communication ends know the PPP

oE SESSION_ID and peer end MAC address, they define a PPPo

E session together.



PADI

PADI: PPPOE Active Discovery Initiation

Host broadcasts PADI datagram to require service from AC

The destination address is broadcast address of Ethernet:0xffffffffff

ff

CODE field is 0x09

SESSION_ID field is 0x0000

PADI should contain at least one ToS tag（ ToS field is 0x0101）



PADI Datagram Format

0 1 2 3

0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1

0xffffffff

0xffff Host_mac_addr

Host_mac_addr (Cont.)

ETHER_TYPE = 0x8863 v = 1 t = 1 CODE = 0x09

SESSION_ID = 0x0000(required) LENGTH = 0x000a

TAG_TYPE = 0x0101 TAG_LENGTH = 0x0000(accept any service)

ff ff ff ff ff ff 00 00 5e 00 63 03 88 63 11 09

00 00 00 0a 01 01 00 00 01 03 00 02 01 00

>>

Dest MAC Addr: ffff.ffff.ffff, Src MAC Addr: 0000.5e00.6303

Discovery Stage, Ver=1, Type=1, Code=PADI, Session ID=0

Tag Service-Name:

Tag Host-Uniq:

01 00 | ..



PADO

PADO: PPPOE Active Discovery Offer

After AC receives PADI packet within service range, it will send

PADO as response

CODE field is 0x07

SESSION_ID field is still 0x0000

PADO grouping must contain a tag-type of AC name (tag_type fiel

d is 0x0102) and one or several ToS tag to indicate the service ty

pe that offer to host.



PADO Datagram Format

0 1 2 3

1 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1

Host_mac_addr

Host_mac_addr（ Cont.） Access_Concentrator_mac_addr

Access_Concentrator_mac_addr (Cont.)


SESSION_ID = 0x0000 LENGTH = 0x0026

TAG_TYPE = 0x0102 TAG_LENGTH = 0x0000

00 00 5e 00 63 03 00 00 5e 00 63 00 88 63 11 07 00 00 00 26 01 01 00 00 01 03 00 02 01 00 01 02

00 18 51 75 69 64 77 61 79 2d 77 76 72 70 30 30 30 30 35 65 30 30 36 33 30 30

>>

Dest MAC Addr: 0000.5e00.6303, Src MAC Addr: 0000.5e00.6300

Discovery Stage, Ver=1, Type=1, Code=PADO, Session ID=0

Tag Service-Name:

Tag Host-Uniq: 01 00 | ..

Tag AC-Name:

51 75 69 64 77 61 79 2d 77 76 72 70 30 30 30 30 | ZXR10-wvrp0000 35 65 30 30 36 33 30 30 | 5e006300



PADR

PADR: PPPOE Active Discovery Request

Host might select one proper PADO group among several PAD

O groups and send PADR to selected AC.

CODE field is 0x19

SESSION_ID field is 0x0000

PADR group must contains a ToS tag to determine the service type

requested from AC （ or switch ） .

If host does not receive PADO within certain period, it will resen

d PADI group and double the time-to-wait.



PADR Datagram Format

0 1 2 3

1 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1

Host_mac_addr

Host_mac_addr（续） Access_Concentrator_mac_addr





00 00 5e 00 63 00 00 00 5e 00 63 03 88 63 11 19 00 00 00 26 01 01 00 00 01 03 00 02 01 00 01 02

00 18 51 75 69 64 77 61 79 2d 77 76 72 70 30 30 30 30 35 65 30 30 36 33 30 30

>>


Discovery Stage, Ver=1, Type=1, Code=PADR, Session ID=0

Tag Service-Name:


Tag AC-Name:

51 75 69 64 77 61 79 2d 77 76 72 70 30 30 30 30 | ZXR10-wvrp0000 35 65 30 30 36 33 30 30 | 5e006300



PADS

PADS: PPPOE Active Discovery Session-confirmation

After received PADR, AC get ready for PPP session and send a PADS

group

CODE field is 0x65

SESSION_ID field is the unique PPPoE session identifier generated by AC.

PADS group must also contain a type tag of AC in order to determine the

service provided to host.

When host receives PADS packets as acknowledgement, two ends enter

PPP Session phase.



PADS Datagram Format

0 1 2 3

1 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1

Host_mac_addr

Host_mac_addr（ Cont.） Access_Concentrator_mac_addr





00 00 5e 00 63 03 00 00 5e 00 63 00 88 63 11 65 00 01 00 26 01 01 00 00 01 03 00 02 01 00 01 02

00 18 51 75 69 64 77 61 79 2d 77 76 72 70 30 30 30 30 35 65 30 30 36 33 30 30

>>


Discovery Stage, Ver=1, Type=1, Code=PADS, Session ID=1

Tag Service-Name:


Tag AC-Name:

51 75 69 64 77 61 79 2d 77 76 72 70 30 30 30 30 | ZXR10-wvrp0000 35 65 30 30 36 33 30 30 | 5e006300




Course Content







PPPoE Session Phase

User’s host will perform PPP session with AC based upon the PPP

session parameters negotiated in Discovery phase.

Once a PPPoE session begins, PPP data is able to send in any other

PPP encapsulation.

PPPoE Datagram is transferred bearing in Data field of Ethernet frame

SESSION_ID must be the value assigned in Discovery phase and cannot be

changed.

ETHER_TYPE field is set as 0x8864

CODE must be set as 0x00

PPPoE payload contains a PPP frame, starting from PPP Protocol-ID

All Ethernet frames are sent as Unicast.



Session Phase Datagram

0 1 2 3

0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1

Access_Concentrator_mac_addr

Access_Concentrator_mac_addr(c) Host_mac_addr

Host_mac_addr (cont)


SESSION_ID = 0x1234 LENGTH = 0x????

PPP PROTOCOL = 0xc021 PPP payload . . . . . .

*0.266047 ZXR10-wvrp PPPOEC/8/debugging:Ethernet0/1/0: PPPoE Client OUT, Len =36

00 00 5e 00 63 00 00 00 5e 00 63 03 88 64 11 00

00 01 00 10 c0 21 01 00 00 0e 01 04 05 aa 05 06

66 2d 04 00

>>


Session Stage, Ver=1, Type=1, Session ID=1



PADT

PADT: PPPOE Active Discovery Terminate

PADT is used to terminate session, can be sent anytime after

session established by host or AC.

PADT packet requires no tags.

CODE field is 0xa7

SESSION_ID field is the session identifier of PPP session that to be

terminated.

PPP peer end should terminate PPPoE session using PPP

protocol. If PPP cannot be used, use PADT as substitute.



PADT Datagram Format

0 1 2 3

1 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1

Host_mac_addr

Host_mac_addr (Cont.) Access_Concentrator_mac_addr


ETHER_TYPE = 0x8863 v = 1 t = 1 CODE = 0xa7


00 00 5e 00 63 02 00 00 5e 00 63 00 88 63 11 a7 00 01 00 00 >> Dest MAC Addr: 0000.5e00.6302, Src MAC Addr: 0000.5e00.6300 Discovery Stage, Ver=1, Type=1, Code=PADT, Session ID=1




Course Content

• Chapter 2 PPPoE Configuration

Section 1 Basic Configuration of Router PPPoE Client

Section 2 Configuration Case



PPPoE Client Configuration of Router

Permanent dial configuration in Ethernet Interface modedialer pppoe-client-pool-member <pool-number> <priority-number> permanent

Dial-on-demand configuration in Ethernet Interface Modedialer pppoe-client-pool-member <pool-number> <priority-number> on-demand

Create and enter a dialer interfaceinterface dialer<dialer-number>

Bind dialer pool number in interface modedialer pool <pool-number>

Define dial-on-demand trigger rule in Global configuration modedialer list <group-number> protocol ip {access-list <pool-number>| permit| deny}

Bind dial-on-demand trigger rule in Dialer interface mode, range 1~100dialer group <group-number>




Course Content

• Chapter 2 PPPoE Configuration

Section 1 Basic Configuration of Router PPPoE Client

Section 2 Configuration Case



Configuration Case(1)PPPoE Server

10.10.1.2/24

PC1

10.10.1.1/24

PC2

PPPoE Cl i entR1As a PPPoE Client, R1 will perform permanent dial to PPPoE Server and dialer on Client does not negotiate address from Server. PPPoE Server is a CISCO router, which has configured with Server function.

Run PPPoE Client on Router R1 , data will reach router first and perform PPPoE encapsulation and then access to PPPoE Server (AC) via Ethernet the R1 connected to, finally reach Internet. No need dial-in software on PC.



Configuration Case(2)

PPPoE Client permanent dial, configuration of R1:

ZXR10(config)#interface fei_1/1ZXR10(config-if)#dialer pppoe-client-pool-member 1 1 permanentZXR10(config-if)#exitZXR10(config)#interface dialer1ZXR10(config-if)#ip address 10.10.1.2 255.255.255.0ZXR10(config-if)#dialer pool 1ZXR10(config-if)#exit



Configuration Case (3)

PPPoE Client Dial-on-Demand, configuration of R1:

ZXR10(config)#interface fei_1/1ZXR10(config-if)#dialer pppoe-client-pool-member 1 1 on-demandZXR10(config-if)#exitZXR10(config)#dialer list 10 protocol ip permitZXR10(config)#interface dialer1ZXR10(config-if)#ip address 10.10.1.2 255.255.255.0ZXR10(config-if)#dialer pool 1ZXR10(config-if)#dialer group 10ZXR10(config-if)#exit



Summary

PPPoE protocol include two phases: Discovery and Session Phase

PPPoE Datagram is transferred borne in Ethernet data field

PPPoE Discovery phase have four type of datagram: PADI, PADO, PA

DR and PADS.

PADT datagram in PPPoE is used to terminate a session.

In PPPoE Discovery phase, Ether_Type field is 0x8863

In PPPoE Session phase, Ether_Type field is 0x8864

Documents

PPPoE Principles and Configuration