WAN

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PPPoE

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HDLC

-no authentication

-no cross-vendor support

- default L2 encapsulation for cisco routers

- no address

- HDLS thinks physical layer is always up

point-to-point protocol

- Operates in LLC sublayer of Layer L2.

L2 layer:

---------------------------------

LLC sublayer - upper layer protocol,

- -- -- --- --- --- --

MAC sublayer - mac address related, when device can send data etc.

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- open standard:

- PPP waits for physical layer to come up.

-PPP is like TCP. establish connection first and then transfer data.

-No layer 3 to layer 2 resolution is required

PPP Steps:

1) step 1 : LCP - link control protocol.

2) Step 2: Authentication (option)

3) Step 3: NCP - network control protocol

Authentication:

PAP

- password Send as clear text

-2-way handshake

- by default, hostname is send username

router-A ---------------------------------------------------------- router-B

interaface------------------------------------------------------- username rtra pass cisco

encapsulation ppp

ppp pap sent-username rtra password cisco

CHAP

-

encapsulation ppp

interface

ppp chap hostname rtr1-------------------------------------------

ppp chap password cisco

Frame-relay

DLCI: 10 bit number. 0-15 and 1007-1023 are reserved.

LMI:

1)keepalive btw router and FR switch

2) DLCI number are given

3) LMI uses reserved DLCI 0 and 1023

LMI types:

1) cisco

2)Q993a

3) ANSI

Inverse ARP:

- gives details of layer 3 destination IP for a local DLCI

- does not work on sub-interfaces

DE: Discard eligible

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