PPP

Basic Configuration

Server

R1(config)# int l0
R1(config-if)# ip add 1.1.1.1 255.255.255.255
R1(config-if)# exit

R1(config)# int s2/0
R1(config-if)# encapsulation ppp
R1(config-if)# !we do not want to use an ip address in the client subnet
R1(config-if)# ip unnumbered l0
R1(config-if)# peer default ip address pool POOL
R1(config-if)# exit

R1(config)# ip local pool POOL 10.0.0.100 10.0.0.199

Client

R2(config)# int s2/0
R2(config-if)# encapsulation ppp
R2(config-if)# ip add negotiated

Authentication

One-way

CHAP

R1(config)# username R2 password cisco
R1(config)# int s2/0
R1(config-if)# ppp authentication chap

R2(config)# int s2/0
R2(config-if)# ppp chap hostname R2
R2(config-if)# ppp chap password cisco

PAP

R1(config)# username R2 password cisco
R1(config)# int s2/0
R1(config)# ppp authentication pap

R2(config)# int s2/0
R2(config-if)# ppp pap sent-username R2 password cisco

Advance Feature

MLPPP

PPP multilink(MLPPP) allows us to bundle multiple physical interfaces running PPP into a single logical bundle called a multilink interface.

Something like etherchannel, but used in PPP.

R1(config)# int multilink1
R1(config-if)# encap ppp
R1(config-if)# ip add 10.0.0.1 255.255.255.0
R1(config-if)# !we want to set the minimum link to maintain the multilink
R1(config-if)# ppp multilink links minimum 2
R1(config-if)# exit

R1(config)# int s2/0
R1(config-if)# encap ppp
R1(config-if)# ppp multilink
R1(config-if)# ppp multilink group 1

R1(config)# int s2/1
R1(config-if)# encap ppp
R1(config-if)# ppp multilink
R1(config-if)# ppp multilink group 1

Link Fragmentation and Interleaving

LFI is a link efficiency mechanism that runs in conjunction with MLPPP.

LFI reduces delay by fragmenting large frames, and then "interleaving" small delay sensitive frames with the fragments.

ppp multilink interleave
!maximum real-time traffic delay
ppp multilink fragment-delay <ms>

Compression

There are 2 types of compression.

Payload Compression
Compression

Payload Compression

There are 3 types of payload compression.

Stacker
Predictor
MPPC

Stacker uses the Lempel-Ziv algorithm(LZS). It searches data stream for repeated information and replaces with tokens. It has comparatively better compression than Predictor but more CPU overhead and less memory overhead.

Predictor predicts characters in a stream using a compression dictionary.

MPPC also uses LZS algorithm but is Microsoft specific.

compress interface level command

TCP/RTP Header Compression

Legacy: ip tcp header-compression or ip rtp header-compression
In MQC: compress header ip tcp or compress header ip rtp in policy-map

PPP

PPP