Multi-Link PPPD

Owned by Nathaniel Halbrooks
Last updated: Feb 05, 2024
4 min read

The Linux PPP/Multi-Link PPP solution is comprised of:

  1. Linux PPPD daemon

  2. Sangoma AFT A101/2/4/8 T1/E1 & AFT S518/ADSL cards

Sangoma has updated the PPPD Linux daemon to properly support Multi-Link PPP protocol.  The original pppd-2.4.4 has a major architectural bug that caused it to fail on PPP recovery.   This document will describe how to install and configure Multi-Link PPP with Sangoma cards. 

PPPD Release ........................ ppp-2.4.4.5.tgz (2008-06-11)

 

 

Wanpipe Installation

  1. Download latest STABLE wanpipe release
    -->Dowload wanpipe release

  2. Untar wanpipe releaes
    --> tar xfz wanpipe-<ver>.tgz

  3. Install wanpipe release
    --> cd wanpipe-<ver>
    --> ./Setup install 
          Use all default options

  4. Confirm successfull install
    --> wanrouter version
    --> wanrouter hwprobe

 

 

pppd Installation

  1. Untar pppd release into /usr/src directory
    --> tar xfz pppd-<ver>.tgz

  2. Compile PPPD
    --> make

  3. Install PPPD
    --> make install

 

 

Configuration

3. Wanpipe Setup/Configuration

Configure Sangoma Card for TTY mode
    /usr/sbin/wancfg

Select Card Type:  
    A10x, A30x or S51x           
          
Choose Protocol:
    TTY

Configure interface:
    Select TTY MINOR number
    TTY MINOR represents a TTY port.
    Options: 0,1,2 - 8  
    Default: 0

    It binds a WANPIPE device driver to the /dev/ttyWPX device, where X=(0,1,2,..).
        
For example MINOR number 0 binds a Wanpipe TTY driver to /dev/ttyWP0. Thus, when pppd daemon opens the /dev/ttyWP0 it will reach the device driver whose Minor number is 0.

Note: TTY_MINOR must differ for each Wanpipe device.

Save and Exit

4. Start wanpipe:
wanrouter start wanpipe1

Check /var/log/messages.
    You should see this event:
    ...
    w1g1: TTY Driver Init: Major 240, Minor Range 0-7
    w1g1: TTY Sync Dev Minor 0 : /dev/ttyWP0
    ...
    
    Now the driver is ready for pppd connection.

5. PPPD Setup 

Create a device node:
To interface a PPPD daemon to the WANPIPE TTY driver a /dev/ttyWPX X={0,1,3...) device must be created.
    
    ex: mknod -m 666 /dev/ttyWP0 c 240 0
          mknod -m 666 /dev/ttyWP1 c 240 1        
          mknod -m 666 /dev/ttyWP2 c 240 2
            ...
            
        Note: 240 is the Major Number; 0,1,2... are the Minor Numbers

        Note: On newer Linux releases, this is done for you automatically

Configure PPP Daemon options: 
    Create a text file in /etc/ppp/options
    Copy and Paste the following:

    -------CUT HERE ----------------------
    persist
    defaultroute
    asyncmap 0
    sync
    lcp-echo-interval 1
    lcp-echo-failure 5

    nobsdcomp
    nodeflate
    nopcomp
    novj
    novjccomp
    noaccomp -am

    multilink

    #On some CISCO routers we must
    #be in silent mode
    #silent

    #DEBUG Only should be commented out in production
    #nodetach
    #debug
    #kdebug 2

    -------CUT HERE ----------------------


Bind Wanpipe device to PPP Daemon
Create a text file /etc/ppp/peers/isp_wanpipeX (X=1 to 16)

    -------CUT HERE----------------------
    ttyWP0          #Bind to WANPIPE device wanpipe1
    sync
    multilink
    #201.1.1.1:201.1.1.2       #Enter IP Address for PPP link here

    #user bonded-isp-username

    -------CUT HERE----------------------
NOTE: The text files must be the same for all the wanpipe devices being binded. 
  

6. PPPD Operation
All wanpipe devices should be started before pppd is started.
   wanrouter start

Once the Wanpipe device is started, PPP connection can be established by calling the pppd call script (created by wancfg):
    pppmon isp_wanpipe1

 

Operation

  1. pppmon startup utility

    The pppmon utility is used to start the pppd process in Multi-Link Mode. It will monitor the pppd processes and restart them if certain conditions are reached.  pppmon is critical to multilink reliability. 

    --> pppmon isp_wanpipe1 isp_wanpipe2 isp_wanpipe3
     

  2. ppp utility applications  

    --> pppstart 
    (first kills pppmon/pppd  and then starts pppmon from init script...)

    --> pppstop 
    (kills pppmon pppd) 

    --> pppstate 
    (sends signal to pppd and greps the logs: displays state of each ppp link)

 

 

pppmon Options

To adjust pppmon options one should open pppmon using vi.  After modifying pppmon options, run make install to re-install new pppmon.

->  cd ppp-<ver>/
->  vi scrips/multilink/pppmon
->  make install

 
#Enable log rotate/truncate
#on a specific log file.  If the log file
#reaches maximum size the file will be
#truncated. 
#LOGROTATE_FILE=/tmp/log
#LOGROTATE_MAX_SIZE=5000 #KB


PING_CHECK_TIMEOUT=120          #Ping check frequency (s)
PING_CONFIRM_CHECK_TIMEOUT=20    #Ping timeout before confirming ping
PMON_LOOP_TIMEOUT=1        #E1 check

#Restart wanrouter if all mlppp  
#go down to indicate to other side
#that all ports went down and
#IPCP will be restarted
#Options: 0: disable
#         1: enable
WANROUTER_RESTART_ON_ALL_DOWN=1    


#Wanrouter restart timeout
#before starting up the wanpipe ports
#This option works in conjunction with
#above option.
WANROUTER_DOWN_TIMEOUT=10

 

 

Sample Cisco 1600 Setup

 
 This example setup should be given to an ISP that doesn't
know how to setup up Mulitlink PPP on a Cisco box :)

  Scenaraio:
 Two Wanpipe adapters connected back to back to a CISCO 1600 via two
WAN T1 lines, running MULTILINK PPP, in order to bundle two T1 lines
for geater than T1 throughput.

          1) Enter the CISCO configuration mode
                Cisco>enable
                Cisco>password: <enter password>
                Cisco#
        2) Configure Global Mulitlink PPP protocol
                Cisco# config
                Cisco(config)# multilink virtual_template 1
                Cisco(config)# exit
        3) Configure Serial0 device for Multilink PPP
                Cisco# config
                Cisco(config)# interface serial0
                Cisco(config-if)# encapsulation ppp
                Cisco(config-if)# no ip address
                Cisco(config-if)# ppp multilink
                Cisco(config-if)# no shutdown
                Cisco(config-if)# exit
        4) Configure Serial1 device for Multilink PPP
                Cisco(config)# interface serial1
                Cisco(config-if)# encapsulation ppp
                Cisco(config-if)# no ip address
                Cisco(config-if)# ppp multilink
                Cisco(config-if)# no shutdown
                Cisco(config-if)# exit
        5) Configure virtual_template interface
                Cisco(config)# interface virtual_template 1
                Cisco(config-if)# encapsulation ppp
                Cisco(config-if)# ip address <local ip> <netmask>
                Cisco(config-if)# ppp multilink
                Cisco(config-if)# exit
                Cisco(config)# exit


Back to Back situation
----------------------
If you are setting up WANPIPE back to back Multilink
against an external router:
        Interface (onboard FT1 CSU/DSU):
                Cable: Back to Back T1 cable (Part number: 624).
        Interface (V35):
                Cable: Back to Back V34 Cable (Part number: 609)
                Clocking: Clocking must be set to INTERNAL on the
                          WANPIPE side.
        For all sangoma cables please refer to:
                http://www.sangoma.com/faqcable.htm

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