Using sethdlc utility to configure Tahoe cards

Sethdlc utility is used to configure Tahoe cards. Its main function is to select the protocol used on the WAN link:

• Cisco^®HDLC:
  sethdlc th0 cisco
  

• Synchronous PPP:
  sethdlc th0 ppp
  

• Frame Relay:
  sethdlc th0 fr [lmi type [parameter]]
  
  where:
  • type is LMI type: ansi, ccitt, cisco
  • parameter is a Frame Relay parameter: t391 value, n391 value, n392 value
  Moreover in case of Frame Relay protocol you can create and delete PVCs (Permanent Virtual Channels) with given DLCI values:
  sethdlc th0 create 99
  sethdlc th0 delete 99
  After creating a PVC, a new 'pvc' interface is created with name derived from DLCI value - e.g. pvc99 in above example.

In case of Tahoe 971/972 cards you also have to specify, which timeslots are used for transmission. Timeslots can be given in two ways - as a list of numbers (from 1 to 32) and ranges separated by commas or as a string of zeros and ones (where '0' means an unused slot and '1' - an used one, with the first slot at the beginning of the string):

• sethdlc th0 slotmap 2-8,20-21,25
  
• sethdlc th0 slotmap 01111111000000000001100010000000
  

Use of the first timeslot automaticaly enables unframed mode, where whole 2048 kbps are used for data transfer. Otherwise the first timeslot is used for framing synchronization.

The command below enables and disables, respectively, transmission of the CRC4 checksum:

• sethdlc th0 crc4 on
  
• sethdlc th0 crc4 off
  

• sethdlc th0 short
  
• sethdlc th0 long
  

After configuring a card using the sethdlc utility you can proceed to regular interface configuration (using th0, th1 or pvc## interfaces), routing setup, etc.

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