ipBalance

R1#sh run int serial 3/1
Building configuration...

Current configuration : 112 bytes
!
interface Serial3/1
description to R2
ip address 100.100.100.1 255.255.255.252
serial restart-delay 0
end

[Cisco Router2]

R2#sh run int serial 3/1
Building configuration...

Current configuration : 112 bytes
!
interface Serial3/1
description to R1
ip address 100.100.100.2 255.255.255.252
serial restart-delay 0
end

[Cisco Router1 with compression]

R1#sh run int serial 3/1
Building configuration...

Current configuration : 127 bytes
!
interface Serial3/1
description to R2
ip address 100.100.100.1 255.255.255.252
compress stac <-- it makes fast link, but CPU intensive command
serial restart-delay 0
end

[Cisco Router2 with compression]

R1#sh run int serial 3/1
Building configuration...

Current configuration : 127 bytes
!
interface Serial3/1
description to R1
ip address 100.100.100.2 255.255.255.252
compress stac <-- Both sides need to be configred.
serial restart-delay 0
end

[Debug HDLC]

R2#debug serial interface

Serial network interface debugging is on
  *Mar 1 00:57:04.103: Serial3/1: HDLC myseq 341, mineseen 341*, yourseen 10, line up
  *Mar 1 00:57:14.103: Serial3/1: HDLC myseq 342, mineseen 341, yourseen 10, line up
  *Mar 1 00:57:24.103: Serial3/1: HDLC myseq 343, mineseen 341, yourseen 10, line up
  *Mar 1 00:57:34.119: Serial3/1: HDLC myseq 344, mineseen 341, yourseen 10, line down
  *Mar 1 00:57:35.119: %LINEPROTO-5-UPDOWN: Line protocol on Serial3/1, changed state to down
  *Mar 1 00:57:44.103: Serial3/1: HDLC myseq 345, mineseen 341, yourseen 10, line down

R2#u all
All possible debugging has been turned off
R2#