2610 with NM-4A/S acting as a terminal server

As mentioned previously, my 2509 was on its way out and that I needed a replacement terminal server.

I had a 2610 with NM-4A/S that used to be my frame switch using back-to-back DCE-DTE serial cables against a number of 2500s from my CCNP studies. With the appropriate RS-232 cables this ended up being  a fairly cheap replacement as 2509s and 2511s still go for a pretty penny on ebay.

The NM-4A/S is a 4 port network module that can operate in synchronous or asynchronous mode.  The first thing to do is to set the ports to asynch.

interface Serial1/0
 physical-layer async
 no ip address
 no ip directed-broadcast
 no shutdown
!
interface Serial1/1
 physical-layer async
 no ip address
 no ip directed-broadcast
 no shutdown
!
interface Serial1/2
 physical-layer async
 no ip address
 no ip directed-broadcast
 no shutdown
!
interface Serial1/3
 physical-layer async
 no ip address
 no ip directed-broadcast
 no shutdown
!

Then we need to set the line configuration up - firstly we need to associate the line (vty) against the physical interface

2610#sh line
 Tty Typ     Tx/Rx    A Modem  Roty AccO AccI   Uses   Noise  Overruns   Int
   0 CTY              -    -      -    -    -      0       1     0/0       -
  33 TTY   9600/9600  -    -      -    -    -      4       0     0/0     Se1/0
  34 TTY   9600/9600  -    -      -    -    -      7       0     0/0     Se1/1
  35 TTY   9600/9600  -    -      -    -    -      1       0     0/0     Se1/2
  36 TTY   9600/9600  -    -      -    -    -      1       0     0/0     Se1/3
  65 AUX   9600/9600  - inout     -    -    -      0       0     0/0       -
* 66 VTY              -    -      -    -    -      2       0     0/0       -
  67 VTY              -    -      -    -    -      1       0     0/0       -
  68 VTY              -    -      -    -    -      0       0     0/0       -
  69 VTY              -    -      -    -    -      0       0     0/0       -
  70 VTY              -    -      -    -    -      0       0     0/0       -

We can see vty 33 is associated with Se1/0 through to vty 36 with Se1/3, so we add the terminal server config to those lines

line 33 36
 modem InOut
 transport preferred telnet
 transport input all

To test it out, we just need to telnet to the router and add 2000 to the line number (In this case for Se1/1 we would telnet to port 2034)

adam@labserver1:~$ telnet 192.168.1.250 2034
Trying 192.168.1.250...
Connected to 192.168.1.250.
Escape character is '^]'.

3750-2>en
3750-2#sh run | inc hostname
hostname 3750-2

One of the interesting things that I noticed is that the serial ports don't appear to be considered operational - I don't know if this is because the carrier detect pins aren't working, it certainly does work, just doesn't give the impression from a show int or show controller

2610#sh int s1/1
Serial1/1 is down, line protocol is down
  Hardware is CD2430 in async mode
  MTU 1500 bytes, BW 9 Kbit, DLY 100000 usec, rely 255/255, load 1/255
  Encapsulation SLIP, loopback not set
  DTR is pulsed for 5 seconds on reset
  Last input never, output never, output hang never
  Last clearing of "show interface" counters never
  Input queue: 0/75/0/0 (size/max/drops/flushes); Total output drops: 0
  Queueing strategy: weighted fair
  Output queue: 0/1000/64/0 (size/max total/threshold/drops)
     Conversations  0/0/256 (active/max active/max total)
     Reserved Conversations 0/0 (allocated/max allocated)
  5 minute input rate 0 bits/sec, 0 packets/sec
  5 minute output rate 0 bits/sec, 0 packets/sec
     0 packets input, 0 bytes, 0 no buffer
     Received 0 broadcasts, 0 runts, 0 giants, 0 throttles
     0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored, 0 abort
     0 packets output, 0 bytes, 0 underruns
     0 output errors, 0 collisions, 1 interface resets
     0 output buffer failures, 0 output buffers swapped out
     0 carrier transitions
2610#sh controllers s1/1
CD2430 Slot 1, Port 1, Controller 0, Channel 1, Revision 15
Serial Interface Control 5:1 Register (0x40800806) is 0x0
Serial Modem Control Register (0x40800808) is 0x4
  RS-232 DTE cable
Channel mode is asynchronous serial
idb 0x80A4ECD8, buffer size 1500,
Global registers
  rpilr 0x2, rir 0x1, risr 0x0, rfoc 0x0, rdr 0xD
  tpilr 0x1, tir 0x1, tisr 0x2, tftc 0x10, tdr 0x0
  mpilr 0x3, mir 0x3, misr 0x20
  bercnt 0xFF, stk 0x0
Per-channel registers for channel 1
  Option registers
  0x17 0x00 0x04 0xA7 0xA0 0x00 0x00
  Command and status registers
  cmr 0xC2, ccr 0x00, csr 0x88, msvr-rts 0x23, msvr-dtr 0x23
  Clock option registers
  rcor 0x81, rbpr 0x68, tcor 0x20, tbpr 0x68
  Interrupt registers
  ier 0xA9, livr 0x04, licr 0x04
  DMA buffer status 0x09
  DMA receive registers
  arbaddr 0x1579D98, arbcnt 1524, arbsts 0x1
  brbaddr 0x15796D8, brbcnt 1524, brbsts 0x1
  rcbaddr 0x15796D8
  DMA transmit registers
  atbaddr 0x1552660, atbcnt 1, atbsts 0x62
  btbaddr 0x1552660, btbcnt 1, btbsts 0x62
  tcbaddr 0x1552661
  Special character registers
  schr1 0x11, schr2 0x13, schr3 0x00, schr4 0x00
  scrl 0x0, scrh 0x0, lnxt 0x0
Buffer information
  Rx ttycnt 0, sysbuf 0 0
  Tx ttycnt 0
  Rx Buffs: inpk 80A424D0/80A422B4 inheadpk 0 dataq 0 0 0
            pakq 80A426EC 80A426EC 1
  Tx Buffs: outpk 0  txpkq 80A42098 80A41E7C 2
  Priv Flags: 0