PA-POS Back to Back

Unanswered Question
Mar 19th, 2010

Dear Gurus,


I have 2 7206 with PA-POS-OC3SMI configure back to back, i have the interface up/up but i cannot ping the ip address with increaseing CRC. Below is my basic config.


7206-A
interface POS3/0
ip address 10.10.3.41 255.255.255.252
no keepalive
clock source internal
no cdp enable
end



7206-B
interface POS1/0
ip address 10.10.3.42 255.255.255.252
no keepalive
no cdp enable
end


TIA.

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Giuseppe Larosa Fri, 03/19/2010 - 03:43

Hello Jepoy,


I suspect the two PA are using a different CRC or one has scrambing enabled compare the output of

sh int pos


on both devices


crc can be crc16 or crc32 ; scrambling can be enabled or disabled.



or PA are different or they have different default settings in different IOS images


Edit:

also enable keepalive to be able to detect cabling errors


Hope to help

Giuseppe

jeffersoncbriones Fri, 03/19/2010 - 05:32

Hi Guiseppe,


Thanks for the tips again, here's the output of my interfaces. Still i've hard encoded crc and enable keepalives, still the port is up but i cant even ping the local ip address on the pos.


7206-B#sh interfaces pos 1/0
POS1/0 is up, line protocol is up
  Hardware is Packet over Sonet
  Internet address is 10.10.3.42/30
  MTU 3000 bytes, BW 155000 Kbit, DLY 100 usec,
     reliability 152/255, txload 1/255, rxload 1/255
  Encapsulation HDLC, crc 32, loopback not set
  Keepalive set (10 secs)
  Scramble enabled
  Last input 00:00:00, output 02:38:03, output hang never
  Last clearing of "show interface" counters 09:06:32
  Input queue: 0/900/0/0 (size/max/drops/flushes); Total output drops: 0
  Queueing strategy: weighted fair
  Output queue: 0/1000/1500/0 (size/max total/threshold/drops)
     Conversations  0/1/256 (active/max active/max total)
     Reserved Conversations 0/0 (allocated/max allocated)
     Available Bandwidth 116250 kilobits/sec
  5 minute input rate 189000 bits/sec, 22 packets/sec
  5 minute output rate 0 bits/sec, 0 packets/sec
     1123707 packets input, 2073838413 bytes, 0 no buffer
     Received 426371 broadcasts, 0 runts, 19874647 giants, 0 throttles
              0 parity
     71076982 input errors, 19932579 CRC, 0 frame, 31269756 overrun, 0 ignored,
0 abort
     1397 packets output, 35288 bytes, 0 underruns
     0 output errors, 0 applique, 6 interface resets
     0 output buffer failures, 0 output buffers swapped out
     6 carrier transitions



7206-A#sh interfaces pos 3/0
POS3/0 is up, line protocol is up
  Hardware is Packet over Sonet
  Description:
  Internet address is 10.10.3.41/30
  MTU 3000 bytes, BW 155000 Kbit, DLY 100 usec,
     reliability 146/255, txload 1/255, rxload 1/255
  Encapsulation HDLC, crc 32, loopback not set
  Keepalive set (10 secs)
  Scramble enabled
  Last input 02:39:04, output 02:37:48, output hang never
  Last clearing of "show interface" counters never
  Input queue: 0/900/0/0 (size/max/drops/flushes); Total output drops: 1
  Queueing strategy: weighted fair
  Output queue: 0/1000/1500/0 (size/max total/threshold/drops)
     Conversations  0/1/256 (active/max active/max total)
     Reserved Conversations 0/0 (allocated/max allocated)
     Available Bandwidth 116250 kilobits/sec
  5 minute input rate 0 bits/sec, 0 packets/sec
  5 minute output rate 0 bits/sec, 0 packets/sec
     994783 packets input, 4038877857 bytes, 0 no buffer
     Received 947212 broadcasts, 2 runts, 780917 giants, 0 throttles
              0 parity
     2696244 input errors, 712031 CRC, 0 frame, 1203294 overrun, 0 ignored, 0 ab
ort
     1609 packets output, 42456 bytes, 0 underruns
     0 output errors, 0 applique, 13 interface resets
     0 output buffer failures, 0 output buffers swapped out
     22 carrier transitions

Giuseppe Larosa Fri, 03/19/2010 - 06:11

Hello Jepoy,


I don't understand:

how is it possible to have an interface up/up with keepalive set when:


>> Last input 00:00:00, output 02:38:03, output hang never


>> Last input 02:39:04, output 02:37:48, output hang never


second interface should be up/down if keepalive is set.


I would try to reset the interface with


int pos3/0

shut


controller pos3/0

shut


and then unshut


you can also use enc ppp to take advantage of more advanced PPP debug ouput


Hope to help

Giuseppe

jeffersoncbriones Fri, 03/19/2010 - 06:26

HI Guissepe,


The interface are down now, here's the full config and output.


7206-B#sh run interface pos 1/0
Building configuration...


Current configuration : 269 bytes
!
interface POS1/0
ip address 10.10.3.42 255.255.255.252
load-interval 30
crc 32
pos framing sdh
no pos report slos
no pos report slof
no pos report plop
no pos report sf-ber
no pos report b1-tca
no pos report b2-tca
no pos report b3-tca
no cdp enable
end
POS1/0 is up, line protocol is down
  Hardware is Packet over Sonet
  Internet address is 10.10.3.42/30
  MTU 4470 bytes, BW 155000 Kbit, DLY 100 usec,
     reliability 165/255, txload 1/255, rxload 1/255
  Encapsulation HDLC, crc 32, loopback not set
  Keepalive set (10 sec)
  Scramble disabled
  Last input 00:00:00, output 00:00:47, 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: fifo
  Output queue: 0/40 (size/max)
  30 second input rate 277000 bits/sec, 8 packets/sec
  30 second output rate 0 bits/sec, 0 packets/sec
     37642 packets input, 110066984 bytes, 0 no buffer
     Received 30006 broadcasts, 0 runts, 998465 giants, 0 throttles
              0 parity
     9002107 input errors, 920843 CRC, 0 frame, 7082799 overrun, 0 ignored, 0 ab
ort
     30 packets output, 1120 bytes, 0 underruns
     0 output errors, 0 applique, 6 interface resets
     0 output buffer failures, 0 output buffers swapped out



7206-A#sh run in pos 3/0
Building configuration...


Current configuration : 337 bytes
!
interface POS3/0
description :To LAOAG MPLS
ip address 10.10.3.41 255.255.255.252
no ip proxy-arp
load-interval 30
crc 32
clock source internal
pos framing sdh
no pos report slos
no pos report slof
no pos report plop
no pos report sf-ber
no pos report b1-tca
no pos report b2-tca
no pos report b3-tca
no cdp enable
end
#sh int pos 3/0
POS3/0 is up, line protocol is down
  Hardware is Packet over Sonet
  Description: :To LAOAG MPLS
  Internet address is 10.10.3.41/30
  MTU 4470 bytes, BW 155000 Kbit, DLY 100 usec,
     reliability 128/255, txload 1/255, rxload 1/255
  Encapsulation HDLC, crc 32, loopback not set
  Keepalive set (10 sec)
  Scramble disabled
  Last input 00:01:46, output 00:01:28, output hang never
  Last clearing of "show interface" counters 00:30:18
  Input queue: 0/75/0/0 (size/max/drops/flushes); Total output drops: 0
  Queueing strategy: fifo
  Output queue: 0/40 (size/max)
  30 second input rate 0 bits/sec, 0 packets/sec
  30 second output rate 0 bits/sec, 0 packets/sec
     11279 packets input, 25728325 bytes, 0 no buffer
     Received 5763 broadcasts, 3 runts, 157481 giants, 0 throttles
              0 parity
     1077673 input errors, 207716 CRC, 0 frame, 712473 overrun, 0 ignored, 0 abo
rt
     38 packets output, 2192 bytes, 0 underruns
     0 output errors, 0 applique, 5 interface resets
     0 output buffer failures, 0 output buffers swapped out
     3 carrier transitions

Giuseppe Larosa Sat, 03/20/2010 - 05:14

Hello Jepoy,

another thought:

being the two PA single mode, the signal may be too strong causing loss of frame delineation.


in this case the addition of a 5dB or 10DB in line attenuator could be a solution.


you can check this with

sh controller pos 3/0




see

http://www.fiberattenuator.com/


A way to build a home made attenuator is to wrap fiber cable over a pen to make strict curves but this can cause fiber damage


Hope to help

Giuseppe

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