Help with Interfaces Errors on Satellite WAN Circuit

Unanswered Question
Jul 25th, 2007

Hello all,

I have recently connected my site to a remote office using a 9.744 Mbps point-to-point serial circuit over Satellite. I am seeing very strange errors on the interfaces and would appreciate assistance. Please reference the attached network diagram with the follow-up post containing the "show interfaces" below. The connection from my building to the satellite teleport is over ATM. I am seeing "output drops" on both sides of ATM circuit. The ATM circuit is one 9.744 Mbps PVC. I am also seeing errors on both HSSI interfaces. The HSSI circuit is timed off the satellite modem that is connected to the HSSI interface of Router B. I noticed by doing a show controllers that the receicved timing on the HSSI interface moves from 9743538 to 9745120 approximtely once every 30 seconds. However, I can not directly correlate the timing drift to the interface errors.

Thank you for your help.

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wedwardsvt Wed, 07/25/2007 - 10:08

Router A ATM Interface (ATM 2/0):

RouterA#sh int atm 2/0

ATM2/0 is up, line protocol is up

Hardware is RS8234 ATM DS3

Description: ATM Trunk

MTU 4470 bytes, sub MTU 4470, BW 45000 Kbit, DLY 190 usec,

reliability 255/255, txload 1/255, rxload 1/255

Encapsulation ATM, loopback not set

Encapsulation(s): AAL5

1023 maximum active VCs, 2 current VCCs

VC Auto Creation Disabled.

VC idle disconnect time: 300 seconds

Last input 00:00:01, output 00:00:00, output hang never

Last clearing of "show interface" counters 5w0d

Input queue: 0/75/0/0 (size/max/drops/flushes); Total output drops: 8901043

Queueing strategy: Per VC Queueing

30 second input rate 131000 bits/sec, 14 packets/sec

30 second output rate 47000 bits/sec, 14 packets/sec

121292189 packets input, 741762298 bytes, 0 no buffer

Received 0 broadcasts, 0 runts, 0 giants, 0 throttles

0 input errors, 5 CRC, 0 frame, 0 overrun, 0 ignored, 0 abort

112122802 packets output, 3956918578 bytes, 0 underruns

0 output errors, 0 collisions, 0 interface resets

0 output buffer failures, 0 output buffers swapped out

Router B ATM Interface (atm 4/0):

RouterB#sh int atm 4/0

ATM4/0 is up, line protocol is up

Hardware is RS8234 ATM DS3

Description: ATM

MTU 4470 bytes, sub MTU 4470, BW 9744 Kbit, DLY 190 usec,

reliability 255/255, txload 1/255, rxload 1/255

Encapsulation ATM, loopback not set

Encapsulation(s): AAL5

1023 maximum active VCs, 1 current VCCs

VC Auto Creation Disabled.

VC idle disconnect time: 300 seconds

Last input 00:00:00, output 00:00:00, output hang never

Last clearing of "show interface" counters 1d22h

Input queue: 0/75/0/0 (size/max/drops/flushes); Total output drops: 194973

Queueing strategy: Per VC Queueing

30 second input rate 43000 bits/sec, 8 packets/sec

30 second output rate 8000 bits/sec, 7 packets/sec

13834546 packets input, 3469090240 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

15460961 packets output, 123454412 bytes, 0 underruns

0 output errors, 0 collisions, 0 interface resets

0 output buffer failures, 0 output buffers swapped out

wedwardsvt Wed, 07/25/2007 - 10:08

Router B HSSI interface (hssi 3/0):

RouterB#sh int hssi 3/0

Hssi3/0 is up, line protocol is up

Hardware is M1T-HSSI-B

Description: SATCOM LINK

Internet address is 10.1.2.5/30

MTU 4470 bytes, BW 9744 Kbit, DLY 200 usec,

reliability 255/255, txload 1/255, rxload 1/255

Encapsulation PPP, LCP Open

Open: IPCP, crc 16, loopback not set

Keepalive set (10 sec)

Restart-Delay is 0 secs

Last input 00:00:03, output 00:00:00, output hang never

Last clearing of "show interface" counters 02:52:13

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 6000 bits/sec, 6 packets/sec

30 second output rate 0 bits/sec, 0 packets/sec

128737 packets input, 17418447 bytes, 0 no buffer

Received 0 broadcasts, 0 runts, 0 giants, 0 throttles

0 parity

584 input errors, 574 CRC, 0 frame, 5 overrun, 0 ignored, 5 abort

138174 packets output, 87933979 bytes, 0 underruns

0 output errors, 0 applique, 0 interface resets

0 output buffer failures, 0 output buffers swapped out

0 carrier transitions LC=down CA=up TM=down LB=down TA=up LA=down

HSSI DTE, received clockrate 9745120

HSSI DTE, received clockrate 9743538

Router C HSSI Interface (hssi 1/0):

RouterC#sh int hssi 1/0

Hssi1/0 is up, line protocol is up

Hardware is M1T-HSSI-B

Description: SATCOM LINK

Internet address is 10.1.2.6/30

MTU 4470 bytes, BW 9744 Kbit, DLY 200 usec,

reliability 255/255, txload 1/255, rxload 1/255

Encapsulation PPP, LCP Open

Open: IPCP, crc 16, loopback not set

Keepalive set (10 sec)

Restart-Delay is 0 secs

Last input 00:00:00, output 00:00:00, output hang never

Last clearing of "show interface" counters 2d02h

Input queue: 0/75/0/0 (size/max/drops/flushes); Total output drops: 9917

Queueing strategy: fifo

Output queue: 0/40 (size/max)

30 second input rate 24000 bits/sec, 8 packets/sec

30 second output rate 7000 bits/sec, 8 packets/sec

15556907 packets input, 1154275136 bytes, 0 no buffer

Received 0 broadcasts, 202 runts, 0 giants, 0 throttles

0 parity

4858695 input errors, 2514675 CRC, 0 frame, 1380169 overrun, 0 ignored, 963851 abort

18890347 packets output, 1964671150 bytes, 2316 underruns

Paolo Bevilacqua Wed, 07/25/2007 - 11:14

Hi,

only router C has a severely errored interface, can you have the satellite modem checked for correct SNR as likely the problem lies in there.

As you see on router B the HSSI clock can fluctuate a little without causing any problem.

wedwardsvt Wed, 07/25/2007 - 13:17

Thank you very much for the reply. We're currently looking into replacing the SAT modem connected to router C. The circuit had been running pretty well for about 4 weeks until we begun seeing errors this past week. What concerns me are the output packet drops on the ATM interface. I have noticed the clock fluctuating on the HSSI interface from 9743538 to 9745528, while the ATM is a constant 9744000. Do you think that the mismatch of speeds could be causing this? If not, do you have any ideas on how I could troubleshoot?

Paolo Bevilacqua Wed, 07/25/2007 - 17:32

Hi, if had worked 4 fine weeks it's just a matter of checking something on the dish and related equipment and fix it. For example a faulty lnb can bring SNR low enough for the error correction on the sat link not suffice anymore.

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