Interface input and CRC errors. VPN tunnel

[sean.zawadski]

Hi,

at my company we have a remote site that is connected to our cisco ASA using a cisco 831 router. One the remote end they are using a fairly slow DSL connection. 

We are trying to run some software on some clients and that software needs to update through that VPN tunnel. The software always fails to update saying that the files do not match. 
 

I believe packets are being dropped causing this file mismatch.

I'm pretty damn new at this so i could be way off base but i looked at the interface on the remote end it is getting input and CRC errors.

I had the technician there replace the Ethernet cable going to that interface.

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MTU 1500 bytes, BW 10000 Kbit, DLY 1000 usec, 
     reliability 255/255, txload 1/255, rxload 1/255
  Encapsulation ARPA, loopback not set
  Keepalive set (10 sec)
  Full-duplex, 10Mb/s
  ARP type: ARPA, ARP Timeout 04:00:00
  Last input 00:00:00, output 00:00:00, output hang never
  Last clearing of "show interface" counters 3d04h
  Input queue: 0/75/0/0 (size/max/drops/flushes); Total output drops: 0
  Queueing strategy: fifo
  Output queue: 0/40 (size/max)
  5 minute input rate 1000 bits/sec, 2 packets/sec
  5 minute output rate 1000 bits/sec, 2 packets/sec
     296615 packets input, 148941577 bytes, 0 no buffer
     Received 41094 broadcasts, 0 runts, 0 giants, 0 throttles
     543 input errors, 70 CRC, 0 frame, 0 overrun, 0 ignored
     0 input packets with dribble condition detected
     284530 packets output, 148429980 bytes, 0 underruns
     0 output errors, 0 collisions, 0 interface resets
     0 babbles, 0 late collision, 0 deferred
     0 lost carrier, 0 no carrier
     0 output buffer failures, 0 output buffers swapped out

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Any ideas or suggestions?

Thanks,

Sean

[kevin.szatkowski]

I would suggest a methodical approach to troubleshooting this.  First CRC has to deal with Ethernet specifically that LAN segment only (between the DSL device and router), input is CRC and other errors combined but not always equal.  This guide has an explanation (http://www.cisco.com/en/US/docs/internetworking/troubleshooting/guide/tr1904.html)  Personally, I don't think there is a lot of errors to suspect a layer 1 or 2 issue.

So start with the protocol running the software patch, ie FTP, SCP, etc to identify if it's TCP or UDP.  Then using Iperf (https://iperf.fr/) break the LAN segments up and test from source to destination.  I.e

Source Iperf server <--> Switch (1st Test Iperf client) <--> Internal Router (2nd Test Iperf client) <--> WAN Router (3rd Test Iperf client) <--> ASA (4th Test Iperf client) <--> DSL (5th Test Iperf client) <--> Router (6th Test Iperf client) <--> End client (7th Test Iperf client)

Good Luck, Kevin