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New Member

"Cisco - Microwave link - Cisco" connection drop

I have configured a microwave connection in my Cisco router to connect to a remote PC. It looks like this: -

Cisco3660Router (Ethernet) ->

MicrowaveA ->

MicrowaveB (Ethernet) ->


The connection is working fine and it stays up all the time.

My problem happens when I replaced the RemotePC with a Cisco3640 router. Like this: -

Cisco3660Router (Ethernet) ->

MicrowaveA ->

MicrowaveB (Ethernet) ->


This new connection work fine at first but it drops after some time (less than 24 hours). In order for me to recover the connection, I have to restart MicrowaveB device. It worked again after the restart.

Any idea on how to troubleshoot this?

Thanks in advance.


Re: "Cisco - Microwave link - Cisco" connection drop

when it drops what is the status of ethernet interface in cisco3640 (speed/duplex/up/down)?

when it drops can you still ping the new router? i'am afraid you have an IP address conflict some where.

New Member

Re: "Cisco - Microwave link - Cisco" connection drop

I'm using ping to monitor the connection. The ping works initially but fails after some time (less than 24 hours).

I have not check the status (Line Protocol) of Ethernet interface of my Cisco3640 but I believe it is DOWN. I'm using Speed 10 and Full Duplex on my Cisco.

I don't think its due to IP address conflict because the RemotePC is using the same IP address as the Ethernet port of Cisco3640 Router. There is no problem when using RemotePC.


Re: "Cisco - Microwave link - Cisco" connection drop

when it is down take a copy of show interface fastethernet x/y and paste it here so we can have an idea about errors, drops, resets....

New Member

Re: "Cisco - Microwave link - Cisco" connection drop

I notice something strange about the interface. It has very high 'Input Errors' and 'CRC'. What could be the cause of this?

FastEthernet0/1 is up, line protocol is up

Hardware is AmdFE, address is 0009.4318.da42 (bia 0009.4318.da42)

Internet address is

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)

Half-duplex, 10Mb/s, 100BaseTX/FX

ARP type: ARPA, ARP Timeout 04:00:00

Last input 00:07:35, output 00:00:00, output hang never

Last clearing of "show interface" counters 1d14h

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 0 bits/sec, 0 packets/sec

5 minute output rate 1000 bits/sec, 1 packets/sec

1629348 packets input, 328530613 bytes

Received 2592 broadcasts, 0 runts, 0 giants, 0 throttles

1837 input errors, 1837 CRC, 0 frame, 0 overrun, 0 ignored

0 watchdog

0 input packets with dribble condition detected

1649026 packets output, 167042924 bytes, 0 underruns

0 output errors, 7842 collisions, 0 interface resets


New Member

Re: "Cisco - Microwave link - Cisco" connection drop

with CRC and collision errors, probably a speed mismatch...define bandwith and speed on your interface...


Re: "Cisco - Microwave link - Cisco" connection drop

as you can see the interface is in half duplex and 10Mbps

do you find this normal? i think it should be 100mbps and fullduplex

New Member

Re: "Cisco - Microwave link - Cisco" connection drop

The reason why I am using 10mbps is because I am using 10mbps on one Router and 10/100mbps on another router.

I think I have found the culprit to my connection drop problem. When I use half-duplex the connection is stable but when I switched to full-duplex, it drops after less than 24hrs. This is strange because the microwave device supports both half and full duplex.

Anyway, I have decided to use 10mbps half-duplex. The connection is running for several days already without going down.