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router looses connectivity every 7 days

Posted on 2011-03-24
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Last Modified: 2012-05-11
I have a Cisco router that is losing connectivity from a remote network.

the basic setup is that there are 2 offices that are connected through a vpn through 2 ASAs. At the remote office, there is a 3750 that routes between different VLANs. One one of the VLANs is a router used for call manager express.

me ------------- ASA ------(vpn)---------ASA-----------3750---------CME router

From my office, the CME router become unreachable about every 7-8 days. however I can still reach the 3750 that it is connected to. I can telnet into the CME router from the 3750 and then ping my network and then connection is then fixed.

Any ideas on why this would happen? We use static routes.




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Question by:ryan80
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shubhanshu_jaiswal earned 125 total points
ID: 35207888
may be it looses arp entry for your network....have you specified static route in the router for your network...
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by:ryan80
ID: 35207959
my crappy diagram should have looked like this:

me---3750---ASA---(vpn)----ASA---3750----CME router

also in between the ASA's are the gateway routers for the network, but since it is only the CME router that is having issues and not the entire remote office network that is having issues, I figured that these routers should not play any role in the issue.

there are static routes on the 3750s on each end.
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by:shubhanshu_jaiswal
ID: 35207980
what about the CME router....does it have any routes for your network...
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by:shubhanshu_jaiswal
ID: 35207984
I am not familiar with CME router...but i guess we can configure the routes in the CME Router...correct if i am wrong...
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by:arnold
ID: 35208435
It sounds as though the CME is either loosing the default gateway given that you are able to connect to it from the 3750
Are you trunking/bonding ports on the 3750 to two network interfaces on the CME as a means of failover?
CME might have a configuration typo on one of those ports.

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by:ryan80
ID: 35208535
the CME  router is just a cisco 2921 router.

It just has a default route configured in it which points to the 3750 it is connected to. The ports are just access ports.

If it goes down again I will check to see if it looses the default gateway. how would that even happen?
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by:arnold
ID: 35209057
Check whether you have CRC errors on the 2921.
Do you have it configured for sysloging i.e. so you can see events as they happen?

prior to ping accessing the CME see what the arp table on the 3750 has for the IP of the CME.
ARP table corruption.
Do you have something that happens on a seven day cycle, i.e. a system is connected to the network/turned on a matching schedule?
Are there any events/errors recorded on the 3750?
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by:jmeggers
jmeggers earned 125 total points
ID: 35209665
CME is Call Manager Express.  

Just a thought, but what are the timers on the VPN tunnel?  Is the tunnel dropping in conjunction with losing connectivity with CME?
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by:ryan80
ID: 35209727
no, the tunnel didn't go down during the period that connectivity has been lost. I had checked on the timers when it went down and it had been up for several days before the issue and has been since it happened. Also the 3750 in the remote office is still accessible through the VPN tunnel, even though the CME router is not.
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by:shubhanshu_jaiswal
ID: 35209761
Did you try connecting CME Router to different port on Cisco 3750 Switch...
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by:ryan80
ID: 35210463
no, it is at a remote site and I have not had that done.

If it happens again, I will be doing a lot more collection of interface and device information to help troubleshoot.
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Expert Comment

by:deepdraw
ID: 35220933
Does this router get an ip lease for 7 days?
Maybe you could paste a config.

Greg
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Author Comment

by:ryan80
ID: 35226334
no, its a static IP. Also it is just a generalization of 7 days. I have seen it down 2 times. one time it was 7 1/2 days, the other it was just under 9 days.
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by:deepdraw
ID: 35226876
I would enable cdp,
can we see the config of the device?

Greg
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by:ryan80
ID: 35233362
The config is actually very simple. It is only used for CME, so the following is all that is configured on the router asides from the phone config.

CDP is enabled on the device.



interface GigabitEthernet0/0
 description TO 3750 Switch
 ip address 10.4.1.1 255.255.255.0
 duplex auto
 speed auto
 h323-gateway voip interface
 h323-gateway voip bind srcaddr 10.4.1.1
 



ip forward-protocol nd
!
ip http server
no ip http secure-server
ip http path flash:
!
ip route 0.0.0.0 0.0.0.0 10.4.1.20
ip route 10.4.1.2 255.255.255.255 SM1/0
!
logging esm config
logging trap debugging
logging 10.10.10.27

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by:deepdraw
deepdraw earned 125 total points
ID: 35236186
so the device that is connected and you can connect, can you try show cdp neighbors
and see if it can see the device.
ie if its sending hello packets it should stay connected.

Greg
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by:arnold
arnold earned 125 total points
ID: 35240533
you have 10.4.1.x segment on two interfaces?
E/0/0 and sm1/0?
do both interfaces have the same routing paths to the outside?
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Author Comment

by:ryan80
ID: 35240886
sm1/0 is the voicemail module. I belive that it only communicates with the router itself, but it routes properly to any Ip address.
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Author Closing Comment

by:ryan80
ID: 35344234
thanks for the ideas. It hasnt dropped again recently, but I will test a numer of things if it does.

Everthing looks normal in the setup, it was running for 4 months without issue before the drop. I will see what happens.
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