Remote VPN sites routing to each other through central office

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Apr 20th, 2010
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I have an odd issue here that I'm not sure what would be causing it.

We have a main office with a VPN 3005 concentrator, and multiple construction sites connected to it with VPN 3002 HW clients or ASA 5505s.

Home office (PVT): 10.0.x.x

Remote Site 1: 192.168.11.x

Remote Site 2: 192.168.12.x

For some reason Site 1 cannot ping Site 2 the first time, unless you initiate a ping from Site 2 at the same time.

Once you run the ping command from both HW clients at these locations, they respond fine until the power is cycled.  The routes seem to be fine, but I'm not sure what would cause it to timeout unless a ping is initiated from both ends?

Further documentation can be provided if requested. I just wanted to see if it was something simple I was overlooking.


192.168.11.x pings 192.168.12.x - Timeout

Site 1 and Site 2 ping each other at the same time - Reply

After success - Site 1 can ping Site 2 without Site 2 client initiating ping command

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Jennifer Halim Tue, 04/20/2010 - 14:33
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Since both site 1 and site 2 are both hardware client, they would need to initiate the VPN tunnel towards the main office first before they can communicate with each other.

It could be a possibility that both sites have not built the VPN tunnel towards the main office, therefore, when you try to ping from site 1 to site 2, that invoke the VPN tunnel from site 1 towards the main office. At this time, ping fails. However, when you try to ping from site 2 to site 1, that invoke the VPN tunnel from site 2 towards the main office. Now both site 1 and 2 have established the VPN towards the main office, hence they can communicate with each other.

alatechpro Tue, 04/20/2010 - 14:48
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No, I don't think that is it because the VPN light is green the whole time, and devices at the home office are always accessible to each remote site (therefore the tunnel is up).

Also, pinging the first time will only work if you initiate it from both devices at the same time. I know SITE 1 and SITE 2 have the tunnel up, because I connect to them from the home office with their private IPs that are only accessible through the tunnel. To get it to work, I have both VPN HW Clients logged in through the web admin interface and initiate the pings commands from both clients at roughly the same time. It doesn't have to be EXACT, just as long as one of the devices was still sending ICMP to the other.

droeun141 Wed, 04/21/2010 - 05:09
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You have site 1 remote subnet allowed in site 2 crytpo ACL on central site? (and vice versa)

alatechpro Wed, 04/21/2010 - 13:57
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I don't think there is place on the concentrator for that...FYI: it doesn't use the CISCO IOS, nor do the VPN 3002 HW

clients. That makes it a pain when looking at the config!


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