SA question/issue

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Nov 11th, 2008
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Hi everybody


I am having a lot of trouble with a IPSec site-to-site between an ASA and an ISA server. The is established and can work for hours but, I think, when the IKE/IPSec SA's re-negotiate there can be a dropout. I have tried deleting all IKE and IPSec SAs (clear crypto ipsec/isakmp ...) at both ends and the tunnel then re-negotiates without a problem. However, when I look at active SA's there is 1 active IKE SA but 2 active IPSec SA's... Is this normal? Could this be causing a problem when the SA's timout and try to renegotiate? I am very new to this so any help would be much appreciated.


Thanks a lot


Colin


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Jon Marshall Tue, 11/11/2008 - 04:05
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Colin


The SA's used in phase 2 ie. what you call the IPSEC SA's are unidirectional. So to eastablish 2 way communication between 2 devices you need 2 SA's. So this is normal behaviour.


Sounds like what may be happening is that one end times out but the other end doesn't. The end that has timed out tries to renegotiate but the other end rejects it because as far as it is concerned the tunnel is still up. Perhaps your timers for tunnel establishement/teardown do not match on both devices.


IPSEC can be very picky between different vendor devices. In addition to Cisco's site you may want to visit Microsoft site and look for ISA to Pix/ASA configurations. If i get time later i'll have a look but both Cisco's and Microsoft's site have a lot of good resources.


Jon

cmgowcity Tue, 11/11/2008 - 04:18
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Thanks Jon for clearing that up. I will check the differences in the lifetimes at each side - I can see this easily on the ASA but will need to try and find it on the ISA Server...


Cheers


Colin

cmgowcity Tue, 11/11/2008 - 06:01
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I have attached the oakley.log starting just before the tunnel went down and finishing just after the tunnel came backup - without intervention of any kind... I realise it is a lot to look through but if anybody can see what is happening while it is down it would be a great help - as I said I am very new to all this.


Thanks a lot


Colin


cmgowcity Tue, 11/11/2008 - 07:26
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Please ignore the oakley log as the ASA was re-booted by somebody on site!


Thanks


Colin

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