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Selection of proposals



Hi All,

The scenario I sent in yesterday didnt give all the details and I am
modifying it to give the exact scenario...

       If we have  SG1, SG2 and IPSec capable host H2 in the following
scenario,


   	  |--------ESPtunnel---- |
	  |                      |
         SG1 ----------------- SG2 ----------- H2
         |						|
         |------------------AH Tunnel-----------|


and the security policies are as follows.

At SG1 OutBound Policy is 

 Proposal #1:  
          For SG2 :  ESP with 3DES
                  or ESP with DES
          For H2  :  AH with SHA1
                  or AH with MD5

At SG2 we have the Inbound Policy as
  
  Proposal # 1 :
            ESP with 3DES
            or ESP with DES

H2 has the inbound policy as
  
  Proposal # 1:
            AH with MD5

     
During IKE negotiation,  SG1 sends out the SAPayload(with the two
transforms it has) to SG2 and H2. SG2 will select Transform #1 of SG1 and
H2 will select Transform # 2 of SG1. Because of this, an SA bundle that
perfectly matches the proposal cannot be formed by SG1. However, SG2 is
capable of processing with DES and had SG2 selected this, it could have
formed an SA bundle at SG1.

Do we just reject the proposal at this stage or is it permitted to send the
two transforms as different proposal payloads in independent SA payloads
and try to see if a match can be found amongst all available proposals? The
problem here is, of course, the fact that H2 and SG2 look at the individual
and independent SPDs while SG1 looks at the combined SA bundle.

Any suggestions will be appreciated.


-Thanks a lot
 Rohit



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