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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: IPSEC target and transport modeWell, as usual, I replace the term Transport, with Tunnel until no one can understand what I intended to say. Corrections below following the xxxxxx which crossed out the word Tunnel. . . . John L. Hufferd Senior Technical Staff Member (STSM) IBM/SSG San Jose Ca Main Office (408) 256-0403, Tie: 276-0403, eFax: (408) 904-4688 Home Office (408) 997-6136, Cell: (408) 499-9702 Internet address: hufferd@us.ibm.com John Hufferd/San Jose/IBM@IBMUS@ece.cmu.edu on 03/30/2002 05:58:24 PM Sent by: owner-ips@ece.cmu.edu To: "Bernard Aboba" <bernard_aboba@hotmail.com> cc: thorpej@wasabisystems.com, ips@ece.cmu.edu Subject: Re: IPSEC target and transport mode These reasons you mentioned here, and the resulting performance were some of the reasons I thought we voted to make Transport a "Must implement". It is also true that David Black may have caused some of the Tunnel folks to have rolled over on this issue, but I believe, a number of folks understood various aspects of what you have said here, and wanted to use xxxxxx Transport mode, and wanted it to be a "Must Implement" since if xxxxxx Transport mode, is not implemented by the other side, it can cause your side to have poorer performance, even if you can support the higher performance that come with Transport mode. But more then David's statements, the thing that I understood helped get agreement on the MUST/MUST for Transport and Tunnel, was the fact that almost all the IPsec stacks that are available on the market come with both Transport and Tunnel. So it is now possible for iSCSI to not only operate at high speed, and support the key features mentioned below, but can interoperate with HW that can only pass through Tunnel mode. I feel that Transport is the most capable and high performance mode, but feel that tunnel is also needed for firewalls that do not accept Transport at this time. But, it seems clear to me, that if we have Transport mode as a MUST (along with Tunnel), that the various hardware along the way, such as the firewalls, will be quickly adjusted to support Transport, since each vendor will see the potential advantages of having their product support iSCSI traffic in the most efficient manner. However, we will be able to operate with Tunnel mode until most vendors HW will be able to support Transport mode through their equipment (such as firewalls etc.) So again, I feel that our original vote to support both Transport and Tunnel as Must implements, was the right decision, and best for iSCSI and the customer. I propose we let the original agreement stand. . . . John L. Hufferd Senior Technical Staff Member (STSM) IBM/SSG San Jose Ca Main Office (408) 256-0403, Tie: 276-0403, eFax: (408) 904-4688 Home Office (408) 997-6136, Cell: (408) 499-9702 Internet address: hufferd@us.ibm.com "Bernard Aboba" <bernard_aboba@hotmail.com>@ece.cmu.edu on 03/30/2002 05:51:18 AM Sent by: owner-ips@ece.cmu.edu To: thorpej@wasabisystems.com, ips@ece.cmu.edu cc: Subject: Re: IPSEC target and transport mode >I really don't like this idea. > >While it is true that Tunnel Mode >does not require the use of a gateway, Transport Mode is actually >the more general mode. > >It is possible to combine Transport Mode with any arbitrary something-in-IP >tunneling protocol (IP-IP, GRE, etc.). In the case of >Transport Mode + >IP-IP tunneling, you achieve something that is equivalent to Tunnel Mode, >thus satisfying those who need it (I >suggest that everyone read >draft-touch-ipsec-vpn-03.txt). Having worked with transport mode tunnels for a few years now (L2TP), we have come to the same conclusion. By linking SA selection to next hop forwarding, tunnel mode complicates routing considerably. Transport mode tunnels are more compatible with dynamic routing protocols. Today most tunnel mode vendors only support either static routing or BGP run down the tunnel, and that makes it very difficult for enterprise customers to manage and deploy large numbers of tunnels. Although it can be done, Tunnel mode is also more difficult to implement as an interface than Transport mode IP-IP. There already is pushback on iSCSI HBAs that cannot act as a full fledged interface; this will ensure that this continues to be a problem many years into the future. >Transport Mode is also less expensive from a processing point of view. >If you use Tunnel Mode with no gateway (i.e. inner-dest==outer-dest, >outer-source==inner-source), you still have to de-encap the packet and >re-process it, which is something you don't have to do in Transport >Mode. It would seem to me that this additional cost might be a concern in the 10 Gbps case in particular. _________________________________________________________________ Chat with friends online, try MSN Messenger: http://messenger.msn.com
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