>>>>> "Yoav" == Yoav Nir <[email protected]> writes:
    >> You didn't take my comments too far; I think you realized that I was in
    >> fact saying two things:
    >> 
    >> 1) when traffic is redirected, MUST it be redirected directly to the
    >> real endpoint?  (There might be issues of in-band double NAT that

    >> 2) when traffic is redirected, MAY it be redirected more than once?

    Yoav> Aren't these really the same question?  

case1: Q1:yes, Q2: yes.  
       Must redirect to final end point, but it is okay for redirection
       to occur multiple times.  This implies that when A is redirected
       to H2, that no SA is created with H2, but rather there is an
       immediate redirection to H3, and again to B.

case2: Q1:yes, Q2: no
       Must redirect to final end point, but redirection not permitted.
       H1 must get address of B via "magic" and tell A about it.

case3: Q1:no, Q2: yes.
       final end point not required, multiple redirection.
       H1 can redirect to H2.  A sends traffic to H2.
       H2 can decide to send a new redirect to H3 based upon seeing
       what traffic is arriving.  
       (Note that B might get redirected by H2 for traffic for A to H2,
       and now we have A<-->H2<-->B, and now H2 actually knows about 
       both A and B, and either easily link them directly, or realize
       that neither are directly reachable, and since H2 has plentiful
       bandwidth, it doesn't care...)
        
case4: Q1:no, Q2: no.
       H1 should either redirect to B directly, or can redirect to
       H3, but H1 has to know whether or not B is directly reachable.
       At the same time, H3 might be redirecting B to H1 if A is not 
       reachable, and we might have asymmetric routing.  
       This might screw the SPD on A and B if your SPD is strict 4301.

    Yoav> IOW it should be a requirement that H1 (in the diagram of your
    Yoav> previous mail) be able to send more information about the
    Yoav> topology behind H2 than just "B is behind H2", such as "D and
    Yoav> H3 are also behind H2". But A should be required to not expect
    Yoav> it. 

    Yoav> So H1 MUST be able to tell A that B is behind H2. It MAY be
    Yoav> able to tell A that D is also behind H2, or that B is actually
    Yoav> behind H3, or the actual address of B. 

So, you just created a requirement for H1<->H2 communication :-)

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