RE: IPsec & Markers

> >>
> > The Markers are to enable the receiving side to locate the start of 
> > MPA Frames even when TCP Segments are received out-of-order.
> 
> Out of order or "unaligned"?  When the entire FPDU fits in 
> the TCP segment (e.g. aligned), I have no problem locating 
> the start of MPA Frames, in (TCP sequence) order or not.
> 
Unfortunately, just because an FPDU might fit in a TCP segment, does not
mean that it MUST always be aligned.  It is legal (but unwise) for a
sender to segment the TCP stream at other than FPDU boundaries.

> > Even with IPSEC enabled a received out-of-order TCP Segment is not 
> > necessarily an MPA Frame.  Without markers how would the receiver 
> > locate the MPA Frame boundary?
> 
> Sec 5.3 says "MPA MUST encapsulate the ULPDU such that there 
> is exactly one ULPDU contained in one FPDU."  With IPsec, 
> there will be no middlebox that can re-segment TCP segments.  
> What I put in the IPsec
> (e.g.) tunnel will come out the other end of the tunnel.
> 
> MikeC
Same comment as above, while ULPDU (i.e. DDP segments) must fit exactly
into FPDU, there is no absolute requirement that FPDUs must fit exactly
into TCP segments.
> 
> --