RE: [pilc] interoperability issue with TCP PEP

["Lakshmi Priya" <[e-mail]>]

hi,
   Thanks, Eric.

Guess I was not very clear with my question.
Consider the scenario below:

H1-P1 -> terrestial link
P1--P2 -> satellite link
H2-P2 -> terrestial link

End host	PEP node	PEP node	End host

H1 ----------P1------------P2----------H2

In a split PEP connection there would be 3 TCP connections (between the
nodes).
If PEP is transparent to end user the session properties (atleast the 4
tuples H1,H2,srcport1,dstport1)
should be the same for the TCP sessions between H1-P1 and P2-H2.Both these
sessions would ideally be spoofed with session tuples -
H1,H2,srcport1,dstport1 as expected by end users H1 and H2. This can be done
in many ways, since there is no specification. The information of the
session just needs to be passed from P1 to P2.

Eric, as per your reply
>> It seems that an ideally constructed transport proxy would leave all the
relevant information (obviously port numbers, but also bidirectional
sequence
space, urgent pointers, I suppose the Push flag and any IP header service
markings) undisturbed.

      It means the P1-P2 session should also retain the same properties as
the end host sessions. This is one of the methods of passing the
information. But this is not standardised. One could use a totally new set
of properties over P1-P2, may be even a different protocol, and yet pass on
the session information from P1 to P2 for the terrestial sessions using any
other control packet.

In this aspect, if P1 and P2 are 2 different implementations, I foresee an
interoperability issue.
Please correct me if I am wrong.

regards,
Lakshmi



-----Original Message-----
From: Eric Travis [mailto:[e-mail]]
Sent: Monday, 2 August 2004 10:07 PM
To: [e-mail]
Cc: [e-mail]
Subject: RE: [pilc] interoperability issue with TCP PEP


Lakshmi,

This is interesting:

>But yet it does not suggest any ways to interoperate PEP i.e. the means of
>informing the other PEP node (in a split connection)of the end host session
>information which has been spoofed. Hope the DVB-RCS standard would help
>clarify on these aspects.
>
>
What sort of information do you have in mind, and in what manner would
the other node make use of this information?

It seems that an ideally constructed transport proxy would leave all the
relevant information (obviously port numbers, but also bidirectional
sequence
space, urgent pointers, I suppose the Push flag and any IP header service
markings) undisturbed.

While an intermediate proxy may very well [need to] resegment the data
in the
flow,  this would be transparent to the ultimate end-system anyway it
isn't clear
if this activity needs to be conveyed to the peer-proxy.

Is there some other information that you had in mind?

Eric



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