[multipathtcp] Some questions for proxy work

Yoshifumi Nishida <nishida@sfc.wide.ad.jp> Thu, 27 April 2017 06:58 UTC

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From: Yoshifumi Nishida <nishida@sfc.wide.ad.jp>
Date: Wed, 26 Apr 2017 23:58:40 -0700
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Subject: [multipathtcp] Some questions for proxy work
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We've seen active discussions on doing proxy work in the WG.
I just would like to clarify several points from simple cases before
discussing detailed mechanisms in proxy.

Let's say we have end points E1, E2, middle points M1, M2, and we have a
communication path like this.

   E1 ------- M1 ====== M2 ------ E2

Now, we know E1 and E2 use TCP for communication. Also, we know there are
multiple paths between M1 and M2.

The bandwidth of E1-M1 and E2-M2 are relatively large compared to any one
of paths in M1-M2 or we know there will be heavy congestion in some paths
in M1-M2.

In this scenario, do we see any advantages for using MPTCP between M1-M2 or
not? Or, do we see any problems or concerns to use MPTCP here?

Some folks might say we can use routing techniques or bundling IP tunnels
here. But, I guess we'll need to handle reorder packets and proper
congestion controls across multiple paths.