Subject: RE: WG next steps

From: "Tony Li" <[email-masked]>
Date: Thu, 14 Nov 2002 12:05:07 -0800

|   That is a very questionable proposition. Today, the transport layer
|   measures round trip times to manage retransmissions, and 
|   maintain window
|   sizes to match sending rates with available network capacity. In a
|   multi-homed environment, you would expect the transport to 
|   assess RTT
|   and capacity for the various available paths and to make intelligent
|   decisions about which packet goes on what path. Clearly, 
|   you want some
|   aggregation, but there is certainly value in providing the transport
|   with handles for directing traffic one way or another, which implies
|   dealing with addresses or locators.

Not necessarily.  If the network layer provided the transport with
an opaque handle for each path, then the transport layer wouldn't
have to touch locators at all.  The network layer would still
need to inform the transport layer of path changes, but again, this
could be done via the handle.

Tony

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From: Masataka Ohta <[email-masked]>
Date: Fri, 15 Nov 2002 10:25:54 +0859 ()

Tony Li;

> could be done via the handle.

The interaction is more complex.

For example, if the current path fails, it is detected by the
transport/applicaiton layer. Thus, it is necessary for the
transport/application layer tell the network layer use an alternative
locator.

Later, as the original path may be resumed, it is also necessary
for the transport/application layer tell the network layer try an
old locator. Note that there may be several old locators.

To do so, transport/application layer and network layer must have
common identification mechanism of locators.

It is much easier for the transport/applicaiton layer to handle
locators directly. Then, all the information necessary for
transport/application layer control is included in the IP header.

						Masataka Ohta

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From: Michael Richardson <[email-masked]>
Date: Fri, 15 Nov 2002 00:20:30 -0500

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>>>>> "Tony" == Tony Li <[email-masked]> writes:
    Tony> Not necessarily.  If the network layer provided the transport with
    Tony> an opaque handle for each path, then the transport layer wouldn't
    Tony> have to touch locators at all.  The network layer would still
    Tony> need to inform the transport layer of path changes, but again, this
    Tony> could be done via the handle.

  If you do IPsec between every set of end-points, then you can easily insert
the appropriate End-point-identifiers for the transport layer.  Bellovin has
pointed out that once you've authenticated the packet via IPsec, you just
don't care what's in the IP header. (This is often an argument why against
AH.)

  You don't really have to do this at all - you just hang all the PCB info on
the incoming IPsec SPD entry, but this is an implementation short-cut. 

]       ON HUMILITY: to err is human. To moo, bovine.           |  firewalls  [
]   Michael Richardson, Sandelman Software Works, Ottawa, ON    |net architect[
] [email-masked] http://www.sandelman.ottawa.on.ca/ |device driver[
] panic("Just another Debian GNU/Linux using, kernel hacking, security guy"); [

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From: "marcelo bagnulo" <[email-masked]>
Date: Fri, 15 Nov 2002 12:07:57 +0100

Hello Masataka,

> transport/application layer control is included in the IP header.

Do you consider LIN6 to be a transport or application layer solution?

If i understand it correctly, LIN6 manages multiple locators (LIN6 address)
while presenting only one identifier (LIN6 generalized ID ) to transport and
application layer. This is what i understand by an opaque handling of
locators by the network layer.

Quoting from draft-teraoka-ipng-lin6-01.txt

"The LIN6 generalized
    ID is 128 bits in length and is used in the transport layer and the
    upper layers.  LIN6 generalized ID is the identifier of the node in the
    transport layer and the upper layers and does not change even if the
    node moves.  The LIN6 address is also 128 bits in length and is used in
    the network layer.  The LIN6 address specifies both the location and the
    identifier of the node.  "

In this case, transport and application layer have no knowledge of locators
and can not select them.

Regards, marcelo

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From: Masataka Ohta <[email-masked]>
Date: Sat, 16 Nov 2002 09:47:00 +0859 ()

Marcelo

> Hello Masataka,

Hi,

> Do you consider LIN6 to be a transport or application layer solution?

As was discussed in IETF ML about a few monthes ago, it is not
meaningful to distinguish transport and applicaiton layers, unless
your network is QoS aware.

> Quoting from draft-teraoka-ipng-lin6-01.txt

We modified it a lot.

> In this case, transport and application layer have no knowledge of locators

See the paper for new API.

						Masataka Ohta

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From: RJ Atkinson <[email-masked]>
Date: Fri, 15 Nov 2002 21:48:00 -0500

On Friday, Nov 15, 2002, at 00:20 America/Montreal, Michael Richardson 
> don't care what's in the IP header. (This is often an argument why 

There is an attack that Bellovin overlooks, so AH actually does matter.
(Caveat: This is controversial, because I *never* am first to discuss 
attacks
in public.)

Ran