Subject: [midcom] peer-to-peer or client-server

From: "Bob Penfield" <[email-masked]>
Date: Tue, 7 Aug 2001 09:54:41 -0400

Hello again,

I have noticed that there seems to be a disconnect between the way many
people view the relationship between the midcom agent and the middlebox in
the many informal discussion going on and the text in the framework and
requirements drafts. Both drafts state that it is a peer-to-peer protocol
where either the midcom agent or the middlebox can initiate the
communication between them. However, I and some other people see it more as
a client-server relationship where the midcom agent initiates the
communication. The midcom agent requests the services of the middlebox, and
the middlebox responds with yes or no (hopefully with a reason). The
middlebox may send asynchronous notifications for certain events (such as
timeout), but it does not request any services from the midcom agent.

Also, I have a related specific issue with the requirements. In section 5.4
it states:

   Either the agent or the Middlebox can choose to initiate a
   connection prior to any data traffic. Alternately, either party
   (Middlebox or the MIDCOM Agent) may choose to initiate a connection
   only upon noticing application specific traffic.

I find the second sentence troubling. I thought the main idea was to take
application intelligence (which would be required to "notice application
specific traffic") out of the middlebox and put it in the agent.

Hopefully we can discuss this at the meeting on Friday. Although please
don't wait till then to voice your professional reasoned opinions.

cheers,
(-:bob

Robert F. Penfield
Chief Software Architect
Acme Packet, Inc.
130 New Boston Street
Woburn, MA 01801
[email-masked]

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From: "Christopher A. Martin" <[email-masked]>
Date: Tue, 07 Aug 2001 16:57:54 -0500

comments inline between ">>" tags

-----Original Message-----
From: [email-masked] [mailto:[email-masked]]On Behalf Of
Bob Penfield
Sent: Tuesday, August 07, 2001 8:55 AM
To: midcom mail-list
Subject: [midcom] peer-to-peer or client-server

Hello again,

Totally agree, relationship acts more in client server fashion, and if it
did act as a peer to peer could introduce a security vulnerability.
>>
>> Right. In terms of service requests, the Policy server is the element
that would orchestrate services at the middlebox level in my mind, before
any MIDCOM Agent involvment. Services such as local access policy, trustedd
MIDCOM agents etc..isnt that right?

>>
>> I think to clarify why Bobs statement makes sense to me, in this
reference, using the example of a SIP invite, the middlebox is not
performing the initiation, rather the initiating SIP client (through the
predefined policy, setup by the policy server, to allow SIP traffic through
to the Network Server(NS) and associated MIDCOM Agent)is performing this
task of requesting the action by sending the SIP INVITE to the NS which in
turn begins the MIDCOM AGENT process of middlebox control.  All this time
the middlebox does nothing until the MIDCOM AGENT requests the actions of
the middlebox (such as the NAT translation and/or related dynamic packet
filter definition, in the case of a firewall/NAT middlebox,).

The middlebox is not acting with intelligence at this level at all, merely
following policy dictated by the policy server. Because of this I do not
believe that either sentence of 5.4 is accurate statement as it implies
application intelligence of the middlebox, which would be required to
initiate a connection.

At least this is what I get from this paragraph.

Have a drink for me since I couldnt make it this time...as a Chris proxy if
you will   :^)
cheers,
(-:bob

Robert F. Penfield
Chief Software Architect
Acme Packet, Inc.
130 New Boston Street
Woburn, MA 01801
[email-masked]

---

From: Jiri Kuthan <[email-masked]>
Date: Thu, 09 Aug 2001 15:32:13 +0200

I also have trouble understanding why Midcom protocol is called
a peer-to-peer protocol. I would prefer labelling it 
a client(agent)-server(middlebox) protocol. I am not aware of strong 
reasons why a middlebox should initiate midcom-communication to an agent.

-Jiri

--
Jiri Kuthan            http://iptel.org/~jiri