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Re: latest beep draft

Arvind Jamwal wrote:

Hi Andy,

To make my point clear...

If we were to use just the <session-id>, then the schema for hello message
will have to be:

    <!--
      <hello> element
      -->
    <xs:complexType name="helloType">
      <xs:sequence>
        <xs:element ref="capability"/>
        <xs:element ref="session-id" minOccurs="0" maxOccurs="1"/>
      </xs:sequence>
    </xs:complexType>
    <xs:element name="hello" type="helloType"/>

With the above schema constraint, the node has no way to guess if
the session-id was omitted by error or by intention (becasue the peer is a
manager).


I don't care that much one way or another.  If the WG wants to add this,
then the WG should speak up.

I don't think this is a very important corner case, since it's based on mis-implementation.
We are talking about a fundamental piece of data (session-id). If an agent sends
a hello message that says "I'm an agent" but omits the session-id, then the protocol
specification has not been followed and the implementation is broken -- it doesn't
matter if the <role> element is there or not.

Andy

 But, with the following schema constraint, the node will always know the
peer's role (manager/agent)
 and can give an error if <session-id> was omitted for the agent role.

    <!--
      <hello> element
      -->
    <xs:complexType name="helloType">
      <xs:sequence>
        <xs:element ref="capability"/>
        <xs:element ref="role" minOccurs="1" maxOccurs="1"/>
        <xs:element ref="session-id" minOccurs="0" maxOccurs="1"/>
      </xs:sequence>
    </xs:complexType>
    <xs:element name="hello" type="helloType"/>

Thoughts?
-Arvind


----- Original Message -----
From: "Arvind Jamwal" <ajamwal@cisco.com>
To: "Andy Bierman" <ietf@andybierman.com>
Cc: "'Eliot Lear'" <lear@cisco.com>; <sberl@cisco.com>; "'netconf'"
<netconf@ops.ietf.org>
Sent: Friday, April 01, 2005 1:33 AM
Subject: Re: latest beep draft




Sure, <session-id> would do the trick but I hate the idea of having xml
elements with overloaded meanings.

Also, I was wondering how you will define a common XML schema for the


hello


message?
For the agent, <session-id> element is required and for the manager it is


an


error to include it.

Having a role element will help.

-Arvind

----- Original Message -----
From: "Andy Bierman" <ietf@andybierman.com>
To: <ajamwal@cisco.com>
Cc: "'Eliot Lear'" <lear@cisco.com>; <sberl@cisco.com>; "'netconf'"
<netconf@ops.ietf.org>
Sent: Thursday, March 31, 2005 12:30 PM
Subject: Re: latest beep draft




Arvind Jamwal wrote:



Hi Andy,

Would it make sense to specify the role as part of the hello message


rather


than relying on the presense/absense of session-id element?




Why?
Can you think of a reason why the <session-id> can't be used?
By design, the agent gives out the session ID.  This isn't something
that can change once decided.

The WG already decided that it would be a very rare case (e.g.,
misconfiguration)
in which an agent connects to another agent or mgr to mgr.   And if this
ever happens,
the worst case scenario is that it uses up 1 TCP control block on an
idle connection.
That's why the #manager and #agent capabilities were removed from an
early draft.

Andy



What I am proposing is the following change to the hello message:

 <hello xmlns="urn:ietf:params:xml:ns:netconf:base:1.0">
   <capabilities>
     <capability>
       urn:ietf:params:xml:ns:netconf:base:1.0
     </capability>
     ...
   </capabilities>
   <role>agent</role>         <------- new role element
   <session-id>4</session-id>
 </hello>

Comments?

-Arvind Jamwal



-----Original Message-----
From: owner-netconf@ops.ietf.org [mailto:owner-netconf@ops.ietf.org] On
Behalf Of Andy Bierman
Sent: Tuesday, March 29, 2005 11:29 AM
To: Eliot Lear
Cc: sberl@cisco.com; 'netconf'
Subject: Re: latest beep draft

Eliot Lear wrote:





We talked about this.  A netconf manager is certainly going to know it
is a netconf manager and a netconf agent is certainly going to know
it's a netconf agent.  This leaves two cases:
o where the server is also a client
o where a client is misconfigured

I think this could be handled with a netconf capability that says
"iam-manager" or "iam-agent", but as I recall consensus was against
me.  Now, I could introduce that concept as an option in the
<greeting> in the BEEP protocol mappin if there are no objections.
That would handle the corner case...




I don't want special-case handling for BEEP.
Steve already provided the answer -- only a NETCONF peer acting in the


agent


role should send the <session-id> element in the capabilities exchange.


If


neither send it or both send it, then the session should be shut down
immediately.

Andy





Eliot

Steven Berl (sberl) wrote:





Not sure if it is too late for comments on this doc, but here it is
anyway.

Section 2.1 last paragraph
"it is assumed that each knows its role in the conversation."

What happens when this assumption is wrong? How is it detected, and
what actions are to be taken?

If I am a manager and I receive a <rpc> from someone I thought was an
agent, what should I do? Probably close the channel.
If 2 agents connect to each other, they can exchange <hello> messages
and then sit there forever waiting for the other to send an <rpc> of
some sort.
I suppose the agents could detect this by noticing that the received
<hello> has a <session-id> element, and that only other agents send
this element.
The action again should probably be to close the channel.

This situation is specific to BEEP because the SSH mapping specifies
that only managers can initiate sessions.
-steve





-----Original Message-----
From: owner-netconf@ops.ietf.org [mailto:owner-netconf@ops.ietf.org]
On Behalf Of Eliot Lear
Sent: Tuesday, March 22, 2005 1:24 AM
To: netconf
Subject: latest beep draft

I believe I have addressed issues raised in the WG last call. Can
those who had comments (Juergen, Wes) take a quick scan? In


particular:


- addressed security issues regarding SASL & TLS
- added examples - are these enough?
- clarified use of <hello> and <greeting>

The draft is at the following URL and is still relatively short:

http://www.ietf.org/internet-drafts/draft-ietf-netconf-beep-04.txt

Eliot




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