Re: [netconf] Pullback tcp-client-server also?

["Joe Clarke (jclarke)" <[e-mail]>]

As I thought about this more and consider Med’s DHC example, I kept coming back to how services are defined in a UNIX /etc/services file.  In Med’s example, DHCPv4 and DHCPv6 each have different services for client and server.  If I were implementing the “tcp-server-grouping” for a given service on a host, a leaf-list would be sufficient (as I’d have two different daemons or at least two different config blocks for v4 and v6).

However, Med is making the point that if this was to be implemented at a controller or higher abstraction level he wants to offer a “DHC” service as a single entity.  In this case, he’d like to have all DHC-capabilities under one service config (albeit that is more of an example for UDP server).

Concretely, I think he is proposing something like the attached snippet (Med, correct me if I’m wrong).  In this case, if I had an SSH server as an example that used different ports for different address families I would have (in XML):

<tcp-server xmlns="urn:ietf:params:xml:ns:yang:ietf-tcp-server">
  <local-bind>
    <local-address>0.0.0.0</local-address>
    <local-port>22</local-port>
    <keepalives>
      <idle-time>7200</idle-time>
      <max-probes>9</max-probes>
      <probe-interval>75</probe-interval>
    </keepalives>
  </local-bind>
  <local-bind>
    <local-address>::</local-address>
    <local-port>22022</local-port>
    <keepalives>
      <idle-time>7200</idle-time>
      <max-probes>9</max-probes>
      <probe-interval>75</probe-interval>
    </keepalives>
  </local-bind>
</tcp-server>

Yes, this adds complexity in order to get more flexibility, but you can still do the same ports for a given server such as:

<tcp-server xmlns="urn:ietf:params:xml:ns:yang:ietf-tcp-server">
  <local-bind>
    <local-address>0.0.0.0</local-address>
    <local-port>22</local-port>
    <keepalives>
      <idle-time>7200</idle-time>
      <max-probes>9</max-probes>
      <probe-interval>75</probe-interval>
    </keepalives>
  </local-bind>
  <local-bind>
    <local-address>::</local-address>
    <local-port>22</local-port>
    <keepalives>
      <idle-time>7200</idle-time>
      <max-probes>9</max-probes>
      <probe-interval>75</probe-interval>
    </keepalives>
  </local-bind>
</tcp-server>


  Joe

From: netconf <[e-mail]> on behalf of [e-mail] <[e-mail]>
Date: Tuesday, March 19, 2024 at 21:31
To: Mahesh Jethanandani <[e-mail]>
Cc: Netconf <[e-mail]>
Subject: Re: [netconf] Pullback tcp-client-server also?
Re,

Yes.

Cheers,
Med

De : Mahesh Jethanandani <[e-mail]>
Envoyé : mercredi 20 mars 2024 11:27
À : BOUCADAIR Mohamed INNOV/NET <[e-mail]>
Cc : Kent Watsen <[e-mail]>; Netconf <[e-mail]>
Objet : Re: [netconf] Pullback tcp-client-server also?

Hi Med,


On Mar 20, 2024, at 11:04 AM, [e-mail]<mailto:[e-mail]> wrote:

Re-,

As Joe rightfully mentioned, running different instances is likely to happen at the device level. For that case, the leaf-list approach is just fine.

Now, when the model is reused in upper layers (network or service models), that would not be sufficient. Think about a DHC service model which hides the internal of the service (whether this is dhcp or dhcpv6) but simply needs to expose where the dhc service is enabled: distinct ports are required for that case.

[mj] So a list of local-address and local-port?

Cheers.


Cheers,
Med

De : Kent Watsen <[e-mail]<mailto:[e-mail]>>
Envoyé : mercredi 20 mars 2024 10:48
À : BOUCADAIR Mohamed INNOV/NET <[e-mail]<mailto:[e-mail]>>
Cc : Joe Clarke (jclarke) <[e-mail]<mailto:[e-mail]>>; Rob Wilton (rwilton) <[e-mail]<mailto:[e-mail]>>; [e-mail]<mailto:[e-mail]>
Objet : Re: [netconf] Pullback tcp-client-server also?

Hi Med,

Do you mean a list of “local-address + local-port” tuples?

Can you post a concrete proposal?

K.


On Mar 20, 2024, at 10:36 AM, [e-mail]<mailto:[e-mail]> wrote:

Re-,

This would address the first cases I mentioned, but not the third one.

At least some narrative text is needed to explain the intended use of distinct port per AF. A cleaner approach would to model this is as a list keyed per AF.

Cheers,
Med

De : Kent Watsen <[e-mail]<mailto:[e-mail]>>
Envoyé : mercredi 20 mars 2024 10:29
À : Joe Clarke (jclarke) <[e-mail]<mailto:[e-mail]>>
Cc : BOUCADAIR Mohamed INNOV/NET <[e-mail]<mailto:[e-mail]>>; Rob Wilton (rwilton) <[e-mail]<mailto:[e-mail]>>; [e-mail]<mailto:[e-mail]>
Objet : Re: [netconf] Pullback tcp-client-server also?

Thanks Med and Joe.  I had a sidebar with Rob and Mahesh, and we’re going to do this update in Auth48.

Let us (the WG) agree on the exact change.
  1) change ‘leaf’ to ‘leaf-list’
  2) tweak the ‘description’ to say that it’s a list

Anything else?  Do we need to disallow shadows?  (e.g., two wildcards)

K.


On Mar 20, 2024, at 9:02 AM, Joe Clarke (jclarke) <[e-mail]<mailto:[e-mail]>> wrote:

I agree with Med.  Your description is an either/or, but one server might do something like:

tcp46      0      0 *.9100                 *.*                    LISTEN <== Listen on all v4 and v6 addresses

Or:

tcp4       0      0 127.0.0.1.25           *.*                    LISTEN <==Listen on just v4 on an explicit address

Or:

tcp6       0      0 ::1.25   *.*                              LISTEN <== Listen on just v6 on an explicit address

In the first case, I’d think you’d at least need a leaf-list to hold both 0.0.0.0 and ::.  In the second two cases, you’d want this service to have a leaf list for 127.0.0.1 and ::1.

Joe

From: netconf <[e-mail]<mailto:[e-mail]>> on behalf [e-mail]<mailto:[e-mail]><[e-mail]<mailto:[e-mail]>>
Date: Tuesday, March 19, 2024 at 18:23
To: Kent Watsen <[e-mail]<mailto:[e-mail]>>, Rob Wilton (rwilton) <[e-mail]<mailto:[e-mail]>>
Cc: [e-mail]<mailto:[e-mail]> <[e-mail]<mailto:[e-mail]>>
Subject: Re: [netconf] Pullback tcp-client-server also?
Hi Kent, all,

When I initially raised the issue for the UDP grouping, I had in mind any, IPv4/IPv6 explicit address bindings, and eventually listening on distinct port numbers per AF. Given this is a reusable model, these cases should be all covered.

Cheers,
Med

De : netconf <[e-mail]<mailto:[e-mail]>> De la part deKent Watsen
Envoyé : mercredi 20 mars 2024 06:54
À : Rob Wilton <[e-mail]<mailto:[e-mail]>>
Cc : [e-mail]<mailto:[e-mail]>
Objet : [netconf] Pullback tcp-client-server also?

Rob, Netconf,

Regarding support for “dual-stack”, do we need to convert from a “leaf” to a “leaf-list”?

Please note that the existing text says that a wildcard card may be used to bind to all addresses:


leaf local-address {

      type inet:ip-address;

      mandatory true;

      description

        "The local IP address to listen on for incoming

         TCP client connections.  INADDR_ANY (0.0.0.0) or

         INADDR6_ANY (0:0:0:0:0:0:0:0 a.k.a. ::) MUST be

         used when the server is to listen on all IPv4 or

         IPv6 address.";

    }

Good enough?

Kent


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