Network Configuration Protocol (NETCONF) Proxy
draft-wangzheng-netconf-proxy-00
The information below is for an old version of the document.
| Document | Type |
This is an older version of an Internet-Draft whose latest revision state is "Expired".
|
|
|---|---|---|---|
| Authors | Zitao Wang , Guangying Zheng | ||
| Last updated | 2017-03-13 | ||
| RFC stream | (None) | ||
| Formats | |||
| Additional resources | |||
| Stream | Stream state | (No stream defined) | |
| Consensus boilerplate | Unknown | ||
| RFC Editor Note | (None) | ||
| IESG | IESG state | I-D Exists | |
| Telechat date | (None) | ||
| Responsible AD | (None) | ||
| Send notices to | (None) |
draft-wangzheng-netconf-proxy-00
NETCONF Working Group Z. Wang
Internet-Draft G. Zheng
Intended status: Standards Track Huawei Technologies
Expires: September 14, 2017 March 13, 2017
Network Configuration Protocol (NETCONF) Proxy
draft-wangzheng-netconf-proxy-00
Abstract
This document presents Network Configuration Protocol (NETCONF) Proxy
through which NETCONF requests can be forwarded to a target host. It
would be useful when a client does not have direct network access to
a target host.
Status of This Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet-
Drafts is at http://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress."
This Internet-Draft will expire on September 14, 2017.
Copyright Notice
Copyright (c) 2017 IETF Trust and the persons identified as the
document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents
(http://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents
carefully, as they describe your rights and restrictions with respect
to this document. Code Components extracted from this document must
include Simplified BSD License text as described in Section 4.e of
the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License.
Wang & Zheng Expires September 14, 2017 [Page 1]
Internet-Draft Netconf Proxy March 2017
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
1.1. Motivation . . . . . . . . . . . . . . . . . . . . . . . 2
1.2. Requirements Terminology . . . . . . . . . . . . . . . . 3
2. Solution Overview . . . . . . . . . . . . . . . . . . . . . . 3
3. The NETCONF Client . . . . . . . . . . . . . . . . . . . . . 5
4. The Proxy . . . . . . . . . . . . . . . . . . . . . . . . . . 6
5. The Target . . . . . . . . . . . . . . . . . . . . . . . . . 7
6. New attribute: target-id . . . . . . . . . . . . . . . . . . 8
7. YANG DATA MODEL . . . . . . . . . . . . . . . . . . . . . . . 8
7.1. Overview . . . . . . . . . . . . . . . . . . . . . . . . 8
7.2. YANG Module . . . . . . . . . . . . . . . . . . . . . . . 9
8. Security Considerations . . . . . . . . . . . . . . . . . . . 11
9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 11
10. Normative References . . . . . . . . . . . . . . . . . . . . 11
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 11
1. Introduction
This document proposes a NETCONF Proxy mechanism. The mechanism
extends the NETCONF protocol [RFC6241] which provides a standard way
to set up NETCONF session. At its core, the mechanism defined here
introduces a set of new operations which allow a client to forward
NETCONF requests to a target host through an intermediary NETCONF
proxy server, especially in case where client would otherwise not
have direct network access to a target host. The document also
includes YANG data model which extend the model and RPCs defined
within [RFC6241].
1.1. Motivation
NETCONF provide a RPC-based mechanism to facilitate communication
between a client and a server. The client can be a script or
application typically running as part of a network manager. The
server is typically a network device [RFC6241]. However, the network
manager may not have direct network access to the target network
devices. For example, some target network devices may locate in a
network with private addresses behind a NAT device or a firewall.
Thus, network manager cannot direct communicate with these target
devices.
NETCONF Call Home [RFC8071] provides a mechanism that allows NETCONF
Servers to initiate a connection with a NETCONF client, reversing the
normal direction of NETCONF session setup. This allows a NETCONF
Server, e.g. a networking device that needs to be managed, to reach
out to a NETCONF Client, e.g. an Operations Support System of an SDN
controller, in order to be managed. By reversing the direction in
Wang & Zheng Expires September 14, 2017 [Page 2]
Internet-Draft Netconf Proxy March 2017
which NETCONF sessions are normally set up, problems such as
establishing connectivity with devices behind a firewall can be
alleviated. However, NETCONF Call Home requires that the server
knows its client by way of configuration or discovery. It does not
address the scenarios as presented below:
1. In some NFV scenarios, VNF instances are running in a private
network. To reduce the management resources (like IP resources,
bandwidth, etc) of large-scale management activities, these VNF
instances may not be assigned IP addresses. Then the element
management system (EMS), which located in public network, cannot
be aware of the addresses of VNF instances. Therefore, the
element management system (EMS) is difficult to manage these VNF
instances via NETCONF protocol.
2. And in some cloud network scenarios, the gateway network element
(GNE) and non-gateway network elements (N-GNEs) communicate with
each other using some private protocol. And these non-gateway
network elements (N-GNEs) may not IP devices. Therefore, the
cloud centre EMS (element management system) cannot be aware of
the addresses of N-GENs. Thus, the element management system
(EMS) is difficult to manage these N-GNE devices via NETCONF
protocol.
To solve that problem, this document proposes a NETCONF Proxy
mechanism. The proxy can acts as an intermediary between manager and
target device, therefore the client can set up a NETCONF session to a
target through a NETCONF Proxy.
The mechanism allows the client to subsequently direct NETCONF
requests to the server, to receive responses, and to subscribe to
notifications from the server. While the NETCONF Proxy can be used
to traverse NAT boundaries, it should be noted that it does not apply
NAT mappings for contents carried as part of the NETCONF payload;
specifically, it does not substitute IP address information that is
carried as part of data nodes.
1.2. Requirements Terminology
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in RFC 2119 [RFC2119].
2. Solution Overview
The diagram below illustrates how the client can set up a NETCONF
session to a target through the NETCONF proxy.
Wang & Zheng Expires September 14, 2017 [Page 3]
Internet-Draft Netconf Proxy March 2017
client proxy target ID:A1
| | |
| | |
| <hello> | |
|<--------------------------->| |
| | |
| <get> | |
| <target-list> | |
|---------------------------->| |
| | |
|<----------------------------| |
| <reply target-list: | |
| targetID=A1, | |
| protocol, | |
| Authen...> | |
| | |
| <hello targetID="A1" > | |
|---------------------------->| |
| | authenticate & connect |
| |------------------------->|
| | |
| | <hello targetID="A1" > |
| |------------------------->|
| |<-------------------------|
|<----------------------------| |
| | |
| <rpc messageID="101" | |
|---------------------------->| |
| target="A1" | |
| xmlns="urn:xxxx"> | |
| <get-config> | |
This diagram makes the following points:
1. The client initiates the connection using the SSH/TLS transport
protocol. When the NETCONF session is established, the client
and proxy MUST send a <hello> element containing a list of that
peer's capabilities. The proxy SHOULD send at least the
"netconf" and "proxy" capabilities. And other rules of
capabilities exchange described in section 8 of [RFC6241].
2. The client sends a <get> RPC to proxy to retrieve the "target-
list" of the proxy.
3. The proxy responds with a <get-reply> RPC which containing
"target-list" attributes. The "target-list" attributes includes
Wang & Zheng Expires September 14, 2017 [Page 4]
Internet-Draft Netconf Proxy March 2017
the target's information such as target-id, protocol,
authentication, etc.
4. The client receive a <get-reply> RPC from the proxy, and looks up
the value of "target-list". Then the client constructs a <hello>
message according to the received "target-list". This <hello>
massage SHOULD contain at least a "target-id" attribute. And
then client sends this <hello> message to proxy and waits for a
reply.
5. The proxy receives the <hello> message and checks the value of
"target-id" attribute:
If the target is not found, then an "invalid-target" error
will be returned.
If the target can be found, then the proxy initiates a
connection to corresponding target. And then proxy forwards
the <hello> message, which received from client, to
corresponding target.
6. The target receives the <hello> message and then responds a
<hello> message containing a list of capabilities. The rules of
capabilities exchange described in section 8 of [RFC6241].
7. Now, client established a NETCONF session to a target through
NETCONF Proxy. Subsequently, the client can direct NETCONF
requests to the target, to receive responses, and to subscribe to
notifications from the target.
3. The NETCONF Client
The term "client" is defined in [RFC6241], Section 1.1 "client". In
the context of network management, the NETCONF client might be a
network management system for example a EMS (element management
system).
The client operation describes as follows:
1. The client initiates a connection to proxy using the SSH/TLS
transport protocol [RFC6242]. How to establish an SSH/TLS transport
connection is described in [RFC6242]
2. When the NETCONF session is established, the client sends a
<hello> message to proxy, then waits for a reply. This <hello>
message contains a list of client's capabilities.
Wang & Zheng Expires September 14, 2017 [Page 5]
Internet-Draft Netconf Proxy March 2017
3. After capabilities exchange, the client sends a <get> RPC to
proxy to retrieve the "target-list" of the proxy, then waits for a
reply.
4. The client receive a <get-reply> RPC from the proxy, looks up the
value of "target-list", and then constructs a <hello> message
according to the received "target-list". This <hello> massage SHOULD
contain at least a "target-id" attribute. For example, if the client
received "target-list" containing "target-id=A1", then the client
constructs <hello> message:
C: <hello xmlns="urn:ietf:params:xml:ns:netconf:base:1.0">
C: <target-id>A1</target-id>
C: <capability>foo<capability>
C: </hello>
And then client sends this <hello> message to proxy and waits for a
reply.
5. If the reply presents the "capabilities" of target, the proxy
connection is established. Subsequently, the client can direct
NETCONF requests to the target, to receive responses, and to
subscribe to notifications from the target.
6. If the reply contains the "invalid-target" error, the process
turn to step (4) or aborts.
7. Otherwise, the client interprets the error and aborts.
4. The Proxy
The Proxy should ensure that requests given by client for a
particular target device should reach the target device and the
operations should be executed on that target device and the response
should be given back to the client.
The proxy operation describes as follows:
1. When the NETCONF session is established, the proxy sends a
<hello> element containing a list of proxy's capabilities. The proxy
SHOULD send at least the "netconf" and "proxy" capabilities. And
other rules of capabilities exchange described in section 8 of
[RFC6242].
Wang & Zheng Expires September 14, 2017 [Page 6]
Internet-Draft Netconf Proxy March 2017
2. The proxy receives the <get> RPC and then responds with a <get-
reply> RPC which containing "target-list" attributes. The "target-
list" attributes SHOULD includes the target's information such as
target-id, protocol, authentication, etc. The following example
shows a "target-list":
<target-list>
<target-id>A1</target-id>
<protocol>protocol-foo</protocol>
<authentication>authentication-foo</authentication>
</target-list>
3. The proxy receives the <hello> message and checks the value of
"target-id" attribute:
If the target is not found in target-list, then an "invalid-
target" error will be returned.
If the target can be found in target-list, the proxy checks the
corresponding "protocol" and "authentication" of the "target-id".
And then, the proxy uses corresponding protocol to establish a
connection to the target. After session established, the proxy
forwards the <hello> message, which received from client, to
corresponding target.
4. If the reply presents the "capabilities" of target, the proxy
connection is established. Subsequently, the proxy transports the
messages received from the client to the target and vice versa.
5. The Target
The term "target" is equivalent to the term "server" which is defined
in [RFC6242], Section 1.1 "server". In the context of network
management, the target is typically a network device.
The target operations describes as follows:
1. If the connection between the proxy and the target established.
And target receives the <hello> message from the proxy, and then
responds a <hello> message containing a list of capabilities. The
rules of capabilities exchange described in section 8 of [RFC6242].
2. After client established a NETCONF session to a target through
NETCONF Proxy. The client sends a series of one or more RPC request
messages, which cause the server to respond with a corresponding
series of RPC reply messages.
Wang & Zheng Expires September 14, 2017 [Page 7]
Internet-Draft Netconf Proxy March 2017
6. New attribute: target-id
A proxy can be used by a client to connect to several servers and to
maintain multiple NETCONF sessions. A client may use the proxy even
to maintain multiple NETCONF sessions with the same NETCONF server.
When issuing a NETCONF request, a client must therefore differentiate
between NETCONF sessions. To solve this problem, a new attribute
"target-id" is defined. This attribute allow the proxy to forward
RPC to corresponding target.
For example:
The following <rpc> element invokes the NETCONF <get> method and
includes the "target-id" attribute:
<rpc message-id="101"
target-id="A1"
xmlns="urn:ietf:params:xml:ns:netconf:base:1.0">
<get/>
</rpc>
<rpc-reply message-id="101"
target-id="A1"
xmlns="urn:ietf:params:xml:ns:netconf:base:1.0">
<data>
<!-- contents here... -->
</data>
</rpc-reply>
7. YANG DATA MODEL
7.1. Overview
The YANG data model for NETCONF Proxy is depicted in the following
figure. Following Yang tree convention in the depiction, brackets
enclose list keys, "rw" means configuration, "ro" operational state
data, "?" designates optional nodes, "*" designates nodes that can
have multiple instances. A "+" at the end of a line indicates that
the line is to be concatenated with the subsequent line.
Wang & Zheng Expires September 14, 2017 [Page 8]
Internet-Draft Netconf Proxy March 2017
module: ietf-netconf-proxy
+--rw proxy {proxy}?
+--rw proxy-name? string
+--rw target-list* [target-id]
+--rw target-id string
+--rw protocol? string
+--rw authentication? string
7.2. YANG Module
<CODE BEGINS> file "ietf-netconf-proxy@2017-03-09.yang"
module ietf-netconf-proxy {
namespace "urn:ietf:params:xml:ns:yang:ietf-netconf-proxy";
prefix np;
organization
"IETF NETCONF (Network Configuration) Working Group";
contact
"WG Web: http://tools.ietf.org/wg/netconf
WG List: netconf@ietf.org
WG Chair: Mehmet Ersue
mehmet.ersue@nsn.com
Editor: zitao wang
wangzitao@huawei.com";
description
"NETCONF Protocol Data Types and Protocol Operations.
Copyright (c) 2011 IETF Trust and the persons identified as
the document authors. All rights reserved.
Redistribution and use in source and binary forms, with or
without modification, is permitted pursuant to, and subject
to the license terms contained in, the Simplified BSD License
set forth in Section 4.c of the IETF Trust's Legal Provisions
Relating to IETF Documents
(http://trustee.ietf.org/license-info).
This YANG module describe how to define a netconf proxy";
revision 2017-03-09 {
description
Wang & Zheng Expires September 14, 2017 [Page 9]
Internet-Draft Netconf Proxy March 2017
"Initial revision";
reference
"draft-wang-netconf-proxy";
}
feature proxy {
description
"Netconf proxy";
}
container proxy {
if-feature proxy;
leaf proxy-name{
type string;
description
"Proxy name";
}
list target-list {
key "target-id";
leaf target-id{
type string;
description
"Target ID";
}
leaf protocol {
type string;
description
"Support protocols";
}
leaf authentication {
type string;
description
"Authentication";
}
description
"List for target information";
}
description
"Container for NETCONF Proxy";
}
}
<CODE ENDS>
Wang & Zheng Expires September 14, 2017 [Page 10]
Internet-Draft Netconf Proxy March 2017
8. Security Considerations
The security considerations described in [RFC6242] and [RFC7589], and
by extension [RFC4253], [RFC5246] apply here as well.
9. IANA Considerations
TBD
10. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<http://www.rfc-editor.org/info/rfc2119>.
[RFC4253] Ylonen, T. and C. Lonvick, Ed., "The Secure Shell (SSH)
Transport Layer Protocol", RFC 4253, DOI 10.17487/RFC4253,
January 2006, <http://www.rfc-editor.org/info/rfc4253>.
[RFC5246] Dierks, T. and E. Rescorla, "The Transport Layer Security
(TLS) Protocol Version 1.2", RFC 5246,
DOI 10.17487/RFC5246, August 2008,
<http://www.rfc-editor.org/info/rfc5246>.
[RFC6241] Enns, R., Ed., Bjorklund, M., Ed., Schoenwaelder, J., Ed.,
and A. Bierman, Ed., "Network Configuration Protocol
(NETCONF)", RFC 6241, DOI 10.17487/RFC6241, June 2011,
<http://www.rfc-editor.org/info/rfc6241>.
[RFC6242] Wasserman, M., "Using the NETCONF Protocol over Secure
Shell (SSH)", RFC 6242, DOI 10.17487/RFC6242, June 2011,
<http://www.rfc-editor.org/info/rfc6242>.
[RFC7589] Badra, M., Luchuk, A., and J. Schoenwaelder, "Using the
NETCONF Protocol over Transport Layer Security (TLS) with
Mutual X.509 Authentication", RFC 7589,
DOI 10.17487/RFC7589, June 2015,
<http://www.rfc-editor.org/info/rfc7589>.
[RFC793] Postel, J., "TRANSMISSION CONTROL PROTOCOL", STD 7,
September 1981, <https://www.ietf.org/rfc/rfc793.txt>.
Authors' Addresses
Wang & Zheng Expires September 14, 2017 [Page 11]
Internet-Draft Netconf Proxy March 2017
Zitao Wang
Huawei Technologies
101 Software Avenue, Yuhua District
Nanjing
China
EMail: wangzitao@huawei.com
Guangying Zheng
Huawei Technologies
101 Software Avenue, Yuhua District
Nanjing
China
EMail: zhengguangying@huawei.com
Wang & Zheng Expires September 14, 2017 [Page 12]