Internet DRAFT - draft-chen-opswg-nettunnel-model-considerations
draft-chen-opswg-nettunnel-model-considerations
Network Working Group X. Chen
Internet-Draft S. Zhuang
Intended status: Informational Huawei
Expires: April 21, 2016 October 19, 2015
Considerations on Layered Network Tunnel Service Model
draft-chen-opswg-nettunnel-model-considerations-00
Abstract
Tunnel is one typical service provided by carrier IP network.
Network Tunnel service model can provide the northbound interface of
network-level tunnel service of the controller to try to simplify the
Tunnel provision without involving too much details of Tunnel
implementation on the device. This document gives exploratory
description about the requirement of network-level Tunnel service and
how to define the data model which will provide the guidance for the
future definition of the concrete data model.
Requirements Language
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].
Status of This Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
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This Internet-Draft will expire on April 21, 2016.
Copyright Notice
Copyright (c) 2015 IETF Trust and the persons identified as the
document authors. All rights reserved.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Scope . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. Consideration of Tunnel Service Model . . . . . . . . . . . . 3
4. Network Tunnel Service Model . . . . . . . . . . . . . . . . 4
4.1. Overview . . . . . . . . . . . . . . . . . . . . . . . . 4
4.2. Design of Data Model . . . . . . . . . . . . . . . . . . 5
5. Network MPLS TE Tunnel Service Model . . . . . . . . . . . . 5
5.1. Overview . . . . . . . . . . . . . . . . . . . . . . . . 5
5.2. Design of Data Model . . . . . . . . . . . . . . . . . . 6
6. Network IP Tunnel Service Model . . . . . . . . . . . . . . . 7
7. Pre-configuration and Operational Data . . . . . . . . . . . 7
8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 8
9. Security Considerations . . . . . . . . . . . . . . . . . . . 8
10. References . . . . . . . . . . . . . . . . . . . . . . . . . 8
10.1. Normative References . . . . . . . . . . . . . . . . . . 8
10.2. References . . . . . . . . . . . . . . . . . . . . . . . 8
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 9
1. Introduction
Tunnel is one typical service provided by carrier IP network. The
network tunnel service model is defined to satisfy the common
requirement of most tunnel services. It's convenient for the
operators to set up the tunnel which serves for the network
applications without caring about the details of different types of
tunnels which are eventually setup in the network device. The
generic properties of the different tunnels and the properties which
the network-level tunnels need such as source address of the tunnel
are defined and such service model is referred to as network tunnel
service model.
Some tunnels can support traffic engineering such as bandwidth
assurance, setting up the tunnel according to the explicit path which
is specified by the user. The generic traffic engineering properties
are defined for the network-level applications and such service model
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is referred to as network MPLS TE tunnel service model. This service
model is based on the network tunnel service model.
This document introduces the description of northbound interface of
network-level tunnel service and give the pseudo data model tree to
explain the idea.
2. Scope
The network tunnel service model is defined to satisfy the common
requirement of most tunnel services. The network tunnel service
defined here is only based on Layer 3 topology and called L3 tunnel.
The tunnel will be used for carrying VPN service and the tunnel used
for IPv6 transition is not within the scope. Currently the
northbound interface of network tunnel service only includes the
point-to-point tunnel and in the future the model would include
point-to-multipoint and multipoint-to-multipoint tunnel to support
the multicast service.
The controller will process the network tunnel service model and
finally notify the network device to create the tunnel. The
configured network tunnels on the controller includes mainly IP
tunnel and MPLS TE tunnel. The LDP and SR-BE path which are able to
be created on network device can carry VPN service too. But such
tunnels are automatically set up according to the route and are not
necessary to set up by controller.
3. Consideration of Tunnel Service Model
The network tunnel service model is defined to satisfy the common
requirement of most tunnel services. It's convenient for the
operators to set up the tunnel which serves for the network
applications without caring about the details of different types of
tunnels which are eventually setup in the network device. Now there
are several device-level data models about tunnel are proposed in
IETF. I-D.zheng-intarea-gre-yang [I-D.zheng-intarea-gre-yang]
defines the data model of GRE tunnel. I-D.liu-rtgwg-ipipv4-tunnel-
yang [I-D.liu-rtgwg-ipipv4-tunnel-yang] defines the data model of IP
in IP tunnel. I-D.tran-ipecme-yang-ipsec
[I-D.tran-ipecme-yang-ipsec] defines the data model of IPsec tunnel.
I-D.ietf-teas-yang-te [I-D.ietf-teas-yang-te] defines the data model
of MPLS RSVP-TE tunnel. Different types of tunnels have specific
tunnel attributes and there are some generic attributes all of these
tunnels possess. The operators are normally interested in these
common attributes. The generic network tunnel data model is made up
of these common properties and the properties which the network-level
tunnels need like source address of the tunnel.
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In case of MPLS TE tunnel service the services of traffic engineering
include bandwidth assurance, setting up the tunnel according to the
explicit path which is specified by the user etc. The generic
traffic engineering properties are configured for the network-level
applications and the tunnel services which support traffic
engineering can be provided, There is the requirement of global
reoptimization of the network-level tunnels which means the network
usability can be increased by computing the new path for all the
tunnels and rebuilding the tunnels. Therefore the data model should
define the actions used by operator to trigger the progress of global
reoptimization. such data model is referred to as network MPLS TE
tunnel data model. This data model is based on the network tunnel
data model.
In case of IP tunnel service the common attributes has been defined
in network tunnel data model. If there are other generic specific
attributes for IP tunnel and how to define the generic network IP
tunnel data model should be discussed.
The relationship of the network tunnel data model, network MPLS TE
tunnel data model, network IP tunnel data model is shown in the
following figure:
+---------------------+
| network tunnel | o: augment
+---------------------+
o o
/ \
/ \
+------------------------+ +-------------------+
| network MPLS TE tunnel | | network IP tunnel |
+------------------------+ +-------------------+
Figure 1: Relationship of Network Tunnel Service Model,
Network MPLS TE Tunnel Model, Network IP Tunnel Model
4. Network Tunnel Service Model
4.1. Overview
When the operators use the tunnel service they normally only indicate
the addresses of both network devices to set up the tunnel. They
don't care about the specific tunnel technology. The controller has
internal or preconfigured policy to choose the proper specific tunnel
technology. The users may consider the tunnel is unidirectional or
bidirectional or the tunnel is IP tunnel or MPLS TE tunnel. If they
don't configure the controller creates unidirectional tunnel and the
MPLS TE tunnel by default. The default policy is implementation-
specific.
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The network tunnel data model is provided to users to customize their
requirement for tunnel services on the controller.
4.2. Design of Data Model
The configuration of network tunnel service model should include: the
tunnel name, the source and destination addresses, the type of tunnel
which indicates the tunnel is IP or MPLS TE, the direction indicator
of the tunnel which defines the tunnel is unidirectional or
bidirectional. The user can control the state of the tunnel by
manually to set the tunnel down . Different tunnel with the different
tunnel name can have the same pair of source and destination
addresses.
Following is a simplified tree representation of the data model for
generic network tunnel service configuration.
+--rw network-tunnel
+--rw p2p-network-tunnels
+--rw tunnel* [tunnel-name]
+--rw tunnel-name
+--rw tunnel-type
+--rw direction
+--rw admin-status?
+--rw source
+--rw destination
5. Network MPLS TE Tunnel Service Model
5.1. Overview
The operators often configure the following traffic engineering
attributes: bandwidth, the explicit-path, priority, color, protection
and different TE technology can support the common attributes. The
generic traffic engineering properties are configured for the
network-level applications by the network MPLS TE tunnel data model
on the controller. The network-level tunnel services configured on
the controller are supported by RSVP-TE tunnel, Segment-Routing TE
tunnel, static TE tunnel created on network device.
The requirement of global reoptimization of the network-level tunnels
is the network usability can be increased by computing the new path
for all the tunnels and rebuilding the tunnels. Sometimes the
operators require the reoptimization to specific tunnel. Therefore
the data model should define the actions used by operator to trigger
the progress of reoptimization.
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The network MPLS TE tunnel data model is based on the network tunnel
data model.
5.2. Design of Data Model
The configuration of network tunnel service model should include:
bandwidth of the tunnel, the explicit path which is made up of one or
more hops, priority where the tunnel the higher priority can be setup
and hold than lower priority, color which is defined by affinity, if
the end-to-end hotstandby protection is needed.
The rpc defines the global reoptimization and the reoptimization of
the specific tunnel.
Following is a simplified graphical representation of the data model
for generic MPLS TE tunnel service configuration.
module: network-te-tunnel
augment /network-tunnel/p2p-network-tunnels/tunnel:
+--rw te-tunnel-constraints
+--rw bandwidth?
+--rw priority?
+--rw affinities?
+--rw path-constraint?
| +--rw hop list?
| +--rw hop-limit?
+--rw hotstandby?
+--rw affinities?
+--rw path-constraint?
+--rw hop list?
+--rw hop-limit?
Following is a simplified graphical representation of the data model
for generic MPLS TE tunnel service rpc.
module: network-te-tunnel
augment /network-tunnel/p2p-network-tunnels/tunnel:
+---x reoptimization
| +--ro input
| +--ro if-reoptimization
+---x reoptimization-by-tunnel
| +--ro input
| +--ro tunnel-name
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6. Network IP Tunnel Service Model
The common attributes for IP tunnel service have been defined in
network tunnel data model. After the controller processes and
converts the network tunnel data model the controller can notify the
network device to create one specific type of IP tunnel. It's not
necessary for the operator to care about the details of different
types of IP tunnels which are eventually setup in the network device.
But if the operator would like to specify the more attributes of IP
tunnel by the northbound interface the network IP tunnel data model
is needed to be defined through augment of Network Tunnel Service
Model.
The different IP tunnel technology can be applied in different
application scenario such as MPLS in UDP used for load balance, GRE
used for load balance or security, IPsec used for security. Even for
the same usage of load balance, MPLS in UDP and GRE will adopt
different implementation parameters. Thus the IP tunnel attributes
to satisfy different uses are hard to be unified and maybe all IP
tunnel specific attributes have to be defined in the service model
which will deviate the rules of definition of service models. There
should be further discussion.
7. Pre-configuration and Operational Data
This document focuses on the design of the data model of the service
configuration which the business users care about. Actually system
administrators have to configure the pre-configuration data to help
the controller convert the network service configuration to the
device-level configuration. The typical of pre-configuration of
network Tunnel service models may provide the policy of the models
conversion and the resources used for conversion. For example the
network MPLS TE tunnel model can be implemented by RSVP-TE tunnel,
SR-TE tunnel, static CR-LSP. The pre-configuration can define the
policy to select the implementation mode for specific Network TE
Tunnel service model. On the other hand, when implement the network
TE Tunnel model with RSVP-TE tunnel, the tunnel ID of RSVP-TE tunnel
needs to be allocated dynamically by the controller. The pre-
configuration can define the resource pool of tunnel ID for
allocation.
It's challenging to define the operational data of network service
data model because the normal users and the system administrators
have different perspective. The business users maybe care only about
the limited maintenance information but the system administrators
need to know more details. For network MPLS TE tunnel model the
state and the path information of the tunnel maybe sufficient to the
business users but system administrators maybe need to know the type,
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tunnel identifier and specific attributes of the tunnel. There
should be further discussion.
8. IANA Considerations
This document makes no request of IANA.
9. Security Considerations
This document does not introduce new security threat.
10. References
10.1. 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>.
10.2. References
[I-D.ietf-teas-yang-te]
Saad, T., Gandhi, R., Liu, X., Beeram, V., Shah, H., Chen,
X., Jones, R., and B. Wen, "A YANG Data Model for Traffic
Engineering Tunnels and Interfaces", draft-ietf-teas-yang-
te-01 (work in progress), October 2015.
[I-D.liu-rtgwg-ipipv4-tunnel-yang]
Liu, Y. and A. Foldes, "Yang Data Model for IPIPv4
Tunnel", draft-liu-rtgwg-ipipv4-tunnel-yang-01 (work in
progress), July 2015.
[I-D.tran-ipecme-yang-ipsec]
Tran, K., "Yang Data Model for Internet Protocol Security
(IPSec)", draft-tran-ipecme-yang-ipsec-00 (work in
progress), May 2015.
[I-D.zheng-intarea-gre-yang]
Zheng, L., Pignataro, C., Penno, R., and Z. Wang, "Yang
Data Model for Generic Routing Encapsulation (GRE)",
draft-zheng-intarea-gre-yang-00 (work in progress), July
2015.
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Authors' Addresses
Xia Chen
Huawei
Huawei Bld., No.156 Beiqing Rd.
Beijing 100095
China
Email: jescia.chenxia@huawei.com
Shunwan Zhuang
Huawei
Huawei Bld., No.156 Beiqing Rd.
Beijing 100095
China
Email: zhuangshunwan@huawei.com
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