Internet DRAFT - draft-khc-spring-openflow-interworking-use-cases
draft-khc-spring-openflow-interworking-use-cases
SPRING WG F. Hu
Internet-Draft ZTE Corporation
Intended status: Informational B. Khasnabish
Expires: February 8, 2015 ZTE TX Inc.
H. Cankaya
Fujitsu
August 7, 2014
SPRING OpenFlow Interworking Use Cases
draft-khc-spring-openflow-interworking-use-cases-00.txt
Abstract
This draft discusses interworking (IW) of OpenFlow and Segment
routing. Several possible scenarios are introduced in this document.
We believe that such discussion and research are helpful for both
deployment/implementation and wider acceptance of the segment routing
technology.
Status of This Memo
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provisions of BCP 78 and BCP 79.
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This Internet-Draft will expire on February 8, 2015.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Conventions and Abbreviations . . . . . . . . . . . . . . . . 3
3. Data Center (DC) Inter-connection . . . . . . . . . . . . . . 3
4. OpenFlow Based WAN Control . . . . . . . . . . . . . . . . . 4
5. Interworking of OpenFlow and BGP Edge Routers . . . . . . . . 5
6. Implementation Examples . . . . . . . . . . . . . . . . . . . 6
7. High-Level Requirements . . . . . . . . . . . . . . . . . . . 6
8. Security Considerations . . . . . . . . . . . . . . . . . . . 6
9. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 6
10. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 6
11. Normative References . . . . . . . . . . . . . . . . . . . . 7
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 7
1. Introduction
Segment Routing (SR) leverages the source routing paradigm. An
ingress node steers a packet through a controlled set of
instructions, called segments, by pre-pending the packet with an SR
header. A segment can represent any instruction, topological or
service-based. A segment can have a local semantic to an SR node or
global within an SR domain. Segment Routing allows one to enforce a
flow through any topological path and service chaining while
maintaining per-flow state only at the ingress node to the Segment
Routing domain
The Segment Routing architecture is described in
([I-D.filsfils-rtgwg-segment-routing]) The Segment Routing control
plane is agnostic to the data plane, and hence it can be applied to
both MPLS (and its many variants) and IPv6.
OpenFlow is a communications protocol and open interface defined
between the control and forwarding layers([OpenFlow]). It allows
direct access to and manipulation of the forwarding plane of network
devices such as switches and routers, both physical and virtual
(hypervisor-based).
This document introduces several scenarios and discusses the
interworking between segment routing and openflow.
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2. Conventions and Abbreviations
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 [RFC2119].
3. Data Center (DC) Inter-connection
Modern day DCs are increasingly utilizing Openflow protocol now,
while the WAN network keeps maintaining the traditional IP/MPLS
network. Therefore, there exits a need for interworking between
OpenFlow and the traditional IP/MPLS network. This scenario
discusses how to control the inter-DC flow based on the SDN
architecture and segment routing technology.
As shown in Figure 1, the data center is controlled by one or several
OF controllers, and all the switches and routers support flow
forwarding. The switches and routers communicate with OF controller
by OpenFlow protocol. The router is the layer 3 gateway for that
data center. The IP/MPLS network between the data centers support
segment routing technology. The segment routing label stacks are
encapsulated in the edge routers of the data center.
The security app and Traffic Engineering app are the application
layer. They communicate with controller through north bound
interface. If there are some policies, such as TE App, or security
App and policy App for the inter-flow forwarding, the Apps download
the service decision to the controller to result into forwarding
instance, and the forwarding instances are downloaded to the gateway
router of the data center to or from the forwarding label stack.
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+--------------+ +-------------+ +-------------+
| TE App | |Security App | | Policy App |
+--------------+ +-------------+ +-------------+
.....................................................................................
+-------------+ +-------------+
|OF Controller| |OF Controller|
+------+------+ +------+------+
| |
................|..................................................|................
+---------------+--------------+ +-------------+---------------+
| | | |
| +-------+ | -------- | +-------+ |
| +---+ | Switch| | / \ | | Switch| +---+ |
| |VM | +-------+ +-------+ | / IP/MPLS \ | +-------+ +-------+ |VM | |
| +---+ | Router| ---|- ------------|---| | Router| +---+ |
| +-------+ | \ (Segment / | +-------+ |
| +-------+ | \Forwarding)/ | +-------+ |
| |Switch | | ---------- | |Switch | |
| +-------+ | | +-------+ |
| Data Center 1 | | Data Center 2 |
+------------------------------+ +-----------------------------+
Figure 1: Data Center Inter-connection
4. OpenFlow Based WAN Control
Figure 2 shows an SDN based WAN control scenario. The controller is
introduced to the WAN network. The controller should support an
externally visible Discovery Service and a Routing Service. The
Discovery Service is responsible for bootstrapping and configuring
the network, discovering node-capabilities, discovering and
maintaining the topology graph, providing statistics and
troubleshooting services and finally implementing an API for the
Routing Service as well as external requests. The Routing Service is
responsible for default routing on the configured network using
Segment Routing principles like Node Segments and ECMP. It should
also support capabilities allowing for Policy Routing, Traffic
Engineering and Steering.
The transit routers (Route 2 and Router 3) are only responsible for
MPLS label forwarding. The SR forwarding tables could be built by
the controller or the IGP protocols
([I-D.ietf-isis-segment-routing-extensions])
([I-D.ietf-ospf-segment-routing-extensions]).
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+-------+ +---------+ +----------+
|Routing| |Discovery| |Forwarding|
|Service| |Service | |Service |
+-------+ +---------+ +----------+
+--------------+
| Controller |
+--------------+ \
/ | | \ Control Plane
.............../......|.........|....\.................
/ +--V-----+ | \
/ |Router2 | | \
+--------++ +--------+ | +---------+
| Ingress | | | Router4 |
| Router1 | V +---------+
+---------+ +--------+
| Router3|
+--------+
Figure 2: SDN-Based WAN Control
5. Interworking of OpenFlow and BGP Edge Routers
There are four PEs, two of them (PE1 and PE3) support Openflow
protocol, and the other two(PE2 and PE4) support traditional BGP
protocol as shown in Figure 3. The routes on the PE2 and PE4 are
reflected to PE1 and PE3 through the BGP route reflector. For
unified control and interoperability the OF controller needs to
interpret the route control messages from the BGP route reflector/
controller, and vice versa. The details of the interface and the
messages that need to be exchanged between OF Controller and BGP
Route Reflector/Controller need to be determined (future work).
We introduce an OF controller in the network and an application layer
server. The Apps in the Server can have visibility to the routes
from BGP RR as the figure shows. This makes it feasible to export
the route to OF controller. The OF controller make its forwarding
decision based on the route exported from application and the
application policy. The forwarding decision is made of label stack
and downloaded to PE2 and PE4. The PE2 and PE3 are responsible for
the segment routing encapsulation as ingress routers.
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+------------+
| Application|
+------------+
/ \
................../.............\.........
/ \
+--------------+ +--------+
|OF Controller |-------------| BGP RR |
+--------------+ +--------+
| \ / |
..........|.........\...../...........|.....
| \/ |
+------+ / \ +------+|
| PE1 | / \ | PE3 ||
+------+ / \ +------+|
/ |
+-----+ / Traditional +-------+
| PE2 | / IP/MPLS network | PE4 |
+-----+ +-------+
Figure 3: Interworking of OpenFlow and BGP Edge Routers
6. Implementation Examples
We plan to discuss the high-level implementation options in a later
version of this draft or in a companion document.
7. High-Level Requirements
We note that the high-level requirements of SR OF interworking depend
on both the IW architecture and applications or services. A
companion draft will discuss these in details.
8. Security Considerations
We plan to discuss the security considerations in a later version of
this draft or in a companion document.
9. Acknowledgements
In progress.
10. IANA Considerations
We plan to discuss the IANA considerations in a later version of this
draft.
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11. Normative References
[I-D.filsfils-rtgwg-segment-routing]
Filsfils, C., Previdi, S., Bashandy, A., Decraene, B.,
Litkowski, S., Horneffer, M., Milojevic, I., Shakir, R.,
Ytti, S., Henderickx, W., Tantsura, J., and E. Crabbe,
"Segment Routing Architecture", draft-filsfils-rtgwg-
segment-routing-01 (work in progress), October 2013.
[I-D.ietf-isis-segment-routing-extensions]
Previdi, S., Filsfils, C., Bashandy, A., Gredler, H.,
Litkowski, S., Decraene, B., and J. Tantsura, "IS-IS
Extensions for Segment Routing", draft-ietf-isis-segment-
routing-extensions-02 (work in progress), June 2014.
[I-D.ietf-ospf-segment-routing-extensions]
Psenak, P., Previdi, S., Filsfils, C., Gredler, H.,
Shakir, R., Henderickx, W., and J. Tantsura, "OSPF
Extensions for Segment Routing", draft-ietf-ospf-segment-
routing-extensions-01 (work in progress), July 2014.
[OpenFlow]
"OpenFlow Switch Specification, Version 1.3.4", March
2014.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
Authors' Addresses
Fangwei Hu
ZTE Corporation
No.889 Bibo Rd
Shanghai 201203
China
Phone: +86 21 68897637
Email: hu.fangwei@zte.com.cn
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Bhumip Khasnabish
ZTE TX Inc.
55 Madison Avenue, Suite 160
Morristown, New Jersey 07960
USA
Phone: +001-781-752-8003
Email: bhumip.khasnabish@ztetx.com, vumip1@gmail.com
URI: http://tinyurl.com/bhumip/
Hakki Cankaya
Fujitsu
2801 Telecom Parkway
Richardson, Texas 75082
USA
Phone: +001-972-479-2592
Email: hakki.cankaya@us.fujitsu.com
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