Routing Optimization with SDN in Data Center Networks
draft-kong-sdnrg-routing-optimization-sdn-in-dc-04
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 | Qian Kong , Tao Gao , Dajiang Wang , Zhenyu Wang , Jiayu Wang, Bingli Guo , Shanguo Huang | ||
| Last updated | 2018-04-04 | ||
| 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-kong-sdnrg-routing-optimization-sdn-in-dc-04
Network Working Group A. Rousskov
Request for Comments: 4037 The Measurement Factory
Category: Standards Track March 2005
Open Pluggable Edge Services (OPES) Callout Protocol (OCP) Core
Status of This Memo
This document specifies an Internet standards track protocol for the
Internet community, and requests discussion and suggestions for
improvements. Please refer to the current edition of the "Internet
Official Protocol Standards" (STD 1) for the standardization state
and status of this protocol. Distribution of this memo is unlimited.
Copyright Notice
Copyright (C) The Internet Society (2005).
Abstract
This document specifies the core of the Open Pluggable Edge Services
(OPES) Callout Protocol (OCP). OCP marshals application messages
from other communication protocols: An OPES intermediary sends
original application messages to a callout server; the callout server
sends adapted application messages back to the processor. OCP is
designed with typical adaptation tasks in mind (e.g., virus and spam
management, language and format translation, message anonymization,
or advertisement manipulation). As defined in this document, the OCP
Core consists of application-agnostic mechanisms essential for
efficient support of typical adaptations.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1. Scope . . . . . . . . . . . . . . . . . . . . . . . . . 4
1.2. OPES Document Map . . . . . . . . . . . . . . . . . . . 5
1.3. Terminology . . . . . . . . . . . . . . . . . . . . . . 6
2. Overall Operation . . . . . . . . . . . . . . . . . . . . . . 7
2.1. Initialization . . . . . . . . . . . . . . . . . . . . . 7
2.2. Original Dataflow . . . . . . . . . . . . . . . . . . . 8
2.3. Adapted Dataflow . . . . . . . . . . . . . . . . . . . . 8
2.4. Multiple Application Messages . . . . . . . . . . . . . 9
2.5. Termination . . . . . . . . . . . . . . . . . . . . . . 9
2.6. Message Exchange Patterns . . . . . . . . . . . . . . . 9
2.7. Timeouts . . . . . . . . . . . . . . . . . . . . . . . . 10
2.8. Environment . . . . . . . . . . . . . . . . . . . . . . 11
3. Messages . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
Rousskov Standards Track [Page 1]
RFC 4037 OPES Callout Protocol Core March 2005
3.1. Message Format . . . . . . . . . . . . . . . . . . . . . 12
3.2. Message Rendering . . . . . . . . . . . . . . . . . . . 13
3.3. Message Examples . . . . . . . . . . . . . . . . . . . . 14
3.4. Message Names . . . . . . . . . . . . . . . . . . . . . 15
4. Transactions . . . . . . . . . . . . . . . . . . . . . . . . . 15
5. Invalid Input . . . . . . . . . . . . . . . . . . . . . . . . 16
6. Negotiation . . . . . . . . . . . . . . . . . . . . . . . . . 16
6.1. Negotiation Phase . . . . . . . . . . . . . . . . . . . 17
6.2. Negotiation Examples . . . . . . . . . . . . . . . . . . 18
7. 'Data Preservation' Optimization . . . . . . . . . . . . . . . 20
8. 'Premature Dataflow Termination' Optimizations . . . . . . . . 21
8.1. Original Dataflow . . . . . . . . . . . . . . . . . . . 22
8.2. Adapted Dataflow . . . . . . . . . . . . . . . . . . . . 23
8.3. Getting Out of the Loop . . . . . . . . . . . . . . . . 24
9. Protocol Element Type Declaration Mnemonic (PETDM) . . . . . . 25
9.1 Optional Parameters . . . . . . . . . . . . . . . . . 27
10. Message Parameter Types . . . . . . . . . . . . . . . . . . . 28
10.1. uri. . . . . . . . . . . . . . . . . . . . . . . . . . 28
10.2. uni. . . . . . . . . . . . . . . . . . . . . . . . . . 28
10.3. size . . . . . . . . . . . . . . . . . . . . . . . . . 29
10.4. offset . . . . . . . . . . . . . . . . . . . . . . . . 29
10.5. percent . . . . . . . . . . . . . . . . . . . . . . . 29
10.6. boolean. . . . . . . . . . . . . . . . . . . . . . . . 30
10.7. xid . . . . . . . . . . . . . . . . . . . . . . . . . 30
10.8. sg-id. . . . . . . . . . . . . . . . . . . . . . . . . 30
10.9. modp. . . . . . . . . . . . . . . . . . . . . . . . . 30
10.10. result. . . . . . . . . . . . . . . . . . . . . . . . 30
10.11. feature . . . . . . . . . . . . . . . . . . . . . . . 32
10.12. features. . . . . . . . . . . . . . . . . . . . . . . 32
10.13. service . . . . . . . . . . . . . . . . . . . . . . . 32
10.14. services. . . . . . . . . . . . . . . . . . . . . . . 33
10.15. Dataflow Specializations. . . . . . . . . . . . . . . 33
11. Message Definitions . . . . . . . . . . . . . . . . . . . . . 33
11.1. Connection Start (CS) . . . . . . . . . . . . . . . . 34
11.2. Connection End (CE) . . . . . . . . . . . . . . . . . 35
11.3. Service Group Created (SGC) . . . . . . . . . . . . . 35
11.4. Service Group Destroyed (SGD) . . . . . . . . . . . . 36
11.5. Transaction Start (TS). . . . . . . . . . . . . . . . 36
11.6. Transaction End (TE). . . . . . . . . . . . . . . . . 36
11.7. Application Message Start (AMS) . . . . . . . . . . . 37
11.8. Application Message End (AME) . . . . . . . . . . . . 37
11.9. Data Use Mine (DUM) . . . . . . . . . . . . . . . . . 38
11.10. Data Use Yours (DUY). . . . . . . . . . . . . . . . . 39
11.11. Data Preservation Interest (DPI). . . . . . . . . . . 39
11.12. Want Stop Receiving Data (DWSR) . . . . . . . . . . . 40
11.13. Want Stop Sending Data (DWSS) . . . . . . . . . . . . 41
11.14. Stop Sending Data (DSS) . . . . . . . . . . . . . . . 41
11.15. Want Data Paused (DWP). . . . . . . . . . . . . . . . 42
Rousskov Standards Track [Page 2]
RFC 4037 OPES Callout Protocol Core March 2005
11.16. Paused My Data (DPM). . . . . . . . . . . . . . . . . 43
11.17. Want More Data (DWM). . . . . . . . . . . . . . . . . 43
11.18. Negotiation Offer (NO). . . . . . . . . . . . . . . . 44
11.19. Negotiation Response (NR) . . . . . . . . . . . . . . 45
11.20. Ability Query (AQ). . . . . . . . . . . . . . . . . . 46
11.21. Ability Answer (AA) . . . . . . . . . . . . . . . . . 46
11.22. Progress Query (PQ) . . . . . . . . . . . . . . . . . 47
11.23. Progress Answer (PA). . . . . . . . . . . . . . . . . 47
11.24. Progress Report (PR). . . . . . . . . . . . . . . . . 48
12. IAB Considerations . . . . . . . . . . . . . . . . . . . . . 48
13. Security Considerations . . . . . . . . . . . . . . . . . . . 48
14. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 50
15. Compliance . . . . . . . . . . . . . . . . . . . . . . . . . 50
15.1. Extending OCP Core . . . . . . . . . . . . . . . . . . 51
A. Message Summary . . . . . . . . . . . . . . . . . . . . . . . 52
B. State Summary . . . . . . . . . . . . . . . . . . . . . . . 53
C. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 54
16. References . . . . . . . . . . . . . . . . . . . . . . . . . 54
16.1. Normative References . . . . . . . . . . . . . . . . . 54
16.2. Informative References . . . . . . . . . . . . . . . . 54
Author's Address. . . . . . . . . . . . . . . . . . . . . . . . . 55
Full Copyright Statement. . . . . . . . . . . . . . . . . . . . . 56
1. Introduction
The Open Pluggable Edge Services (OPES) architecture [RFC3835]
enables cooperative application services (OPES services) between a
data provider, a data consumer, and zero or more OPES processors.
The application services under consideration analyze and possibly
transform application-level messages exchanged between the data
provider and the data consumer.
The OPES processor can delegate the responsibility of service
execution by communicating with callout servers. As described in
[RFC3836], an OPES processor invokes and communicates with services
on a callout server by using an OPES callout protocol (OCP). This
document specifies the core of that protocol ("OCP Core").
The OCP Core specification documents general application-independent
protocol mechanisms. A separate series of documents describes
application-specific aspects of OCP. For example, "HTTP Adaptation
with OPES" [OPES-HTTP] describes, in part, how HTTP messages and HTTP
meta-information can be communicated over OCP.
Section 1.2 provides a brief overview of the entire OPES document
collection, including documents describing OPES use cases and
security threats.
Rousskov Standards Track [Page 3]
RFC 4037 OPES Callout Protocol Core March 2005
1.1. Scope
The OCP Core specification documents the behavior of OCP agents and
the requirements for OCP extensions. OCP Core does not contain
requirements or mechanisms specific for application protocols being
adapted.
As an application proxy, the OPES processor proxies a single
application protocol or converts from one application protocol to
another. At the same time, OPES processor may be an OCP client,
using OCP to facilitate adaptation of proxied messages at callout
servers. It is therefore natural to assume that an OPES processor
takes application messages being proxied, marshals them over OCP to
callout servers, and then puts the adaptation results back on the
wire. However, this assumption implies that OCP is applied directly
to application messages that OPES processor is proxying, which may
not be the case.
OPES processor scope callout server scope
+-----------------+ +-----------------+
| pre-processing | OCP scope | |
| +- - - - - - - - - - - - - - - - - - -+ |
| iteration | <== ( application data ) ==> | adaptation |
| +- - - - - - - - - - - - - - - - - - -+ |
| post-processing | | |
+-----------------+ +-----------------+
An OPES processor may preprocess (or postprocess) proxied application
messages before (or after) they are adapted at callout servers. For
example, a processor may take an HTTP response being proxied and pass
it as-is, along with metadata about the corresponding HTTP
connection. Another processor may take an HTTP response, extract its
body, and pass that body along with the content-encoding metadata.
Moreover, to perform adaptation, the OPES processor may execute
several callout services, iterating over several callout servers.
Such preprocessing, postprocessing, and iterations make it impossible
to rely on any specific relationship between application messages
being proxied and application messages being sent to a callout
service. Similarly, specific adaptation actions at the callout
server are outside OCP Core scope.
This specification does not define or require any specific
relationship among application messages being proxied by an OPES
processor and application messages being exchanged between an OPES
processor and a callout server via OCP. The OPES processor usually
provides some mapping among these application messages, but the
processor's specific actions are beyond OCP scope. In other words,
this specification is not concerned with the OPES processor role as
Rousskov Standards Track [Page 4]
RFC 4037 OPES Callout Protocol Core March 2005
an application proxy or as an iterator of callout services. The
scope of OCP Core is communication between a single OPES processor
and a single callout server.
Furthermore, an OPES processor may choose which proxied application
messages or information about them to send over OCP. All proxied
messages on all proxied connections (if connections are defined for a
given application protocol), everything on some connections, selected
proxied messages, or nothing might be sent over OCP to callout
servers. OPES processor and callout server state related to proxied
protocols can be relayed over OCP as application message metadata.
1.2. OPES Document Map
This document belongs to a large set of OPES specifications produced
by the IETF OPES Working Group. Familiarity with the overall OPES
approach and typical scenarios is often essential when one tries to
comprehend isolated OPES documents. This section provides an index
of OPES documents to assist the reader with finding "missing"
information.
o "OPES Use Cases and Deployment Scenarios" [RFC3752] describes a
set of services and applications that are considered in scope for
OPES and that have been used as a motivation and guidance in
designing the OPES architecture.
o The OPES architecture and common terminology are described in "An
Architecture for Open Pluggable Edge Services (OPES)" [RFC3835].
o "Policy, Authorization, and Enforcement Requirements of OPES"
[RFC3838] outlines requirements and assumptions on the policy
framework, without specifying concrete authorization and
enforcement methods.
o "Security Threats and Risks for OPES" [RFC3837] provides OPES risk
analysis, without recommending specific solutions.
o "OPES Treatment of IAB Considerations" [RFC3914] addresses all
architecture-level considerations expressed by the IETF Internet
Architecture Board (IAB) when the OPES WG was chartered.
o At the core of the OPES architecture are the OPES processor and
the callout server, two network elements that communicate with
each other via an OPES Callout Protocol (OCP). The requirements
for this protocol are discussed in "Requirements for OPES Callout
Protocols" [RFC3836].
Rousskov Standards Track [Page 5]
RFC 4037 OPES Callout Protocol Core March 2005
o This document specifies an application agnostic protocol core to
be used for the communication between an OPES processor and a
callout server.
o "OPES Entities and End Points Communications" [RFC3897] specifies
generic tracing and bypass mechanisms for OPES.
o The OCP Core and communications documents are independent from the
application protocol being adapted by OPES entities. Their
generic mechanisms have to be complemented by application-specific
profiles. "HTTP Adaptation with OPES" [OPES-HTTP] is such an
application profile for HTTP. It specifies how
application-agnostic OPES mechanisms are to be used and augmented
in order to support adaptation of HTTP messages.
o Finally, "P: Message Processing Language" [OPES-RULES] defines a
language for specifying what OPES adaptations (e.g., translation)
must be applied to what application messages (e.g., e-mail from
bob@example.com). P language is intended for configuring
application proxies (OPES processors).
1.3. Terminology
In this document, the keywords "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]. When used with the normative meanings, these keywords
will be all uppercase. Occurrences of these words in lowercase
constitute normal prose usage, with no normative implications.
The OPES processor works with messages from application protocols and
may relay information about those application messages to a callout
server. OCP is also an application protocol. Thus, protocol
elements such as "message", "connection", or "transaction" exist in
OCP and other application protocols. In this specification, all
references to elements from application protocols other than OCP are
used with an explicit "application" qualifier. References without
the "application" qualifier refer to OCP elements.
OCP message: A basic unit of communication between an OPES processor
and a callout server. The message is a sequence of octets
formatted according to syntax rules (section 3.1). Message
semantics is defined in section 11.
application message: An entity defined by OPES processor and callout
server negotiation. Usually, the negotiated definition would
match the definition from an application protocol (e.g., [RFC2616]
definition of an HTTP message).
Rousskov Standards Track [Page 6]
RFC 4037 OPES Callout Protocol Core March 2005
application message data: An opaque sequence of octets representing a
complete or partial application message. OCP Core does not
distinguish application message structures (if there are any).
Application message data may be empty.
data: Same as application message data.
original: Referring to an application message flowing from the OPES
processor to a callout server.
adapted: Referring to an application message flowing from an OPES
callout server to the OPES processor.
adaptation: Any kind of access by a callout server, including
modification, generation, and copying. For example, translating
or logging an SMTP message is adaptation of that application
message.
agent: The actor for a given communication protocol. The OPES
processor and callout server are OCP agents. An agent can be
referred to as a sender or receiver, depending on its actions in a
particular context.
immediate: Performing the specified action before reacting to new
incoming messages or sending any new messages unrelated to the
specified action.
OCP extension: A specification extending or adjusting this document
for adaptation of an application protocol (a.k.a., application
profile; e.g., [OPES-HTTP]), new OCP functionality (e.g.,
transport encryption and authentication), and/or new OCP Core
version.
2. Overall Operation
The OPES processor may use the OPES callout protocol (OCP) to
communicate with callout servers. Adaptation using callout services
is sometimes called "bump in the wire" architecture.
2.1. Initialization
The OPES processor establishes transport connections with callout
servers to exchange application messages with the callout server(s)
by using OCP. After a transport-layer connection (usually TCP/IP) is
established, communicating OCP agents exchange Connection Start (CS)
messages. Next, OCP features can be negotiated between the processor
and the callout server (see section 6). For example, OCP agents may
negotiate transport encryption and application message definition.
Rousskov Standards Track [Page 7]
RFC 4037 OPES Callout Protocol Core March 2005
When enough settings are negotiated, OCP agents may start exchanging
application messages.
OCP Core provides negotiation and other mechanisms for agents to
encrypt OCP connections and authenticate each other. OCP Core does
not require OCP connection encryption or agent authentication.
Application profiles and other OCP extensions may document and/or
require these and other security mechanisms. OCP is expected to be
used, in part, in closed environments where trust and privacy are
established by means external to OCP. Implementations are expected
to demand necessary security features via the OCP Core negotiation
mechanism, depending on agent configuration and environment.
2.2. Original Dataflow
When the OPES processor wants to adapt an application message, it
sends a Transaction Start (TS) message to initiate an OCP transaction
dedicated to that application message. The processor then sends an
Application Message Start (AMS) message to prepare the callout server
for application data that will follow. Once the application message
scope is established, application data can be sent to the callout
server by using Data Use Mine (DUM) and related OCP message(s). All
of these messages correspond to the original dataflow.
2.3. Adapted Dataflow
The callout server receives data and metadata sent by the OPES
processor (original dataflow). The callout server analyses metadata
and adapts data as it comes in. The server usually builds its
version of metadata and responds to the OPES processor with an
Application Message Start (AMS) message. Adapted application message
data can be sent next, using Data Use Mine (DUM) OCP message(s). The
application message is then announced to be "completed" or "closed"
by using an Application Message End (AME) message. The transaction
may be closed by using a Transaction End (TE) message, as well. All
these messages correspond to adapted data flow.
+---------------+ +-------+
| OPES | == (original data flow) ==> |callout|
| processor | <== (adapted data flow) === |server |
+---------------+ +-------+
The OPES processor receives the adapted application message sent by
the callout server. Other OPES processor actions specific to the
application message received are outside scope of this specification.
Rousskov Standards Track [Page 8]
RFC 4037 OPES Callout Protocol Core March 2005
2.4. Multiple Application Messages
OCP Core specifies a transactions interface dedicated to exchanging a
single original application message and a single adapted application
message. Some application protocols may require multiple adapted
versions for a single original application message or even multiple
original messages to be exchanged as a part of a single OCP
transaction. For example, a single original e-mail message may need
to be transformed into several e-mail messages, with one custom
message for each recipient.
OCP extensions MAY document mechanisms for exchanging multiple
original and/or multiple adapted application messages within a single
OCP transaction.
2.5. Termination
Either OCP agent can terminate application message delivery,
transaction, or connection by sending an appropriate OCP message.
Usually, the callout server terminates adapted application message
delivery and the transaction. Premature and abnormal terminations at
arbitrary times are supported. The termination message includes a
result description.
2.6. Message Exchange Patterns
In addition to messages carrying application data, OCP agents may
also exchange messages related to their configuration, state,
transport connections, application connections, etc. A callout
server may remove itself from the application message processing
loop. A single OPES processor can communicate with many callout
servers and vice versa. Though many OCP exchange patterns do not
follow a classic client-server model, it is possible to think of an
OPES processor as an "OCP client" and of a callout server as an "OCP
server". The OPES architecture document [RFC3835] describes
configuration possibilities.
The following informal rules illustrate relationships between
connections, transactions, OCP messages, and application messages:
o An OCP agent may communicate with multiple OCP agents. This is
outside the scope of this specification.
o An OPES processor may have multiple concurrent OCP connections to
a callout server. Communication over multiple OCP connections is
outside the scope of this specification.
Rousskov Standards Track [Page 9]
RFC 4037 OPES Callout Protocol Core March 2005
4. Data center interconnect
As shown in Fig.1, we employ the cascaded MEMS-switches. The inter-
cluster MEMS in the core is in charge of the communication between
ToRs in different clusters. Multiple SFPs and SCFDM transceivers are
implemented to realize the mixed transmission whose bandwidth demand
is either fixed grid or flexible grid. To provide flexible switching
functionality, we proposed the module named Mux/Demux & SSS which is
illustrated in Fig.2. Optical components such as coupler, Spectrum
Selective Switches (SSS), Arrayed Waveguide Grating (AWG), and
circulator are attached to a backplane to further increase the
flexibility of coping with different traffic demands. In Fig.2, the
symbol "@" represents a circulator which is a passive non-reciprocal
three-port device, and an optical signal entering any port is
transmitted to the next port in rotation(only). The coupler is a
passive device which is used to split and combine signals in the
optical network and can have multiple inputs and outputs. The SSS is
typical an 1xN optical component that can partition the spectrum of
input signal to different ports. The AWG is a passive data-rate
independent optical device that route each wavelength of an input to
a different output. Using this module, traffic can be deliberately
added and dropped through these components, and can be merged and
switched to the same destination together through AWG or coupler, and
also can be separated by SSS and switched to the different output
ports for purpose of realizing Multi-Input Multi-Output(MIMO)
switching. At the same time, each ToR has both SFP and SCFDM
transceivers which can realize fixed or flexible grid traffic
switching. Thus, each rack can communicate with multiple racks
simultaneous and high interconnect efficiency can be achieved as
arbitrary traffic inter or intra ToRs can be switched using fine
bandwidth rather than fixed grid bandwidth.
+----------------+ +----------------+ +----------------+
|Mux/Demux &SSS 1| |Mux/Demux &SSS 2| |Mux/Demux &SSS 3| ...
+----------------+ +----------------+ +----------------+
| | | | | | | | |
| | | | | | | | |
+----------------------------------------------------------------+
| Optical OXC |
+----------------------------------------------------------------+
| | | | | |
| | | | | |
+--------------+ +--------------+ +--------------+
| SFP|BV-TX/RX | | SFP|BV-TX/RX | | SFP|BV-TX/RX |
| ToR 1 | | ToR 2 | | ToR 3 |
+--------------+ +--------------+ +--------------+
Kong, et al. Expires October 08, 2018 [Page 5]
Internet-Draft Routing Optimization with SDN in DC Networks April 2018
Figure 1: Schematic of architecture in data center
+------------------------------------------------------------------+
| |
+------------------------------------------------------------------+
A A A A | | | |
+---|---------------------|--------|------|--------|--|--|-----|--+
| | V | | | | | | |
| | +--------------@ V | +---------+ | |
| | | +----------A--------@ V | AWG | | |
| | | | +-----|---------A------@ +---------+ | |
| | | | | | | A | | |
| | V V V | | | +--------+ |
| | +---------+ +---------------------+ |
| +-----| Coupler | | SSS | |
| +---------+ +---------------------+ |
+-----------------------------------------------------------------+
Figure 2: Mux/Demux &&& SSS
5. Traffic-Monitor based routing in data center networks
The proposed architecture which is based on SDN technology is shown
in Fig.3. Resource Computation Element (RCE) is responsible for
allocating available port resource to configure the backplane to
sever the new coming request based on the resource information
provided by the Resource Management Element (RME).RME storages all of
the port and spectrum information. Both RCE and RME are controlled by
a SDN controller. In particular, RCE can be implemented with certain
algorithm for routing and allocating spectrum optimally and RME can
also be configured by the SDN controller.
When a new traffic comes from ToRs, RCE inquiries the RME for the
available port resource and other information to compute the most
suitable route and allocate appropriate spectrum. If there is no
available resource for the moment, the request will be stored in the
buffer. The traffic monitor provides all the traffic request
information both come and in the buffer in order to evaluate the type
of the traffic, and then passes the information to RME to execute the
processing scheme which we will discuss about later.
Kong, et al. Expires October 08, 2018 [Page 6]
Internet-Draft Routing Optimization with SDN in DC Networks April 2018
After finishing computing the optimized route, the optical switching
module is configured through an agent to allocate appropriate
bandwidth for the request. With the implement of bandwidth variable
component and the capacity of both fixed and flexible grid switching,
the optical backplane can be ordered to allocate exactly appropriate
bandwidth for coming demands. As a consequence, the requests from the
ToRs are satisfied with the optimized route and high resource
utilizing.
+---------------------------------|-----------+
---+---+---+ | SDN controller |
+---> | | |----+-->+--------------+ +--------------+ |
| ---+---+---+ | | Resource |----->| Resource | |
| Buffer | | Computation | | Management | |
| ---+---+---+ | | Element |<-----| Element | |
| +-> | | |----+-->+--------------+ +--------------+ |
| | ---+---+---+ +----------A----------------------------------+
| | | |
| | | v
| | +--------------------+------+
| | +---------+ +----+ +-----+ | Agent|
| +--| Request |---->|ToRs|---->|Tx/Rx|-----> +------+------+------+
| +---------+ +----+ +-----+ | Optical |
| +---------+ +----+ +-----+ | Switching |
+----| Request |---->|ToRs|---->|Tx/Rx|-----> | Module |
+---------+ +----+ +-----+ +--------------------+
+------------+ A
| Traffic | |
| Monitor |----+
+------------+
Figure 3: Traffic Monitor implemented architecture
6. Dynamic traffic demand recognition scheme
With the implement of traffic monitor, the proposed architecture can
support the new switching requirements by executing dynamic traffic
demand recognition scheme through RME which is described above. We
monitor the traffic before they come, and evaluate the type of
traffic demand, and then allocate appropriate bandwidth according to
the request. When traffic comes, it is arbitrated by RME whether it
is a flexible grid signal to determine where it goes. A flexible grid
signal is transferred to the SCFDM transceiver and then arbitrated
whether it is intra-data center request. If it is, optical components
such as SSS and coupler will be placed to set or reuse connection.
Similarly, a fixed grid signal is transferred to SFP module and
arbitrated whether it is intra-cluster request to determine where it
Kong, et al. Expires October 08, 2018 [Page 7]
Internet-Draft Routing Optimization with SDN in DC Networks April 2018
will be transferred next step. Thus, bandwidth with fine granularity
can be allocated to satisfy the dynamic traffic demand in data center
network. For instance, mice flow can be served directly by being
modulated to SCFDM transmitter. At the meantime, elephant flow can
also be divided into fixed and flexible grid signal. Fixed grid
signal can be switched to the WDM SFP transceivers which support
2.5 Gbps and 10 Gbps transmission. Flexible grid traffic demand can
be served by the SCFDM transceivers. Such algorithm can allocate
optimized bandwidth to potential request. Thus, both mice and
elephant flow can be served by either using the already existing
connection or setup new route to avoid frequent configuration of the
optical backplane.
7. Security Considerations
Security in the communication between ToRs through Optical Backplane
in data center network is to be addressed. While the security of the
architecture described in this document greatly depends on the
security of communication mechanism itself such as communication
protocols, processing procedure and so on. However, the architecture
that implements the traffic monitor can improve the security of
switching in data center network by evaluating the type of coming
traffic.
8. IANA Considerations
This document includes no request to IANA.
9. Conclusions and Use Cases
Data centers have received more and more attention as a result of
increasing demand for storing and switching large volumes of data.
With the advantage of open programmatic interface and privacy of
operations, SDN tends to be applied to data center so as to improve
the spectrum efficiency and bandwidth utilizing.
This document describes an architecture where a traffic monitor is
implemented and bandwidth variable components are adopted. Due to the
capacity of monitoring the traffic before they come, we can evaluate
the type of the requests and inquires RME whose function is to store
all ports information whether they are occupied or released. Based on
obtained the available resource information from RME, RCE then
allocate appropriate bandwidth for the request which may be fixed or
flexible grid. Rather than allocating the bandwidth with rigid and
coarse granularity, the new switching requirements are supported to
satisfy the dynamic traffic demand in data center networks. As a
Kong, et al. Expires October 08, 2018 [Page 8]
Internet-Draft Routing Optimization with SDN in DC Networks April 2018
consequence, the spectrum efficiency is optimized and bandwidth
utilization is increased dramatically.
With the feature of switching traffic using both fixed and flexible
grid bandwidth, the proposed architecture can be well adopted in
various network structure especially in data center network. For
example, it can be accustomed to the scenario where data flow is big
and duration time is long such as data migration in the midnight, as
well as the scenario where data flow is slight and duration time is
short such as a Web request.
10. References
10.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
10.2. Informative References
[KT12] C. Kachris, and I. Tomkos, "A Survey on Optical Interconnects
for Data Centers," 2012.
Kong, et al. Expires October 08, 2018 [Page 9]
Internet-Draft Routing Optimization with SDN in DC Networks April 2018
Authors' Addresses
Qian Kong
Beijing University of Posts and Telecommunications
Email: kongqian@bupt.edu.cn
Tao Gao
Beijing University of Posts and Telecommunications
Email: taogao@bupt.edu.cn
Dajiang Wang
ZTE Corporation
Email: wang.dajiang@zte.com.cn
Zhenyu Wang
ZTE Corporation
Email: wang.zhenyu1@zte.com.cn
Jiayu Wang
ZTE Corporation
Email: wang.jiayu1@zte.com.cn
Bingli Guo
Beijing University of Posts and Telecommunications
Email: guobingli@bupt.edu.cn
Shanguo Huang
Beijing University of Posts and Telecommunications
Email: shghuang@bupt.edu.cn
Kong, et al. Expires October 08, 2018 [Page 10]