Internet DRAFT - draft-penno-pcp-asdn
draft-penno-pcp-asdn
Network Working Group R. Penno
Internet-Draft T. Reddy
Intended status: Standards Track Cisco Systems, Inc.
Expires: April 02, 2014 M. Boucadair
France Telecom
D. Wing
Cisco
S. Vinapamula
Juniper Networks, Inc.
September 29, 2013
Application Enabled SDN (A-SDN)
draft-penno-pcp-asdn-00
Abstract
To allow traversal of firewalls or provide additional network
services such as QoS or supplemental bandwidth, it is necessary to
deploy application-aware network elements. Such network elements are
costly to create, deploy, and are unable to adequately cope with
changes to the application itself, stifling innovation.
This document describes a different approach, where the application
explicitly signals its needs to the network.
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.
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 April 02, 2014.
Penno, et al. Expires April 02, 2014 [Page 1]
Internet-Draft A-SDN September 2013
Copyright Notice
Copyright (c) 2013 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.
Table of Contents
1. Problem Statement . . . . . . . . . . . . . . . . . . . . . . 2
2. Scope . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. Proposed Approach . . . . . . . . . . . . . . . . . . . . . . 4
4. Protocols . . . . . . . . . . . . . . . . . . . . . . . . . . 6
5. A-SDN Flows . . . . . . . . . . . . . . . . . . . . . . . . . 6
5.1. Signaling Prior to Flow Creation . . . . . . . . . . . . 7
5.2. Signaling After Flow Creation . . . . . . . . . . . . . . 8
5.3. Flow Removal Event . . . . . . . . . . . . . . . . . . . 8
5.4. Flow Modification . . . . . . . . . . . . . . . . . . . . 8
6. Use Cases . . . . . . . . . . . . . . . . . . . . . . . . . . 8
6.1. Flow Prioritization . . . . . . . . . . . . . . . . . . . 8
6.2. Flow High availability . . . . . . . . . . . . . . . . . 9
6.3. On-demand Bandwidth . . . . . . . . . . . . . . . . . . . 9
6.4. Analytics and Reporting . . . . . . . . . . . . . . . . . 9
7. Security Considerations . . . . . . . . . . . . . . . . . . . 9
8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 9
9. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 9
10. References . . . . . . . . . . . . . . . . . . . . . . . . . 10
10.1. Normative References . . . . . . . . . . . . . . . . . . 10
10.2. Informative References . . . . . . . . . . . . . . . . . 10
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 11
1. Problem Statement
In the context of ongoing efforts to add more automation and promote
means to dynamically interact with network resources (e.g., SDN-
labeled efforts) [I-D.sin-sdnrg-sdn-approach], various proposals are
made to accommodate the needs of Network Providers to program the
network with flow information and its associated metadata in order to
apply policies such as traffic prioritization.
Penno, et al. Expires April 02, 2014 [Page 2]
Internet-Draft A-SDN September 2013
Usually this programming is driven by a (centralized) controller that
gather flow-related information and associated metadata through an
army of probes, receiving a copy of the first packets of the flow, or
even having to be on-path for the first few packets of the flow but
not necessarily subsequent packets. But most of observed flows in
current usages are dynamic, time-bound (short lived for some of
them), possibly encrypted, peer-to-peer, possibly asymmetric, and
might have different priorities depending on network conditions,
direction, time of the day, and other factors.
This means that hairpinning of packets through a controller, deep
packet inspection, and other similar static methods such as portals
cannot be employed successfully to glean flow and metadata
information, and subsequently program the network. Therefore new
methods must be devised.
Unlike network-centric techniques, this document proposed an approach
which involved hosts and applications.
2. Scope
Considerations related to dynamic network provisioning negotiation
are out of scope. The reader can refer to
[I-D.boucadair-connectivity-provisioning-protocol] for more details.
The proposed architecture is not a replacement to existing legacy
techniques. It is an enhancement to existing network infrastructure
and service infrastructure than can be empowered by new features to
better accommodate application-specific needs while network and
services resources are also optimized and better partitioned.
This document does not propose to update all existing/future
applications to signal their network resources requirements; only a
subset of applications having specific connectivity requirements and
which require differentiated treatment at the network side are
expected to be updated to support the framework defined in this
document.
This document does not require an end-to-end signalling before actual
invocation of a service.
This document does not make any assumption on how differentiated
connectivity is delivered to end users. It is up to each
administrative entity managing a network to enforce its own
engineering policies, techniques and protocols. Note, differentiated
connectivity services can be provided by one or a combination of
several dimension (forwarding, routing, resources management). It is
out of scope of this document to elaborate on such aspects.
Penno, et al. Expires April 02, 2014 [Page 3]
Internet-Draft A-SDN September 2013
3. Proposed Approach
In order to offer more automation and dynamicity in resource usage
and invocation, this document proposes an architecture that is
composed of three parts:
1. Applications running on the end points (UEs, Server at a Data
Centers, CPE routers) must communicate or install flow and
associated metadata on network Elements. Means to discover such
Network Elements may be supported.
2. On the network side, a PDP (Policy Decision Point, [RFC2753]) is
responsible for orchestrating resources, generating policies and
trigger provisioning-related operations.
3. The PDP configures the on-path devices to accommodate the
signaled flow (e.g., open pinhole in the firewall, provide
prioritized network services for the flow).
The diagram below depicts the general architecture and message flow
for the Application-Enabled SDN (A-SDN).
Controller
+---------------+
| PDP |
. __ . __ . __ . __ . __ . __ . | |
| | ________ |
. | |REST | |
| +----------->|Server | |
. Flow | 2 | '--------' |
| Install | +-----.---------+
. Req | |
3| | 3 . Flow
. | | Install
| +------------|------+ .
. | Middlebox | |
________ | | _________________ | ____v____ _________
| | ____v___ || |I|REST || | Router | ... | Router |
| Client |..|Switch |....|| Server|W|Client || | Switch | | Switch |
+--------+ | | || |F| || '---------' '---------'
. '-------' |+-----------------+|
. +-------------------+
. ^
. .
. 1 .
.. . . . . . . . . . . . . . .
SDN signaling
Penno, et al. Expires April 02, 2014 [Page 4]
Internet-Draft A-SDN September 2013
Request (Flow + Metadata)
.... e.g., PCP
---- e.g., REST
-.-. e.g., COPS-PR, Netconf, Openflow
A middlebox could be a CPE router, edge router, switch, wireless
access LAN controller, mobile gateway in 3GPP networks [RFC6459], or
any other flow-aware device.
This architecture provides several advantages such as:
o Host driven: The host (or application) is responsible for
requesting proper flows and associated metadata based on each
individual application needs. These needs may be time variant,
and driven by processes only understood by the applications (or
their users). The end host is the only entity in the system that
has all of the information required to make the correct service
request . This approach is compliant with requirements specific
to encrypted and multi-party flows.
o Network Authorization: If network access control is required, then
the host could also get authorization from the Application Server
trusted by the network in order to install flows and associated
actions (e.g., policies). The Application Server could be
deployed in a third party network. This is important for networks
which do not trust the host.
o Immediate incremental value for endpoints and applications: If,
for example, a CPE router that supports this architecture is
installed, applications could signal flow characteristics to the
network on both directions, traffic prioritization, firewall
pinholes and other services without changing the rest of the
network. Meaning, although steps 2 and 3 of the picture above
provide important end-to-end additional value they are not
necessary for end-to-edge.
o Access agnostic: An application should not care if it is on an
ADSL, Cable, Wi-Fi, 3G, Ethernet or other network type.
o Works across administrative domains: Home Network -> ISP1. Home
Network communicates with ISP1 using PCP.
o NAT and firewall aware: The flow information fed into the PDP will
have pre and post NAT information, allowing provisioning using
scoped IP addresses.
Penno, et al. Expires April 02, 2014 [Page 5]
Internet-Draft A-SDN September 2013
o Extensible: Client protocol can be extended to provide a wide
range of flow associated metadata.
o Multi-interface support: Based on network conditions clients can
switch from a Wi-Fi to a 3G interface, or install flows over
certain paths
4. Protocols
The first element of this architecture could be met by using the Port
Control Protocol (PCP) [RFC6887]. Indeed, PCP Flow Extension
[I-D.wing-pcp-flowdata] allows a PCP Client, usually a host, to
signal flow characteristics to the network, and the network to signal
its ability to accommodate that flow back to the host.
For example, a video streaming client knowing the address of the
remote server can request the required flow characteristics; for
example N-Mbps of upstream bandwidth, M-Mbps of downstream bandwidth,
low-latency, low-jitter etc. The network authorizes the request and
signals back to the host that it can (fully or partially) accommodate
the flow.
The second element of this architecture requires a protocol that has
built-in primitives for reliable near-real-time messages and,
ideally, sharing of information about network availability between
the network device and PDP. This element can be met by using REST,
Extensible Messaging and Presence Protocol (XMPP) [RFC6120] or
similar protocol.
Finally, the PDP should be able to install flows in routers or
switches and assign them a series of actions, modify flow actions,
collect statistics, or (more importantly) extend the provisioning of
these flows end-to-end. This third element of the architecture can
be met by using any of several flow provisioning protocols as part of
the PDP:
o PCP with the THIRD_PARTY option
o Netconf [RFC6241], COPS-PR [RFC3084] , or any similar protocol.
This document does not make any assumption on that interface.
5. A-SDN Flows
+---------------+
| PDP |
. __ . __ . __ . __ . __ . __ . | |
| | ________ |
. | |REST | |
Penno, et al. Expires April 02, 2014 [Page 6]
Internet-Draft A-SDN September 2013
| +----------->|Server | |
. Flow | 2 | '--------' |
| Install | +-----.---------+
. Req | |
3| | 3 . Flow
. | | Install
| +------------|------+ .
. | Middlebox | |
________ | | _________________ | ____v____ _________
| PCP | ____v___ || PCP |I|REST || | Router | ... | Router |
| Client |..|Switch |....|| Server|W|Client || | Switch | | Switch |
+--------+ | | || |F| || '---------' '---------'
. '-------' |+-----------------+|
. +-------------------+
. ^
. .
. 1 .
.. . . . . . . . . . . . . . .
PCP PEER
Req
.... PCP Message
---- REST Messages
-.-. Netconf, COPS, etc.
5.1. Signaling Prior to Flow Creation
When an end host installs a flow in the middlebox through a PCP
message a REST API call is made to the PDP. This message will carry
the following information:
o Match condition: e.g., source/destination IP, source/destination
port, L4 Protocol, Port, VLAN Id etc.
o Metadata: e.g., metadata conveyed in PCP FLOWDATA option.
o Lifetime: e.g., lifetime in PCP response will be mapped to
idle_timeout and hard_timeout will be set to zero for the flow
entry. (idle_timeout and hard_timeout are defined in OpenFlow
switching protocol). This way PCP client is aware when the flow
entry will be removed.
The PDP uses an appropriate protocol (e.g., netconf, COPS-PR,
Openflow, etc.) to add/delete and modify flows and its metadata. For
example Openflow controller using Openflow protocol version 1.3
[OpenFlow] would get the information of configured queues and
Penno, et al. Expires April 02, 2014 [Page 7]
Internet-Draft A-SDN September 2013
associated property of each queue. The Openflow controller will
either associate the flow with relevant queue or instruct the
openflow-enabled network device to rewrite the DifServ CodePoint bits
for the flow based on the metadata in REST message.
5.2. Signaling After Flow Creation
The application can create a implicit flow normally as with a TCP
connection and later decide that it needs to modify it, for example,
extending its lifetime or associating metadata such as bandwidth,
delay, jitter, loss.
The mechanism is very similar to flow creation but does not require a
pre-signaling step.
5.3. Flow Removal Event
When a application-driven flow times out or is explicitly deleted, a
REST API call is generated in the case the controller wants to be
notified. This allows the PDP to delete the flow from other devices
in the network.
The PDP could also decide on its own to remove the installed flow.
In this case a PCP unsolicited response will be sent to the PCP
Client owner of such flow.
5.4. Flow Modification
After the PDP is notified of a flow creation, it can decide to modify
its metadata. In order to do that the controller will send modify
flow message through the appropriate protocol.
If the PDP succeeds in modifying a flow, a PCP unsolicited response
will be sent to the PCP Client owner of such flow.
6. Use Cases
This section describes some use-cases in which A-SDNs can be
beneficial.
6.1. Flow Prioritization
A video streaming client that wants to have a low loss, medium delay
service signals these flow characteristics in PCP FLOWDATA option.
PCP server would convey this metadata to a PDP which would in turn
add flow entry with inbound DSCP AF32 on SDN-enabled network devices.
Penno, et al. Expires April 02, 2014 [Page 8]
Internet-Draft A-SDN September 2013
Packets matching this flow will be marked AF32 and internally put in
an appropriate queue. More importantly, video packets should be
marked as close as possible to the source.
6.2. Flow High availability
One of the ways for the PCP Server to determine that the flows are
for business critical application is by using third party
authorization. A PCP server for such flows will checkpoint all the
state associated for such flows on the corresponding backup of active
for high availability. At a high level, this authorization works by
the PCP client first obtaining a cryptographic token from the
authorizing network element (e.g., call controller) and includes that
token in the PCP request. The PCP server in the network validates
the token and grants access.
6.3. On-demand Bandwidth
In managed or unmanaged services deployments an enterprise many times
needs more bandwidth for the entire link (all flows) or just some
specific applications. Moreover, it does not need those permanently
but just for a certain period of time. In this case the branch
router can dynamically request this service from the network,
streamlining service activation and modification.
6.4. Analytics and Reporting
Authorized applications within data centers and enterprises can
attach metadata such as media-type, application-id and group to the
flows which allows for ease and streamlined analytics and reporting
without deep packet inspection.
7. Security Considerations
Security considerations in [RFC6887] and PCP Authentication
[I-D.ietf-pcp-authentication] may need to be taken into account. For
REST mutual authentication is required and TLS could be used for
message integrity. Security-related consideration for the protocol
enabled between the PDP and underlying nodes are discussed in
[RFC6241] [RFC3084].
8. IANA Considerations
This document does not require any action from IANA.
9. Acknowledgments
TODO.
Penno, et al. Expires April 02, 2014 [Page 9]
Internet-Draft A-SDN September 2013
10. References
10.1. Normative References
[I-D.wing-pcp-flowdata]
Wing, D., Penno, R., and T. Reddy, "PCP Flowdata Option",
draft-wing-pcp-flowdata-00 (work in progress), July 2013.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC6120] Saint-Andre, P., "Extensible Messaging and Presence
Protocol (XMPP): Core", RFC 6120, March 2011.
[RFC6887] Wing, D., Cheshire, S., Boucadair, M., Penno, R., and P.
Selkirk, "Port Control Protocol (PCP)", RFC 6887, April
2013.
10.2. Informative References
[I-D.boucadair-connectivity-provisioning-protocol]
Boucadair, M. and C. Jacquenet, "Connectivity Provisioning
Negotiation Protocol (CPNP)", draft-boucadair-
connectivity-provisioning-protocol-00 (work in progress),
May 2013.
[I-D.ietf-pcp-authentication]
Wasserman, M., Hartman, S., and D. Zhang, "Port Control
Protocol (PCP) Authentication Mechanism", draft-ietf-pcp-
authentication-01 (work in progress), October 2012.
[I-D.sin-sdnrg-sdn-approach]
Boucadair, M. and C. Jacquenet, "Software-Defined
Networking: A Service Provider's Perspective", draft-sin-
sdnrg-sdn-approach-03 (work in progress), June 2013.
[OpenFlow]
OpenFlow, ., "OpenFlow Switch Specification", February
2011, <http://www.openflow.org/documents/openflow-
spec-v1.1.0.pdf>.
[RFC2753] Yavatkar, R., Pendarakis, D., and R. Guerin, "A Framework
for Policy-based Admission Control", RFC 2753, January
2000.
Penno, et al. Expires April 02, 2014 [Page 10]
Internet-Draft A-SDN September 2013
[RFC3084] Chan, K., Seligson, J., Durham, D., Gai, S., McCloghrie,
K., Herzog, S., Reichmeyer, F., Yavatkar, R., and A.
Smith, "COPS Usage for Policy Provisioning (COPS-PR)", RFC
3084, March 2001.
[RFC4594] Babiarz, J., Chan, K., and F. Baker, "Configuration
Guidelines for DiffServ Service Classes", RFC 4594, August
2006.
[RFC6241] Enns, R., Bjorklund, M., Schoenwaelder, J., and A.
Bierman, "Network Configuration Protocol (NETCONF)", RFC
6241, June 2011.
[RFC6459] Korhonen, J., Soininen, J., Patil, B., Savolainen, T.,
Bajko, G., and K. Iisakkila, "IPv6 in 3rd Generation
Partnership Project (3GPP) Evolved Packet System (EPS)",
RFC 6459, January 2012.
Authors' Addresses
Reinaldo Penno
Cisco Systems, Inc.
170 West Tasman Drive
San Jose 95134
USA
Email: repenno@cisco.com
Tirumaleswar Reddy
Cisco Systems, Inc.
Cessna Business Park, Varthur Hobli
Sarjapur Marathalli Outer Ring Road
Bangalore, Karnataka 560103
India
Email: tireddy@cisco.com
Mohamed Boucadair
France Telecom
Rennes 35000
France
Email: mohamed.boucadair@orange.com
Penno, et al. Expires April 02, 2014 [Page 11]
Internet-Draft A-SDN September 2013
Dan Wing
Cisco Systems, Inc.
170 West Tasman Drive
San Jose, California 95134
USA
Email: dwing@cisco.com
Suresh Vinapamula
Juniper Networks, Inc.
1194 N Mathilda Ave
Sunnyvale, California 94089
USA
Email: sureshk@juniper.net
Penno, et al. Expires April 02, 2014 [Page 12]
