One document matched: draft-penno-pcp-asdn-00.xml
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<rfc category="std" docName="draft-penno-pcp-asdn-00" ipr="trust200902">
<front>
<title abbrev="A-SDN">Application Enabled SDN (A-SDN)</title>
<author fullname="Reinaldo Penno" initials="R." surname="Penno">
<organization>Cisco Systems, Inc.</organization>
<address>
<postal>
<street>170 West Tasman Drive</street>
<city>San Jose</city>
<region></region>
<code>95134</code>
<country>USA</country>
</postal>
<phone></phone>
<email>repenno@cisco.com</email>
<uri></uri>
</address>
</author>
<author fullname="Tirumaleswar Reddy" initials="T." surname="Reddy">
<organization>Cisco Systems, Inc.</organization>
<address>
<postal>
<street>Cessna Business Park, Varthur Hobli</street>
<street>Sarjapur Marathalli Outer Ring Road</street>
<city>Bangalore</city>
<region>Karnataka</region>
<code>560103</code>
<country>India</country>
</postal>
<email>tireddy@cisco.com</email>
</address>
</author>
<author fullname="Mohamed Boucadair" initials="M." surname="Boucadair">
<organization>France Telecom</organization>
<address>
<postal>
<street></street>
<city>Rennes</city>
<region></region>
<code>35000</code>
<country>France</country>
</postal>
<email>mohamed.boucadair@orange.com</email>
</address>
</author>
<author fullname="Dan Wing" initials="D." surname="Wing">
<organization abbrev="Cisco">Cisco Systems, Inc.</organization>
<address>
<postal>
<street>170 West Tasman Drive</street>
<city>San Jose</city>
<region>California</region>
<code>95134</code>
<country>USA</country>
</postal>
<email>dwing@cisco.com</email>
</address>
</author>
<author fullname="Suresh Vinapamula" initials="S." surname="Vinapamula">
<organization>Juniper Networks, Inc.</organization>
<address>
<postal>
<street>1194 N Mathilda Ave</street>
<city>Sunnyvale</city>
<region>California</region>
<code>94089</code>
<country>USA</country>
</postal>
<phone></phone>
<email>sureshk@juniper.net</email>
<uri></uri>
</address>
</author>
<date day="" month="" year="" />
<abstract>
<t>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.</t>
<t>This document describes a different approach, where the application
explicitly signals its needs to the network.</t>
<!--
<t>In the context of ongoing efforts to add more automation and promote
means to dynamically interact with network resources (e.g., SDN-labeled
efforts), 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.</t>
<t>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.</t>
<t>Unlike network-centric techniques, this document proposed an approach
which involved hosts and applications.</t>
-->
</abstract>
<note title="Requirements Language">
<t>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 <xref
target="RFC2119">RFC 2119</xref>.</t>
</note>
</front>
<middle>
<section title="Problem Statement">
<t>In the context of ongoing efforts to add more automation and promote
means to dynamically interact with network resources (e.g., SDN-labeled
efforts) <xref target="I-D.sin-sdnrg-sdn-approach"></xref>, 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.</t>
<t>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.</t>
<t>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.</t>
<t>Unlike network-centric techniques, this document proposed an approach
which involved hosts and applications.</t>
</section>
<section title="Scope">
<t>Considerations related to dynamic network provisioning negotiation
are out of scope. The reader can refer to <xref
target="I-D.boucadair-connectivity-provisioning-protocol"></xref> for
more details.</t>
<t>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.</t>
<t>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.</t>
<t>This document does not require an end-to-end signalling before actual
invocation of a service.</t>
<t>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.</t>
</section>
<section title="Proposed Approach">
<t>In order to offer more automation and dynamicity in resource usage
and invocation, this document proposes an architecture that is composed
of three parts:</t>
<t><list style="numbers">
<t>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.</t>
<t>On the network side, a PDP (Policy Decision Point, <xref
target="RFC2753"></xref>) is responsible for orchestrating
resources, generating policies and trigger provisioning-related
operations.</t>
<t>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).</t>
</list></t>
<t>The diagram below depicts the general architecture and message flow
for the Application-Enabled SDN (A-SDN).</t>
<figure>
<preamble></preamble>
<artwork><![CDATA[
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
Request (Flow + Metadata)
.... e.g., PCP
---- e.g., REST
-.-. e.g., COPS-PR, Netconf, Openflow]]></artwork>
<postamble>A middlebox could be a CPE router, edge router, switch,
wireless access LAN controller, mobile gateway in 3GPP networks <xref
target="RFC6459"></xref>, or any other flow-aware device.</postamble>
</figure>
<t></t>
<t>This architecture provides several advantages such as:</t>
<t><list style="symbols">
<t>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.</t>
<t>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.</t>
<t>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.</t>
<t>Access agnostic: An application should not care if it is on an
ADSL, Cable, Wi-Fi, 3G, Ethernet or other network type.</t>
<t>Works across administrative domains: Home Network -> ISP1.
Home Network communicates with ISP1 using PCP.</t>
<t>NAT and firewall aware: The flow information fed into the PDP
will have pre and post NAT information, allowing provisioning using
scoped IP addresses.</t>
<t>Extensible: Client protocol can be extended to provide a wide
range of flow associated metadata.</t>
<t>Multi-interface support: Based on network conditions clients can
switch from a Wi-Fi to a 3G interface, or install flows over certain
paths</t>
</list></t>
</section>
<section title="Protocols">
<t>The first element of this architecture could be met by using the Port
Control Protocol (PCP) <xref target="RFC6887"></xref>. Indeed, PCP Flow
Extension <xref target="I-D.wing-pcp-flowdata"></xref> 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.</t>
<t>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.</t>
<t>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) <xref target="RFC6120"></xref> or
similar protocol.</t>
<t>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:</t>
<t><list style="symbols">
<t>PCP with the THIRD_PARTY option</t>
<t>Netconf <xref target="RFC6241"></xref>, COPS-PR <xref
target="RFC3084"></xref> , or any similar protocol. This document
does not make any assumption on that interface.</t>
</list></t>
</section>
<section title="A-SDN Flows">
<t><figure>
<artwork><![CDATA[ +---------------+
| PDP |
. __ . __ . __ . __ . __ . __ . | |
| | ________ |
. | |REST | |
| +----------->|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.]]></artwork>
</figure></t>
<section title="Signaling Prior to Flow Creation">
<t>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:</t>
<t><list style="symbols">
<t>Match condition: e.g., source/destination IP,
source/destination port, L4 Protocol, Port, VLAN Id etc.</t>
<t>Metadata: e.g., metadata conveyed in PCP FLOWDATA option.</t>
<t>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.</t>
</list></t>
<t>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 <xref
target="OpenFlow"></xref> would get the information of configured
queues and 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.</t>
</section>
<section title="Signaling After Flow Creation">
<t>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.</t>
<t>The mechanism is very similar to flow creation but does not require
a pre-signaling step.</t>
</section>
<section title="Flow Removal Event">
<t>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.</t>
<t>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.</t>
</section>
<section title="Flow Modification">
<t>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.</t>
<t>If the PDP succeeds in modifying a flow, a PCP unsolicited response
will be sent to the PCP Client owner of such flow.</t>
</section>
</section>
<section title="Use Cases">
<t>This section describes some use-cases in which A-SDNs can be
beneficial.</t>
<section title="Flow Prioritization">
<t>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.</t>
<t>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.</t>
</section>
<section title="Flow High availability">
<t>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.</t>
</section>
<section title="On-demand Bandwidth">
<t>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.</t>
</section>
<section title="Analytics and Reporting">
<t>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.</t>
</section>
</section>
<section anchor="security" title="Security Considerations">
<t>Security considerations in <xref target="RFC6887"></xref> and PCP
Authentication <xref target="I-D.ietf-pcp-authentication"></xref> 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 <xref target="RFC6241"></xref> <xref
target="RFC3084"></xref>.</t>
</section>
<section anchor="IANA" title="IANA Considerations">
<t>This document does not require any action from IANA.</t>
</section>
<section title="Acknowledgments">
<t>TODO.</t>
</section>
</middle>
<back>
<references title="Normative References">
<?rfc include="reference.RFC.2119"?>
<?rfc include="reference.RFC.6120"?>
<?rfc include="reference.RFC.6887"?>
<?rfc include='reference.I-D.wing-pcp-flowdata'?>
</references>
<references title="Informative References">
<?rfc include="reference.RFC.4594"?>
<?rfc include='reference.RFC.2753'?>
<?rfc include='reference.RFC.6459'?>
<?rfc include='reference.I-D.sin-sdnrg-sdn-approach'?>
<?rfc include='reference.I-D.boucadair-connectivity-provisioning-protocol'?>
<?rfc include='reference.I-D.ietf-pcp-authentication'?>
<?rfc include='reference.RFC.3084'?>
<?rfc include='reference.RFC.6241'?>
<reference anchor="OpenFlow"
target="http://www.openflow.org/documents/openflow-spec-v1.1.0.pdf">
<front>
<title>OpenFlow Switch Specification</title>
<author fullname="OpenFlow" surname="OpenFlow">
<organization>OpenFlow</organization>
</author>
<date month="February" year="2011" />
</front>
</reference>
<!---->
</references>
</back>
</rfc>
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