ALTO WG K. Gao
Internet-Draft Tsinghua University
Intended status: Standards Track J. Zhang
Expires: January 9, 2017 Tongji University
Y. Yang
Yale University
July 8, 2016
ALTO Flow Cost Service
draft-gao-alto-fcs-00.txt
Abstract
OpenFlow [openflow] is the current standard southbound protocol for
Software-Defined Networking. In this document, we define a new
service, namely the Flow Cost Service, for clients in a OpenFlow-
enabled network to query the network information.
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 January 9, 2017.
Copyright Notice
Copyright (c) 2016 IETF Trust and the persons identified as the
document authors. All rights reserved.
Gao, et al. Expires January 9, 2017 [Page 1]
Internet-Draft Flow Cost Service July 2016
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. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Basic Data Types . . . . . . . . . . . . . . . . . . . . . . 3
2.1. Flow ID . . . . . . . . . . . . . . . . . . . . . . . . . 3
2.2. Typed Header Field . . . . . . . . . . . . . . . . . . . 3
2.3. Cost Confidence . . . . . . . . . . . . . . . . . . . . . 4
3. Flow Cost Service . . . . . . . . . . . . . . . . . . . . . . 4
3.1. Media Type . . . . . . . . . . . . . . . . . . . . . . . 4
3.2. HTTP Method . . . . . . . . . . . . . . . . . . . . . . . 4
3.3. Accept Input Parameters . . . . . . . . . . . . . . . . . 4
3.4. Capabilities . . . . . . . . . . . . . . . . . . . . . . 5
3.5. Response . . . . . . . . . . . . . . . . . . . . . . . . 6
3.6. Errors . . . . . . . . . . . . . . . . . . . . . . . . . 7
3.7. Example . . . . . . . . . . . . . . . . . . . . . . . . . 8
4. Security Considerations . . . . . . . . . . . . . . . . . . . 10
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 10
5.1. Media Types . . . . . . . . . . . . . . . . . . . . . . . 10
5.2. Header Field . . . . . . . . . . . . . . . . . . . . . . 11
6. Acknowledgement . . . . . . . . . . . . . . . . . . . . . . . 11
7. References . . . . . . . . . . . . . . . . . . . . . . . . . 11
7.1. Normative References . . . . . . . . . . . . . . . . . . 11
7.2. Informative References . . . . . . . . . . . . . . . . . 12
7.3. URIs . . . . . . . . . . . . . . . . . . . . . . . . . . 12
Appendix A. Tables . . . . . . . . . . . . . . . . . . . . . . . 13
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 14
1. Introduction
With the emerging technologies in the data plane, where multiple
header fields can be used to determine the forwarding path, networks
are moving to more flexible routing mechanism beyond the simple
destination-based routing. As a consequence, the endpoint cost
service (ECS), which depends on only source and destination IP
addresses as currently defined, is no longer sufficient to provide
accurate cost information.
Gao, et al. Expires January 9, 2017 [Page 2]
Internet-Draft Flow Cost Service July 2016
In this document, we consider the extension of ALTO service which
provides the cost service, for networks using flow-based routing such
as Software-Defined Networks using OpenFlow switches. The flow-based
routing, in general, provides a more fine-grained control over the
packets than destination-based routing. Consider those packets from
a specific source to a specific destination. With destination-based
routing, these packets will always use the same path, and hence ECS
can provide the same routing cost. Flow-based routing, however, can
partition these packets into multiple subsets (flows), where
different subsets (flows) can go through different paths, and hence
have different routing cost values. For example, large science data
flows may go through a DMZ path with low cost, and other traffic may
need to go through more security checks, with higher costs. Although
one may still use ECS, which may provide an aggregated cost (e.g.,
average), the result can be inaccurate and misleading.
To satisfy the growing demand of obtaining accurate costs in a
network using flow-based routing, a new ALTO service named the flow
cost service (FCS) is defined.
2. Basic Data Types
The flow cost service introduces some new basic data types, as
defined below.
2.1. Flow ID
A flow ID has the same format as a PIDName, as defined in [RFC7285]
Section 10.1 [1]. It is used to uniquely identify a flow in a flow
cost service request.
2.2. Typed Header Field
A typed header field represents a particular field in a network
protocol that can be obtained at the application layer. It is
represented by the protocol name and the field name, concatenated by
the colon (':', U+003A). The typed header fields are case
insensitive.
For example, "ipv4:source" and "IPv4:source" both represent the
source address field used in IPv4 and "tcp:destination" represents
the destination port for a TCP connection.
See Table 2 for a list of proposed typed header fields.
Gao, et al. Expires January 9, 2017 [Page 3]
Internet-Draft Flow Cost Service July 2016
2.3. Cost Confidence
A cost confidence is defined as a JSON integer within the range of
[0, 100]. It represents the ALTO servers' estimation on the accuracy
of the returned costs. The larger the cost confidence is, the more
accurate the path cost SHOULD be. If the cost value is very
accurate, for example, a unique path can be identified for a flow
with the provided information, the ALTO server SHOULD provide a cost
confidence of 100.
The cost confidence CAN be used as an evidence of ambiguous paths,
which is often associated with insufficient information in a query.
If the ALTO clients find the associated cost confidence value is low,
it can narrow down the flow header space in the query by adding
optional fields or use IP addresses instead of prefixes.
The cost confidence value can be computed in several ways. For
example, ALTO servers MAY use the following formula for some cost
metrics:
c = 100 * (1 - |deviation / mean|)
0 if c <= 0
confidence =
round(c) if c > 0
where mean and deviation are computed from the cost values of all
possible paths.
3. Flow Cost Service
A flow cost service provides information about costs for each
individual flows specified in the requests.
3.1. Media Type
The media type of the flow cost service is "application/alto-
flowcost+json".
3.2. HTTP Method
The flow cost service is requested using the HTTP POST method.
3.3. Accept Input Parameters
The input parameters of the flow cost service MUST be encoded as a
JSON object of type FlowCostRequest in the body of an HTTP POST
Gao, et al. Expires January 9, 2017 [Page 4]
Internet-Draft Flow Cost Service July 2016
request. The media type of the request MUST be "application/alto-
flowcostparams+json".
object {
FlowFilterMap flows;
} FlowCostRequest : MultiCostRequestBase;
object {
[CostType cost-type;]
[CostType multi-cost-types<1..*>;]
[CostType testable-cost-types<1..*>;]
[JSONString constraints<0..*>;]
[JSONString or-constraints<0..*><0..*>;]
} MultiCostRequestBase;
object-map {
FlowId -> FlowFilter;
} FlowFilterMap;
object-map {
TypedHeaderField -> JSONValue;
} FlowFilter;
flows: A map of flow filters for which path costs are to be
returned. Each flow filter is identified by a unique FlowId, as
defined in Section 2.1. The value types of a field is protocol-
specific, see Table 3 for the value types associated with typed
header fields in Table 2.
cost-type: The same as defined in [I-D.ietf-alto-multi-cost]
Section 4.2.2 [2].
multi-cost-types: The same as defined in [I-D.ietf-alto-multi-cost]
Section 4.2.2 [3].
testable-cost-types, constraints, or-constraints: The same as
defined in [I-D.ietf-alto-multi-cost] Section 4.2.2 [4].
3.4. Capabilities
The capabilities of the flow cost service is a JSON object of type
FlowCostCapabilities:
object {
TypedHeaderField required<1..*>;
[TypedHeaderField optional<1..*>;]
} FlowCostCapabilities : FilteredCostMapCapabilities;
Gao, et al. Expires January 9, 2017 [Page 5]
Internet-Draft Flow Cost Service July 2016
with fields:
required: A list of required typed header fields. These fields are
essential to find the path cost for a given flow and MUST be
provided in a flow filter.
optional: A list of optional typed header fields. The ALTO server
MAY leverage the values of the optional fields to find more
accurate costs.
3.5. Response
The "meta" field of a flow cost response MUST contain the same cost
type information as defined in [I-D.ietf-alto-multi-cost]
Section 4.2.3 [5].
The data component of a flow cost service is named "flow-cost-map",
which is a JSON object of type FlowCostMap:
object {
FlowCostMap flow-cost-map;
[FlowCostMap flow-cost-confidences;]
} FlowCostResponse : ResponseEntityBase;
object-map {
FlowId -> JSONValue;
} FlowCostMap;
flow-cost-map: A dictionary map with each key (flow ID) representing
a flow specified in the request. For each flow, the cost MUST
follow the format defined in [I-D.ietf-alto-multi-cost]
Section 4.2.3 [6].
flow-cost-confidences: A dictionary map with each key (flow ID)
representing a flow specified in the request. For a single cost,
the cost confidence for each flow MUST follow the specification in
Section 2.3. If the query is using multiple costs where the costs
are returned as a JSONArray, the cost confidence MUST also be a
JSONArray where each element represents the cost confidence value
computed for the corresponding cost type.
3.5.1. Ambiguous Paths
Since new forwarding abstractions support fine-grained routing, for
example, OpenFlow 1.5 [OF15] has defined 38 header match fields, it
is possible that the ALTO server cannot determine the path using the
provided header fields. The computation for costs with ambiguous
paths is implementation-specific, the servers can choose to return an
Gao, et al. Expires January 9, 2017 [Page 6]
Internet-Draft Flow Cost Service July 2016
integrated result of all possible paths, or simply use the cost of a
random path. The ALTO servers SHOULD provide cost confidences to
justify the accuracy of the provided cost values.
The ALTO server SHOULD be able to determine a unique path when all
the optional typed header fields are provided without masks for a
flow, however, the client SHOULD NOT assume this always holds.
3.6. Errors
The ALTO servers can provide more information to the clients when
requests have errors. The FlowCostErrorMap below can provide basic
information about two most common errors for the flow cost service.
The ALTO servers MAY include it as the data component of an ALTO
error response. If multiple errors are identified, the ALTO server
MUST return exactly one error code according to [RFC7285]
Section 8.5.2 [7].
object-map {
FlowId -> FlowCostError;
} FlowCostErrorMap;
object {
[TypedHeaderField conflicts<2..*>;]
[TypedHeadreField missing<2..*>;]
[TypedHeaderField unsupported<1..*>;]
} FlowFilterError;
conflicts: A list of conflicting typed header fields. See
Section 3.6.1 for details.
missing: A list of missing typed header fields. See Section 3.6.2
for details.
unsupported: A list of unsupported typed header fields. See
Section 3.6.3 for details.
3.6.1. Conflicts
Some header fields may have conflicts. For example, IPv4 fields and
IPv6 fields can never appear in the same packet, nor can TCP and UDP
ports. These header fields MUST not be included in the same flow
filter, otherwise the ALTO server MUST return an ALTO error response,
with the error code "E_INVALID_FIELD_VALUE". As specified in
[RFC7285] Section 8.5.2 [8], the ALTO server MAY include the "field"
and the "value" in the "meta" field. In this case, the ALTO server
MUST use the flow ID as the "field" and the flow filter as the
"value". However, the recommended approach is to use the
Gao, et al. Expires January 9, 2017 [Page 7]
Internet-Draft Flow Cost Service July 2016
FlowCostErrorMap, where the server CAN provide the conflicting typed
header fields in the "conflicts" field of the FlowFilterError
associated with the corresponding flow ID.
3.6.2. Missing Fields
The "E_MISSING_FIELD" error code is originally designed to report the
absence of required JSON fields. In the flow cost service, the
required typed header fields are implementation-specific and the ALTO
servers MUST declare the required fields in the capabilities. If any
required header field is missing, the ALTO server MUST return an ALTO
error response, with the error code "E_MISSING_FIELD". The ALTO
server CAN follow the steps defined in [RFC7285] Section 8.5.2 [9] to
indicate the location of the missing field. An alternative approach
which is also recommended, is that the server provide the missing
typed header fields in the "missing" field of the FlowFilterError
associated with the corresponding flow ID.
3.6.3. Unsupported Fields
If a query contains unsupported typed header fields, e.g., those not
in the "required" nor the "optional" capabilities, the ALTO server
MUST return an ALTO error response, with the error code
"E_INVALID_FIELD_VALUE". Like how the conflicting header fields are
handled in Section 3.6.1, the ALTO servers CAN report unsupported
typed header fields in the "unsupported" field associated with the
corresponding flow ID.
3.7. Example
Gao, et al. Expires January 9, 2017 [Page 8]
Internet-Draft Flow Cost Service July 2016
POST /flowcost/lookup HTTP/1.1
HOST: alto.example.com
Content-Length: 521
Content-Type: application/alto-flowcostparams+json
Accept: application/alto-flowcost+json,application/alto-error+json
{
"cost-type": {
"cost-mode": "numerical",
"cost-metric": "routingcost"
},
"flows": {
"l3-flow": {
"ipv4:source": "192.168.1.1",
"ipv4:destination": "192.168.1.2"
},
"optional-l3-flow": {
"ipv4:source": "192.168.1.1",
"ipv4:destination": "192.168.1.2"
"ethernet:source": "12:34:56:78:00:01",
"ethernet:destination": "12:34:56:78:00:02"
},
"l3-flow-aggr": {
"ipv4:source": "192.168.1.0/24",
"ipv4:destination": "192.168.2.0/24"
}
}
}
Gao, et al. Expires January 9, 2017 [Page 9]
Internet-Draft Flow Cost Service July 2016
HTTP/1.1 200 OK
Content-Length: 312
Content-Type: application/alto-flowcost+json
{
"meta": {
"cost-type": {
"cost-mode": "numerical",
"cost-metric": "routingcost"
},
},
"flow-cost-map": {
"l3-flow": 10,
"l3-flow-aggr": 50
"optional-l3-flow": 5,
},
"flow-cost-confidences": {
"l3-flow": 70,
"l3-flow-aggr": 40,
"optional-l3-flow": 90
}
}
4. Security Considerations
This document has not conducted its security analysis.
5. IANA Considerations
This document defines two new entries to be registered to
application/alto-* media types.
5.1. Media Types
This document registers two media types, listed in Table 1.
+--------------+--------------------------+----------------+
| Type | Subtype | Specification |
+--------------+--------------------------+----------------+
| application | alto-flowcost+json | Section 3.5 |
| application | alto-flowcostparam+json | Section 3.3 |
+--------------+--------------------------+----------------+
Table 1: ALTO FCS Media Types
Type name: application
Gao, et al. Expires January 9, 2017 [Page 10]
Internet-Draft Flow Cost Service July 2016
Subtype name: This document registers two subtypes, as listed in
Table 1.
Required parameters: n/a
Optional parameters: n/a
Encoding considerations: Encoding considerations are identical to
those specified for the "applicatoin/json" media type. See
[RFC7159].
Security considerations: Security considerations are identical to
those specified in [RFC7285] Section 15 [10].
Interoperability considerations: n/a
Published specification: This document is the specification for
these media types. See Table 1 for the section documenting each
media type.
Applications that use this media type: ALTO servers and ALTO clients
with the extension to support the flow cost service, either
standalone or embedded within other applications.
Additional information: n/a
Person & email address to contact for further information: See
Authors' Addresses.
Intended usage: COMMON
Restrictions on usage: n/a
Author: See Authors' Addresses.
5.2. Header Field
TBD: Create the "ALTO Header Field Name Registry".
6. Acknowledgement
7. References
7.1. Normative References
Gao, et al. Expires January 9, 2017 [Page 11]
Internet-Draft Flow Cost Service July 2016
[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>.
7.2. Informative References
[I-D.ietf-alto-multi-cost]
Randriamasy, S., Roome, W., and N. Schwan, "Multi-Cost
ALTO", draft-ietf-alto-multi-cost-02 (work in progress),
June 2016.
[I-D.wang-alto-ecs-flow]
Shen, X., Zhang, J., Wang, J., and Q. Xiang, "ALTO
Extension: Endpoint Cost Service for Flows", draft-wang-
alto-ecs-flows-01 (work in progress), April 2016.
[OF15] Foundation, O., "Openflow switch specification v1. 5.0",
2014,
<https://www.opennetworking.org/images/stories/downloads/
sdn-resources/onf-specifications/openflow/openflow-switch-
v1.5.0.noipr.pdf>.
[openflow]
McKeown, N., Anderson, T., Balakrishnan, H., Parulkar, G.,
Peterson, L., Rexford, J., Shenker, S., and J. Turner,
"Openflow: enabling innovation in campus networks", 2008.
[RFC7159] Bray, T., Ed., "The JavaScript Object Notation (JSON) Data
Interchange Format", RFC 7159, DOI 10.17487/RFC7159, March
2014, <http://www.rfc-editor.org/info/rfc7159>.
[RFC7285] Alimi, R., Ed., Penno, R., Ed., Yang, Y., Ed., Kiesel, S.,
Previdi, S., Roome, W., Shalunov, S., and R. Woundy,
"Application-Layer Traffic Optimization (ALTO) Protocol",
RFC 7285, DOI 10.17487/RFC7285, September 2014,
<http://www.rfc-editor.org/info/rfc7285>.
7.3. URIs
[1] https://tools.ietf.org/html/rfc7285#section-10.1
[2] https://tools.ietf.org/html/draft-ietf-alto-multi-cost-02#4.2.2
[3] https://tools.ietf.org/html/draft-ietf-alto-multi-cost-02#4.2.2
[4] https://tools.ietf.org/html/draft-ietf-alto-multi-cost-02#4.2.2
Gao, et al. Expires January 9, 2017 [Page 12]
Internet-Draft Flow Cost Service July 2016
[5] https://tools.ietf.org/html/draft-ietf-alto-multi-cost-02#4.2.3
[6] https://tools.ietf.org/html/draft-ietf-alto-multi-cost-02#4.2.3
[7] https://tools.ietf.org/html/rfc7285#section-8.5.2
[8] https://tools.ietf.org/html/rfc7285#section-8.5.2
[9] https://tools.ietf.org/html/rfc7285#section-8.5.2
[10] ttps://tools.ietf.org/html/rfc7285#section-15
Appendix A. Tables
+------------+--------------+------------------------------+
| Protocol | Field Name | Description |
+------------+--------------+------------------------------+
| Ethernet | source | The source MAC address |
| | destination | The destination MAC address |
| | vlan-id | VLAN-ID from 802.1Q header |
| IPv4 | source | IPv4 source address |
| | destination | IPv4 destination address |
| IPv6 | source | IPv6 source address |
| | destination | IPv6 destination address |
| TCP | source | TCP source port |
| | destination | TCP destination port |
| UDP | source | UDP source port |
| | destination | UDP destination port |
+------------+--------------+------------------------------+
Table 2: Protocols and Field Names.
Gao, et al. Expires January 9, 2017 [Page 13]
Internet-Draft Flow Cost Service July 2016
+-----------------------+-------------------------------------------+
| Typed Header Field | Acceptable Value Type |
+-----------------------+-------------------------------------------+
| ethernet:source | JSONString as MAC address |
| ethernet:destination | |
| ethernet:vlan-id | JSONNumber in the range of [1, 4094] |
| ipv4:source | JSONString as IPv4 address or IPv4 prefix |
| ipv4:destination | |
| ipv6:source | JSONString as IPv6 address or IPv6 prefix |
| ipv6:destination | |
| tcp:source | JSONNumber in the range of [0, 65535] |
| tcp:destination | 0 serves as a wildcard value |
| udp:source | |
| udp:destination | |
+-----------------------+-------------------------------------------+
Table 3: Value Types for Typed Header Fields
Authors' Addresses
Kai Gao
Tsinghua University
30 Shuangqinglu Street
Beijing 100084
China
Email: gaok12@mails.tsinghua.edu.cn
Jingxuan Jensen Zhang
Tongji University
4800 CaoAn Road
Shanghai 201804
China
Email: jingxuan.n.zhang@gmail.com
Y. Richard Yang
Yale University
51 Prospect St
New Haven CT
USA
Email: yry@cs.yale.edu
Gao, et al. Expires January 9, 2017 [Page 14]