Internet DRAFT - draft-krishnan-sfc-oam-req-framework
draft-krishnan-sfc-oam-req-framework
SFC Working Group R. Krishnan
Internet Draft Brocade
Category: Informational A. Ghanwani
Dell
Pedro A. Aranda Gutierrez
D. R. Lopez
Telefonica I+D
J. Halpern
S. Kini
Ericsson
Andy Reid
BT
Expires: October 2014 July 3, 2014
SFC OAM Requirements and Framework
draft-krishnan-sfc-oam-req-framework-00
Abstract
This document discusses SFC OAM requirements and proposes a SFC OAM
Framework to handle these requirements.
Status of this Memo
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This Internet-Draft will expire on April, 2014.
Copyright Notice
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This document is subject to BCP 78 and the IETF Trust's Legal
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respect to this document.
Conventions used in this document
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 [RFC 2119].
Table of Contents
1. Introduction...................................................3
1.1. Acronyms..................................................4
2. SFC OAM Requirements...........................................4
2.1. Topologies................................................4
2.2. Connectivity..............................................4
2.2.1. Connectivity Check...................................4
2.2.2. SFP Trace............................................5
2.3. Performance...............................................5
2.4. Leakage of OAM Messages...................................5
2.5. Appliance Types...........................................5
3. IANA Considerations............................................6
4. Security Considerations........................................6
5. Acknowledgements...............................................6
6. References.....................................................6
6.1. Normative References......................................6
6.2. Informative References....................................6
Authors' Addresses................................................7
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1. Introduction
Operations, administration, and maintenance (OAM) is the general
term applied to monitoring both the connectivity and performance in
the network [RFC 6291] [RFC 7276]. The goal of SFC OAM then is to
monitor these attributes for a service function chain (SFC).
Some clarification is needed regarding the scope of this work. SFC
OAM does will not attempt to monitor the actual services. Also, SFC
OAM does not replace or obviate the need for transport-level OAM
functions such as NVO3 OAM, IEEE 802.1ag, MPLS OAM, or whatever else
may be applicable depending on the network technology that the SFC
is implemented on.
The following figure depicts the layering of OAM.
+--+ +-+ +-+ +--+ +-+ +-+ +--+ +---+ +-+ +-+ +---+ +--+ +-+ +--+
|ES|-|B|-|B|-|SF|-|R|-|R|-|SF|-|NVE|-|B|-|B|-|NVE|-|SF|-|B|-|ES|
+--+ +-+ +-+ +--+ +-+ +-+ +--+ +---+ +-+ +-+ +---+ +--+ +-+ +--+
X------------------------------------------------------------X (APP)
x------------o-------------------------o (SFC)
x-------------x (NVO3)
x---x (L3/MPLS)
x---x x---x (L2)
ES: End Station
B: IEEE 802.1Q Bridge
R: Router or LSR
NVE: Network Virtualization Edge
SF: Service function (or SFF)
X: Maintenance End Point (MEP)
O: Maintenance Intermediate Point (MIP)
Figure 1: Layered OAM Architecture
The SFC layer resides above the transport layer (where the transport
layer can simply be implemented using VLANs or may be done using
overlays such as VXLAN or NVGRE), and below the application layer
(APP). As mentioned earlier, depending on the underlying network
technology, other OAM layers may be present (NVO3 OAM [NVO3 OAM],
L3/MPLS OAM [RFC 7276], IEEE 802.1ag CFM [IEEE 802.1ag], etc.). The
use of the terms maintenance end point (MEP) and maintenance (MIP)
are consistent with IEEE 802.1Q are simply used to denote points
where monitoring services are configured.
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The systems denoted SF refer to devices in the network that either
insert, modify, remove, or access the service chain header (SCH)
[SCH draft]. These nodes may implement the actual service function
(as would be the case for an SF-aware appliance) or they may be
proxy nodes such as SFFs with the service function itself residing
in a different device (as would be the case for an SF-unaware
appliance).
1.1. Acronyms
DPI: Deep Packet Inspection
MPLS: Multiprotocol Label Switching
NVGRE: Network Virtualization using Generic Routing Encapsulation
OAM: Operations, Administration, and Maintenance
SF: Service Function
SFC: Service Function Chain
SFP: Service Function Path
VXLAN: Virtual Extensible LAN
2. SFC OAM Requirements
2.1. Topologies
Mechanisms must be provided to monitor the entire SFP or just a
portion of the SFP.
SFC OAM must also be able to handle various topologies that can be
created such a point-to-point or multipoint.
2.2. Connectivity
2.2.1. Connectivity Check
The purpose of the connectivity check tool is to test the liveness
of a given service function along a given SFP (service function
path).
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Mechanisms must be provided so that the SFC OAM messages may be sent
along the same path that a given data packet would follow. In other
words, it should be possible to construct SFC OAM packets that would
be treated by network devices such as bridges and routers as they
would handle regular data packets on that SFP from the standpoint of
functions such as link aggregation and equal cost multipath.
2.2.2. SFP Trace
The purpose of SFP trace is to provide the list of SFs that comprise
the service function chain as defined by the SCH.
Mechanisms must be provided so that the SFC OAM messages may be sent
along the same path that a given data packet would follow. In other
words, it should be possible to construct SFC OAM packets that would
be treated by network devices such as bridges and routers as they
would handle regular data packets on that SFP from the standpoint of
functions such as link aggregation and equal cost multipath.
2.3. Performance
It must be possible to measure various parameters of a given SFP
such as the loss, delay, and delay variation through the service
chain.
[ Ed Note: Details TBD ]
2.4. Leakage of OAM Messages
Mechanisms must be provided to ensure that OAM messages are received
only by devices that need to process them. These messages must
never be forwarded to devices that would terminate such messages as
result of not knowing how to process them.
2.5. Appliance Types
SFC OAM must provide tools that operate through various types of
appliances including:
. Transparent appliances: These appliances typically do not make
any modifications to the packet. In such cases, the SFF may be
able to process OAM messages.
. Appliances that modify the packet: These appliances modify
packet fields. Certain appliances may modify only the headers
corresponding to the network over which it is transported, e.g.
the MAC headers or overlay headers. In other cases, the IP
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header of the application's packet may be modified, e.g. NAT.
In yet other cases, the application session itself may be
terminated and a new session initiated, e.g. a load balancer
that offers HTTPS termination.
In general, it should be possible to allow or disallow having a
given SF operate on an OAM packet in the same way that it would on
a regular data packet, but with the awareness that it is operating
on an OAM packet. It is essential to recognize the OAM message so
that its status (as an OAM message) can be preserved as it is
processed through the normal data path.
3. IANA Considerations
This draft does not have any IANA considerations.
4. Security Considerations
TBD
5. Acknowledgements
6. References
6.1. Normative References
6.2. Informative References
[RFC 2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels," March 1997.
[RFC 6291] Andersson, L. et al., "Guidelines for the Use of the
"OAM" Acronym in the IETF," June 2011
[RFC 7276] Mizrahi, T. et al., "An Overview of Operations,
Administration, and Maintenance (OAM) Tools," June 2014
[NVO3 OAM] Senevirathne, T., "NVO3 Fault Management,"
https://datatracker.ietf.org/doc/draft-tissa-nvo3-oam-
fm/?include_text=1, August 2014
[STEALTH FIREWALL] Brandon Gillespie "Stealth firewalls",
http://www.giac.org/paper/gsec/629/stealth-firewalls/101440
[SCH draft] Quinn, P. et al., "Network Service Header,"
https://datatracker.ietf.org/doc/draft-quinn-sfc-nsh/, February 2014
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Authors' Addresses
Ram Krishnan
Brocade Communications
ramk@brocade.com
Anoop Ghanwani
Dell
anoop@alumni.duke.edu
Pedro A. Aranda Gutierrez
Telefonica I+D
Don Ramon de la Cruz, 82
Madrid, 28006, Spain
+34 913 129 041
pedroa.aranda@tid.es
Diego Lopez
Telefonica I+D
Don Ramon de la Cruz, 82
Madrid, 28006, Spain
+34 913 129 041
diego@tid.es
Joel Halpern
Ericsson
joel.halpern@ericsson.com
Sriganesh Kini
Ericsson
Sriganesh.kini@ericsson.com
Andy Reid
BT
andy.bd.reid@bt.com
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