I2RS J. Clarke
Internet-Draft G. Salgueiro
Intended status: Informational C. Pignataro
Expires: November 28, 2015 Cisco
May 27, 2015
Interface to the Routing System (I2RS) Traceability: Framework and
Information Model
draft-ietf-i2rs-traceability-03
Abstract
This document describes a framework for traceability in the Interface
to the Routing System (I2RS) and information model for that
framework. It specifies the motivation, requirements, use cases, and
defines an information model for recording interactions between
elements implementing the I2RS protocol. This framework provides a
consistent tracing interface for components implementing the I2RS
architecture to record what was done, by which component, and when.
It aims to improve the management of I2RS implementations, and can be
used for troubleshooting, auditing, forensics, and accounting
purposes.
Status of This Memo
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provisions of BCP 78 and BCP 79.
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This Internet-Draft will expire on November 28, 2015.
Copyright Notice
Copyright (c) 2015 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
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Terminology and Conventions . . . . . . . . . . . . . . . . . 3
3. Motivation . . . . . . . . . . . . . . . . . . . . . . . . . 3
4. Use Cases . . . . . . . . . . . . . . . . . . . . . . . . . . 3
5. Information Model . . . . . . . . . . . . . . . . . . . . . . 4
5.1. I2RS Traceability Framework . . . . . . . . . . . . . . . 4
5.2. I2RS Trace Log Mandatory Fields . . . . . . . . . . . . . 5
5.3. End of Message Marker . . . . . . . . . . . . . . . . . . 7
5.4. I2RS Trace Log Extensibility and Optional Fields . . . . 8
6. Examples . . . . . . . . . . . . . . . . . . . . . . . . . . 8
7. Operational Guidance . . . . . . . . . . . . . . . . . . . . 8
7.1. Trace Log Creation . . . . . . . . . . . . . . . . . . . 8
7.2. Trace Log Temporary Storage . . . . . . . . . . . . . . . 9
7.3. Trace Log Rotation . . . . . . . . . . . . . . . . . . . 9
7.4. Trace Log Retrieval . . . . . . . . . . . . . . . . . . . 9
7.4.1. Retrieval Via Syslog . . . . . . . . . . . . . . . . 10
7.4.2. Retrieval Via I2RS Information Collection . . . . . . 10
7.4.3. Retrieval Via I2RS Pub-Sub . . . . . . . . . . . . . 10
8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 11
9. Security Considerations . . . . . . . . . . . . . . . . . . . 11
10. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 11
11. References . . . . . . . . . . . . . . . . . . . . . . . . . 11
11.1. Normative References . . . . . . . . . . . . . . . . . . 12
11.2. Informative References . . . . . . . . . . . . . . . . . 12
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 12
1. Introduction
The architecture for the Interface to the Routing System
([I-D.ietf-i2rs-architecture]) specifies that I2RS Clients wishing to
retrieve or change routing state on a routing element MUST
authenticate to an I2RS Agent. The I2RS Client will have a unique
identity it provides for authentication, and should provide another,
opaque identity for applications communicating through it. The
programming of routing state will produce a return code containing
the results of the specified operation and associated reason(s) for
the result. All of this is critical information to be used for
understanding the history of I2RS interactions.
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This document describes use cases for I2RS traceability. Based on
these use cases, the document proposes an information model and
reporting requirements to provide for effective recording of I2RS
interactions. In this context, effective troubleshooting means being
able to identify what operation was performed by a specific I2RS
Client, what was the result of the operation, and when that operation
was performed.
Discussions about the retention of the data logged as part of I2RS
traceability, while important, are outside of the scope of this
document.
2. Terminology and Conventions
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 [RFC2119].
The architecture specification for I2RS [I-D.ietf-i2rs-architecture]
defines additional terms used in this document that are specific to
the I2RS domain, such as "I2RS Agent", "I2RS Client", etc. The
reader is expected to be familiar with the terminology and concepts
defined in [I-D.ietf-i2rs-architecture].
The IP addresses used in the example in this document correspond to
the documentation address blocks 192.0.2.0/24 (TEST-NET-1),
198.51.100.0/24 (TEST-NET-2) and 203.0.113.0/24 (TEST-NET-3) as
described in [RFC5737].
3. Motivation
As networks scale and policy becomes an increasingly important part
of the control plane that creates and maintains the forwarding state,
operational complexity increases as well. I2RS offers more granular
and coherent control over policy and control plane state, but it also
removes or reduces the locality of the policy that has been applied
to the control plane at any individual forwarding device. The
ability to automate and abstract even complex policy-based controls
highlights the need for an equally scalable traceability function to
provide event-level granularity of the routing system compliant with
the requirements of I2RS (Section 5 of
[I-D.ietf-i2rs-problem-statement]).
4. Use Cases
An obvious motivation for I2RS traceability is the need to
troubleshoot and identify root-causes of problems in these
increasingly complex routing systems. For example, since I2RS is a
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high-throughput multi-channel, full duplex and highly responsive
interface, I2RS Clients may be performing a large number of
operations on I2RS Agents concurrently or at nearly the same time and
quite possibly in very rapid succession. As these many changes are
made, the network reacts accordingly. These changes might lead to a
race condition, performance issues, data loss, or disruption of
services. In order to isolate the root cause of these issues it is
critical that a network operator or administrator has visibility into
what changes were made via I2RS at a specific time.
Some network environments have strong auditing requirements for
configuration and runtime changes. Other environments have policies
that require saving logging information for operational or regulatory
compliance considerations. These requirements therefore demand that
I2RS provides an account of changes made to network element routing
systems.
As I2RS becomes increasingly pervasive in routing environments, a
traceability model offers significant advantages and facilitates the
following use cases:
o Automated event correlation, trend analysis, and anomaly
detection.
o Trace log storage for offline (manual or tools) analysis.
o Improved accounting of routing system operations.
o Standardized structured data format for writing common tools.
o Common reference for automated testing and incident reporting.
o Real-time monitoring and troubleshooting.
o Enhanced network audit, management and forensic analysis
capabilities.
5. Information Model
5.1. I2RS Traceability Framework
This section describes a framework for I2RS traceability based on the
I2RS Architecture. Some notable elements on the architecture are
highlighted herein.
The interaction between the optional northbound application, I2RS
Client, I2RS Agent, the Routing System and the data captured in the
I2RS trace log is shown in Figure 1.
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+----------------+
|Application |
|.............. |
| Application ID |
+----------------+
^
| 0 .. N
|
V
+-------------+
|I2RS Client |
|.............|
| Client ID |
+-------------+
^
| 1 .. N
|
V
+-------------+ +-----------------------------+
|I2RS Agent |---------------->|Trace Log |
| | |.............................|
+-------------+ |Log Entry [1 .. N] |
^ |.............................|
| |Request Timestamp |
| |Client ID |
| |Client Priority |
| ^ |Secondary ID |
Operation + | Result Code |Client Address |
Op Data | |Operation |
V | |Operation Data Present |
| |Operation Data |
| |Transaction ID |
| |Result Code |
| |Result Timestamp |
V |End Of Message |
+-------------+ +-----------------------------+
|Routing |
|System |
+-------------+
Figure 1: I2RS Interaction Trace Log Capture
5.2. I2RS Trace Log Mandatory Fields
In order to ensure that each I2RS interaction can be properly traced
back to the Client that made the request at a specific point in time,
the following information MUST be collected and stored by the Agent.
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The list below describes the fields captured in the I2RS trace log.
Entry ID: This is a unique identifier for each entry in the I2RS
trace log. Since multiple operations can occur from the same
Client at the same time, it is important to have an identifier
that can be unambiguously associated to a specific entry.
Request Timestamp: The specific time, adhering to [RFC3339] format,
at which the I2RS operation was received by the Agent. Given that
many I2RS operations can occur in rapid succession, the use of
fractional seconds MUST be used to provide adequate granularity.
Fractional seconds SHOULD be expressed using human-readable 32-bit
second and 32-bit microsecond granularity in second.microsecond
format.
Client Identity: The I2RS Client identity used to authenticate the
Client to the I2RS Agent.
Client Priority: The I2RS Client priority assigned by the access
control model that authenticates the Client. For example, this
can be set by the NETCONF Access Control Model (NACM) as described
in [RFC6536].
Secondary Identity: This is an opaque identity that may be known to
the Client from a northbound controlling application. This is
used to trace the northbound application driving the actions of
the Client. The Client may not provide this identity to the Agent
if there is no external application driving the Client. However,
this field MUST be logged. If the Client does not provide an
application ID, then the Agent MUST log an UNAVAILABLE value in
the field.
Client Address: This is the network address of the Client that
connected to the Agent. For example, this may be an IPv4 or IPv6
address. [Note: will I2RS support interactions that have no
network address? If so this field will need to be updated.]
Operation: This is the I2RS operation performed. For example, this
may be an add route operation if a route is being inserted into a
routing table.
Operation Data Present: This is a Boolean field that indicates
whether or not addition per-Operation Data is present.
Operation Data: This field comprises the data passed to the Agent
to complete the desired operation. For example, if the operation
is a route add operation, the Operation Data would include the
route prefix, prefix length, and next hop information to be
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inserted as well as the specific routing table to which the route
will be added. The operation data can also include interface
information. If Operation Data is provided, then the Operation
Data Present field MUST be set to TRUE. Some operations may not
provide operation data. In those cases, the Operation Data
Present field MUST be set to FALSE, and this field MUST be empty.
Transaction ID: The Transaction Identity is an opaque string that
represents this particular operation is part of a long-running
I2RS transaction that can consist of multiple, related I2RS
operations. Using this value, one can relate multiple log entries
together as they are part of a single, overall I2RS operation.
[NOTE: The requirements for transactions and long-running requests
are being discussed in the NETCONF working group, and this text
will follow the requirements set forth there.]
Result Code: This field holds the result of the operation. In the
case of RIB operations, this MUST be the return code as specified
in Section 4 of [I-D.nitinb-i2rs-rib-info-model]. The operation
may not complete with a result code in the case of a timeout. If
the operation fails to complete, it MUST still log the attempted
operation with an appropriate result code (e.g., a result code
indicating a timeout).
Result Timestamp: The specific time, adhering to [RFC3339] format,
at which the I2RS operation was completed by the Agent. If the
operation timed out, then this field will contain an all-zeroes
value of "0000-00-00T00:00:00.00". Given that many I2RS
operations can occur in rapid succession, the use of fractional
seconds MUST be used to provide adequate granularity. Fractional
seconds SHOULD be expressed using human-readable 32-bit second and
32-bit microsecond granularity in second.microsecond format.
End Of Message: Each log entry SHOULD have an appropriate End Of
Message (EOM) indicator. See section Section 5.3 below for more
details.
5.3. End of Message Marker
Because of variability within I2RS trace log fields, implementors
MUST use a format-appropriate end of message (EOM) indicator in order
to signify the end of a particular record. That is, regardless of
format, the I2RS trace log MUST provide a distinct way of
distinguishing between the end of one record and the beginning of
another. For example, in a linear formated log (similar to syslog)
the EOM marker may be a newline character. In an XML formated log,
the schema would provide for element tags that denote beginning and
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end of records. In a JSON formated log, the syntax would provide
record separation (likely by comma-separated array elements).
5.4. I2RS Trace Log Extensibility and Optional Fields
[NOTE: This section is TBD based on further development of I2RS WG
milestones.]
6. Examples
Here is a proposed sample of what the fields might look like in an
I2RS trace log. This is only an early proposal. These values are
subject to change.
Entry ID: 1
Request Timestamp: 2013-09-03T12:00:01.21+00:00
Client ID: 5CEF1870-0326-11E2-A21F-0800200C9A66
Client Priority: 100
Secondary ID com.example.RoutingApp
Client Address: 192.0.2.2
Operation: ROUTE_ADD
Operation Data Present: TRUE
Operation Data: PREFIX 203.0.113.0 PREFIX-LEN 24 NEXT-HOP
198.51.100.1
Transaction ID: 2763461
Result Code: SUCCESS(0)
Result Timestamp: 2013-09-03T12:00:01.23+00:00
7. Operational Guidance
Specific operational procedures regarding temporary log storage,
rollover, retrieval, and access of I2RS trace logs is out of scope
for this document. Organizations employing I2RS trace logging are
responsible for establishing proper operational procedures that are
appropriately suited to their specific requirements and operating
environment. In this section we only provide fundamental and
generalized operational guidelines that are implementation-
independent.
7.1. Trace Log Creation
The I2RS Agent interacts with the Routing and Signaling functions of
the Routing Element. Since the I2RS Agent is responsible for
actually making the routing changes on the associated network device,
it creates and maintains a log of operations that can be retrieved to
troubleshoot I2RS-related impact to the network.
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7.2. Trace Log Temporary Storage
The trace information may be temporarily stored either in an in-
memory buffer or as a file local to the Agent. Care should be given
to the number of I2RS operations expected on a given Agent so that
the appropriate storage medium is used and to maximize the
effectiveness of the log while not impacting the performance and
health of the Agent. Another noteworthy consideration is that Client
requests may not always be processed synchronously or within a
bounded time period. Consequently, to ensure that trace log fields,
such as "Operation" and "Result Code", are part of the same trace log
record it may require buffering of the trace log entries. This
buffering may result in additional resource load on the Agent and the
network element.
Section 7.3 talks about rotating the trace log in order to preserve
the operation history without exhausting Agent or network device
resources. It is perfectly acceptable, therefore, to use both an in-
memory buffer for recent operations while rotating or archiving older
operations to a local file.
It is outside the scope of this document to specify the
implementation details (i.e., size, throughput, data protection,
privacy, etc.) for the physical storage of the I2RS log file. Data
retention policies of the I2RS traceability log is also outside the
scope of this document.
7.3. Trace Log Rotation
In order to prevent the exhaustion of resources on the I2RS Agent or
its associated network device, it is RECOMMENDED that the I2RS Agent
implements trace log rotation. The details on how this is achieved
are left to the implementation and outside the scope of this
document. However, it should be possible to do file rotation based
on either time or size of the current trace log. If file rollover is
supported, multiple archived log files should be supported in order
to maximize the troubleshooting and accounting benefits of the trace
log.
7.4. Trace Log Retrieval
Implementors are free to provide their own, proprietary interfaces
and develop custom tools to retrieve and display the I2RS trace log.
These may include the display of the I2RS trace log as Command Line
Interface (CLI) output. However, a key intention of defining this
information model is to establish an vendor-agnostic and consistent
interface to collect I2RS trace data. Correspondingly, retrieval of
the data should also be made vendor-agnostic.
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Despite the fact that export of I2RS trace log information could be
an invaluable diagnostic tool for off-box analysis, exporting this
information MUST NOT interfere with the ability of the Agent to
process new incoming operations.
The following three sections describe potential ways the trace log
can be accessed. At least one of these three MUST be used, with the
I2RS mechanisms being preferred as they are vendor-independent
approaches to retrieving the data.
7.4.1. Retrieval Via Syslog
The syslog protocol [RFC5424] is a standard way of sending event
notification messages from a host to a collector. However, the
protocol does not define any standard format for storing the
messages, and thus implementors of I2RS tracing would be left to
define their own format. So, while the data contained within the
syslog message would adhere to this information model, and may be
consumable by a human operator, it would not be easily parseable by a
machine. Therefore, syslog MAY be employed as a means of retrieving
or disseminating the I2RS trace log contents.
If syslog is used for trace log retrieval, then existing logging
infrastructure and capabilities of syslog [RFC5424] should be
leveraged without the need to define or extend existing formats. For
example, the various fields described in Section 5.2 SHOULD be
modeled and encoded as Structured Data Elements (referred to as "SD-
ELEMENT"), as described in Section 6.3.1 of [RFC5424].
7.4.2. Retrieval Via I2RS Information Collection
Section 6.7 of the I2RS architecture [I-D.ietf-i2rs-architecture]
defines a mechanism for information collection. The information
collected includes obtaining a snapshot of a large amount of data
from the network element. It is the intent of I2RS to make this data
available in an implementor-agnostic fashion. Therefore, the I2RS
trace log SHOULD be made available via the I2RS information
collection mechanism either as a single snapshot or via a
subscription stream.
7.4.3. Retrieval Via I2RS Pub-Sub
Section 6.7 of the I2RS architecture [I-D.ietf-i2rs-architecture]
goes on to define a publish-subscribe mechanism for a feed of changes
happening within the I2RS layer. I2RS Agents SHOULD support
publishing I2RS trace log information to that feed as described in
that document. Subscribers would then receive a live stream of I2RS
interactions in trace log format and could flexibly choose to do a
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number of things with the log messages. For example, the subscribers
could log the messages to a datastore, aggregate and summarize
interactions from a single Client, etc. Using pub-sub for the
purpose of logging I2RS interactions augments the areas described by
[I-D.camwinget-i2rs-pubsub-sec]. The full range of potential
activites is virtually limitless and the details of how they are
performed are outside the scope of this document, however.
8. IANA Considerations
This document makes no request of IANA.
9. Security Considerations
The I2RS trace log, like any log file, reveals the state of the
entity producing it as well as the identifying information elements
and detailed interactions of the system containing it. The
information model described in this document does not itself
introduce any security issues, but it does define the set of
attributes that make up an I2RS log file. These attributes may
contain sensitive information and thus should adhere to the security,
privacy and permission policies of the organization making use of the
I2RS log file.
It is outside the scope of this document to specify how to protect
the stored log file, but it is expected that adequate precautions and
security best practices such as disk encryption, appropriately
restrictive file/directory permissions, suitable hardening and
physical security of logging entities, mutual authentication,
transport encryption, channel confidentiality, and channel integrity
if transferring log files. Additionally, the potentially sensitive
information contained in a log file SHOULD be adequately anonymized
or obfuscated by operators to ensure its privacy.
10. Acknowledgments
The authors would like to thank Alia Atlas for her initial feedback
and overall support for this work. Additionally, the authors
acknowledge Alvaro Retana, Russ White, Matt Birkner, Jeff Haas, Joel
Halpern, Dean Bogdanovich, Ignas Bagdonas, Nobo Akiya, Kwang-koog
Lee, and Alex Clemm for their reviews, contributed text, and
suggested improvements to this document.
11. References
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11.1. Normative References
[I-D.ietf-i2rs-architecture]
Atlas, A., Halpern, J., Hares, S., Ward, D., and T.
Nadeau, "An Architecture for the Interface to the Routing
System", draft-ietf-i2rs-architecture-07 (work in
progress), December 2014.
[I-D.ietf-i2rs-problem-statement]
Atlas, A., Nadeau, T., and D. Ward, "Interface to the
Routing System Problem Statement", draft-ietf-i2rs-
problem-statement-04 (work in progress), June 2014.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
11.2. Informative References
[I-D.camwinget-i2rs-pubsub-sec]
Beck, K., Cam-Winget, N., and D. McGrew, "Using the
Publish-Subscribe Model in the Interface to the Routing
System", draft-camwinget-i2rs-pubsub-sec-00 (work in
progress), July 2013.
[I-D.nitinb-i2rs-rib-info-model]
Bahadur, N., Folkes, R., Kini, S., and J. Medved, "Routing
Information Base Info Model", draft-nitinb-i2rs-rib-info-
model-02 (work in progress), August 2013.
[RFC3339] Klyne, G., Ed. and C. Newman, "Date and Time on the
Internet: Timestamps", RFC 3339, July 2002.
[RFC5424] Gerhards, R., "The Syslog Protocol", RFC 5424, March 2009.
[RFC5737] Arkko, J., Cotton, M., and L. Vegoda, "IPv4 Address Blocks
Reserved for Documentation", RFC 5737, January 2010.
[RFC6536] Bierman, A. and M. Bjorklund, "Network Configuration
Protocol (NETCONF) Access Control Model", RFC 6536, March
2012.
Authors' Addresses
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Joe Clarke
Cisco Systems, Inc.
7200-12 Kit Creek Road
Research Triangle Park, NC 27709
US
Phone: +1-919-392-2867
Email: jclarke@cisco.com
Gonzalo Salgueiro
Cisco Systems, Inc.
7200-12 Kit Creek Road
Research Triangle Park, NC 27709
US
Email: gsalguei@cisco.com
Carlos Pignataro
Cisco Systems, Inc.
7200-12 Kit Creek Road
Research Triangle Park, NC 27709
US
Email: cpignata@cisco.com
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