| I2RS | J. Clarke |
| Internet-Draft | G. Salgueiro |
| Intended status: Informational | C. Pignataro |
| Expires: December 9, 2014 | Cisco |
| June 7, 2014 |
Interface to the Routing System (I2RS) Traceability: Framework and Information Model
draft-clarke-i2rs-traceability-02
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.
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This Internet-Draft will expire on December 9, 2014.
Copyright (c) 2014 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.
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 identifier for applications (or actors) 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.
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.
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].
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]).
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 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:
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 actor, I2RS Client, I2RS Agent, the Routing System and the data captured in the I2RS trace log is shown in Figure 1.
+-------------+
|Actor |
|.............|
| Actor ID |
+-------------+
^
| 0 .. N
|
V
+-------------+
|I2RS Client |
|.............|
| Client ID |
+-------------+
^
| 1 .. N
|
V
+-------------+ +-----------------------------+
|I2RS Agent |---------------->|Trace Log |
| | |.............................|
+-------------+ |Log Entry [1 .. N] |
^ |.............................|
| |Timestamp |
| |Client ID |
| ^ |Actor ID |
Operation + | Result Code |Client Address |
Op Data | |Operation |
V | |Operation Data |
| |Result Code |
V |End Of Message |
+-------------+ +-----------------------------+
|Routing |
|System |
+-------------+
Figure 1: I2RS Interaction Trace Log Capture
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.
The list below describes the fields captured in the I2RS trace log.
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 end of records. In a JSON formated log, the syntax would provide record separation (likely by comma-separated array elements).
[NOTE: This section is TBD based on further development of I2RS WG milestones.]
The following describes the trace log information model using the YANG modeling language [RFC6020].
The structure of the I2RS traceability model, as later defined in the YANG module "i2rs-trace-log", is depicted in the following diagram. This tree representation illustrates the structure of I2RS Trace Log YANG model and does not depict all definitions; it is merely intended to illustrate the overall structure.
module: i2rs-trace-log
+--rw i2rs-trace-log
+--rw log-enable? boolean
+--ro log-entry* [log-entry-id]
+--ro log-entry-id log-entry-id
+--ro timestamp timestamp
+--ro client-id client-id
+--ro actor-id actor-id
+--ro client-addr client-addr
+--ro operation operation
+--ro operation-data operation-data
+--ro result-code result-code
The idea of using a UUID for the Client identifier ensures the ID is unique not just in the scope of the current I2RS Agent, but across Agents as well. This ensures that two clients that are unaware of each other will not allocate the same Client ID. That does not preclude two Clients acting as one for purposes of high availability from sharing the same UUID as generated by one one of the Clients.
The "timestamp" field is defined in [RFC3339]. As stated in Section 5.2 the fractional second format MUST be used to provide proper granularity.
The values for "operation", "operation-data" and "result-code" are suggestions as the protocol has not been defined yet. By making these human-readable (as opposed to opcodes) the log becomes more easily consumable by operators and administrators trying to troubleshoot issues relating to I2RS. Even in cases where the operations or codes might appear as opcodes on the wire, their textual translations MUST be included in the log. The opcodes themselves MAY appear in parentheses after the textual representation.
The I2RS traceability model is defined in the following YANG module.
<CODE BEGINS>
file "i2rs-trace-log@2014-06-06.yang"
module i2rs-trace-log {
yang-version 1;
namespace "urn:TBD:params:xml:ns:yang:i2rs:trace-log";
// This namespace should be considered with other I2RS YANG
// models.
prefix i2rslog;
import ietf-yang-types {
prefix "yang";
}
import ietf-inet-types {
prefix "inet";
}
organization "TBD";
contact
"Joe Clarke jclarke@cisco.com
Gonzalo Salgueiro gsalguei@cisco.com
Carlos Pignataro cpignata@cisco.com";
description
"This module defines the model for I2RS traceability
based on the I2RS architecture as defined in
draft-ietf-i2rs-architecture.
Copyright (c) 2014 IETF Trust and the persons identified as
authors of the code. All rights reserved.
Redistribution and use in source and binary forms, with or
without modification, is permitted pursuant to, and subject
to the license terms contained in, the Simplified BSD License
set forth in Section 4.c of the IETF Trust's Legal Provisions
Relating to IETF Documents
(http://trustee.ietf.org/license-info).";
reference
"draft-ietf-i2rs-architecture: An Architecture for the
Interface to the Routing System";
revision "2014-06-03" {
description "Initial revision";
reference "TBD";
}
typedef log-entry-id {
type uint64;
description
"A unique identifier for I2RS log entries.";
}
typedef timestamp {
type yang:date-and-time;
description
"Timestamp for I2RS transactions.";
}
typedef client-id {
type yang:uuid;
description
"The I2RS Client identifier used to authenticate
the Client to the I2RS Agent.";
}
typedef actor-id {
type union {
type string {
pattern "[^\r\n]+";
}
type enumeration {
enum UNAVAILABLE {
description
"The Actor ID was not
specified by the Client.";
}
}
}
description
"Identifier used to trace the northbound actor
driving the actions of the Client.";
}
typedef client-addr {
type inet:ip-address;
description
"IP address of the client that connected to the
Agent.";
}
typedef operation {
type string {
pattern "[a-zA-Z] [a-zA-Z_\-\(\)]*";
}
description
"This is the I2RS operation performed.";
}
typedef operation-data {
type union {
type string;
type enumeration {
enum NULL {
description
"No additional operation
data was required.";
}
}
}
description
"Data passed to the Agent to complete the desired
operation.";
}
typedef result-code {
type string {
pattern "[a-zA-Z0-9_\-\(\)]+";
}
description
"Result code for the operation.";
}
container i2rs-trace-log {
description
"This is the model for I2RS traceability. An
I2RS log is comprised of the following mandatory
fields. Each field MUST be identified by a unique
log-entry-id.";
leaf log-enable {
type boolean;
default "true";
description
"Enable/Disable I2RS logging.";
}
list log-entry {
key "log-entry-id";
config false;
description
"Each element in an I2RS trace log is
discrete and identified by its unique log
entry ID.";
leaf log-entry-id {
type log-entry-id;
config false;
description
"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.";
}
leaf timestamp {
type timestamp;
config false;
mandatory true;
description
"The specific time, adhering to
RFC3339 format, at which the I2RS
transaction occurred. Given that
many I2RS transactions can occur in
rapid succession, the use of
fractional seconds MUST be used to
provide adequate granularity.";
reference
"RFC 3339: Date and Time on the
Internet: Timestamps";
}
leaf client-id {
type client-id;
config false;
mandatory true;
description
"The I2RS Client identifier used
to authenticate the Client to the
I2RS Agent.";
}
leaf actor-id {
type actor-id;
config false;
mandatory true;
description
"This is an opaque identifier
that may be known to the Client
from a northbound controlling
application. This is used to
trace the northbound actor
driving the actions of the
Client. The Client may not
provide this identifier to the
Agent if there is no external
actor driving the Client. In
that case, the special value,
UNAVAILABLE is used to denote no
Actor ID.";
}
leaf client-addr {
type client-addr;
config false;
mandatory true;
description
"This is the IP address of the
client that connected to the Agent.";
}
leaf operation {
type operation;
config false;
mandatory true;
description
"This is the I2RS operation
performed.";
}
leaf operation-data {
type operation-data;
config false;
mandatory true;
description
"This field comprises the data
passed to the Agent to complete the
desired operation. If no additional
operation data is required, then this
field should be set to the special
value, NULL.";
}
leaf result-code {
type result-code;
config false;
mandatory true;
description
"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
draft-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).";
reference
"draft-nitinb-i2rs-rib-info-model:
Routing Information Base Info Model";
}
}
}
}
<CODE ENDS>
This YANG module imports typedefs from [RFC6021].
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
Timestamp: 2013-09-03T12:00:01.21+00:00
Client ID: 5CEF1870-0326-11E2-A21F-0800200C9A66
Actor ID: com.example.RoutingApp
Client Address: 192.0.2.2
Operation: ROUTE_ADD
Operation Data: PREFIX 203.0.113.0 PREFIX-LEN 24 NEXT-HOP
198.51.100.1
Result Code: SUCCESS(0)
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.
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 transactions that can be retrieved to troubleshoot I2RS-related impact to the network.
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 transactions 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. Section 7.3 talks about rotating the trace log in order to preserve the transaction history without exhausting Agent or network device resources. It is perfectly acceptable, therefore, to use both an in-memory buffer for recent transactions while rotating or archiving older transactions 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.
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.
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 implementor-agnostic and consistent interface to collect I2RS trace data. Correspondingly, retrieval of the data should also be made implementor-agnostic.
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 implementor-independent approaches to retrieving the data.
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.
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.
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 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.
The YANG module implies a namespace that will need to be registered with IANA. However, the I2RS WG will likely request such a namespace for other work, so the registration of that namespace may occur in a separate document. This section will be updated as these WG decisions are made.
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.
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 and Dean Bogdanovich for their reviews, contributed text, and suggested improvements to this document.
| [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", Internet-Draft draft-ietf-i2rs-architecture-00, August 2013. |
| [I-D.ietf-i2rs-problem-statement] | Atlas, A., Nadeau, T. and D. Ward, "Interface to the Routing System Problem Statement", Internet-Draft draft-ietf-i2rs-problem-statement-00, August 2013. |
| [RFC2119] | Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. |
| [RFC6020] | Bjorklund, M., "YANG - A Data Modeling Language for the Network Configuration Protocol (NETCONF)", RFC 6020, October 2010. |
| [RFC6021] | Schoenwaelder, J., "Common YANG Data Types", RFC 6021, October 2010. |
| [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", Internet-Draft draft-camwinget-i2rs-pubsub-sec-00, July 2013. |
| [I-D.nitinb-i2rs-rib-info-model] | Bahadur, N., Folkes, R., Kini, S. and J. Medved, "Routing Information Base Info Model", Internet-Draft draft-nitinb-i2rs-rib-info-model-02, August 2013. |
| [RFC3339] | Klyne, G. 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. |