RFC 8342
Network Management Datastore Architecture (NMDA)
7. YANG Modules
<CODE BEGINS> file "ietf-datastores@2018-02-14.yang" module ietf-datastores { yang-version 1.1; namespace "urn:ietf:params:xml:ns:yang:ietf-datastores"; prefix ds; organization "IETF Network Modeling (NETMOD) Working Group"; contact "WG Web: <https://datatracker.ietf.org/wg/netmod/> WG List: <mailto:netmod@ietf.org> Author: Martin Bjorklund <mailto:mbj@tail-f.com> Author: Juergen Schoenwaelder <mailto:j.schoenwaelder@jacobs-university.de> Author: Phil Shafer <mailto:phil@juniper.net> Author: Kent Watsen <mailto:kwatsen@juniper.net> Author: Rob Wilton <rwilton@cisco.com>"; description "This YANG module defines a set of identities for identifying datastores. Copyright (c) 2018 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 (https://trustee.ietf.org/license-info).
This version of this YANG module is part of RFC 8342
(https://www.rfc-editor.org/info/rfc8342); see the RFC itself
for full legal notices.";
revision 2018-02-14 {
description
"Initial revision.";
reference
"RFC 8342: Network Management Datastore Architecture (NMDA)";
}
/*
* Identities
*/
identity datastore {
description
"Abstract base identity for datastore identities.";
}
identity conventional {
base datastore;
description
"Abstract base identity for conventional configuration
datastores.";
}
identity running {
base conventional;
description
"The running configuration datastore.";
}
identity candidate {
base conventional;
description
"The candidate configuration datastore.";
}
identity startup {
base conventional;
description
"The startup configuration datastore.";
}
identity intended {
base conventional;
description
"The intended configuration datastore.";
}
identity dynamic {
base datastore;
description
"Abstract base identity for dynamic configuration datastores.";
}
identity operational {
base datastore;
description
"The operational state datastore.";
}
/*
* Type definitions
*/
typedef datastore-ref {
type identityref {
base datastore;
}
description
"A datastore identity reference.";
}
}
<CODE ENDS>
<CODE BEGINS> file "ietf-origin@2018-02-14.yang"
module ietf-origin {
yang-version 1.1;
namespace "urn:ietf:params:xml:ns:yang:ietf-origin";
prefix or;
import ietf-yang-metadata {
prefix md;
}
organization
"IETF Network Modeling (NETMOD) Working Group";
contact
"WG Web: <https://datatracker.ietf.org/wg/netmod/>
WG List: <mailto:netmod@ietf.org>
Author: Martin Bjorklund
<mailto:mbj@tail-f.com>
Author: Juergen Schoenwaelder
<mailto:j.schoenwaelder@jacobs-university.de>
Author: Phil Shafer
<mailto:phil@juniper.net>
Author: Kent Watsen
<mailto:kwatsen@juniper.net>
Author: Rob Wilton
<rwilton@cisco.com>";
description
"This YANG module defines an 'origin' metadata annotation and a
set of identities for the origin value.
Copyright (c) 2018 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
(https://trustee.ietf.org/license-info).
This version of this YANG module is part of RFC 8342
(https://www.rfc-editor.org/info/rfc8342); see the RFC itself
for full legal notices.";
revision 2018-02-14 {
description
"Initial revision.";
reference
"RFC 8342: Network Management Datastore Architecture (NMDA)";
}
/*
* Identities
*/
identity origin {
description
"Abstract base identity for the origin annotation.";
}
identity intended {
base origin;
description
"Denotes configuration from the intended configuration
datastore.";
}
identity dynamic {
base origin;
description
"Denotes configuration from a dynamic configuration
datastore.";
}
identity system {
base origin;
description
"Denotes configuration originated by the system itself.
Examples of system configuration include applied configuration
for an always-existing loopback interface, or interface
configuration that is auto-created due to the hardware
currently present in the device.";
}
identity learned {
base origin;
description
"Denotes configuration learned from protocol interactions with
other devices, instead of via either the intended
configuration datastore or any dynamic configuration
datastore.
Examples of protocols that provide learned configuration
include link-layer negotiations, routing protocols, and
DHCP.";
}
identity default {
base origin;
description
"Denotes configuration that does not have a configured or
learned value but has a default value in use. Covers both
values defined in a 'default' statement and values defined
via an explanation in a 'description' statement.";
}
identity unknown {
base origin;
description
"Denotes configuration for which the system cannot identify the
origin.";
}
/*
* Type definitions
*/
typedef origin-ref {
type identityref {
base origin;
}
description
"An origin identity reference.";
}
/*
* Metadata annotations
*/
md:annotation origin {
type origin-ref;
description
"The 'origin' annotation can be present on any configuration
data node in the operational state datastore. It specifies
from where the node originated. If not specified for a given
configuration data node, then the origin is the same as the
origin of its parent node in the data tree. The origin for
any top-level configuration data nodes must be specified.";
}
}
<CODE ENDS>
8. IANA Considerations
8.1. Updates to the IETF XML Registry
This document registers two URIs in the "IETF XML Registry"
[RFC3688]. Following the format in [RFC3688], the following
registrations have been made:
URI: urn:ietf:params:xml:ns:yang:ietf-datastores
Registrant Contact: The IESG.
XML: N/A; the requested URI is an XML namespace.
URI: urn:ietf:params:xml:ns:yang:ietf-origin
Registrant Contact: The IESG.
XML: N/A; the requested URI is an XML namespace.
8.2. Updates to the YANG Module Names Registry
This document registers two YANG modules in the "YANG Module Names" registry [RFC6020]. Following the format in [RFC6020], the following registrations have been made: name: ietf-datastores namespace: urn:ietf:params:xml:ns:yang:ietf-datastores prefix: ds reference: RFC 8342 name: ietf-origin namespace: urn:ietf:params:xml:ns:yang:ietf-origin prefix: or reference: RFC 83429. Security Considerations
This document discusses an architectural model of datastores for network management using NETCONF/RESTCONF and YANG. It has no security impact on the Internet. Although this document specifies several YANG modules, these modules only define identities and a metadata annotation; hence, the "YANG module security guidelines" [YANG-SEC] do not apply. The origin metadata annotation exposes the origin of values in the applied configuration. Origin information may provide hints that certain control-plane protocols are active on a device. Since origin information is tied to applied configuration values, it is only accessible to clients that have the permissions to read the applied configuration values. Security administrators should consider the sensitivity of origin information while defining access control rules.
10. References
10.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/RFC2119, March 1997, <https://www.rfc-editor.org/info/rfc2119>. [RFC6241] Enns, R., Ed., Bjorklund, M., Ed., Schoenwaelder, J., Ed., and A. Bierman, Ed., "Network Configuration Protocol (NETCONF)", RFC 6241, DOI 10.17487/RFC6241, June 2011, <https://www.rfc-editor.org/info/rfc6241>. [RFC7950] Bjorklund, M., Ed., "The YANG 1.1 Data Modeling Language", RFC 7950, DOI 10.17487/RFC7950, August 2016, <https://www.rfc-editor.org/info/rfc7950>. [RFC7952] Lhotka, L., "Defining and Using Metadata with YANG", RFC 7952, DOI 10.17487/RFC7952, August 2016, <https://www.rfc-editor.org/info/rfc7952>. [RFC8040] Bierman, A., Bjorklund, M., and K. Watsen, "RESTCONF Protocol", RFC 8040, DOI 10.17487/RFC8040, January 2017, <https://www.rfc-editor.org/info/rfc8040>. [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, May 2017, <https://www.rfc-editor.org/info/rfc8174>. [W3C.REC-xml-20081126] Bray, T., Paoli, J., Sperberg-McQueen, M., Maler, E., and F. Yergeau, "Extensible Markup Language (XML) 1.0 (Fifth Edition)", World Wide Web Consortium Recommendation REC-xml-20081126, November 2008, <https://www.w3.org/TR/2008/REC-xml-20081126>.
10.2. Informative References
[NETMOD-Operational] Bjorklund, M. and L. Lhotka, "Operational Data in NETCONF and YANG", Work in Progress, draft-bjorklund-netmod- operational-00, October 2012. [OpState-Enhance] Watsen, K., Bierman, A., Bjorklund, M., and J. Schoenwaelder, "Operational State Enhancements for YANG, NETCONF, and RESTCONF", Work in Progress, draft-kwatsen- netmod-opstate-02, February 2016. [OpState-Modeling] Shakir, R., Shaikh, A., and M. Hines, "Consistent Modeling of Operational State Data in YANG", Work in Progress, draft-openconfig-netmod-opstate-01, July 2015. [OpState-Reqs] Watsen, K. and T. Nadeau, "Terminology and Requirements for Enhanced Handling of Operational State", Work in Progress, draft-ietf-netmod-opstate-reqs-04, January 2016. [RFC3688] Mealling, M., "The IETF XML Registry", BCP 81, RFC 3688, DOI 10.17487/RFC3688, January 2004, <https://www.rfc-editor.org/info/rfc3688>. [RFC6020] Bjorklund, M., Ed., "YANG - A Data Modeling Language for the Network Configuration Protocol (NETCONF)", RFC 6020, DOI 10.17487/RFC6020, October 2010, <https://www.rfc-editor.org/info/rfc6020>. [RFC6244] Shafer, P., "An Architecture for Network Management Using NETCONF and YANG", RFC 6244, DOI 10.17487/RFC6244, June 2011, <https://www.rfc-editor.org/info/rfc6244>. [RFC8343] Bjorklund, M., "A YANG Data Model for Interface Management", RFC 8343, DOI 10.17487/RFC8343, March 2018, <https://www.rfc-editor.org/info/rfc8343>. [RFC8344] Bjorklund, M., "A YANG Data Model for IP Management", RFC 8344, DOI 10.17487/RFC8344, March 2018, <https://www.rfc-editor.org/info/rfc8344>.
[With-config-state] Wilton, R., ""With-config-state" Capability for NETCONF/RESTCONF", Work in Progress, draft-wilton-netmod- opstate-yang-02, December 2015. [YANG-SEC] IETF, "YANG Security Guidelines", <https://trac.ietf.org/ trac/ops/wiki/yang-security-guidelines>.
Appendix A. Guidelines for Defining Datastores
The definition of a new datastore in this architecture should be provided in a document (e.g., an RFC) purposed for defining the datastore. When it makes sense, more than one datastore may be defined in the same document (e.g., when the datastores are logically connected). Each datastore's definition should address the points specified in the subsections below.A.1. Define Which YANG Modules Can Be Used in the Datastore
Not all YANG modules may be used in all datastores. Some datastores may constrain which data models can be used in them. If it is desirable that a subset of all modules can be targeted to the datastore, then the documentation defining the datastore must indicate this.A.2. Define Which Subset of YANG-Modeled Data Applies
By default, the data in a datastore is modeled by all YANG statements in the available YANG modules. However, it is possible to specify criteria that YANG statements must satisfy in order to be present in a datastore. For instance, maybe only "config true" nodes, or "config false" nodes that also have a specific YANG extension, are present in the datastore.A.3. Define How Data Is Actualized
The new datastore must specify how it interacts with other datastores. For example, the diagram in Section 5 depicts dynamic configuration datastores feeding into <operational>. How this interaction occurs has to be defined by the particular dynamic configuration datastores. In some cases, it may occur implicitly, as soon as the data is put into the dynamic configuration datastore, while in other cases an explicit action (e.g., an RPC) may be required to trigger the application of the datastore's data.A.4. Define Which Protocols Can Be Used
By default, it is assumed that both the NETCONF and RESTCONF protocols can be used to interact with a datastore. However, it may be that only a specific protocol can be used (e.g., Forwarding and Control Element Separation (ForCES)) or that a subset of all protocol operations or capabilities are available (e.g., no locking or no XPath-based filtering).
A.5. Define YANG Identities for the Datastore
The datastore must be defined with a YANG identity that uses the "ds:datastore" identity, or one of its derived identities, as its base. This identity is necessary, so that the datastore can be referenced in protocol operations (e.g., <get-data>). The datastore may also be defined with an identity that uses the "or:origin" identity, or one of its derived identities, as its base. This identity is needed if the datastore interacts with <operational>, so that data originating from the datastore can be identified as such via the "origin" metadata attribute defined in Section 7. An example of these guidelines in use is provided in Appendix B.Appendix B. Example of an Ephemeral Dynamic Configuration Datastore
This section defines documentation for an example dynamic configuration datastore using the guidelines provided in Appendix A. For brevity, only a terse example is provided; it is expected that a standalone RFC would be written when this type of scenario is fully considered. This example defines a dynamic configuration datastore called "ephemeral", which is loosely modeled after the work done in the I2RS Working Group. +--------------------+----------------------------------------------+ | Name | Value | +--------------------+----------------------------------------------+ | Name | ephemeral | | | | | YANG modules | all (default) | | | | | YANG nodes | all "config true" data nodes | | | | | How applied | changes automatically propagated to | | | <operational> | | | | | Protocols | NETCONF/RESTCONF (default) | | | | | Defining YANG | "example-ds-ephemeral" | | module | | +--------------------+----------------------------------------------+ Properties of the Example "ephemeral" Datastore
module example-ds-ephemeral {
yang-version 1.1;
namespace "urn:example:ds-ephemeral";
prefix eph;
import ietf-datastores {
prefix ds;
}
import ietf-origin {
prefix or;
}
// datastore identity
identity ds-ephemeral {
base ds:dynamic;
description
"The ephemeral dynamic configuration datastore.";
}
// origin identity
identity or-ephemeral {
base or:dynamic;
description
"Denotes data from the ephemeral dynamic configuration
datastore.";
}
}
Appendix C. Example Data
The use of datastores is complex, and many of the subtle effects are
more easily presented using examples. This section presents a series
of example data models with some sample contents of the various
datastores.
The XML [W3C.REC-xml-20081126] snippets that follow are provided as
examples only.
C.1. System Example
In this example, the following fictional module is used: module example-system { yang-version 1.1; namespace urn:example:system; prefix sys; import ietf-inet-types { prefix inet; } container system { leaf hostname { type string; } list interface { key name; leaf name { type string; } container auto-negotiation { leaf enabled { type boolean; default true; } leaf speed { type uint32; units mbps; description "The advertised speed, in Mbps."; } } leaf speed { type uint32; units mbps; config false; description "The speed of the interface, in Mbps."; }
list address {
key ip;
leaf ip {
type inet:ip-address;
}
leaf prefix-length {
type uint8;
}
}
}
}
}
The operator has configured the hostname and two interfaces, so the
contents of <intended> are:
<system xmlns="urn:example:system">
<hostname>foo.example.com</hostname>
<interface>
<name>eth0</name>
<auto-negotiation>
<speed>1000</speed>
</auto-negotiation>
<address>
<ip>2001:db8::10</ip>
<prefix-length>64</prefix-length>
</address>
</interface>
<interface>
<name>eth1</name>
<address>
<ip>2001:db8::20</ip>
<prefix-length>64</prefix-length>
</address>
</interface>
</system>
The system has detected that the hardware for one of the configured
interfaces ("eth1") is not yet present, so the configuration for that
interface is not applied. Further, the system has received a
hostname and an additional IP address for "eth0" over DHCP. In
addition to filling in the default value for the auto-negotiation
enabled leaf, a loopback interface entry is also automatically
instantiated by the system. All of this is reflected in
<operational>. Note how the "origin" metadata attribute for several
"config true" data nodes is inherited from their parent data nodes.
<system
xmlns="urn:example:system"
xmlns:or="urn:ietf:params:xml:ns:yang:ietf-origin">
<hostname or:origin="or:learned">bar.example.com</hostname>
<interface or:origin="or:intended">
<name>eth0</name>
<auto-negotiation>
<enabled or:origin="or:default">true</enabled>
<speed>1000</speed>
</auto-negotiation>
<speed>100</speed>
<address>
<ip>2001:db8::10</ip>
<prefix-length>64</prefix-length>
</address>
<address or:origin="or:learned">
<ip>2001:db8::1:100</ip>
<prefix-length>64</prefix-length>
</address>
</interface>
<interface or:origin="or:system">
<name>lo0</name>
<address>
<ip>::1</ip>
<prefix-length>128</prefix-length>
</address>
</interface>
</system>
C.2. BGP Example
Consider the following fragment of a fictional BGP module: container bgp { leaf local-as { type uint32; } leaf peer-as { type uint32; } list peer { key name; leaf name { type inet:ip-address; } leaf local-as { type uint32; description "... Defaults to ../local-as."; } leaf peer-as { type uint32; description "... Defaults to ../peer-as."; } leaf local-port { type inet:port; } leaf remote-port { type inet:port; default 179; } leaf state { config false; type enumeration { enum init; enum established; enum closing; } } } } In this example model, both bgp/peer/local-as and bgp/peer/peer-as have complex hierarchical values, allowing the user to specify default values for all peers in a single location.
The model also follows the pattern of fully integrating state
("config false") nodes with configuration ("config true") nodes.
There is no separate "bgp-state" hierarchy, with the accompanying
repetition of containment and naming nodes. This makes the model
simpler and more readable.
C.2.1. Datastores
Each datastore represents differing views of these nodes. <running>
will hold the configuration provided by the operator -- for example,
a single BGP peer. <intended> will conceptually hold the data as
validated, after the removal of data not intended for validation and
after any local template mechanisms are performed. <operational>
will show data from <intended> as well as any "config false" nodes.
C.2.2. Adding a Peer
If the user configures a single BGP peer, then that peer will be
visible in both <running> and <intended>. It may also appear in
<candidate> if the server supports the candidate configuration
datastore. Retrieving the peer will return only the user-specified
values.
No time delay should exist between the appearance of the peer in
<running> and <intended>.
In this scenario, we've added the following to <running>:
<bgp>
<local-as>64501</local-as>
<peer-as>64502</peer-as>
<peer>
<name>2001:db8::2:3</name>
</peer>
</bgp>
C.2.2.1. <operational>
The operational datastore will contain the fully expanded peer data,
including "config false" nodes. In our example, this means that the
"state" node will appear.
In addition, <operational> will contain the "currently in use" values
for all nodes. This means that local-as and peer-as will be
populated even if they are not given values in <intended>. The value
of bgp/local-as will be used if bgp/peer/local-as is not provided;
bgp/peer-as and bgp/peer/peer-as will have the same relationship. In
the operational view, this means that every peer will have values for
their local-as and peer-as, even if those values are not explicitly
configured but are provided by bgp/local-as and bgp/peer-as.
Each BGP peer has a TCP connection associated with it, using the
values of local-port and remote-port from <intended>. If those
values are not supplied, the system will select values. When the
connection is established, <operational> will contain the current
values for the local-port and remote-port nodes regardless of the
origin. If the system has chosen the values, the "origin" attribute
will be set to "system". Before the connection is established, one
or both of the nodes may not appear, since the system may not yet
have their values.
<bgp xmlns:or="urn:ietf:params:xml:ns:yang:ietf-origin"
or:origin="or:intended">
<local-as>64501</local-as>
<peer-as>64502</peer-as>
<peer>
<name>2001:db8::2:3</name>
<local-as or:origin="or:default">64501</local-as>
<peer-as or:origin="or:default">64502</peer-as>
<local-port or:origin="or:system">60794</local-port>
<remote-port or:origin="or:default">179</remote-port>
<state>established</state>
</peer>
</bgp>
C.2.3. Removing a Peer
Changes to configuration may take time to percolate through the
various software components involved. During this period, it is
imperative to continue to give an accurate view of the working of the
device. <operational> will contain nodes for both the previous and
current configuration, as closely as possible tracking the current
operation of the device.
Consider the scenario where a client removes a BGP peer. When a peer
is removed, the operational state will continue to reflect the
existence of that peer until the peer's resources are released,
including closing the peer's connection. During this period, the
current data values will continue to be visible in <operational>,
with the "origin" attribute set to indicate the origin of the
original data.
<bgp xmlns:or="urn:ietf:params:xml:ns:yang:ietf-origin"
or:origin="or:intended">
<local-as>64501</local-as>
<peer-as>64502</peer-as>
<peer>
<name>2001:db8::2:3</name>
<local-as or:origin="or:default">64501</local-as>
<peer-as or:origin="or:default">64502</peer-as>
<local-port or:origin="or:system">60794</local-port>
<remote-port or:origin="or:default">179</remote-port>
<state>closing</state>
</peer>
</bgp>
Once resources are released and the connection is closed, the peer's
data is removed from <operational>.
C.3. Interface Example
In this section, we will use this simple interface data model:
container interfaces {
list interface {
key name;
leaf name {
type string;
}
leaf description {
type string;
}
leaf mtu {
type uint16;
}
leaf-list ip-address {
type inet:ip-address;
}
}
}
C.3.1. Pre-provisioned Interfaces
One common issue in networking devices is the support of Field Replaceable Units (FRUs) that can be inserted and removed from the device without requiring a reboot or interfering with normal operation. These FRUs are typically interface cards, and the devices support pre-provisioning of these interfaces. If a client creates an interface "et-0/0/0" but the interface does not physically exist at this point, then <intended> might contain the following: <interfaces> <interface> <name>et-0/0/0</name> <description>Test interface</description> </interface> </interfaces> Since the interface does not exist, this data does not appear in <operational>. When a FRU containing this interface is inserted, the system will detect it and process the associated configuration. <operational> will contain the data from <intended>, as well as nodes added by the system, such as the current value of the interface's MTU. <interfaces xmlns:or="urn:ietf:params:xml:ns:yang:ietf-origin" or:origin="or:intended"> <interface> <name>et-0/0/0</name> <description>Test interface</description> <mtu or:origin="or:system">1500</mtu> </interface> </interfaces> If the FRU is removed, the interface data is removed from <operational>.
C.3.2. System-Provided Interface
Imagine that the system provides a loopback interface (named "lo0") with a default IPv4 address of "127.0.0.1" and a default IPv6 address of "::1". The system will only provide configuration for this interface if there is no data for it in <intended>. When no configuration for "lo0" appears in <intended>, <operational> will show the system-provided data: <interfaces xmlns:or="urn:ietf:params:xml:ns:yang:ietf-origin" or:origin="or:intended"> <interface or:origin="or:system"> <name>lo0</name> <ip-address>127.0.0.1</ip-address> <ip-address>::1</ip-address> </interface> </interfaces> When configuration for "lo0" does appear in <intended>, <operational> will show that data with the origin set to "intended". If the "ip-address" is not provided, then the system-provided value will appear as follows: <interfaces xmlns:or="urn:ietf:params:xml:ns:yang:ietf-origin" or:origin="or:intended"> <interface> <name>lo0</name> <description>loopback</description> <ip-address or:origin="or:system">127.0.0.1</ip-address> <ip-address>::1</ip-address> </interface> </interfaces>
Acknowledgments
This document grew out of many discussions that took place since 2010. Several documents ([NETMOD-Operational] [With-config-state] [OpState-Reqs] [OpState-Enhance] [OpState-Modeling], as well as [RFC6244]), touched on some of the problems of the original datastore model. The following people were authors of these works in progress or were otherwise actively involved in the discussions that led to this document: o Lou Berger, LabN Consulting, L.L.C., <lberger@labn.net> o Andy Bierman, YumaWorks, <andy@yumaworks.com> o Marcus Hines, Google, <hines@google.com> o Christian Hopps, Deutsche Telekom, <chopps@chopps.org> o Balazs Lengyel, Ericsson, <balazs.lengyel@ericsson.com> o Ladislav Lhotka, CZ.NIC, <lhotka@nic.cz> o Acee Lindem, Cisco Systems, <acee@cisco.com> o Thomas Nadeau, Brocade Networks, <tnadeau@lucidvision.com> o Tom Petch, Engineering Networks Ltd, <ietfc@btconnect.com> o Anees Shaikh, Google, <aashaikh@google.com> o Rob Shakir, Google, <robjs@google.com> o Jason Sterne, Nokia, <jason.sterne@nokia.com> Juergen Schoenwaelder was partly funded by Flamingo, a Network of Excellence project (ICT-318488) supported by the European Commission under its Seventh Framework Programme.
Authors' Addresses
Martin Bjorklund Tail-f Systems Email: mbj@tail-f.com Juergen Schoenwaelder Jacobs University Email: j.schoenwaelder@jacobs-university.de Phil Shafer Juniper Networks Email: phil@juniper.net Kent Watsen Juniper Networks Email: kwatsen@juniper.net Robert Wilton Cisco Systems Email: rwilton@cisco.com