Internet Engineering Task Force R. Wilton, Ed.
Internet-Draft D. Ball
Intended status: Standards Track T. Singh
Expires: May 7, 2020 Cisco Systems
S. Sivaraj
Juniper Networks
November 4, 2019
Common Interface Extension YANG Data Models
draft-ietf-netmod-intf-ext-yang-08
Abstract
This document defines two YANG modules that augment the Interfaces
data model defined in the "YANG Data Model for Interface Management"
with additional configuration and operational data nodes to support
common lower layer interface properties, such as interface MTU.
The YANG modules in this document conform to the Network Management
Datastore Architecture (NMDA) defined in RFC 8342.
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 https://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 May 7, 2020.
Copyright Notice
Copyright (c) 2019 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
(https://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents
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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 . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1. Terminology . . . . . . . . . . . . . . . . . . . . . . . 3
1.2. Tree Diagrams . . . . . . . . . . . . . . . . . . . . . . 4
2. Interface Extensions Module . . . . . . . . . . . . . . . . . 4
2.1. Carrier Delay . . . . . . . . . . . . . . . . . . . . . . 5
2.2. Dampening . . . . . . . . . . . . . . . . . . . . . . . . 6
2.2.1. Suppress Threshold . . . . . . . . . . . . . . . . . 7
2.2.2. Half-Life Period . . . . . . . . . . . . . . . . . . 7
2.2.3. Reuse Threshold . . . . . . . . . . . . . . . . . . . 7
2.2.4. Maximum Suppress Time . . . . . . . . . . . . . . . . 7
2.3. Encapsulation . . . . . . . . . . . . . . . . . . . . . . 7
2.4. Loopback . . . . . . . . . . . . . . . . . . . . . . . . 8
2.5. Maximum frame size . . . . . . . . . . . . . . . . . . . 8
2.6. Sub-interface . . . . . . . . . . . . . . . . . . . . . . 8
2.7. Forwarding Mode . . . . . . . . . . . . . . . . . . . . . 9
3. Interfaces Ethernet-Like Module . . . . . . . . . . . . . . . 9
4. Interface Extensions YANG Module . . . . . . . . . . . . . . 10
5. Interfaces Ethernet-Like YANG Module . . . . . . . . . . . . 20
6. Examples . . . . . . . . . . . . . . . . . . . . . . . . . . 24
6.1. Carrier delay configuration . . . . . . . . . . . . . . . 24
6.2. Dampening configuration . . . . . . . . . . . . . . . . . 25
6.3. MAC address configuration . . . . . . . . . . . . . . . . 26
7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 28
8. ChangeLog . . . . . . . . . . . . . . . . . . . . . . . . . . 28
8.1. Version -08 . . . . . . . . . . . . . . . . . . . . . . . 28
8.2. Version -07 . . . . . . . . . . . . . . . . . . . . . . . 28
8.3. Version -06 . . . . . . . . . . . . . . . . . . . . . . . 28
8.4. Version -05 . . . . . . . . . . . . . . . . . . . . . . . 28
8.5. Version -04 . . . . . . . . . . . . . . . . . . . . . . . 28
8.6. Version -03 . . . . . . . . . . . . . . . . . . . . . . . 28
8.7. Version -02 . . . . . . . . . . . . . . . . . . . . . . . 28
9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 29
10. Security Considerations . . . . . . . . . . . . . . . . . . . 29
10.1. ietf-if-extensions.yang . . . . . . . . . . . . . . . . 29
10.2. ietf-if-ethernet-like.yang . . . . . . . . . . . . . . . 30
11. References . . . . . . . . . . . . . . . . . . . . . . . . . 30
11.1. Normative References . . . . . . . . . . . . . . . . . . 30
11.2. Informative References . . . . . . . . . . . . . . . . . 31
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 32
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1. Introduction
This document defines two NMDA compatible [RFC8342] YANG 1.1
[RFC7950] modules for the management of network interfaces. It
defines various augmentations to the generic interfaces data model
[RFC8343] to support configuration of lower layer interface
properties that are common across many types of network interface.
One of the aims of this document is to provide a standard definition
for these configuration items regardless of the underlying interface
type. For example, a definition for configuring or reading the MAC
address associated with an interface is provided that can be used for
any interface type that uses Ethernet framing.
Several of the augmentations defined here are not backed by any
formal standard specification. Instead, they are for features that
are commonly implemented in equivalent ways by multiple independent
network equipment vendors. The aim of this document is to define
common paths and leaves for the configuration of these equivalent
features in a uniform way, making it easier for users of the YANG
model to access these features in a vendor independent way. Where
necessary, a description of the expected behavior is also provided
with the aim of ensuring vendors implementations are consistent with
the specified behaviour.
Given that the modules contain a collection of discrete features with
the common theme that they generically apply to interfaces, it is
plausible that not all implementors of the YANG module will decide to
support all features. Hence separate feature keywords are defined
for each logically discrete feature to allow implementors the
flexibility to choose which specific parts of the model they support.
The augmentations are split into two separate YANG modules that each
focus on a particular area of functionality. The two YANG modules
defined in this document are:
ietf-if-extensions.yang - Defines extensions to the IETF interface
data model to support common configuration data nodes.
ietf-if-ethernet-like.yang - Defines a module for any
configuration and operational data nodes that are common across
interfaces that use Ethernet framing.
1.1. Terminology
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in BCP
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14 RFC 2119 [RFC2119] RFC 8174 [RFC8174] when, and only when, they
appear in all capitals, as shown here.
1.2. Tree Diagrams
Tree diagrams used in this document follow the notation defined in
[RFC8340].
2. Interface Extensions Module
The Interfaces Extensions YANG module provides some basic extensions
to the IETF interfaces YANG module.
The module provides:
o A carrier delay feature used to provide control over short lived
link state flaps.
o An interface link state dampening feature that is used to provide
control over longer lived link state flaps.
o An encapsulation container and extensible choice statement for use
by any interface types that allow for configurable L2
encapsulations.
o A loopback configuration leaf that is primarily aimed at loopback
at the physical layer.
o MTU configuration leaves applicable to all packet/frame based
interfaces.
o A forwarding mode leaf to indicate the OSI layer at which the
interface handles traffic.
o A generic "sub-interface" identity that an interface identity
definition can derive from if it defines a sub-interface.
o A parent interface leaf useable for all types of sub-interface
that are children of parent interfaces.
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The "ietf-if-extensions" YANG module has the following structure:
module: ietf-if-extensions
augment /if:interfaces/if:interface:
+--rw carrier-delay {carrier-delay}?
| +--rw down? uint32
| +--rw up? uint32
| +--ro carrier-transitions? yang:counter64
| +--ro timer-running? enumeration
+--rw dampening! {dampening}?
| +--rw half-life? uint32
| +--rw reuse? uint32
| +--rw suppress? uint32
| +--rw max-suppress-time? uint32
| +--ro penalty? uint32
| +--ro suppressed? boolean
| +--ro time-remaining? uint32
+--rw encapsulation
| +--rw (encaps-type)?
+--rw loopback? identityref {loopback}?
+--rw max-frame-size? uint32 {max-frame-size}?
+--ro forwarding-mode? identityref
augment /if:interfaces/if:interface:
+--rw parent-interface if:interface-ref {sub-interfaces}?
2.1. Carrier Delay
The carrier delay feature augments the IETF interfaces data model
with configuration for a simple algorithm that is used, generally on
physical interfaces, to suppress short transient changes in the
interface link state. It can be used in conjunction with the
dampening feature described in Section 2.2 to provide effective
control of unstable links and unwanted state transitions.
The principle of the carrier delay feature is to use a short per
interface timer to ensure that any interface link state transition
that occurs and reverts back within the specified time interval is
entirely suppressed without providing any signalling to any upper
layer protocols that the state transition has occurred. E.g. in the
case that the link state transition is suppressed then there is no
change of the /if:interfaces/if:interface/oper-status or
/if:interfaces/if:interfaces/last-change leaves for the interface
that the feature is operating on. One obvious side effect of using
this feature that is that any state transition will always be delayed
by the specified time interval.
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The configuration allows for separate timer values to be used in the
suppression of down->up->down link transitions vs up->down->up link
transitions.
The carrier delay down timer leaf specifies the amount of time that
an interface that is currently in link up state must be continuously
down before the down state change is reported to higher level
protocols. Use of this timer can cause traffic to be black holed for
the configured value and delay reconvergence after link failures,
therefore its use is normally restricted to cases where it is
necessary to allow enough time for another protection mechanism (such
as an optical layer automatic protection system) to take effect.
The carrier delay up timer leaf specifies the amount of time that an
interface that is currently in link down state must be continuously
up before the down->up link state transition is reported to higher
level protocols. This timer is generally useful as a debounce
mechanism to ensure that a link is relatively stable before being
brought into service. It can also be used effectively to limit the
frequency at which link state transition events may occur. The
default value for this leaf is determined by the underlying network
device.
2.2. Dampening
The dampening feature introduces a configurable exponential decay
mechanism to suppress the effects of excessive interface link state
flapping. This feature allows the network operator to configure a
device to automatically identify and selectively dampen a local
interface which is flapping. Dampening an interface keeps the
interface operationally down until the interface stops flapping and
becomes stable. Configuring the dampening feature can improve
convergence times and stability throughout the network by isolating
failures so that disturbances are not propagated, which reduces the
utilization of system processing resources by other devices in the
network and improves overall network stability.
The basic algorithm uses a counter that is increased by 1000 units
every time the underlying interface link state changes from up to
down. If the counter increases above the suppress threshold then the
interface is kept down (and out of service) until either the maximum
suppression time is reached, or the counter has reduced below the
reuse threshold. The half-life period determines that rate at which
the counter is periodically reduced by half.
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2.2.1. Suppress Threshold
The suppress threshold is the value of the accumulated penalty that
triggers the device to dampen a flapping interface. The flapping
interface is identified by the device and assigned a penalty for each
up to down link state change, but the interface is not automatically
dampened. The device tracks the penalties that a flapping interface
accumulates. When the accumulated penalty reaches or exceeds the
suppress threshold, the interface is placed in a suppressed state.
2.2.2. Half-Life Period
The half-life period determines how fast the accumulated penalties
can decay exponentially. The accumulated penalty decays at a rate
that causes its value to be reduced by half after each half-life
period.
2.2.3. Reuse Threshold
If, after one or more half-life periods, the accumulated penalty
decreases below the reuse threshold and the underlying interface link
state is up then the interface is taken out of suppressed state and
is allowed to go up.
2.2.4. Maximum Suppress Time
The maximum suppress time represents the maximum amount of time an
interface can remain dampened when a new penalty is assigned to an
interface. The default of the maximum suppress timer is four times
the half-life period. The maximum value of the accumulated penalty
is calculated using the maximum suppress time, reuse threshold and
half-life period.
2.3. Encapsulation
The encapsulation container holds a choice node that is to be
augmented with datalink layer specific encapsulations, such as HDLC,
PPP, or sub-interface 802.1Q tag match encapsulations. The use of a
choice statement ensures that an interface can only have a single
datalink layer protocol configured.
The different encapsulations themselves are defined in separate YANG
modules defined in other documents that augument the encapsulation
choice statement. For example the Ethernet specific basic 'dot1q-
vlan' encapsulation is defined in ietf-if-l3-vlan.yang and the
'flexible' encapsulation is defined in ietf-flexible-
encapsulation.yang, both modules from
[I-D.ietf-netmod-sub-intf-vlan-model].
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2.4. Loopback
The loopback configuration leaf allows any physical interface to be
configured to be in one of the possible following physical loopback
modes, i.e. internal loopback, line loopback, or use of an external
loopback connector. The use of YANG identities allows for the model
to be extended with other modes of loopback if required.
The following loopback modes are defined:
o Internal loopback - All egress traffic on the interface is
internally looped back within the interface to be received on the
ingress path.
o Line loopback - All ingress traffic received on the interface is
internally looped back within the interface to the egress path.
o Loopback Connector - The interface has a physical loopback
connector attached that loops all egress traffic back into the
interface's ingress path, with equivalent semantics to internal
loopback.
2.5. Maximum frame size
A maximum frame size configuration leaf (max-frame-size) is provided
to specify the maximum size of a layer 2 frame that may be
transmitted or received on an interface. The value includes the
overhead of any layer 2 header, the maximum length of the payload,
and any frame check sequence (FCS) bytes. If configured, the max-
frame-size leaf on an interface also restricts the max-frame-size of
any child sub-interfaces, and the available MTU for protocols.
2.6. Sub-interface
The sub-interface feature specifies the minimal leaves required to
define a child interface that is parented to another interface.
A sub-interface is a logical interface that handles a subset of the
traffic on the parent interface. Separate configuration leaves are
used to classify the subset of ingress traffic received on the parent
interface to be processed in the context of a given sub-interface.
All egress traffic processed on a sub-interface is given to the
parent interface for transmission. Otherwise, a sub-interface is
like any other interface in /if:interfaces and supports the standard
interface features and configuration.
For some vendor specific interface naming conventions the name of the
child interface is sufficient to determine the parent interface,
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which implies that the child interface can never be reparented to a
different parent interface after it has been created without deleting
the existing sub-interface and recreating a new sub-interface. Even
in this case it is useful to have a well defined leaf to cleanly
identify the parent interface.
The model also allows for arbitrarily named sub-interfaces by having
an explicit parent-interface leaf define the child -> parent
relationship. In this naming scenario it is also possible for
implementations to allow for logical interfaces to be reparented to
new parent interfaces without needing the sub-interface to be
destroyed and recreated.
2.7. Forwarding Mode
The forwarding mode leaf provides additional information as to what
mode or layer an interface is logically operating and forwarding
traffic at. The implication of this leaf is that for traffic
forwarded at a given layer that any headers for lower layers are
stripped off before the packet is forwarded at the given layer.
Conversely, on egress any lower layer headers must be added to the
packet before it is transmitted out of the interface.
The following forwarding modes are defined:
o Physical - Traffic is being forwarded at the physical layer. This
includes DWDM or OTN based switching.
o Data-link - Layer 2 based forwarding, such as Ethernet/VLAN based
switching, or L2VPN services.
o Network - Network layer based forwarding, such as IP, MPLS, or
L3VPNs.
3. Interfaces Ethernet-Like Module
The Interfaces Ethernet-Like Module is a small module that contains
all configuration and operational data that is common across
interface types that use Ethernet framing as their datalink layer
encapsulation.
This module currently contains leaves for the configuration and
reporting of the operational MAC address and the burnt-in MAC address
(BIA) associated with any interface using Ethernet framing.
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The "ietf-if-ethernet-like" YANG module has the following structure:
module: ietf-if-ethernet-like
augment /if:interfaces/if:interface:
+--rw ethernet-like
+--rw mac-address? yang:mac-address
| {configurable-mac-address}?
+--ro bia-mac-address? yang:mac-address
augment /if:interfaces/if:interface/if:statistics:
+--ro in-drop-unknown-dest-mac-pkts? yang:counter64
4. Interface Extensions YANG Module
This YANG module augments the interface container defined in RFC 8343
[RFC8343].
<CODE BEGINS> file "ietf-if-extensions@2019-11-04.yang"
module ietf-if-extensions {
yang-version 1.1;
namespace "urn:ietf:params:xml:ns:yang:ietf-if-extensions";
prefix if-ext;
import ietf-yang-types {
prefix yang;
reference "RFC 6991: Common YANG Data Types";
}
import ietf-interfaces {
prefix if;
reference
"RFC 8343: A YANG Data Model For Interface Management";
}
import iana-if-type {
prefix ianaift;
reference "RFC 7224: IANA Interface Type YANG Module";
}
organization
"IETF NETMOD (NETCONF Data Modeling Language) Working Group";
contact
"WG Web: <http://tools.ietf.org/wg/netmod/>
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WG List: <mailto:netmod@ietf.org>
Editor: Robert Wilton
<mailto:rwilton@cisco.com>";
description
"This module contains common definitions for extending the IETF
interface YANG model (RFC 8343) with common configurable layer 2
properties.
Copyright (c) 2019 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 XXXX
(https://www.rfc-editor.org/info/rfcXXXX); see the RFC itself
for full legal notices.
The key words 'MUST', 'MUST NOT', 'REQUIRED', 'SHALL', 'SHALL
NOT', 'SHOULD', 'SHOULD NOT', 'RECOMMENDED', 'NOT RECOMMENDED',
'MAY', and 'OPTIONAL' in this document are to be interpreted as
described in BCP 14 (RFC 2119) (RFC 8174) when, and only when,
they appear in all capitals, as shown here.";
revision 2019-11-04 {
description
"Initial revision.";
reference
"RFC XXX, Common Interface Extension YANG Data Models";
}
feature carrier-delay {
description
"This feature indicates that configurable interface
carrier delay is supported, which is a feature is used to
limit the propagation of very short interface link state
flaps.";
reference "RFC XXX, Section 2.1 Carrier Delay";
}
feature dampening {
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description
"This feature indicates that the device supports interface
dampening, which is a feature that is used to limit the
propagation of interface link state flaps over longer
periods.";
reference "RFC XXX, Section 2.2 Dampening";
}
feature loopback {
description
"This feature indicates that configurable interface loopback
is supported.";
reference "RFC XXX, Section 2.4 Loopback";
}
feature max-frame-size {
description
"This feature indicates that the device supports configuring
or reporting the maximum frame size on interfaces.";
reference "RFC XXX, Section 2.5 Maximum Frame Size";
}
feature sub-interfaces {
description
"This feature indicates that the device supports the
instantiation of sub-interfaces. Sub-interfaces are defined
as logical child interfaces that allow features and forwarding
decisions to be applied to a subset of the traffic processed
on the specified parent interface.";
reference "RFC XXX, Section 2.6 Sub-interface";
}
/*
* Define common identities to help allow interface types to be
* assigned properties.
*/
identity sub-interface {
description
"Base type for generic sub-interfaces.
New or custom interface types can derive from this type to
inherit generic sub-interface configuration.";
reference "RFC XXX, Section 2.6 Sub-interface";
}
identity ethSubInterface{
base ianaift:l2vlan;
base sub-interface;
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description
"This identity represents the child sub-interface of any
interface types that uses Ethernet framing (with or without
802.1Q tagging).";
}
identity loopback {
description "Base identity for interface loopback options";
reference "RFC XXX, Section 2.4";
}
identity internal {
base loopback;
description
"All egress traffic on the interface is internally looped back
within the interface to be received on the ingress path.";
reference "RFC XXX, Section 2.4";
}
identity line {
base loopback;
description
"All ingress traffic received on the interface is internally
looped back within the interface to the egress path.";
reference "RFC XXX, Section 2.4";
}
identity connector {
base loopback;
description
"The interface has a physical loopback connector attached that
loops all egress traffic back into the interface's ingress
path, with equivalent semantics to loopback internal.";
reference "RFC XXX, Section 2.4";
}
identity forwarding-mode {
description "Base identity for forwarding-mode options.";
reference "RFC XXX, Section 2.7";
}
identity physical {
base forwarding-mode;
description
"Physical layer forwarding. This includes DWDM or OTN based
optical switching.";
reference "RFC XXX, Section 2.7";
}
identity data-link {
base forwarding-mode;
description
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"Layer 2 based forwarding, such as Ethernet/VLAN based
switching, or L2VPN services.";
reference "RFC XXX, Section 2.7";
}
identity network {
base forwarding-mode;
description
"Network layer based forwarding, such as IP, MPLS, or L3VPNs.";
reference "RFC XXX, Section 2.7";
}
/*
* Augments the IETF interfaces model with leaves to configure
* and monitor carrier-delay on an interface.
*/
augment "/if:interfaces/if:interface" {
description
"Augments the IETF interface model with optional common
interface level commands that are not formally covered by any
specific standard.";
/*
* Defines standard YANG for the Carrier Delay feature.
*/
container carrier-delay {
if-feature "carrier-delay";
description
"Holds carrier delay related feature configuration.";
leaf down {
type uint32;
units milliseconds;
description
"Delays the propagation of a 'loss of carrier signal' event
that would cause the interface state to go down, i.e. the
command allows short link flaps to be suppressed. The
configured value indicates the minimum time interval (in
milliseconds) that the carrier signal must be continuously
down before the interface state is brought down. If not
configured, the behaviour on loss of carrier signal is
vendor/interface specific, but with the general
expectation that there should be little or no delay.";
}
leaf up {
type uint32;
units milliseconds;
description
"Defines the minimum time interval (in milliseconds) that
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the carrier signal must be continuously present and error
free before the interface state is allowed to transition
from down to up. If not configured, the behaviour is
vendor/interface specific, but with the general
expectation that sufficient default delay should be used
to ensure that the interface is stable when enabled before
being reported as being up. Configured values that are
too low for the hardware capabilties may be rejected.";
}
leaf carrier-transitions {
type yang:counter64;
units transitions;
config false;
description
"Defines the number of times the underlying carrier state
has changed to, or from, state up. This counter should be
incremented even if the high layer interface state changes
are being suppressed by a running carrier-delay timer.";
}
leaf timer-running {
type enumeration {
enum none {
description
"No carrier delay timer is running.";
}
enum up {
description
"Carrier-delay up timer is running. The underlying
carrier state is up, but interface state is not
reported as up.";
}
enum down {
description
"Carrier-delay down timer is running. Interface state
is reported as up, but the underlying carrier state is
actually down.";
}
}
config false;
description
"Reports whether a carrier delay timer is actively running,
in which case the interface state does not match the
underlying carrier state.";
}
reference "RFC XXX, Section 2.1 Carrier Delay";
}
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/*
* Augments the IETF interfaces model with a container to hold
* generic interface dampening
*/
container dampening {
if-feature "dampening";
presence
"Enable interface link flap dampening with default settings
(that are vendor/device specific).";
description
"Interface dampening limits the propagation of interface link
state flaps over longer periods.";
reference "RFC XXX, Section 2.2 Dampening";
leaf half-life {
type uint32;
units seconds;
description
"The time (in seconds) after which a penalty would be half
its original value. Once the interface has been assigned
a penalty, the penalty is decreased at a decay rate
equivalent to the half-life. For some devices, the
allowed values may be restricted to particular multiples
of seconds. The default value is vendor/device
specific.";
reference "RFC XXX, Section 2.3.2 Half-Life Period";
}
leaf reuse {
type uint32;
description
"Penalty value below which a stable interface is
unsuppressed (i.e. brought up) (no units). The default
value is vendor/device specific. The penalty value for a
link up->down state change is 1000 units.";
reference "RFC XXX, Section 2.2.3 Reuse Threshold";
}
leaf suppress {
type uint32;
description
"Limit at which an interface is suppressed (i.e. held down)
when its penalty exceeds that limit (no units). The value
must be greater than the reuse threshold. The default
value is vendor/device specific. The penalty value for a
link up->down state change is 1000 units.";
reference "RFC XXX, Section 2.2.1 Suppress Threshold";
}
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leaf max-suppress-time {
type uint32;
units seconds;
description
"Maximum time (in seconds) that an interface can be
suppressed before being unsuppressed if no further link
up->down state change penalties have been applied. This
value effectively acts as a ceiling that the penalty value
cannot exceed. The default value is vendor/device
specific.";
reference "RFC XXX, Section 2.2.4 Maximum Suppress Time";
}
leaf penalty {
type uint32;
config false;
description
"The current penalty value for this interface. When the
penalty value exceeds the 'suppress' leaf then the
interface is suppressed (i.e. held down).";
reference "RFC XXX, Section 2.2 Dampening";
}
leaf suppressed {
type boolean;
config false;
description
"Represents whether the interface is suppressed (i.e. held
down) because the 'penalty' leaf value exceeds the
'suppress' leaf.";
reference "RFC XXX, Section 2.2 Dampening";
}
leaf time-remaining {
when '../suppressed = "true"' {
description
"Only suppressed interfaces have a time remaining.";
}
type uint32;
units seconds;
config false;
description
"For a suppressed interface, this leaf represents how long
(in seconds) that the interface will remain suppressed
before it is allowed to go back up again.";
reference "RFC XXX, Section 2.2 Dampening";
}
}
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/*
* Various types of interfaces support a configurable layer 2
* encapsulation, any that are supported by YANG should be
* listed here.
*
* Different encapsulations can hook into the common encaps-type
* choice statement.
*/
container encapsulation {
when
"derived-from-or-self(../if:type,
'ianaift:ethernetCsmacd') or
derived-from-or-self(../if:type,
'ianaift:ieee8023adLag') or
derived-from-or-self(../if:type, 'ianaift:pos') or
derived-from-or-self(../if:type,
'ianaift:atmSubInterface') or
derived-from-or-self(../if:type, 'ethSubInterface')" {
description
"All interface types that can have a configurable L2
encapsulation.";
}
description
"Holds the OSI layer 2 encapsulation associated with an
interface.";
choice encaps-type {
description
"Extensible choice of layer 2 encapsulations";
reference "RFC XXX, Section 2.3 Encapsulation";
}
}
/*
* Various types of interfaces support loopback configuration,
* any that are supported by YANG should be listed here.
*/
leaf loopback {
when "derived-from-or-self(../if:type,
'ianaift:ethernetCsmacd') or
derived-from-or-self(../if:type, 'ianaift:sonet') or
derived-from-or-self(../if:type, 'ianaift:atm') or
derived-from-or-self(../if:type, 'ianaift:otnOtu')" {
description
"All interface types that support loopback configuration.";
}
if-feature "loopback";
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type identityref {
base loopback;
}
description "Enables traffic loopback.";
reference "RFC XXX, Section 2.4 Loopback";
}
/*
* Allows the maximum frame size to be configured or reported.
*/
leaf max-frame-size {
if-feature "max-frame-size";
type uint32 {
range "64 .. max";
}
description
"The maximum size of layer 2 frames that may be transmitted
or received on the interface (including any frame header,
maximum frame payload size, and frame checksum sequence).
If configured, the max-frame-size also limits the maximum
frame size of any child sub-interfaces. The MTU available
to higher layer protocols is restricted to the maximum frame
payload size, and MAY be further restricted by explicit
layer 3 or protocol specific MTU configuration.";
reference "RFC XXX, Section 2.5 Maximum Frame Size";
}
/*
* Augments the IETF interfaces model with a leaf that indicates
* which mode, or layer, is being used to forward the traffic.
*/
leaf forwarding-mode {
type identityref {
base forwarding-mode;
}
config false;
description
"The forwarding mode that the interface is operating in.";
reference "RFC XXX, Section 2.7 Forwarding Mode";
}
}
/*
* Add generic support for sub-interfaces.
*
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* This should be extended to cover all interface types that are
* child interfaces of other interfaces.
*/
augment "/if:interfaces/if:interface" {
when "derived-from(if:type, 'sub-interface') or
derived-from-or-self(if:type, 'ianaift:atmSubInterface') or
derived-from-or-self(if:type, 'ianaift:frameRelay')" {
description
"Any ianaift:types that explicitly represent sub-interfaces
or any types that derive from the sub-interface identity.";
}
if-feature "sub-interfaces";
description
"Adds a parent interface field to interfaces that model
sub-interfaces.";
leaf parent-interface {
type if:interface-ref;
mandatory true;
description
"This is the reference to the parent interface of this
sub-interface.";
reference "RFC XXX, Section 2.6 Sub-interface";
}
}
}
<CODE ENDS>
5. Interfaces Ethernet-Like YANG Module
This YANG module augments the interface container defined in RFC 8343
[RFC8343] for Ethernet-like interfaces. This includes Ethernet
interfaces, 802.3 LAG (802.1AX) interfaces, VLAN sub-interfaces,
Switch Virtual interfaces, and Pseudo-Wire Head-End interfaces.
<CODE BEGINS> file "ietf-if-ethernet-like@2019-11-04.yang"
module ietf-if-ethernet-like {
yang-version 1.1;
namespace
"urn:ietf:params:xml:ns:yang:ietf-if-ethernet-like";
prefix ethlike;
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import ietf-interfaces {
prefix if;
reference
"RFC 8343: A YANG Data Model For Interface Management";
}
import ietf-yang-types {
prefix yang;
reference "RFC 6991: Common YANG Data Types";
}
import iana-if-type {
prefix ianaift;
reference "RFC 7224: IANA Interface Type YANG Module";
}
organization
"IETF NETMOD (NETCONF Data Modeling Language) Working Group";
contact
"WG Web: <http://tools.ietf.org/wg/netmod/>
WG List: <mailto:netmod@ietf.org>
Editor: Robert Wilton
<mailto:rwilton@cisco.com>";
description
"This module contains YANG definitions for configuration for
'Ethernet-like' interfaces. It is applicable to all interface
types that use Ethernet framing and expose an Ethernet MAC
layer, and includes such interfaces as physical Ethernet
interfaces, Ethernet LAG interfaces and VLAN sub-interfaces.
Additional interface configuration and counters for physical
Ethernet interfaces are defined in
ieee802-ethernet-interface.yang, as part of IEEE Std
802.3.2-2019.
Copyright (c) 2019 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).
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This version of this YANG module is part of RFC XXXX
(https://www.rfc-editor.org/info/rfcXXXX); see the RFC itself
for full legal notices.";
revision 2019-11-04 {
description "Initial revision.";
reference
"RFC XXX, Common Interface Extension YANG Data Models";
}
feature configurable-mac-address {
description
"This feature indicates that MAC addresses on Ethernet-like
interfaces can be configured.";
reference "RFC XXX, Section 3 Interfaces Ethernet-Like Module";
}
/*
* Configuration parameters for Ethernet-like interfaces.
*/
augment "/if:interfaces/if:interface" {
when "derived-from-or-self(if:type, 'ianaift:ethernetCsmacd') or
derived-from-or-self(if:type, 'ianaift:ieee8023adLag') or
derived-from-or-self(if:type, 'ianaift:ifPwType')" {
description "Applies to all Ethernet-like interfaces";
}
description
"Augment the interface model with parameters for all
Ethernet-like interfaces.";
container ethernet-like {
description
"Contains parameters for interfaces that use Ethernet framing
and expose an Ethernet MAC layer.";
leaf mac-address {
if-feature "configurable-mac-address";
type yang:mac-address;
description
"The MAC address of the interface. The operational value
matches the /if:interfaces/if:interface/if:phys-address
leaf defined in ietf-interface.yang.";
}
leaf bia-mac-address {
type yang:mac-address;
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config false;
description
"The 'burnt-in' MAC address. I.e the default MAC address
assigned to the interface if no MAC address has been
explicitly configured on it.";
}
}
}
/*
* Configuration parameters for Ethernet-like interfaces.
*/
augment "/if:interfaces/if:interface/if:statistics" {
when "derived-from-or-self(../if:type,
'ianaift:ethernetCsmacd') or
derived-from-or-self(../if:type,
'ianaift:ieee8023adLag') or
derived-from-or-self(../if:type, 'ianaift:ifPwType')" {
description "Applies to all Ethernet-like interfaces";
}
description
"Augment the interface model statistics with additional
counters related to Ethernet-like interfaces.";
leaf in-drop-unknown-dest-mac-pkts {
type yang:counter64;
units frames;
description
"A count of the number of frames that were well formed, but
otherwise dropped because the destination MAC address did
not pass any ingress destination MAC address filter.
For consistency, frames counted against this drop counters
are also counted against the IETF interfaces statistics. In
particular, they are included in in-octets and in-discards,
but are not included in in-unicast-pkts, in-multicast-pkts
or in-broadcast-pkts, because they are not delivered to a
higher layer.
Discontinuities in the values of this counter can occur at
re-initialization of the management system, and at other
times as indicated by the value of the 'discontinuity-time'
leaf defined in the ietf-interfaces YANG module (RFC 8343).";
}
}
}
<CODE ENDS>
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6. Examples
The following sections give some examples of how different parts of
the YANG modules could be used. Examples are not given for the more
trivial configuration, or for sub-interfaces, for which examples are
contained in [I-D.ietf-netmod-sub-intf-vlan-model].
6.1. Carrier delay configuration
The following example shows how the operational state datastore could
look like for an Ethernet interface without any carrier delay
configuration. The down leaf value of 0 indicates that link down
events as always propagated to high layers immediately, but an up
leaf value of 50 indicates that the interface must be up and stable
for at least 50 msecs before the interface is reported as being up to
the high layers.
<?xml version="1.0" encoding="utf-8"?>
<interfaces
xmlns="urn:ietf:params:xml:ns:yang:ietf-interfaces"
xmlns:ianaift="urn:ietf:params:xml:ns:yang:iana-if-type"
xmlns:if-ext="urn:ietf:params:xml:ns:yang:ietf-if-extensions">
<interface>
<name>eth0</name>
<type>ianaift:ethernetCsmacd</type>
<if-ext:carrier-delay>
<if-ext:down>0</if-ext:down>
<if-ext:up>50</if-ext:up>
</if-ext:carrier-delay>
</interface>
</interfaces>
The following example shows explicit carrier delay up and down values
have been configured. A 50 msec down leaf value has been used to
potentially allow optical protection to recover the link before the
higher layer protocol state is flapped. A 1 second (1000
milliseconds) up leaf value has been used to ensure that the link is
always reasonably stable before allowing traffic to be carried over
it. This also has the benefit of greatly reducing the rate at which
higher layer protocol state flaps could occur.
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<?xml version="1.0" encoding="utf-8"?>
<config xmlns="urn:ietf:params:xml:ns:netconf:base:1.0">
<interfaces
xmlns="urn:ietf:params:xml:ns:yang:ietf-interfaces"
xmlns:ianaift="urn:ietf:params:xml:ns:yang:iana-if-type"
xmlns:if-ext="urn:ietf:params:xml:ns:yang:ietf-if-extensions">
<interface>
<name>eth0</name>
<type>ianaift:ethernetCsmacd</type>
<if-ext:carrier-delay>
<if-ext:down>50</if-ext:down>
<if-ext:up>1000</if-ext:up>
</if-ext:carrier-delay>
</interface>
</interfaces>
</config>
6.2. Dampening configuration
The following example shows what the operational state datastore may
look like for an interface configured with interface dampening. The
'suppressed' leaf indicates that the interface is currently
suppressed (i.e. down) because the 'penalty' is greater than the
'suppress' leaf threshold. The 'time-remaining' leaf indicates that
the interface will remain suppressed for another 103 seconds before
the 'penalty' is below the 'reuse' leaf value and the interface is
allowed to go back up again.
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<?xml version="1.0" encoding="utf-8"?>
<interfaces
xmlns="urn:ietf:params:xml:ns:yang:ietf-interfaces"
xmlns:ianaift="urn:ietf:params:xml:ns:yang:iana-if-type">
<interface>
<name>eth0</name>
<type>ianaift:ethernetCsmacd</type>
<oper-status>down</oper-status>
<dampening
xmlns="urn:ietf:params:xml:ns:yang:ietf-if-extensions">
<half-life>60</half-life>
<reuse>750</reuse>
<suppress>2000</suppress>
<max-suppress-time>240</max-suppress-time>
<penalty>2480</penalty>
<suppressed>true</suppressed>
<time-remaining>103</time-remaining>
</dampening>
</interface>
</interfaces>
6.3. MAC address configuration
The following example shows how the operational state datastore could
look like for an Ethernet interface without an explicit MAC address
configured. The mac-address leaf always reports the actual
operational MAC address that is in use. The bia-mac-address leaf
always reports the default MAC address assigned to the hardware.
<?xml version="1.0" encoding="utf-8"?>
<interfaces
xmlns="urn:ietf:params:xml:ns:yang:ietf-interfaces"
xmlns:ianaift="urn:ietf:params:xml:ns:yang:iana-if-type">
<interface>
<name>eth0</name>
<type>ianaift:ethernetCsmacd</type>
<phys-address>00:00:5E:00:53:30</phys-address>
<ethernet-like
xmlns="urn:ietf:params:xml:ns:yang:ietf-if-ethernet-like">
<mac-address>00:00:5E:00:53:30</mac-address>
<bia-mac-address>00:00:5E:00:53:30</bia-mac-address>
</ethernet-like>
</interface>
</interfaces>
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The following example shows the intended configuration for interface
eth0 with an explicit MAC address configured.
<?xml version="1.0" encoding="utf-8"?>
<config xmlns="urn:ietf:params:xml:ns:netconf:base:1.0">
<interfaces
xmlns="urn:ietf:params:xml:ns:yang:ietf-interfaces"
xmlns:ianaift="urn:ietf:params:xml:ns:yang:iana-if-type">
<interface>
<name>eth0</name>
<type>ianaift:ethernetCsmacd</type>
<ethernet-like
xmlns="urn:ietf:params:xml:ns:yang:ietf-if-ethernet-like">
<mac-address>00:00:5E:00:53:35</mac-address>
</ethernet-like>
</interface>
</interfaces>
</config>
After the MAC address configuration has been successfully applied,
the operational state datastore reporting the interface MAC address
properties would contain the following, with the mac-address leaf
updated to match the configured value, but the bia-mac-address leaf
retaining the same value - which should never change.
<?xml version="1.0" encoding="utf-8"?>
<interfaces
xmlns="urn:ietf:params:xml:ns:yang:ietf-interfaces"
xmlns:ianaift="urn:ietf:params:xml:ns:yang:iana-if-type">
<interface>
<name>eth0</name>
<type>ianaift:ethernetCsmacd</type>
<phys-address>00:00:5E:00:53:35</phys-address>
<ethernet-like
xmlns="urn:ietf:params:xml:ns:yang:ietf-if-ethernet-like">
<mac-address>00:00:5E:00:53:35</mac-address>
<bia-mac-address>00:00:5E:00:53:30</bia-mac-address>
</ethernet-like>
</interface>
</interfaces>
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7. Acknowledgements
The authors wish to thank Eric Gray, Ing-Wher Chen, Jon Culver,
Juergen Schoenwaelder, Ladislav Lhotka, Lou Berger, Mahesh
Jethanandani, Martin Bjorklund, Michael Zitao, Neil Ketley, Qin Wu,
William Lupton, Xufeng Liu, Andy Bierman, and Vladimir Vassilev for
their helpful comments contributing to this document.
8. ChangeLog
XXX, RFC Editor, please delete this change log before publication.
8.1. Version -08
o Initial updates after WG LC comments.
8.2. Version -07
o Minor editorial updates
8.3. Version -06
o Remove reservable-bandwidth, based on Acee's suggestion
o Add examples
o Add additional state parameters for carrier-delay and dampening
8.4. Version -05
o Incorporate feedback from Andy Bierman
8.5. Version -04
o Incorporate feedback from Lada, some comments left as open issues.
8.6. Version -03
o Fixed incorrect module name references, and updated tree output
8.7. Version -02
o Minor changes only: Fix errors in when statements, use derived-
from-or-self() for future proofing.
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9. IANA Considerations
This document defines several new YANG module and the authors
politely request that IANA assigns unique names to the two YANG
module files contained within this document, and also appropriate
URIs in the "IETF XML Registry".
10. Security Considerations
The YANG module defined in this memo is designed to be accessed via
the NETCONF protocol RFC 6241 [RFC6241]. The lowest NETCONF layer is
the secure transport layer and the mandatory to implement secure
transport is SSH RFC 6242 [RFC6242]. The NETCONF access control
model RFC 6536 [RFC6536] provides the means to restrict access for
particular NETCONF users to a pre-configured subset of all available
NETCONF protocol operations and content.
There are a number of data nodes defined in this YANG module which
are writable/creatable/deletable (i.e. config true, which is the
default). These data nodes may be considered sensitive or vulnerable
in some network environments. Write operations (e.g. edit-config) to
these data nodes without proper protection can have a negative effect
on network operations. These are the subtrees and data nodes and
their sensitivity/vulnerability:
10.1. ietf-if-extensions.yang
The ietf-if-extensions YANG module contains various configuration
leaves that affect the behavior of interfaces. Modifying these
leaves can cause an interface to go down, or become unreliable, or to
drop traffic forwarded over it. More specific details of the
possible failure modes are given below.
The following leaf could cause the interface to go down and stop
processing any ingress or egress traffic on the interface. It could
also cause broadcast traffic storms.
o /if:interfaces/if:interface/loopback
The following leaves could cause instabilities at the interface link
layer, and cause unwanted higher layer routing path changes if the
leaves are modified, although they would generally only affect a
device that had some underlying link stability issues:
o /if:interfaces/if:interface/carrier-delay/down
o /if:interfaces/if:interface/carrier-delay/up
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o /if:interfaces/if:interface/dampening/half-life
o /if:interfaces/if:interface/dampening/reuse
o /if:interfaces/if:interface/dampening/suppress
o /if:interfaces/if:interface/dampening/max-suppress-time
The following leaves could cause traffic loss on the interface
because the received or transmitted frames do not comply with the
frame matching criteria on the interface and hence would be dropped:
o /if:interfaces/if:interface/encapsulation
o /if:interfaces/if:interface/max-frame-size
o /if:interfaces/if:interface/forwarding-mode
Changing the parent-interface leaf could cause all traffic on the
affected interface to be dropped. The affected leaf is:
o /if:interfaces/if:interface/parent-interface
10.2. ietf-if-ethernet-like.yang
Generally, the configuration nodes in the ietf-if-ethernet-like YANG
module are concerned with configuration that is common across all
types of Ethernet-like interfaces. The module currently only
contains a node for configuring the operational MAC address to use on
an interface. Adding/modifying/deleting this leaf has the potential
risk of causing protocol instability, excessive protocol traffic, and
general traffic loss, particularly if the configuration change caused
a duplicate MAC address to be present on the local network . The
following leaf is affected:
o interfaces/interface/ethernet-like/mac-address
11. References
11.1. 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>.
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[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>.
[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>.
[RFC8342] Bjorklund, M., Schoenwaelder, J., Shafer, P., Watsen, K.,
and R. Wilton, "Network Management Datastore Architecture
(NMDA)", RFC 8342, DOI 10.17487/RFC8342, March 2018,
<https://www.rfc-editor.org/info/rfc8342>.
[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>.
11.2. Informative References
[I-D.ietf-netmod-sub-intf-vlan-model]
Wilton, R., Ball, D., tapsingh@cisco.com, t., and S.
Sivaraj, "Sub-interface VLAN YANG Data Models", draft-
ietf-netmod-sub-intf-vlan-model-05 (work in progress),
March 2019.
[IEEE802.3.2]
IEEE WG802.3 - Ethernet Working Group, "IEEE
802.3.2-2019", 2019.
[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>.
[RFC6242] Wasserman, M., "Using the NETCONF Protocol over Secure
Shell (SSH)", RFC 6242, DOI 10.17487/RFC6242, June 2011,
<https://www.rfc-editor.org/info/rfc6242>.
[RFC6536] Bierman, A. and M. Bjorklund, "Network Configuration
Protocol (NETCONF) Access Control Model", RFC 6536,
DOI 10.17487/RFC6536, March 2012,
<https://www.rfc-editor.org/info/rfc6536>.
[RFC6991] Schoenwaelder, J., Ed., "Common YANG Data Types",
RFC 6991, DOI 10.17487/RFC6991, July 2013,
<https://www.rfc-editor.org/info/rfc6991>.
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[RFC7224] Bjorklund, M., "IANA Interface Type YANG Module",
RFC 7224, DOI 10.17487/RFC7224, May 2014,
<https://www.rfc-editor.org/info/rfc7224>.
[RFC8340] Bjorklund, M. and L. Berger, Ed., "YANG Tree Diagrams",
BCP 215, RFC 8340, DOI 10.17487/RFC8340, March 2018,
<https://www.rfc-editor.org/info/rfc8340>.
Authors' Addresses
Robert Wilton (editor)
Cisco Systems
Email: rwilton@cisco.com
David Ball
Cisco Systems
Email: daviball@cisco.com
Tapraj Singh
Cisco Systems
Email: tapsingh@cisco.com
Selvakumar Sivaraj
Juniper Networks
Email: ssivaraj@juniper.net
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