| Internet Engineering Task Force | R. Wilton, Ed. |
| Internet-Draft | D. Ball |
| Intended status: Standards Track | Cisco Systems |
| Expires: April 21, 2016 | T. Singh |
| S. Sivaraj | |
| Juniper Networks | |
| October 19, 2015 |
Interface VLAN YANG Data Models
draft-wilton-netmod-intf-vlan-yang-01
This document defines YANG models to add support for classifying traffic received on interfaces as Ethernet/VLAN framed packets to sub-interfaces based on the fields available in the Ethernet/VLAN frame headers. Primarily the classification is based on VLAN identifiers in the 802.1Q VLAN tags, but the model also has support for matching on some other layer 2 frame header fields and is designed to be easily extensible to match on other arbitrary header fields.
The model differs from an IEEE 802.1Q bridge model in that the configuration is interface/sub-interface based as opposed to being based on membership of a 802.1Q VLAN bridge.
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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 http://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 April 21, 2016.
Copyright (c) 2015 IETF Trust and the persons identified as the document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents (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.
This document defines two YANG RFC 6020 [RFC6020] modules that augment the encapsulation choice YANG element defined in Interface Extensions YANG [I-D.wilton-netmod-intf-ext-yang] and the generic interfaces data model defined in RFC 7223 [RFC7223]. The two modules provide configuration nodes to support classification of Ethernet/VLAN traffic to sub-interfaces, that can have interface based feature and service configuration applied to them. In the case of layer 2 Ethernet services, the flexible encapsulation module also supports flexible rewriting of the VLAN tags contained the in frame header.
For reference, a comparison between the sub-interface based YANG model documented in this draft and an IEEE 802.1Q bridge model is described in Appendix A.
In summary, the YANG modules defined in this internet draft are:
In addition, the yang module dot1q-tag-types.yang, that provides definitions for common ways of identifying frames using fields from the 802.1Q VLAN tag, is included in this draft as a temporary reference. This module may be standardized through IEEE 802.1 and subsequently referenced from this draft rather than included in it.
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in RFC 2119 [RFC2119].
Sub-interface: A sub-interface an a small augmentation of a regular interface in the standard YANG module for Interface Management that represents a subset of the traffic handled by its parent interface. As such, it supports both configuration and operational data using any other YANG models that augment or reference interfaces in the normal way. It is defined in Interface Extensions YANG [I-D.wilton-netmod-intf-ext-yang].
A simplified graphical representation of the data model is used in this document. The meaning of the symbols in these diagrams is as follows:
The aim of of the YANG models contained in this draft is to provide the core model that is required to implement VLAN transport services on router based devices.
The secondary aim is to make the model cleanly extensible, both to handle greater depths of VLAN tag stacks if required, and also to allow vendors to extend the model to include additional forms of tag matching and rewriting if desired.
However, the intention is that it should not be necessary to have any vendor specific extensions to any of the YANG models defined in this document to implement standard Ethernet and VLAN services.
The L3 Interface VLAN model provides appropriate leaves for termination of an 802.1Q VLAN tagged segment to a sub-interface based L3 service. It allows for termination of traffic with up to two 802.1Q VLAN tags.
The "if-l3-vlan" YANG module has the following structure:
augment /if:interfaces/if:interface/if-cmn:encapsulation/
if-cmn:encaps-type:
+--:(vlan)
+--rw vlan
+--rw tags
+--rw tag* [index]
+--rw index uint8
+--rw dot1q-tag
+--rw tag-type dot1q-tag-type
+--rw vlan-id dot1q-vlan-id
The Flexible Encapsulation model is designed to allow for the flexible provisioning of layer 2 services. It provides the capability to classify Ethernet/VLAN frames received on an Ethernet trunk interface to sub-interfaces based on the fields available in the layer 2 headers. Once classified to sub-interfaces, it provides the capability to selectively modify fields within the layer 2 headers before the frame is handed off to the appropriate forwarding code for further handling.
The model supports a common core set of layer 2 header matches based on the 802.1Q tag type and VLAN Ids contained within the header up to a tag stack depth of two tags.
The model supports flexible rewrites of the layer 2 frame header for data frames as they are processed on the interface. It defines a set of standard tag manipulations that allow for the insertion, removal, or rewrite of one or two 802.1Q VLAN tags. The expectation is that manipulations are generally implemented in a symmetrical fashion, i.e. if a manipulation is performed on ingress traffic on an interface then the reverse manipulation is always performed on egress traffic out of the same interface. However, the model also allows for asymmetrical rewrites, which may be required to implement some forwarding models (such as E-Tree).
The structure of the model is currently limited to matching or rewriting a maximum of two 802.1Q tags in the frame header but has been designed to be easily extensible to matching/rewriting three or more VLAN tags in future, if required.
The final aim for the model design is for it to be cleanly extensible to add in additional match and rewrite criteria of the layer 2 header, such as matching on the source or destination MAC address, PCP or DEI fields in the 802.1Q tags, or the EtherType of the frame payload. Rewrites can also be extended to allow for modification of other fields within the layer 2 frame header.
The "flexible-encapsulation" YANG module has the following structure:
augment /if:interfaces/if:interface/if-cmn:encapsulation/
if-cmn:encaps-type:
+--:(flexible) {flexible-encapsulation-rewrites}?
+--rw flexible
+--rw match
| +--rw (match-type)
| +--:(default)
| | +--rw default? empty
| +--:(untagged)
| | +--rw untagged? empty
| +--:(priority-tagged)
| | +--rw priority-tagged
| | +--rw tag-type? dot1q:dot1q-tag-type
| +--:(vlan-tagged)
| +--rw vlan-tagged
| +--rw tag* [index]
| | +--rw index uint8
| | +--rw dot1q-tag
| | +--rw tag-type dot1q-tag-type
| | +--rw vlan-id union
| +--rw match-exact-tags? empty
+--rw rewrite {flexible-rewrites}?
+--rw (direction)?
+--:(symmetrical)
| +--rw symmetrical
| +--rw tag-rewrite {tag-rewrites}?
| +--rw pop-tags? uint8
| +--rw push-tags* [index]
| +--rw index uint8
| +--rw dot1q-tag
| +--rw tag-type dot1q-tag-type
| +--rw vlan-id dot1q-vlan-id
+--:(asymmetrical) {asymmetric-rewrites}?
+--rw ingress
| +--rw tag-rewrite {tag-rewrites}?
| +--rw pop-tags? uint8
| +--rw push-tags* [index]
| +--rw index uint8
| +--rw dot1q-tag
| +--rw tag-type dot1q-tag-type
| +--rw vlan-id dot1q-vlan-id
+--rw egress
+--rw tag-rewrite {tag-rewrites}?
+--rw pop-tags? uint8
+--rw push-tags* [index]
+--rw index uint8
+--rw dot1q-tag
+--rw tag-type dot1q-tag-type
+--rw vlan-id dot1q-vlan-id
augment /if:interfaces/if:interface:
+--rw flexible-encapsulation
+--rw local-traffic-default-encaps
+--rw tag* [index]
+--rw index uint8
+--rw dot1q-tag
+--rw tag-type dot1q-tag-type
+--rw vlan-id dot1q-vlan-id
This YANG module augments the encapsultion container defined in Interface Extensions YANG [I-D.wilton-netmod-intf-ext-yang].
<CODE BEGINS> file "if-l3-vlan@2015-10-19.yang"
module if-l3-vlan {
namespace "urn:ietf:params:xml:ns:yang:if-l3-vlan";
prefix if-l3-vlan;
import ietf-interfaces {
prefix if;
}
import iana-if-type {
prefix ianaift;
}
import dot1q-tag-types {
prefix dot1q-tag;
}
import interfaces-common {
prefix if-cmn;
}
organization
"Cisco Systems, Inc.
Customer Service
Postal: 170 W Tasman Drive
San Jose, CA 95134
Tel: +1 1800 553-NETS
E-mail: cs-yang@cisco.com";
contact
"Robert Wilton - rwilton@cisco.com";
description
"This YANG module models L3 VLAN sub-interfaces
";
revision 2015-10-19 {
description "Latest revision";
reference "Internet-Draft draft-wilton-netmod-intf-vlan-yang-01";
}
feature l3-vlan-sub-interfaces {
description
"This feature indicates that the device supports L3 VLAN
sub-interfaces";
}
/*
* Add support for the 802.1Q VLAN encapsulation syntax on layer 3
* terminated VLAN sub-interfaces.
*/
augment "/if:interfaces/if:interface/if-cmn:encapsulation/" +
"if-cmn:encaps-type" {
when "../../if:type = 'ianaift:l2vlan' and
../../if-cmn:transport-layer = 'layer-3'" {
description "Applies only to VLAN sub-interfaces that are
operating at layer 3";
}
if-feature l3-vlan-sub-interfaces;
description "Augment the generic interface encapsulation with an
encapsulation for layer 3 VLAN sub-interfaces";
/*
* Matches a VLAN, or pair of VLAN Ids to classify traffic
* into an L3 service.
*/
case vlan {
container vlan {
description
"Match VLAN tagged frames with specific VLAN Ids";
container tags {
description "Matches frames tagged with specific VLAN Ids";
list tag {
key "index";
min-elements 1;
max-elements 2;
description "The tags to match, with the outermost tag to
match with index 0";
leaf index {
type uint8 {
range "0..1";
}
/*
* Only allow matching on an inner tag (at index 1), if
* also matching on the outer tag at the same time.
*/
must "index = 0 or
count(../../tag[index = 0]/index) > 0" {
error-message
"An inner tag can only be matched on when also
matching on an outer tag";
description
"Only allow matching on an inner tag, if also
matching on the outer tag at the same time";
}
description
"The index into the tag stack, outermost tag first";
}
uses dot1q-tag:dot1q-tag;
}
}
}
}
}
}
<CODE ENDS>
This YANG module augments the encapsultion container defined in Interface Extensions YANG [I-D.wilton-netmod-intf-ext-yang].
This YANG module also augments the interface container defined in RFC 7223 [RFC7223].
<CODE BEGINS> file "flexible-encapsulation@2015-10-19.yang"
module flexible-encapsulation {
namespace "urn:ietf:params:xml:ns:yang:flexible-encapsulation";
prefix flex;
import ietf-interfaces {
prefix if;
}
import interfaces-common {
prefix if-cmn;
}
import dot1q-tag-types {
prefix dot1q-tag;
}
organization
"Cisco Systems, Inc.
Customer Service
Postal: 170 W Tasman Drive
San Jose, CA 95134
Tel: +1 1800 553-NETS
E-mail: cs-yang@cisco.com";
contact
"Robert Wilton - rwilton@cisco.com";
description
"This YANG module describes interface configuration for flexible
VLAN matches and rewrites.";
revision 2015-10-19 {
description "Updated reference to new draft name.";
reference
"Internet-Draft draft-wilton-netmod-intf-vlan-yang-01";
}
feature flexible-encapsulation-rewrites {
description
"This feature indicates whether the network element supports
flexible Ethernet encapsulation that allows for matching VLAN
ranges and performing independent tag manipulations";
}
feature flexible-rewrites {
description
"This feature indicates whether the network element supports
specifying flexible rewrite operations";
}
feature asymmetric-rewrites {
description
"This feature indicates whether the network element supports
specifying different rewrite operations for the ingress
rewrite operation and egress rewrite operation.";
}
feature tag-rewrites {
description
"This feature indicates whether the network element supports
the flexible rewrite functionality specifying flexible tag
rewrites";
}
/*
* flexible-match grouping.
*
* This grouping represents a flexible match.
*
* The rules for a flexible match are:
* 1. default, untagged, priority tag, or a stack of tags.
* - Each tag in the stack of tags matches:
* 1. tag type (802.1Q or 802.1ad) +
* 2. tag value:
* i. single tag
* ii. set of tag ranges/values.
* iii. "any" keyword
*/
grouping flexible-match {
description "Flexible match";
choice match-type {
mandatory true;
description "Provides a choice of how the frames may be
matched";
case default {
description "Default match";
leaf default {
type empty;
description
"Default match. Matches all traffic not matched to any
other peer sub-interface by a more specific
encapsulation.";
} // leaf default
} // case default
case untagged {
description "Match untagged Ethernet frames only";
leaf untagged {
type empty;
description
"Untagged match. Matches all untagged traffic.";
} // leaf untagged
} // case untagged
case priority-tagged {
description "Match priority tagged Ethernet frames only";
container priority-tagged {
description "Priority tag match";
leaf tag-type {
type dot1q-tag:dot1q-tag-type;
description "The 802.1Q tag type of matched priority
tagged packets";
}
}
}
case vlan-tagged {
container vlan-tagged {
description "Matches VLAN tagged frames";
list tag {
key "index";
min-elements 1;
max-elements 2;
description "The tags to match, with the outermost tag to
match assigned index 0";
leaf index {
type uint8 {
range "0..1";
}
must "index = 0 or
count(../../tag[index = 0]/index) > 0" {
error-message "An inner tag can only be matched on
when also matching on an outer tag";
description "Only allow matching on an inner tag, if
also matching on the outer tags at the
same time";
}
description
"The index into the tag stack, outermost tag first";
}
uses dot1q-tag:dot1q-tag-ranges-or-any;
}
leaf match-exact-tags {
type empty;
description
"If set, indicates that all 802.1Q VLAN tags in the
Ethernet frame header must be explicitly matched, i.e.
the EtherType following the matched tags must not be a
802.1Q tag EtherType. If unset then extra 802.1Q VLAN
tags are allowed.";
}
}
}
} // encaps-type
}
/*
* Grouping for tag-rewrite that can be expressed either
* symmetrically, or in the ingress and/or egress directions
* independently.
*/
grouping tag-rewrite {
description "Flexible rewrite";
leaf pop-tags {
type uint8 {
range 1..2;
}
description "The number of tags to pop (or translate if used in
conjunction with push-tags)";
}
list push-tags {
key "index";
max-elements 2;
description "The number of tags to push (or translate if used
in conjunction with pop-tags)";
/*
* Server should order by increasing index.
*/
leaf index {
type uint8 {
range 0..1;
}
/*
* Only allow a push of an inner tag if an outer tag is also
* being pushed.
*/
must "index != 0 or
count(../../push-tags[index = 0]/index) > 0" {
error-message "An inner tag can only be pushed if an outer
tag is also specified";
description "Only allow a push of an inner tag if an outer
tag is also being pushed";
}
description "The index into the tag stack";
}
uses dot1q-tag:dot1q-tag;
}
}
/*
* Grouping for all flexible rewrites of fields in the L2 header.
*
* This currently only includes flexible tag rewrites, but is
* designed to be extensible to cover rewrites of other fields in
* the L2 header if required.
*/
grouping flexible-rewrite {
description "Flexible rewrite";
/*
* Tag rewrite.
*
* All tag rewrites are formed using a combination of pop-tags
* and push-tags operations.
*/
container tag-rewrite {
if-feature tag-rewrites;
description "Tag rewrite. Translate operations are expressed
as a combination of tag push and pop operations.";
uses tag-rewrite;
}
}
augment "/if:interfaces/if:interface/if-cmn:encapsulation/" +
"if-cmn:encaps-type" {
when "../../if:if-cmn = 'if-cmn:ethSubInterface' and
../../if-cmn:transport-layer = 'layer-2'" {
description "Applies only to Ethernet sub-interfaces that are
operating at transport layer 2";
}
description
"Add flexible match and rewrite for VLAN sub-interfaces";
/*
* A flexible encapsulation allows for the matching of ranges and
* sets of VLAN Ids. The structure is also designed to be
* extended to allow for matching/rewriting other fields within
* the L2 frame header if required.
*/
case flexible {
if-feature flexible-encapsulation-rewrites;
description "Flexible encapsulation and rewrite";
container flexible {
description "Flexible encapsulation and rewrite";
container match {
description
"The match used to classify frames to this interface";
uses flexible-match;
}
container rewrite {
if-feature flexible-rewrites;
description "L2 frame rewrite operations";
choice direction {
description "Whether the rewrite policy is symmetrical or
asymmetrical";
case symmetrical {
container symmetrical {
uses flexible-rewrite;
description
"Symmetrical rewrite. Expressed in the ingress
direction, but the reverse operation is applied
to egress traffic";
}
}
/*
* Allow asymmetrical rewrites to be specified.
*/
case asymmetrical {
if-feature asymmetric-rewrites;
description "Asymmetrical rewrite";
container ingress {
uses flexible-rewrite;
description "Ingress rewrite";
}
container egress {
uses flexible-rewrite;
description "Egress rewrite";
}
}
}
}
}
}
}
augment "/if:interfaces/if:interface" {
when "if:type = 'if-cmn:ethSubInterface' and
if-cmn:transport-layer = 'layer-2'" {
description "Any L2 Ethernet sub-interfaces";
}
description "Add flexible encapsulation configuration for VLAN
sub-interfaces";
/*
* All flexible encapsulation specific interface configuration
* (except for the actual encapsulation and rewrite) is contained
* by a flexible-encapsulation container on the interface.
*/
container flexible-encapsulation {
description
"All per interface flexible encapsulation related fields";
/*
* For encapsulations that match a range of VLANs (or Any),
* allow configuration to specify the default VLAN tag values
* to use for any traffic that is locally sourced from an
* interface on the device.
*/
container local-traffic-default-encaps {
description "The VLAN tags to use by default for locally
sourced traffic";
list tag {
key "index";
max-elements 2;
description
"The VLAN tags to use by locally sourced traffic";
leaf index {
type uint8 {
range "0..1";
}
/*
* Only allow an inner tag to be specified if an outer
* tag has also been specified.
*/
must "index = 0 or
count(../../tag[index = 0]/index) > 0" {
error-message "An inner tag can only be specified if an
outer tag has also been specified";
description "Ensure that an inner tag cannot be
specified without an outer tag'";
}
description "The index into the tag stack, outermost tag
assigned index 0";
}
uses dot1q-tag:dot1q-tag;
}
}
}
}
}
<CODE ENDS>
This YANG module has no external imports.
The expectation is that the raw 802.1Q VLAN tag fields types will eventually be standardized in IEEE rather than IETF. They are included here to make the model complete.
The groupings that can be used to generally identify frames based on the fields in the 802.1Q tag may be defined here or in IEEE depending on where is deemed appropriate after discussion with IEEE 802.1.
<CODE BEGINS> file "dot1q-tag-types@2015-10-19.yang"
module dot1q-tag-types {
namespace "urn:ieee:params:xml:ns:yang:dot1q-tag-types";
prefix dot1q;
import ieee-types {
prefix ieee-types;
}
import ieee-dot1q-types {
prefix dot1q-types;
}
organization
"Cisco Systems, Inc.
Customer Service
Postal: 170 W Tasman Drive
San Jose, CA 95134
Tel: +1 1800 553-NETS
E-mail: cs-yang@cisco.com";
contact
"Robert Wilton - rwilton@cisco.com";
description
"This module contains a collection of generally useful YANG types
that are specific to 802.1Q VLANs that can be usefully shared
between multiple models.
Terms and Acronyms
802.1Q: IEEE 802.1Q VLANs
VLAN (vlan): Virtual Local Area Network
";
revision 2015-10-19 {
description "Latest revision, references IEEE types";
reference "Currently defined in:
Internet-Draft draft-wilton-netmod-intf-vlan-yang-01,
but may be standardized in IEEE 802.1";
}
typedef PCP {
type uint8 {
range "0..7";
}
description
"Priority Code Point. PCP is a 3-bit field that refers to the
class of service applied to an 802.1Q VLAN tagged frame. The
field specifies a priority value between 0 and 7, these values
can be used by quality of service (QoS) to prioritize
different classes of traffic.";
reference "IEEE 802.1Q (2014)";
}
/*
* Defines the supported IEEE 802.1Q types that can be used for
* VLAN tag matching.
*/
identity dot1q-tag-vlan-type {
description "Base identity from which all 802.1Q VLAN tag types
are derived from";
}
identity c-vlan {
base dot1q-tag-vlan-type;
description
"An 802.1Q Customer-VLAN tag, normally using the 0x8100
Ethertype";
}
identity s-vlan {
base dot1q-tag-vlan-type;
description
"An 802.1Q Service-VLAN tag, using the 0x88a8 Ethertype
originally introduced in 802.1ad, and incorporated into
802.1Q (2011)";
}
typedef dot1q-tag-type {
type identityref {
base "dot1q-tag-vlan-type";
}
description "Identifies a specific 802.1Q tag type";
reference "IEEE 802.1Q (2014)";
}
/*
* A grouping which represents an 802.1Q VLAN tag, matching both
* the tag Ethertype and a single VLAN Id. The PCP and DEI fields
* in the 802.1Q tag are ignored for tag matching purposes.
*/
grouping dot1q-tag {
description "Grouping to allow configuration to identify a single
802.1Q VLAN tag";
container dot1q-tag {
description "Identifies an 802.1Q VLAN tag with an explicit
tag-type and a single VLAN Id";
leaf tag-type {
type dot1q-tag-type;
mandatory true;
description "VLAN tag type";
}
leaf vlan-id {
type ieee-types:vlanid;
mandatory true;
description "VLAN Id";
}
}
}
/*
* A grouping which represents an 802.1Q VLAN tag, matching both
* the tag Ethertype and a single VLAN Id or "any" to match on any
* VLAN Id. The PCP and DEI fields in the 802.1Q tag are ignored
* for tag matching purposes.
*/
grouping dot1q-tag-or-any {
description "Grouping to allow configuration to identify a single
802.1Q VLAN tag or the 'any' value to match any VLAN
Id not matched by a more specific VLAN Id match";
container dot1q-tag {
description "Identifies an 802.1Q VLAN tag with an explicit
tag-type and a single VLAN Id, or 'any' VLAN Id";
leaf tag-type {
type dot1q-tag-type;
mandatory true;
description "VLAN tag type";
}
leaf vlan-id {
type union {
type ieee-types:vlanid;
type enumeration {
enum "any" {
value 4096;
description
"Matches 'any' VLAN tag in the range 1 to 4094 that
is not matched by a more specific VLAN Id match";
}
}
}
mandatory true;
description "VLAN Id or any";
}
}
}
/*
* A grouping which represents an 802.1Q tag that matches a range
* of VLAN Ids. The PCP and DEI fields in the 802.1Q tag are
* ignored for tag matching purposes.
*/
grouping dot1q-tag-ranges {
description "Grouping to allow configuration to identify an
802.1Q VLAN tag that matches any VLAN Id within a
set of non overlapping VLAN Id ranges";
container dot1q-tag {
description "Identifies an 802.1Q VLAN tag with an explicit
tag-type and and a range of VLAN Ids";
leaf tag-type {
type dot1q-tag-type;
mandatory true;
description "VLAN tag type";
}
leaf vlan-ids {
type dot1q-types:vid-range;
mandatory true;
description "VLAN Ids";
}
}
}
/*
* A grouping which represents an 802.1Q VLAN tag, matching both
* the tag Ethertype and a single VLAN Id, ordered list of ranges,
* or "any" to match on any VLAN Id. The PCP and DEI fields in the
* 802.1Q tag are ignored for tag matching purposes.
*/
grouping dot1q-tag-ranges-or-any {
description "Grouping to allow configuration to identify an
802.1Q VLAN tag that matches any specific VLAN Id
within a set of non overlapping VLAN Id ranges, or
the 'any' value to match any VLAN Id";
container dot1q-tag {
description "Identifies an 802.1Q VLAN tag with an explicit
tag-type, an ordered list of VLAN Id ranges, or
'any' VLAN Id";
leaf tag-type {
type dot1q-tag-type;
mandatory true;
description "VLAN tag type";
}
leaf vlan-id {
type union {
type dot1q-types:vid-range;
type enumeration {
enum "any" {
description "Matches 'any' VLAN tag in the range 1 to
4094";
}
}
}
mandatory true;
description "VLAN Ids or any";
}
}
}
}
<CODE ENDS>
The authors Neil Ketley for his helpful comments contributing to this draft.
This document defines several new YANG module and the authors politely request that IANA assigns unique names to the YANG module files contained within this draft, and also appropriate URIs in the "IETF XML Registry".
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:
The nodes in the if-l3-vlan YANG module are concerned with matching particular frames received on the network device to connect them to a layer 3 forwarding instance, and as such adding/modifying/deleting these nodes has a high risk of causing traffic to be lost because it is not being classified correctly, or is being classified to a separate sub-interface. The nodes, all under the subtree /interfaces/interface/encapsulation/vlan, that are sensitive to this are:
There are many nodes in the flexible-encapsulation YANG module that are concerned with matching particular frames received on the network device, and as such adding/modifying/deleting these nodes has a high risk of causing traffic to be lost because it is not being classified correctly, or is being classified to a separate sub-interface. The nodes, all under the subtree /interfaces/interface/encapsulation/flexible/match, that are sensitive to this are:
There are also many modes in the flexible-encapsulation YANG module that are concerned with rewriting the fields in the L2 header for particular frames received on the network device, and as such adding/modifying/deleting these nodes has a high risk of causing traffic to be dropped or incorrectly processed on peer network devices, or it could cause layer 2 tunnels to go down due to a mismatch in negotiated MTU. The nodes, all under the subtree /interfaces/interface/encapsulation/flexible/rewrite, that are sensitive to this are:
Nodes in the flexible-encapsulation YANG module that are concerned with the VLAN tags to use for traffic sourced from the network element could cause protocol sessions (such as CFM) to fail if they are added, modified or deleted. The nodes, all under the subtree /interfaces/interface/flexible-encapsulation/local-traffic-default-encaps that are sensitive to this are:
| [I-D.wilton-netmod-intf-ext-yang] | Wilton, R., Ball, D., Singh, T. and S. Sivaraj, "Common Interface Extension YANG Data Models", Internet-Draft draft-wilton-netmod-intf-ext-yang-00, July 2015. |
| [RFC2119] | Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/RFC2119, March 1997. |
| [RFC6020] | Bjorklund, M., "YANG - A Data Modeling Language for the Network Configuration Protocol (NETCONF)", RFC 6020, DOI 10.17487/RFC6020, October 2010. |
| [RFC7223] | Bjorklund, M., "A YANG Data Model for Interface Management", RFC 7223, DOI 10.17487/RFC7223, May 2014. |
| [RFC7224] | Bjorklund, M., "IANA Interface Type YANG Module", RFC 7224, DOI 10.17487/RFC7224, May 2014. |
| [RFC6241] | Enns, R., Bjorklund, M., Schoenwaelder, J. and A. Bierman, "Network Configuration Protocol (NETCONF)", RFC 6241, DOI 10.17487/RFC6241, June 2011. |
| [RFC6242] | Wasserman, M., "Using the NETCONF Protocol over Secure Shell (SSH)", RFC 6242, DOI 10.17487/RFC6242, June 2011. |
| [RFC6536] | Bierman, A. and M. Bjorklund, "Network Configuration Protocol (NETCONF) Access Control Model", RFC 6536, DOI 10.17487/RFC6536, March 2012. |
In addition to the sub-interface based YANG model proposed here, the IEEE 802.1Q working group is also developing a YANG model for the configuration of 802.1Q VLANs. This raises the valid question as to whether the models overlap and whether it is necessary or beneficial to have two different models for superficially similar constructs. This section aims to answer that question by summarizing and comparing the two models.
The key features of the sub-interface based configuration model can be summarized as:
The key features of the IEEE 802.1Q bridge configuration model can be summarized as:
Both models can be used for configuring similar basic layer 2 forwarding topologies. The 802.1Q bridge configuration model is optimised for configuring Virtual LANs that span across enterprises and data centers.
The sub-interface model can also be used for configuring equivalent Virtual LAN networks that span across enterprises and data centers, but often requires more configuration to be able to configure the equivalent constructs to the 802.1Q bridge model.
The sub-interface model really excels when implementing flexible L2 and L3 services, where those services may be handled on the same physical interface, and where the VLAN Identifier is being solely used to identify the customer or service that is being provided rather than a Virtual LAN. The sub-interface model provides more flexibility as to how traffic can be classified, how features can be applied to traffic streams, and how the traffic is to be forwarded.
Conversely, the 802.1Q bridge model can also be use to implement L2 services in some scenarios, but only if the forwarding paradigm being used to implement the service is the native Ethernet forwarding specified in 802.1Q - other forwarding paradigms such as pseudowires or VPLS are not supported. The 802.1Q bridge model does not implement L3 services at all, although this can be partly mitigated by using a virtual L3 interface construct that is a separate logical Ethernet-like interface which is a member of the bridge.
In conclusion, it is valid for both of these models to exist since they have different deployment scenarios for which they are optimized. Devices may choose which of the models (or both) to implement depending on what functionality the device is being designed for.