| Internet Engineering Task Force | R. Wilton, Ed. |
| Internet-Draft | D. Ball |
| Intended status: Informational | T. Singh |
| Expires: January 3, 2019 | Cisco Systems |
| S. Sivaraj | |
| Juniper Networks | |
| July 2, 2018 |
Sub-interface VLAN YANG Data Models
draft-ietf-netmod-sub-intf-vlan-model-04
This document defines YANG modules 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. These modules allow configuration of Layer 3 and Layer 2 sub-interfaces (e.g. attachment circuits) that can interoperate with IETF based forwarding protocols; such as IP and L3VPN services; or L2VPN services like VPWS, VPLS, and EVPN. The sub-interfaces also interoperate with VLAN tagged traffic orginating from an IEEE 802.1Q compliant bridge. 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 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 an 802.1Q VLAN bridge.
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This document defines two YANG [RFC7950] modules that augment the encapsulation choice YANG element defined in Interface Extensions YANG and the generic interfaces data model defined in [RFC8343]. 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.
The purpose of these models is to allow IETF defined forwarding protocols, such as IPv6 [RFC2460], Ethernet Pseudo Wires [RFC4448] and VPLS [RFC4761] [RFC4762] to be configurable via YANG when interoperating with VLAN tagged traffic received from an IEEE 802.1Q compliant bridge.
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:
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.
Sub-interface: A sub-interface is 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.
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 primary aim of the YANG modules contained in this draft is to provide the core model that is required to implement VLAN transport services on router based devices that is fully compatible with IEEE 802.1Q compliant bridges.
A secondary aim is for the modules to be structured in such a way that they can be cleanly extended in future.
The modules defined in this document are designed to fully interoperate with IEEE 802.1Q compliant bridges. In particular, the models are restricted to only matching, adding, or rewriting the 802.1Q VLAN tags in frames in ways that are compatible with IEEE 802.1Q compliant bridges.
The modules are structured in such a way that they can be sensibly extended. In particular:
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:
module: ietf-if-l3-vlan
augment /if:interfaces/if:interface/if-cmn:encapsulation/
if-cmn:encaps-type:
+--:(dot1q-vlan)
+--rw dot1q-vlan
+--rw outer-tag!
| +--rw tag-type dot1q-tag-type
| +--rw vlan-id ieee:vlanid
+--rw second-tag!
+--rw tag-type dot1q-tag-type
+--rw vlan-id ieee:vlanid
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:
module: ietf-flexible-encapsulation
augment /if:interfaces/if:interface/if-cmn:encapsulation/
if-cmn:encaps-type:
+--:(flexible)
+--rw flexible
+--rw match
| +--rw (match-type)
| +--:(default)
| | +--rw default? empty
| +--:(untagged)
| | +--rw untagged? empty
| +--:(dot1q-priority-tagged)
| | +--rw dot1q-priority-tagged
| | +--rw tag-type? dot1q-types:dot1q-tag-type
| +--:(dot1q-vlan-tagged)
| +--rw dot1q-vlan-tagged
| +--rw outer-tag!
| | +--rw tag-type dot1q-tag-type
| | +--rw vlan-id union
| +--rw second-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 dot1q-tag-rewrite {dot1q-tag-rewrites}?
| | +--rw pop-tags? uint8
| | +--rw push-tags
| | +--rw outer-tag!
| | | +--rw tag-type dot1q-tag-type
| | | +--rw vlan-id ieee:vlanid
| | +--rw second-tag!
| | +--rw tag-type dot1q-tag-type
| | +--rw vlan-id ieee:vlanid
| +--:(asymmetrical) {asymmetric-rewrites}?
| +--rw ingress
| | +--rw dot1q-tag-rewrite {dot1q-tag-rewrites}?
| | +--rw pop-tags? uint8
| | +--rw push-tags
| | +--rw outer-tag!
| | | +--rw tag-type dot1q-tag-type
| | | +--rw vlan-id ieee:vlanid
| | +--rw second-tag!
| | +--rw tag-type dot1q-tag-type
| | +--rw vlan-id ieee:vlanid
| +--rw egress
| +--rw dot1q-tag-rewrite {dot1q-tag-rewrites}?
| +--rw pop-tags? uint8
| +--rw push-tags
| +--rw outer-tag!
| | +--rw tag-type dot1q-tag-type
| | +--rw vlan-id ieee:vlanid
| +--rw second-tag!
| +--rw tag-type dot1q-tag-type
| +--rw vlan-id ieee:vlanid
+--rw local-traffic-default-encaps!
+--rw outer-tag!
| +--rw tag-type dot1q-tag-type
| +--rw vlan-id ieee:vlanid
+--rw second-tag!
+--rw tag-type dot1q-tag-type
+--rw vlan-id ieee:vlanid
This YANG module augments the encapsultion container defined in Interface Extensions YANG.
<CODE BEGINS> file "ietf-if-l3-vlan@2017-10-30.yang"
module ietf-if-l3-vlan {
yang-version 1.1;
namespace "urn:ietf:params:xml:ns:yang:ietf-if-l3-vlan";
prefix if-l3-vlan;
import ietf-interfaces {
prefix if;
}
import iana-if-type {
prefix ianaift;
}
import ieee802-dot1q-types {
prefix dot1q-types;
}
import ietf-interfaces-common {
prefix if-cmn;
}
organization
"IETF NETMOD (NETCONF Data Modeling Language) Working Group";
contact
"WG Web: <http://tools.ietf.org/wg/netmod/>
WG List: <mailto:netmod@ietf.org>
WG Chair: Lou Berger
<mailto:lberger@labn.net>
WG Chair: Kent Watsen
<mailto:kwatsen@juniper.net>
Editor: Robert Wilton
<mailto:rwilton@cisco.com>";
description
"This YANG module models L3 VLAN sub-interfaces";
revision 2017-10-30 {
description "Latest draft revision";
reference
"Internet-Draft draft-ietf-netmod-sub-intf-vlan-model-03";
}
/*
* 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
"derived-from-or-self(../if:type,
'ianaift:ethernetCsmacd') or
derived-from-or-self(../if:type,
'ianaift:ieee8023adLag') or
derived-from-or-self(../if:type,
'if-cmn:ethSubInterface')" {
description
"Applies only to Ethernet-like interfaces and
sub-interfaces";
}
description
"Augment the generic interface encapsulation with an
basic 802.1Q VLAN encapsulation for sub-interfaces.";
/*
* Matches a single VLAN Id, or pair of VLAN Ids to classify
* traffic into an L3 service.
*/
case dot1q-vlan {
container dot1q-vlan {
must
'count(../../if-cmn:forwarding-mode) = 0 or ' +
'derived-from-or-self(../../if-cmn:forwarding-mode,' +
'"if-cmn:layer-3-forwarding")' {
error-message
"If the interface forwarding-mode leaf is set then it
must be set to an identity that derives from
layer-3-forwarding";
description
"The forwarding-mode leaf on an interface can
optionally be used to enforce consistency of
configuration";
}
description
"Match VLAN tagged frames with specific VLAN Ids";
container outer-tag {
presence "The outermost VLAN tag exists";
description
"Classifies traffic using the outermost VLAN tag on the
frame.";
uses dot1q-types:dot1q-tag-classifier-grouping;
}
container second-tag {
must
'../outer-tag/tag-type = "dot1q-types:s-vlan" and ' +
'tag-type = "dot1q-types:c-vlan"' {
error-message
"When matching two tags, the outermost tag must be
specified and of S-VLAN type and the second outermost
tag must be of C-VLAN tag type";
description
"For IEEE 802.1Q interoperability, when matching two
tags, it is required that the outermost tag exists and
is an S-VLAN, and the second outermost tag is a
C-VLAN";
}
presence "The second outermost VLAN tag exists";
description
"Classifies traffic using the second outermost VLAN tag
on the frame.";
uses dot1q-types:dot1q-tag-classifier-grouping;
}
}
}
}
}
<CODE ENDS>
This YANG module augments the encapsultion container defined in Interface Extensions YANG.
This YANG module also augments the interface container defined in [RFC8343].
<CODE BEGINS> file "ietf-flexible-encapsulation@2017-10-30.yang"
module ietf-flexible-encapsulation {
yang-version 1.1;
namespace
"urn:ietf:params:xml:ns:yang:ietf-flexible-encapsulation";
prefix flex;
import ietf-interfaces {
prefix if;
}
import iana-if-type {
prefix ianaift;
}
import ietf-interfaces-common {
prefix if-cmn;
}
import ieee802-dot1q-types {
prefix dot1q-types;
}
organization
"IETF NETMOD (NETCONF Data Modeling Language) Working Group";
contact
"WG Web: <http://tools.ietf.org/wg/netmod/>
WG List: <mailto:netmod@ietf.org>
WG Chair: Lou Berger
<mailto:lberger@labn.net>
WG Chair: Kent Watsen
<mailto:kwatsen@juniper.net>
Editor: Robert Wilton
<mailto:rwilton@cisco.com>";
description
"This YANG module describes interface configuration for flexible
VLAN matches and rewrites.";
revision 2017-10-30 {
description "Latest draft revision";
reference
"Internet-Draft draft-ietf-netmod-sub-intf-vlan-model-03";
}
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 dot1q-tag-rewrites {
description
"This feature indicates whether the network element supports
the flexible rewrite functionality specifying flexible 802.1Q
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 dot1q-priority-tagged {
description
"Match 802.1Q priority tagged Ethernet frames only";
container dot1q-priority-tagged {
description "802.1Q priority tag match";
leaf tag-type {
type dot1q-types:dot1q-tag-type;
description "The 802.1Q tag type of matched priority
tagged packets";
}
}
}
case dot1q-vlan-tagged {
container dot1q-vlan-tagged {
description "Matches VLAN tagged frames";
container outer-tag {
presence "The outermost VLAN tag exists";
description
"Classifies traffic using the outermost VLAN tag on the
frame.";
uses
'dot1q-types:'+
'dot1q-tag-ranges-or-any-classifier-grouping';
}
container second-tag {
must
'../outer-tag/tag-type = "dot1q-types:s-vlan" and ' +
'tag-type = "dot1q-types:c-vlan"' {
error-message
"When matching two tags, the outermost tag must be
specified and of S-VLAN type and the second
outermost tag must be of C-VLAN tag type";
description
"For IEEE 802.1Q interoperability, when matching two
tags, it is required that the outermost tag exists
and is an S-VLAN, and the second outermost tag is a
C-VLAN";
}
presence "The second outermost VLAN tag exists";
description
"Classifies traffic using the second outermost VLAN tag
on the frame.";
uses
'dot1q-types:'+
'dot1q-tag-ranges-or-any-classifier-grouping';
}
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 dot1q-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)";
}
container push-tags {
description "The 802.1Q tags to push (or translate if used in
conjunction with pop-tags)";
container outer-tag {
presence
"Indicates existence of the outermost VLAN tag to
push/rewrite";
description
"The outermost VLAN tag to push onto the frame.";
uses dot1q-types:dot1q-tag-classifier-grouping;
}
container second-tag {
must
'../outer-tag/tag-type = "dot1q-types:s-vlan" and ' +
'tag-type = "dot1q-types:c-vlan"' {
error-message
"When pushing/rewriting two tags, the outermost tag must be
specified and of S-VLAN type and the second outermost tag
must be of C-VLAN tag type";
description
"For IEEE 802.1Q interoperability, when pushing two tags,
it is required that the outermost tag exists and is an
S-VLAN, and the second outermost tag is a C-VLAN";
}
presence
"Indicates existence of a second outermost VLAN tag to
push/rewrite.";
description
"The second outermost VLAN tag to push onto the frame.";
uses dot1q-types:dot1q-tag-classifier-grouping;
}
}
}
/*
* 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 dot1q-tag-rewrite {
if-feature dot1q-tag-rewrites;
description "Tag rewrite. Translate operations are expressed
as a combination of tag push and pop operations.";
uses dot1q-tag-rewrite;
}
}
augment "/if:interfaces/if:interface/if-cmn:encapsulation/" +
"if-cmn:encaps-type" {
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,
'if-cmn:ethSubInterface')" {
description
"Applies only to Ethernet-like interfaces and
sub-interfaces";
}
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 {
description "Flexible encapsulation and rewrite";
container flexible {
must
'count(../../if-cmn:forwarding-mode) = 0 or ' +
'derived-from-or-self(../../if-cmn:forwarding-mode,' +
'"if-cmn:layer-2-forwarding")' {
error-message
"If the interface forwarding-mode leaf is set then it
must be set to an identity that derives from
layer-2-forwarding";
description
"The forwarding-mode leaf on an interface can
optionally be used to enforce consistency of
configuration";
}
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";
}
}
}
}
/*
* For encapsulations that match a range of VLANs (or Any),
* allow configuration to specify the default 802.1Q VLAN tag
* values to use for any traffic that is locally sourced from
* an interface on the device.
*/
container local-traffic-default-encaps {
presence
"A local traffic default encapsulation has been
specified";
description
"The 802.1Q VLAN tags to use by default for locally
sourced traffic";
container outer-tag {
presence
"Indicates existence of the outermost VLAN tag";
description
"The outermost VLAN tag for locally sourced traffic";
uses dot1q-types:dot1q-tag-classifier-grouping;
}
container second-tag {
must
'../outer-tag/tag-type = "dot1q-types:s-vlan" and ' +
'tag-type = "dot1q-types:c-vlan"' {
error-message
"When specifying two tags, the outermost tag must be
specified and of S-VLAN type and the second outermost
tag must be of C-VLAN tag type";
description
"For IEEE 802.1Q interoperability, when specifying two
tags, it is required that the outermost tag exists and
is an S-VLAN, and the second outermost tag is a
C-VLAN";
}
presence
"Indicates existence of a second outermost VLAN tag.";
description
"The second outermost VLAN tag for locally sourced
traffic";
uses dot1q-types:dot1q-tag-classifier-grouping;
}
}
}
}
}
}
<CODE ENDS>
The following sections give examples of configuring a sub-interface supporting L3 forwarding, and also a sub-interface being used in conjunction with the IETF L2VPN YANG model [I-D.ietf-bess-l2vpn-yang].
This example illustrates a layer 3 sub-interface configured to match traffic with a S-VLAN tag of 10, and C-VLAN tag of 20.
<?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:dot1q-types="urn:ieee:std:802.1Q:yang:ieee802-dot1q-types"
xmlns:if-cmn="urn:ietf:params:xml:ns:yang:ietf-interfaces-common">
<interface>
<name>eth0</name>
<type>ianaift:ethernetCsmacd</type>
</interface>
<interface>
<name>eth0.1</name>
<type>ianaift:l2vlan</type>
<if-cmn:parent-interface>eth0</if-cmn:parent-interface>
<if-cmn:encapsulation>
<dot1q-vlan
xmlns="urn:ietf:params:xml:ns:yang:ietf-if-l3-vlan">
<outer-tag>
<tag-type>dot1q-types:s-vlan</tag-type>
<vlan-id>10</vlan-id>
</outer-tag>
<second-tag>
<tag-type>dot1q-types:c-vlan</tag-type>
<vlan-id>20</vlan-id>
</second-tag>
</dot1q-vlan>
</if-cmn:encapsulation>
<ipv6 xmlns="urn:ietf:params:xml:ns:yang:ietf-ip">
<forwarding>true</forwarding>
<address>
<ip>2001:db8::10</ip>
<prefix-length>32</prefix-length>
</address>
</ipv6>
</interface>
<interface>
<name>eth0.2</name>
<type>ianaift:l2vlan</type>
<if-cmn:parent-interface>eth0</if-cmn:parent-interface>
<if-cmn:encapsulation>
<dot1q-vlan
xmlns="urn:ietf:params:xml:ns:yang:ietf-if-l3-vlan">
<outer-tag>
<tag-type>dot1q-types:s-vlan</tag-type>
<vlan-id>11</vlan-id>
</outer-tag>
</dot1q-vlan>
</if-cmn:encapsulation>
<ipv6 xmlns="urn:ietf:params:xml:ns:yang:ietf-ip">
<forwarding>true</forwarding>
<address>
<ip>2001:db8::11</ip>
<prefix-length>32</prefix-length>
</address>
</ipv6>
</interface>
</interfaces>
</config>
This example illustrates a layer 2 sub-interface 'eth0.3' configured to match traffic with a S-VLAN tag of 10, and C-VLAN tag of 21; and both tags removed before the traffic is passed off to the L2VPN service.
It also illustrates another sub-interface 'eth1.0' under a separate physical interface configured to match traffic with a C-VLAN of 50, and the tag removed before traffic is given to any service. Sub-interface 'eth1.0' is not currently bound to any service and hence traffic classifed to that sub-interface is dropped.
<?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:dot1q-types="urn:ieee:std:802.1Q:yang:ieee802-dot1q-types"
xmlns:if-cmn="urn:ietf:params:xml:ns:yang:ietf-interfaces-common">
<interface>
<name>eth0</name>
<type>ianaift:ethernetCsmacd</type>
</interface>
<interface>
<name>eth0.3</name>
<type>ianaift:l2vlan</type>
<if-cmn:parent-interface>eth0</if-cmn:parent-interface>
<if-cmn:encapsulation>
<flexible
xmlns="urn:ietf:params:xml:ns:yang:ietf-flexible-encapsulation">
<match>
<dot1q-vlan-tagged>
<outer-tag>
<tag-type>dot1q-types:s-vlan</tag-type>
<vlan-id>10</vlan-id>
</outer-tag>
<second-tag>
<tag-type>dot1q-types:c-vlan</tag-type>
<vlan-id>21</vlan-id>
</second-tag>
</dot1q-vlan-tagged>
</match>
<rewrite>
<symmetrical>
<dot1q-tag-rewrite>
<pop-tags>2</pop-tags>
</dot1q-tag-rewrite>
</symmetrical>
</rewrite>
</flexible>
</if-cmn:encapsulation>
</interface>
<interface>
<name>eth1</name>
<type>ianaift:ethernetCsmacd</type>
</interface>
<interface>
<name>eth1.0</name>
<type>ianaift:l2vlan</type>
<if-cmn:parent-interface>eth0</if-cmn:parent-interface>
<if-cmn:encapsulation>
<flexible
xmlns="urn:ietf:params:xml:ns:yang:ietf-flexible-encapsulation">
<match>
<dot1q-vlan-tagged>
<outer-tag>
<tag-type>dot1q-types:c-vlan</tag-type>
<vlan-id>50</vlan-id>
</outer-tag>
</dot1q-vlan-tagged>
</match>
<rewrite>
<symmetrical>
<dot1q-tag-rewrite>
<pop-tags>1</pop-tags>
</dot1q-tag-rewrite>
</symmetrical>
</rewrite>
</flexible>
</if-cmn:encapsulation>
</interface>
</interfaces>
<network-instances
xmlns="urn:ietf:params:xml:ns:yang:ietf-network-instance">
<network-instance
xmlns:l2vpn="urn:ietf:params:xml:ns:yang:ietf-l2vpn">
<name>p2p-l2-1</name>
<description>Point to point L2 service</description>
<l2vpn:type>l2vpn:vpws-instance-type</l2vpn:type>
<l2vpn:signaling-type>
l2vpn:ldp-signaling
</l2vpn:signaling-type>
<endpoint xmlns="urn:ietf:params:xml:ns:yang:ietf-l2vpn">
<name>local</name>
<ac>
<name>eth0.3</name>
</ac>
</endpoint>
<endpoint xmlns="urn:ietf:params:xml:ns:yang:ietf-l2vpn">
<name>remote</name>
<pw>
<name>pw1</name>
</pw>
</endpoint>
<vsi-root>
</vsi-root>
</network-instance>
</network-instances>
<pseudowires
xmlns="urn:ietf:params:xml:ns:yang:ietf-pseudowires">
<pseudowire>
<name>pw1</name>
<configured-pw>
<peer-ip>2001:db8::50></peer-ip>
<pw-id>100</pw-id>
</configured-pw>
</pseudowire>
</pseudowires>
</config>
The authors would particularly like to thank John Messenger, Glenn Parsons, and Dan Romascanu for their help progressing this draft.
The authors would also like to thank Alex Campbell, Eric Gray, Giles Heron, Marc Holness, Iftekhar Hussain, Neil Ketley, William Lupton, John Messenger, Glenn Parsons, Ludwig Pauwels, Joseph White, Vladimir Vassilev, and members of the IEEE 802.1 WG for their helpful reviews and feedback on 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. The lowest NETCONF layer is the secure transport layer and the mandatory to implement secure transport is SSH RFC 6242. The NETCONF access control model RFC 6536 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/dot1q-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.ietf-netmod-intf-ext-yang] | Wilton, R., Ball, D., tsingh@juniper.net, t. and S. Sivaraj, "Common Interface Extension YANG Data Models", Internet-Draft draft-ietf-netmod-intf-ext-yang-05, July 2017. |
| [RFC2119] | Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/RFC2119, March 1997. |
| [RFC7224] | Bjorklund, M., "IANA Interface Type YANG Module", RFC 7224, DOI 10.17487/RFC7224, May 2014. |
| [RFC7950] | Bjorklund, M., "The YANG 1.1 Data Modeling Language", RFC 7950, DOI 10.17487/RFC7950, August 2016. |
| [RFC8174] | Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, May 2017. |
| [RFC8343] | Bjorklund, M., "A YANG Data Model for Interface Management", RFC 8343, DOI 10.17487/RFC8343, March 2018. |
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.