Internet DRAFT - draft-litkowski-spring-sr-yang
draft-litkowski-spring-sr-yang
SPRING Working Group S. Litkowski
Internet-Draft Orange Business Service
Intended status: Standards Track Y. Qu
Expires: December 25, 2015 Cisco Systems
P. Sarkar
Juniper Networks
J. Tantsura
Ericsson
June 23, 2015
YANG Data Model for Segment Routing
draft-litkowski-spring-sr-yang-01
Abstract
This document defines a YANG data model ([RFC6020]) for segment
routing ([I-D.ietf-spring-segment-routing]) configuration and
operation. This YANG model is intended to be used on network
elements to configure or operate segment routing. This document
defines also generic containers that SHOULD be reused by IGP protocol
modules to support segment routing.
Requirements Language
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in [RFC2119].
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 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 December 25, 2015.
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Copyright Notice
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.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
1.1. Tree diagram . . . . . . . . . . . . . . . . . . . . . . 3
2. Design of the Data Model . . . . . . . . . . . . . . . . . . 3
3. Configuration . . . . . . . . . . . . . . . . . . . . . . . . 5
4. IGP Control plane configuration . . . . . . . . . . . . . . . 6
4.1. IGP interface configuration . . . . . . . . . . . . . . . 6
4.1.1. Adjacency SID properties . . . . . . . . . . . . . . 6
4.1.1.1. Bundling . . . . . . . . . . . . . . . . . . . . 6
4.1.1.2. Protection . . . . . . . . . . . . . . . . . . . 7
5. States . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
6. Notifications . . . . . . . . . . . . . . . . . . . . . . . . 7
7. YANG Module . . . . . . . . . . . . . . . . . . . . . . . . . 8
8. Security Considerations . . . . . . . . . . . . . . . . . . . 20
9. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 20
10. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 21
11. Normative References . . . . . . . . . . . . . . . . . . . . 21
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 21
1. Introduction
This document defines a YANG data model for segment routing
configuration and operation. This document does not define the IGP
extensions to support segment routing but defines generic groupings
that SHOULD be reused by IGP extension modules. The reason of this
design choice is to not require implementations to support all IGP
extensions. For example, an implementation may support IS-IS
extension but not OSPF.
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1.1. Tree diagram
A simplified graphical representation of the data model is presented
in Section 2.
The meaning of the symbols in these diagrams is as follows:
o Brackets "[" and "]" enclose list keys.
o Curly braces "{" and "}" contain names of optional features that
make the corresponding node conditional.
o Abbreviations before data node names: "rw" means configuration
(read-write), and "ro" state data (read-only).
o Symbols after data node names: "?" means an optional node and "*"
denotes a "list" or "leaf-list".
o Parentheses enclose choice and case nodes, and case nodes are also
marked with a colon (":").
o Ellipsis ("...") stands for contents of subtrees that are not
shown.
2. Design of the Data Model
As the module definition is just starting, it is expected that there
will be changes as the module matures.
module: ietf-segment-routing
augment /rt:routing/rt:routing-instance:
+--rw segment-routing
+--rw transport-type? identityref
+--rw bindings
| +--rw mapping-server {mapping-server}?
| | +--rw policy* [name]
| | +--rw name string
| | +--rw ipv4
| | | +--rw mapping-entry* [prefix]
| | | +--rw prefix inet:ipv4-prefix
| | | +--rw value-type? enumeration
| | | +--rw start-sid uint32
| | | +--rw range? uint32
| | +--rw ipv6
| | +--rw mapping-entry* [prefix]
| | +--rw prefix inet:ipv6-prefix
| | +--rw value-type? enumeration
| | +--rw start-sid uint32
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| | +--rw range? uint32
| +--rw connected-prefix-sid-map
| +--rw ipv4
| | +--rw ipv4-prefix-sid* [prefix]
| | +--rw prefix inet:ipv4-prefix
| | +--rw value-type? enumeration
| | +--rw start-sid uint32
| | +--rw range? uint32
| | +--rw last-hop-behavior? enumeration {sid-last-hop-behavior}?
| +--rw ipv6
| +--rw ipv6-prefix-sid* [prefix]
| +--rw prefix inet:ipv6-prefix
| +--rw value-type? enumeration
| +--rw start-sid uint32
| +--rw range? uint32
| +--rw last-hop-behavior? enumeration {sid-last-hop-behavior}?
+--rw srgb* [lower-bound upper-bound]
+--rw lower-bound uint32
+--rw upper-bound uint32
augment /rt:routing-state/rt:routing-instance:
+--ro segment-routing
+--ro node-capabilities
| +--ro transport-planes* [transport-plane]
| | +--ro transport-plane identityref
| +--ro segment-stack-push-limit? uint8
| +--ro readable-label-stack-depth? uint8
+--ro label-blocks*
| +--ro lower-bound? uint32
| +--ro upper-bound? uint32
| +--ro size? uint32
| +--ro free? uint32
| +--ro used? uint32
+--ro global-sid-list
+--ro sid* [target sid source source-protocol binding-type]
+--ro target string
+--ro sid uint32
+--ro algorithm? uint8
+--ro source inet:ip-address
+--ro used? boolean
+--ro source-protocol leafref
+--ro binding-type enumeration
notifications:
+---n segment-routing-global-sid-collision
| +--ro received-target? string
| +--ro original-target? string
| +--ro index? uint32
| +--ro routing-protocol? leafref
+---n segment-routing-index-out-of-range
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+--ro received-target? string
+--ro received-index? uint32
+--ro routing-protocol? leafref
3. Configuration
This module augments the "/rt:routing/rt:routing-instance:" with a
segment-routing container. This container defines all the
configuration parameters related to segment-routing for this
particular routing-instance.
The segment-routing configuration is split in global routing-instance
configuration and interface configuration.
The global configuration includes :
o segment-routing transport type : The underlying transport type for
segment routing. The version of the model limits the transport
type to an MPLS dataplane. The transport-type is only defined
once for a particular routing-instance and is agnostic to the
control plane used. Only a single transport-type is supported in
this version of the model.
o bindings : Defines prefix to SID mappings. The operator can
control advertisement of Prefix-SID independently for IPv4 and
IPv6. Two types of mappings are available :
* Mapping-server : maps non local prefixes to a segment ID.
Configuration of bindings does not automatically allow
advertisement of those bindings. Advertisement must be
controlled by each routing-protocol instance (see Section 4).
Multiple mapping policies may be defined.
* Connected prefixes : maps connected prefixes to a segment ID.
Advertisement of the mapping will be done by IGP when enabled
for segment routing (see Section 4). The SID value can be
expressed as an index (default), or an absolute value. The
"last-hop-behavior" configuration dictates the PHP behavior:
"explicit-null", "php", or "non-php".
o SRGB (Segment Routing Global Block): Defines a list of label
blocks represented by a pair of lower-bound/upper-bound labels.
The SRGB is also agnostic to the control plane used. So all
routing-protocol instance will have to advertise the same SRGB.
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4. IGP Control plane configuration
Support of segment-routing extensions for a particular IGP control
plane is done by augmenting routing-protocol configuration with
segment-routing extensions. This augmentation SHOULD be part of
separate YANG modules in order to not create any dependency for
implementations to support all protocol extensions.
This module defines groupings that SHOULD be used by IGP segment
routing modules.
The "controlplane-cfg" grouping defines the generic global
configuration for the IGP.
The "enabled" leaf enables segment-routing extensions for the
routing-protocol instance.
The "bindings" container controls the routing-protocol instance's
advertisement of local bindings and the processing of received
bindings.
4.1. IGP interface configuration
The interface configuration is part of the "igp-interface-cfg"
grouping and includes Adjacency SID properties.
4.1.1. Adjacency SID properties
4.1.1.1. Bundling
This section is a first proposal on how to use S-bit in Adj-SID to
create bundles. Authors would like to trigger discussion based on
this first proposal.
In case of parallel IP links between routers, an additional Adjacency
SID may be advertised representing more than one adjacency (i.e., a
bundle of adjacencies). The "advertise-adj-group-sid" configuration
controls whether or not an additional adjacency SID is advertised.
The "advertise-adj-group-sid" would be a list of "group-id". The
"group-id" will permit to identify interfaces that must be bundled
together.
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+-------+ +------+
| | ------- L1 ---- | |
| R1 | ------- L2 ---- | R2 |
| | ------- L3 ---- | |
| | ------- L4 ---- | |
+-------+ +------+
In the figure above, R1 and R2 are interconnected by four links. A
routing protocol adjacency is established on each link. Operator
would like to create segment-routing Adj-SID that represent some
bundles of links. We can imagine two different bundles : L1/L2 and
L2/L3. To achieve this behavior, the service provider will configure
a "group-id" X for both interfaces L1 and L2 and a "group-id" Y for
both interfaces L3 and L3. This will result in R1 advertising an
additional Adj-SID for each adjacency, for example a Adj-SID with S
flag set and value of 400 will be added to L1 and L2. A Adj-SID with
S flag set and value of 500 will be added to L3 and L4. As L1/L2 and
L3/L4 does not share the same "group-id", a different SID value will
be allocated.
4.1.1.2. Protection
The "advertise-protection" defines how protection for an interface is
advertised. It does not control the activation or deactivation of
protection. If the "single" option is used, a single Adj-SID will be
advertised for the interface. If the interface is protected, the
B-Flag for the Adj-SID advertisement will be set. If the "dual"
option is used and if the interface is protected, two Adj-SIDs will
be advertised for the interface adjacencies. One Adj-SID will always
have the B-Flag set and the other will have the B-Flag clear. This
option is intended to be used in the case of traffic engineering
where a path must use either protected segments or non-protected
segments.
5. States
The operational states contains information reflecting the usage of
allocated SRGB labels.
It also includes a list of all global SIDs, their associated
bindings, and other information such as the source protocol and
algorithm.
6. Notifications
The model proposes two notifications for segment-routing.
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o segment-routing-global-sid-collision: Raised when a control plane
advertised index is already associated with another target (in
this version, the only defined targets are IPv4 and IPv6
prefixes).
o segment-routing-index-out-of-range: Raised when a control plane
advertised index fall outside the range of SRGBs configured for
the network device.
7. YANG Module
<CODE BEGINS> file "ietf-segment-routing@2015-06-23.yang"
module ietf-segment-routing {
namespace "urn:ietf:params:xml:ns:"
+ "yang:ietf-segment-routing";
prefix sr;
import ietf-inet-types {
prefix "inet";
}
import ietf-routing {
prefix "rt";
}
organization
"IETF SPRING Working Group";
contact
"WG List: <mailto:spring@ietf.org>
Editor: Stephane Litkowski
<mailto:stephane.litkowski@orange.com>
Acee Lindem
<mailto:acee@cisco.com>
Yingzhen Qu
<mailto:yiqu@cisco.com>
Pushpasis Sarkar
<mailto:psarkar@juniper.net>
Ing-Wher Chen
<mailto:ing-wher.chen@ericsson.com>
Jeff Tantsura
<jeff.tantsura@ericsson.com>
";
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description
"The YANG module defines a generic configuration model for
Segment routing common across all of the vendor
implementations.";
revision 2015-06-22 {
description
"
* Prefix SID config moved to
connected-prefix-sid-map in global SR cfg
rather than IGP.
";
reference "draft-litkowski-spring-sr-yang-01";
}
revision 2015-04-23 {
description "
* Node flag deprecated from prefixSID
* SR interface cfg moved to protocol
* Adding multiple binding policies for SRMS
";
reference "";
}
revision 2015-02-27 {
description "Initial";
reference "draft-litkowski-spring-sr-yang-00";
}
/* Identities */
identity segment-routing-transport {
description
"Base identity for segment routing transport.";
}
identity segment-routing-transport-mpls {
base segment-routing-transport;
description
"This identity represents MPLS transport for segment
routing.";
}
/* Features */
feature mapping-server {
description
"Support of SRMS.";
}
feature sid-last-hop-behavior {
description
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"Configurable last hop behavior.";
}
/* Groupings */
grouping controlplane-cfg {
container segment-routing {
leaf enabled {
type boolean;
default false;
description
"Enables segment-routing
protocol extensions.";
}
container bindings {
container advertise {
leaf-list policies {
type string;
description
"List of policies to be advertised.";
}
description
"Authorize the advertise
of local mappings in binding TLV.";
}
leaf receive {
type boolean;
default true;
description
"Authorize the reception and usage
of binding TLV.";
}
description
"Control of binding advertisement
and reception.";
}
description
"segment routing global config.";
}
description
"Defines protocol configuration.";
}
grouping sid-value-type {
leaf value-type {
type enumeration {
enum index {
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description
"The value will be
interpreted as an index.";
}
enum absolute {
description
"The value will become
interpreted as an absolute
value.";
}
}
default index;
description
"This leaf defines how value
must be interpreted.";
}
description
"Defines how the SID value is expressed.";
}
grouping ipv4-sid-cfg {
leaf prefix {
type inet:ipv4-prefix;
description
"connected prefix sid.";
}
uses sid-value-type;
leaf start-sid {
type uint32;
mandatory true;
description
"Value associated with
prefix. The value must
be interpreted in the
context of value-type.";
}
leaf range {
type uint32;
description
"Describes how many SIDs could be
allocated.";
}
description
"This grouping defines cfg of prefix SID.";
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}
grouping ipv6-sid-cfg {
leaf prefix {
type inet:ipv6-prefix;
description
"connected prefix sid.";
}
uses sid-value-type;
leaf start-sid {
type uint32;
mandatory true;
description
"Value associated with
prefix. The value must
be interpreted in the
context of value-type.";
}
leaf range {
type uint32;
description
"Describes how many SIDs could be
allocated.";
}
description
"This grouping defines cfg of prefix SID.";
}
grouping last-hop-behavior {
leaf last-hop-behavior {
if-feature sid-last-hop-behavior;
type enumeration {
enum explicit-null {
description
"Use explicit-null for the SID.";
}
enum no-php {
description
"Do no use PHP for the SID.";
}
enum php {
description
"Use PHP for the SID.";
}
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}
description
"Configure last hop behavior.";
}
description
"Defines last hop behavior";
}
grouping igp-interface-cfg {
container segment-routing {
container adjacency-sid {
list advertise-adj-group-sid {
key group-id;
leaf group-id {
type uint32;
description
"The value is an internal value to identify
a group-ID. Interfaces with the same
group-ID will be bundled together.
";
}
description
"Control advertisement of S flag.
Enable to advertise a common Adj-SID
for parallel links.";
}
leaf advertise-protection {
type enumeration {
enum "single" {
description
"A single Adj-SID is associated
with the adjacency and reflects
the protection configuration.";
}
enum "dual" {
description
"Two Adj-SIDs will be associated
with the adjacency if interface
is protected. In this case
one will be enforced with
backup flag set, the other
will be enforced to backup flag unset.
In case, protection is not configured,
a single Adj-SID will be advertised
with backup flag unset.";
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}
}
description
"If set, the Adj-SID refers to an
adjacency being protected.";
}
description
"Defines the adjacency SID properties.";
}
description
"container for SR interface cfg.";
}
description
"Grouping for IGP interface cfg.";
}
/* Cfg */
augment "/rt:routing/rt:routing-instance" {
description
"This augments routing-instance
configuration with segment-routing.";
container segment-routing {
leaf transport-type {
type identityref {
base segment-routing-transport;
}
default "segment-routing-transport-mpls";
description "Dataplane to be used.";
}
container bindings {
container mapping-server {
if-feature mapping-server;
list policy {
key name;
leaf name {
type string;
description
"Name of the mapping policy.";
}
container ipv4 {
list mapping-entry {
key prefix;
uses ipv4-sid-cfg;
description
"Mapping entries.";
}
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description
"IPv4 mapping entries.";
}
container ipv6 {
list mapping-entry {
key prefix;
uses ipv6-sid-cfg;
description
"Mapping entries.";
}
description
"IPv6 mapping entries.";
}
description
"Definition of mapping policy.";
}
description
"Configuration of mapping-server
local entries.";
}
container connected-prefix-sid-map {
container ipv4 {
list ipv4-prefix-sid {
key prefix;
uses ipv4-sid-cfg;
uses last-hop-behavior;
description
"List of prefix SID
mapped to IPv4 local prefixes.";
}
description
"Parameters associated with IPv4 prefix SID";
}
container ipv6 {
list ipv6-prefix-sid {
key prefix;
uses ipv6-sid-cfg;
uses last-hop-behavior;
description
"List of prefix SID
mapped to IPv6 local prefixes.";
}
description
"Parameters associated with IPv6 prefix SID";
}
description
"Prefix SID configuration.";
}
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description
"List of bindings.";
}
list srgb {
key "lower-bound upper-bound";
ordered-by user;
leaf lower-bound {
type uint32;
description
"Lower value in the block.";
}
leaf upper-bound {
type uint32;
description
"Upper value in the block.";
}
description
"List of global blocks to be
advertised.";
}
description
"segment routing global config.";
}
}
/* Operational states */
augment "/rt:routing-state/rt:routing-instance" {
description
"This augments the operational states
with segment-routing.";
container segment-routing {
container node-capabilities {
list transport-planes {
key transport-plane;
leaf transport-plane {
type identityref {
base segment-routing-transport;
}
description
"Transport plane supported";
}
description
"List of supported transport planes.";
}
leaf segment-stack-push-limit {
type uint8;
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description
"Describes the number of segments
that can be pushed by the node.";
}
leaf readable-label-stack-depth {
type uint8;
description
"Number of MPLS labels that
can be read in the stack.";
}
description
"Shows the SR capability of the node.";
}
list label-blocks {
leaf lower-bound {
type uint32;
description
"Lower bound of the label block.";
}
leaf upper-bound {
type uint32;
description
"Upper bound of the label block.";
}
leaf size {
type uint32;
description
"Number of indexes in the block.";
}
leaf free {
type uint32;
description
"Number of indexes free in the block.";
}
leaf used {
type uint32;
description
"Number of indexes used in the block.";
}
description
"List of labels blocks currently
in use.";
}
container global-sid-list {
list sid {
key "target sid source source-protocol binding-type";
ordered-by system;
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leaf target {
type string;
description
"Defines the target of the binding.
It can be a prefix or something else.";
}
leaf sid {
type uint32;
description
"Index associated with the prefix.";
}
leaf algorithm {
type uint8;
description
"Algorithm to be used for the prefix
SID.";
}
leaf source {
type inet:ip-address;
description
"IP address of the router than own
the binding.";
}
leaf used {
type boolean;
description
"Defines if the binding is used
in forwarding plane.";
}
leaf source-protocol {
type leafref {
path "/rt:routing-state/rt:routing-instance/" +
"rt:routing-protocols/rt:routing-protocol/rt:name";
}
description
"Rtg protocol that owns the binding";
}
leaf binding-type {
type enumeration {
enum prefix-sid {
description
"Binding is learned from
a prefix SID.";
}
enum binding-tlv {
description
"Binding is learned from
a binding TLV.";
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}
}
description
"Type of binding.";
}
description
"Binding.";
}
description
"List of prefix and SID associations.";
}
description
"Segment routing operational states.";
}
}
/* Notifications */
notification segment-routing-global-sid-collision {
leaf received-target {
type string;
description
"Target received in the controlplane that
caused SID collision.";
}
leaf original-target {
type string;
description
"Target already available in database that have the same SID
as the received target.";
}
leaf index {
type uint32;
description
"Value of the index used by two different prefixes.";
}
leaf routing-protocol {
type leafref {
path "/rt:routing-state/rt:routing-instance/" +
"rt:routing-protocols/rt:routing-protocol/rt:name";
}
description
"Routing protocol reference that received the event.";
}
description
"This notification is sent when a new mapping is learned
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, containing mapping
where the SID is already used.
The notification generation must be throttled with at least
a 5 second gap. ";
}
notification segment-routing-index-out-of-range {
leaf received-target {
type string;
description
"Target received in the controlplane
that caused SID collision.";
}
leaf received-index {
type uint32;
description
"Value of the index received.";
}
leaf routing-protocol {
type leafref {
path "/rt:routing-state/rt:routing-instance/" +
"rt:routing-protocols/rt:routing-protocol/rt:name";
}
description
"Routing protocol reference that received the event.";
}
description
"This notification is sent when a binding
is received, containing a segment index
which is out of the local configured ranges.
The notification generation must be throttled with at least
a 5 second gap. ";
}
}
<CODE ENDS>
8. Security Considerations
TBD.
9. Acknowledgements
Authors would like to thank Derek Yeung, Acee Lindem, Greg Hankins,
Hannes Gredler, Uma Chunduri, Jeffrey Zhang, Shradda Hedge for their
contributions.
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Internet-Draft sr-yang-cfg June 2015
10. IANA Considerations
TBD.
11. Normative References
[I-D.ietf-spring-segment-routing]
Filsfils, C., Previdi, S., Decraene, B., Litkowski, S.,
and R. Shakir, "Segment Routing Architecture", draft-ietf-
spring-segment-routing-03 (work in progress), May 2015.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC6020] Bjorklund, M., "YANG - A Data Modeling Language for the
Network Configuration Protocol (NETCONF)", RFC 6020,
October 2010.
Authors' Addresses
Stephane Litkowski
Orange Business Service
Email: stephane.litkowski@orange.com
Yingzhen Qu
Cisco Systems
Email: yiqu@cisco.com
Pushpasis Sarkar
Juniper Networks
Email: psarkar@juniper.net
Jeff Tantsura
Ericsson
Email: jeff.tantsura@ericsson.com
Litkowski, et al. Expires December 25, 2015 [Page 21]
