Virtual NAS (vNAS) Support for DNAS
draft-bng-radext-virtual-nas-for-dnas-01
The information below is for an old version of the document.
| Document | Type |
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|---|---|---|---|
| Authors | Raghunadha Reddy Pocha , Chandrashekhar Jamadarkhani , Satyanarayana Danda , Nishad M , Nagappa Chinnannavar | ||
| Last updated | 2017-12-06 | ||
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draft-bng-radext-virtual-nas-for-dnas-01
Network Working Group RaghunadhaReddy. Pocha, Ed.
Internet-Draft ChandraShekar. Jamadarkhani, Ed.
Intended status: Standards Track Satyanarayana. Danda
Expires: June 8, 2018 Nishad. M
Nagappa. Chinnannavar
Cisco Systems
December 5, 2017
Virtual NAS (vNAS) Support for DNAS
draft-bng-radext-virtual-nas-for-dnas-01
Abstract
This specification defines a framework for interacting North bound
(AAA/Policy) servers of the Client resides in Cloud and/or
Distributed Network environment with High-Availability to achieve
fewer use-cases. First, NAS Client resides in Cloud or Virtualized
or Distributed Network Access System to perform Authorization,
Authentication and Accounting procedures with AAA Servers. Second,
AAAA/Policy Servers provide dynamic policy information for
subscribers of supporting in NAS Clients resides in Cloud or
Virtualized or Distributed Network environment. Finally, Handling of
Accounting related issues in better way for subscribers supported in
Cloud or Virtualized or Distributed Network environment under High-
Available conditions.
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 June 8, 2018.
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Copyright Notice
Copyright (c) 2017 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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described in the Simplified BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1. Outline of the document . . . . . . . . . . . . . . . . . 3
1.2. General Terminology . . . . . . . . . . . . . . . . . . . 4
1.3. Distributed Network Access Systems . . . . . . . . . . . 4
1.4. Processing Dynamic Author Request in DNAS . . . . . . . . 5
2. Conventions used in this document . . . . . . . . . . . . . . 6
3. Problem Areas . . . . . . . . . . . . . . . . . . . . . . . . 6
3.1. AAA Operations in DNAS . . . . . . . . . . . . . . . . . 6
3.1.1. Intimating DNAS/DNAE status to AAA Server . . . . . . 7
3.1.2. Dealing with AAA Operations for DNAS with High
Availability . . . . . . . . . . . . . . . . . . . . 7
3.2. AAA Operations in AAA Server . . . . . . . . . . . . . . 10
3.2.1. Policy-Enforcement from AAA Server . . . . . . . . . 10
3.2.2. Maintaining Accounting Records on AAA Server for end-
users . . . . . . . . . . . . . . . . . . . . . . . . 10
4. Importance of vNAS in DNAS . . . . . . . . . . . . . . . . . 10
4.1. Defining vNAS for DNAS . . . . . . . . . . . . . . . . . 11
4.2. vNAS for AAA Operations . . . . . . . . . . . . . . . . . 12
4.3. vNAS for Dynamic Author Request Processing . . . . . . . 13
4.4. Dealing with vNAS for DNAS under High Available Scenarios 13
5. vNAS role in AAA Server for DNAS . . . . . . . . . . . . . . 14
6. Formal Syntax . . . . . . . . . . . . . . . . . . . . . . . . 15
7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 15
8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 15
9. Security Considerations . . . . . . . . . . . . . . . . . . . 15
10. Informative References . . . . . . . . . . . . . . . . . . . 15
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 16
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1. Introduction
In a Distributed Network Access Systems (DNAS) of containing network
elements of having interaction with AAA systems to perform
Authorization, authentication and Accounting (AAA) operations for
end-users. Each Distributed Network Access Element (DNAE) in DNAS
acts as NAS client which will interact with AAA server using
Distributed Network Access Controller?s (DNAC?s) connecting
parameters using source-ip-address, source-port and shared-secret.
All DNAEs in DNAS shall interact with DNAC locally either using
proprietary mechanism or custom defined environment which will avoid
DNAEs to be exposed to AAA Server and are morphed by DNAC identify
parameters. Phenomenally this will leads to challenges for AAA
Servers to authorize end-users based on NAS-Client parameters and
difficult to maintain accounting records as unware complete NAS-
Client information. And also, it?s difficult for DNAC to segregate
and distribute received Dynamic Author requests for respective users
from AAA Servers towards DNAEs. Under high availability conditions
for DNAS located geographically or DNAEs located in DNAS, AAA Servers
unware to maintain accounting records for node or element failures.
A mechanism should exist to intimate AAA Server about DNAS/DNAE
failure or recovering status by including relevant Radius Attributes
in Accounting Records. This document outlines the problems
encountered in DNAS for AAA operations, Policy exchange and high
available scenarios. Furthermore, the document proposes solutions or
possible approaches of related to elements in Distributed Network
systems. The purpose of this document is to introduce virtual-NAS
(vNAS) and other Radius attributes as solution to help Distributed
Network Systems to solve above said problems by including values in
Authentication, Accounting and dynamic author attributes. With this
approach, the goal is to allow the construction of standardized,
interoperable implementations to allow DNAS in data centers or in
cloud. Section 1.2 gives terminology and overview of DNAS and
respective elements. Section 3 describes the problem space details.
Section 4 describes Importance of vNAS in DNAS in more detail.
Section 5 talks about vNAS role in AAA Server for DNAS, and rest of
the sections are about other aspects of IETF draft.
1.1. Outline of the document
The document gives a high level overview of proposal. It then
describes the overall solution of interacting with AAA Servers for
Distributed Network Access Systems by leveraging existing or adding
new Radius attributes.
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1.2. General Terminology
Distributed Network Access System (DNAS): It is a physical system
resides in Data Center or cloud of having one or more Control-
Plane(CP) and/or Data-Plane(DP) aggregated as different/same network
elements.
Distributed Network Access Element (DNAE): It is logically defined
system in a physical system resides in DNAS which shall act as
Control-Plane or Data-Plane.
Virtual Machine (VM): A software implementation of a physical machine
that runs programs as if they were executing on a physical, Non-
virtualized machine. Applications (generally) do not know they are
running on a VM as opposed to running on a "bare metal" host
orserver, though some systems provide a para-virtualization
environment that allows an operating system or application to be
aware of the presence of virtualization for optimization purposes.
Virtual NAS (vNAS): This is a string that uniquely identifies a
Distributed Network Element in DNAS.
Control-Plane: A software implementation of a physical machine which
known to process only control packets.
Data-Plane: A virtualized based or proprietary platform based
physical machine which shall process forward data packets of end-
users towards core networks and vice versa.
Aggregated Control-Plane (Aggr-CP) or Proxy Control-Plane (Proxy-CP):
A software implementation of a physical machine, one of the DNAE
which shall act as an entry or exit point for entire DNAS and
interact with AAA Server on behalf of other DNAEs in a DNAS. Proxy-
CP/Aggr-CP role is superset of control-plane.
1.3. Distributed Network Access Systems
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XXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
XX XX
XX +---------------+ XX
XX |Distributed | XX
XX |Network Access | XX
XX |Element(CP/DP) | XX +--------+
XX +---------------+ +------------+ XX Radius Interface |
XX +-----+ |Distributed +--XX------------>| |
XX N No.of Elements |Network Acce| XX | AAA |
XX |ss Element | XX | Server |
XX in DNAS | (Proxy-CP) |---XX------------| |
XX +-----+ +------------+ XX +--------+
XX +---------------+ XX
XX |Distributed | XX
XX |Network Access | XX
XX |Element(CP/DP) | XX
XX +---------------+ XX
XX XX
XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
Distributed Network Access System
Figure 1. Interaction of DNAS with AAA Server
In Figure 1, DNAS is Distributed Network Access Sytem which shall
sevice end-users in any deployment models like broadband or any
celluar or Mobile Packet Core(MPC) or Evolved Packet Core(EPC) for
voice, video, data services. This DNAS shall be a Prioriety hardware
or Virtualized machine which is placed in Cloud or data network
centers. Each DNAS shall have several DNAEs which shall serve end-
users based on deployment models, these DNAEs shall act as CP-DP as
single entity or each DNAE shall act as either CP or DP. In any of
the model, DNAS shall maintain centralized Control-Plane(CP) which
shall interact with AAA Server for AAA Operations and these CP shall
be called as Proxy-CP or Aggr-CP, refered in whole document. No.of
DNAEs in DNAS is purely depends on hardware architecture and
resources.
1.4. Processing Dynamic Author Request in DNAS
In DNAS Architecture of consisting of several CPs to support AAA
operations for end-users and assume that there is one common CP which
act as a proxy and shall interact with AAA Server on behalf of all
CPs as mentioned in section 1.3. Under these conditions, AAA Server
may send Dynamic Author Request as per RFC 5716 without including
proper NAS-Identifier of DNAE. These messages shall be cumbersome
for aggregated control-plane to forward the request to respective
DNAEs and today these can be achieved by broadcasting the message to
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all DNAEs. This is a bottle neck for DNAS performance on handling
Dynamic Author Requests. As the message is broadcasted to all
respective CPs, the Proxy-CP shall wait to receive responses from
respective CPs to honor the received Dynamic Author Request to AAA
Server. This will provide delay for final response packet to AAA
Server, which in turn degrade the overall performance of AAA
interaction.
2. Conventions used in this document
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].
In this document, these words will appear with that interpretation
only when in ALL CAPS. Lower case uses of these words are not to be
interpreted as carrying significance described in RFC 2119. In this
document, the characters ">>" preceding an indented line(s) indicates
a statement using the key words listed above. This convention aids
reviewers in quickly identifying or finding the portions of this RFC
covered by these keywords.
3. Problem Areas
The following subsections describe aspects of Distributed Network
Systems that pose problems for AAA Operations. Different problem
aspects may arise based on the network architecture and scale along
with High Availability conditions.
3.1. AAA Operations in DNAS
In DNAS Architectures, it?s always good to provide NAS client
information to AAA Server while performing AAA operations to end-
user. In current deployment models, NAS-IP-Address, NAS-Port and
NAS-Identifier are the key attributes which will specify the NAS-
Client information. Having these attributes right from beginning of
transactions (from Authorization/Accounting) shall help to the end-
users from billing perspective and also policy enforcement.
In DNAS Architecture, the concept of NAS-Identifier has to be
elaborated to individual DNAEs so that it can meet the
specifications. A methodology is defined with concept of
vNAS(Virtual-NAS) under section [4] to deal with DNAS and section [6]
shall define the definition of vNAS.
For Accounting-On and Accounting-Off transactions for Node UP/Down
failures, inclusion of NAS-Identifier and it?s value plays a vital
role as AAA Server shall keep Accounting records for on-going end-
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user transactions and also helpful to push policies for existing
subscribers.
3.1.1. Intimating DNAS/DNAE status to AAA Server
Today, NAS Client notify the status of the system UP/DOWN using
Accounting On/Off transactions to AAA Server to inform the system
credentials. Based on this information, AAA Server shall maintain
this information to maintain the accounting records for end-users
whenever accounting records are received from respective NAS-Client
and also enforce the dynamic policies to NAS-Client using Dynamic
Authorization procedures for end-users.
In a given DNAS, there is no methodology in place to intimate DNAS/
DNAE identifiers to maintain at AAA Server level to serve the above
said functionality fully.
3.1.2. Dealing with AAA Operations for DNAS with High Availability
This is a high availability scenario where multiple DNASs are located
geographically to serve end-users for AAA operations in N:M
Redundancy model where N and M are no.of DNASs in Active-Active or
Active-Standby model.
A system in DNAS with high available conditions, always has to
publish system identifiers to AAA Server whenever HSRP redundancy
states are changed. This mechanism shall help at AAA level to serve
the NAS-Client to push dynamic policies and also to maintain the
accounting records for end-users.
There are multiple ways of having DNASs under high available
scenarios.
In Figure-2, the DNAEs across DNAS are in redundancy mode. That
means, DNAE in DNAS-1 shall have respective redundancy mode in DNAS-
2. Similarly, Aggr-CP/Proxy-CP of DNAS-1 shall have respective
redundancy node another DNAS-2. The redundancy handling of Control-
Plane/Data-Plane is not going to be discussed in this draft and it?s
completely implementation dependent.
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XXXXXXXXXXXXXXXXXXXXXXXXXXXXX
XX XX
XX +-------+ XXX
+------------+ DNAE | XX
| XX | CP/DP | XX
| XX +-------+ +------------+ XX
| XX +-----+ | DNAE | XX
| XX N No.of DNAEs | (Aggr-CP/ +-----------+
| XX in DNAS | Proxy|CP) +----+X |
| XX +-----+ +------------+ |X |
| XX +-------+ X| |
| XX | DNAE | XX| |
| +-------+ CP/DP | XX | |
| | XX +-------+ XX | |
| | XX XX | |
| | XX DNAS-1 XX | |
| | XXXXXXXXXXXXXXXXXXXXXXXXXXXXXX | +---v-----+
Redundant links | | AAA |
of DNAEs across DNAS | | Server |
| | XXXXXXXXXXXXXXXXXXXXXXXXXXXXX | | |
| | XX XX | +---^-----+
| | XX +-------+ XXX | |
| | XX | DNAE | XX | |
| +------^+ CP/DP | XX | |
| XX +-------+ +------------+ XX| |
| XX +-----+ | DNAE +^---+ |
| XX N No.of DNAEs | (Aggr-CP/ +-----------+
| XX in DNAS | Proxy|CP) | XX
| XX +-----+ +------------+ XX
| XX +-------+ XX
| XX | DNAE | XX
+-----------^+ CP/DP | XX
XX +-------+ XX
XX XX
XX DNAS-2 XX
XXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
Figure 2. DNAEs across DNAS in High Available Scenarios
Unlike Figure-2 DNAS Redundancy topology, Figure-3 explains the
redundancy within the DNAEs as well. Where each DNAEs have several
HSRP groups which shall serve certain end-users in redundancy mode
across DNAEs and DNAS. The redundancy handling of Control-Plane/
Data-Plane is not going to be discussed in this draft and it?s
completely implementation dependent.
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+------------------------------------------------------+
| +----------------------------+ |
| | +----------+ +----------+ | |
| | |Redundancy| |Redundancy| +---------+ |
| | | Group 1 | |Group ..M | | | |
| | +----------+ +----------+ | | |
| | | | |
| | DNAE-1 | +------v----------+ |
| +----------------------------+ | Aggregate/ | |
| | Proxy +------------+
| +----------------------------+ | Control-Plane | | |
| | +----------+ +----------+ | +------^----------+ | |
| | |Redundancy| |Redundancy| | | | |
| | | Group 1 | |Group ..N | | | | |
| | +----------+ +----------+ | | | |
| | +---------+ | |
| | DNAE-N | | |
| +----------------------------+ | |
| | +-----v-----+
| Distributed Network Access System | | AAA |
+------------------------------------------------------+ | Server |
+-----------+
+------------------------------------------------------+ |
| | |
| +----------------------------+ | |
| | +----------+ +----------+ | | |
| | |Redundancy| |Redundancy| | | |
| | | Group 1 | |Group ..M | +---------+ | |
| | +----------+ +----------+ | | | |
| | | | | |
| || DNAE-1 | +------v----------+ | |
| +----------------------------+ | Aggregate/ | | |
| | Proxy +------------+
| +----------------------------+ | Control-Plane | |
| | +----------+ +----------+ | +------^----------+ |
| | |Redundancy| |Redundancy| | | |
| | | Group 1 | |Group ..N | | | |
| | +----------+ +----------+ | | |
| | +---------+ |
| || DNAE-N | |
| +----------------------------+ |
| |
| Distributed Network Access System |
+------------------------------------------------------+
Figure 3. Redundancy Groups inside DNAEs across DNAS in HA Scenarios
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For all above approaches, there is no mechanism to handling
accounting records at AAA level and pushing dynamic policies across
DNAS for end-users.
The following subsections describe aspects of Distributed Network
Systems that pose problems for AAA Operations. Different problem
aspects may arise based on the network architecture and scale along
with High Availability conditions.
3.2. AAA Operations in AAA Server
AAA Server shall maintain NAS-Client information whenever respective
NAS Clients are UP/DOWN so that it?s easy to push Dynamic Policies
and also to maintain accounting records for end-users of respective
NAS-Client based on identifiers that are received as part of
Accounting On/Off messages. The same is applicable under High
available conditions as explained in earlier sections.
3.2.1. Policy-Enforcement from AAA Server
In DNAS Architecture based deployment models, enforcing policies from
AAA Server using Dynamic Authorization procedures are never be easy
as the elements in DNAS are not much exposed to AAA Server. This
will restrict AAA Server to send all Dynamic Authorization request
messages to CP-Proxy of DNAS, DNAS has to broadcast those messages to
all DNAEs in it. Since DNAS is going to take more time because of
broadcast to it?s DNAEs, the AAA Server will continue to retransmit
the Dynamic Authorization request. This will impact the performance
on interactions between AAA Server and DNAS
3.2.2. Maintaining Accounting Records on AAA Server for end-users
Maintaining the accounting records with respective DNAS/DNAE element
identifiers shall helpful for better billing of subscriber movement
across DNAS/DNAE based on deployment models. This will also helpful
to enforce new policies based on newly received DNAS/DNAE
identifiers. Today, majority of deployment models are not of DNAS
based and mostly maintaining accounting records are based on nas-ip-
address and nas-identifier. Nas-IP-Address is unique per DNAS and
there is no identifier to discriminate the individual DNAEs. This
shall enforce limitation on AAA Server to achieve the actual
functionality in DNAS Architecture.
4. Importance of vNAS in DNAS
vNAS is Virtual-NAS shall defined in DNAS to identify a DNAE which is
included as an attribute on performing authorization, authentication
and accounting transactions for end-user. This vNAS value shall help
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to identifier the NAS-Client in DNAS environment for end-user so that
AAA Server operations shall be easier to operate w.r.to round-trip-
time and resource utilization.
4.1. Defining vNAS for DNAS
vNAS is Virtual-NAS shall defined in DNAS to identify a DNAE
uniquely. As defined in Figure-1, DNAS system consists of various
DNAEs which will act as control-plane and data-plane. However, there
is one element which can interact with AAA Server which is known as
Aggregated Control-Plane (Aggr-CP) or Proxy Control-Plane (Proxy-CP).
The Proxy-CP shall provide vNAS for each DNAE uniquely in DNAS
environment whenever the DNAE is spawned/booting-time. Proxy-CP
shall maintain the vNAS Table of having mapping between vNAS vs DNAEs
so that all AAA operations shall be unicasted to respective DNAE
based on vNAS table lookup for a received vNAS value.
The aim of defining or generation of vNAS should be unique for each
DNAE as this vNAS value shall be included in Radius NAS-Identifier of
Radius messages. The generation of vNAS on Proxy-CP shall be done in
many ways and shall vary from deployment models. The following are
fewer approaches of generating the vNAS for DNAE,
1) Using DNAE naming conventions used in DNAS. 2) Using DNAE bit
mapping. 3) Using DNAE Name + Boot-up TimeStamp 4) Using DNAS Name +
DNAE Name + Boot-Up Timestamp. 5) Using DNAS Name + DNAE Name +
Group-Id
The approach (1), (2) and (3) shall provide uniqueness within the
system but not across DNASs. Approach (4) shall provide uniqueness
across DNAS where AAA Server also shall identify the entire DNAE
information in DNAS environment. Approach (5) shall provide vNAS
uniqueness across DNAS for high availability cases where each Group-
Id represents on Group when DNAEs have multiple Groups in it under
high availability cases.
Approach-1, Aggr-CP/Proxy-CP DNAS shall generate DNAE name while
spawning the DNAE in DNAS environment and maintain the strict mapping
internally on Aggr-CP/Proxy-CP. This solution shall work for
standalone systems.
Approach-2, There is no naming convention here. It?s more of like
how the dynamic/static bit mapping is maintained at Aggr-CP/Proxy-CP
whenever DNAE boots up. This solution shall work for standalone
systems.
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Approach-3, Aggr-CP/Proxy-CP of DNAS shall generate DNAE name along
with Boot-UP timestamp. This shall provide more uniqueness within
DNAS and good for standalone systems only.
Approach-4, Aggr-CP/Proxy-CP of DNAS shall generate DNAE name by
considering the DNAS name along with Boot-UP timestamp of DNAE. This
shall provide more uniqueness across DNAS and is perfect for
Redundancy models across DNAS (as defined in Figure-2).
Approach-5, This use case is special use case as defined in Figure-3.
Aggr-CP/Proxy-CP of DNAS shall generate vNAS by considering DNAS
name, DNAE name and HSRP Group-name which shall provide more
uniqueness across DNAS and is perfect for Redundancy models across
DNAS.
The ultimate goal of generating vNAS is to have more uniqueness
across DNAS where multiple DNAS are deployed in a network to provide
services to end-users.
Based on approaches defined and network topology conditions, let the
Centralized Configuration Manager provides unique vNAS to DNAEs in
DNAS using NetConf/Yang.
The vNAS identifier value shall include in NAS-Identifier as defined
in [4]. The generation of vNAS should fit the length values of NAS-
Identifier.
4.2. vNAS for AAA Operations
DNAS shall perform AAA Operations for end-user by sending
authentication, accounting messages. In all these messages, DNAS
shall include NAS-IP-Address and NAS-Identifier. In a given DNAS
system, there are multiple ways of interacting with AAA Server.
One of the way is, individual DNAEs shall send triggers for AAA
operations internally to Proxy-CP and Proxy-CP shall send out AAA
Messages after including nas-ip-address and vNAS Identifier. In this
case, DNAEs are not exposed with AAA configuration parameters and
complete owns of AAA messages transactions are well taken care by
Proxy-CP only.
Another way of sending messages are, individual DNAEs AAA
configuration i.e., DNAEs are aware of NAS-IP-Address of DNAS and AAA
Server information. This will help DNAEs to include NAS-IP-Address
and vNAS as NAS-Identifier in AAA messages. In this case the
complete ownership of AAA message transactions are taken by
individual DNAEs except Dynamic-Authorization-Requests which will be
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dealt in section 4.3. Holding unique NAS-IP-Address by each DNAE is
ruled out in DNAS environment.
4.3. vNAS for Dynamic Author Request Processing
AAA Server shall use Dynamic Author Requests end-user to intimate
session termination by sending Disconnect-Request or pushing dynamic-
policies or other much needed interim session information by sending
Change-Of-Authorization to NAS-Client where the end-user AAA context
is maintained which is as per [9].
Based on sections 4.2 and 5, AAA Server shall include vNAS values in
NAS-Identifier of Dynamic-Authorization-Request message for end-user
which are targeted to DNAEs located in DNAS where the end-user AAA
Context is maintained so that request shall be processed. Since, the
DNAEs doesn?t have direct interaction with AAA Server and vice versa
? the dynamic-author request messages shall sent to Proxy-CP of DNAS.
The DNAS of Proxy-CP shall process the received request and look for
NAS-Identifier value which is nothing but vNAS value. Proxy-CP
Search for vNAS table to match the vNAS value for fetching the DNAE
so that the request shall be unicasted internally to respective DNAE.
There are several ways of handling Dynamic-Author Request at Proxy-CP
on DNAS. One of the approach is, Proxy-CP shall act as a message
dispatcher to DNAE after vNAS lookup where proxy-cp shall not
maintain any message transaction. DNAE shall respond back to DNAS as
defined in section 4.2 via Proxy-CP or directly to AAA Server. Any
delay of processing Proxy-CP shall keep forwarding any retransmitted
messages
Another approach is, Proxy-CP can maintain the message context so
that the DNAE shall respond with status of message to Proxy-CP and
Proxy-CP shall send final response to AAA Server. Proxy-CP of DNAS
will trigger an internal timer to wait for response message from
DNAE. And also, DNAS shall silently drop any retransmitted messages
received from AAA Server in this duration.
4.4. Dealing with vNAS for DNAS under High Available Scenarios
Under high availability scenarios defined in section 3.1.3, where
multiple DNASs are located geographically to serve end-users for AAA
operations in N:M Redundancy model where N and M are no.of DNASs are
in Active-Active or Active-Standby model.
A system in DNAS with high available conditions, always has to
publish system identifiers to AAA Server whenever HSRP redundancy
states are changed. This mechanism shall help at AAA level to serve
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the NAS-Client to push dynamic policies and also to maintain the
accounting records for end-users.
Under high available conditions, DNAS shall have different NAS-IP-
Address unless the AAA Server are connected core links. For any
deployment case, AAA Servers are not exposed to core-link and hence,
the Active/Standby DNAS shall have different NAS-IP-Address.
Whenever switchover happened, OLD DNAS and respective DNAEs in it
shall send Accounting-Off and Accounting-Request with Acct-Status-
Type STOP for individual end-users to close outstanding accounting
transactions. Similarly, the new DNAS and respective DNAEs role is
exchanged i.e., Standby -> Active. The new DNAS and respective DNAEs
state start sending Accounting-On and Accounting-Request with Acct-
Status-Type START for individual end-users to open accounting
transactions.
Updating the NAS-IP-Address in DNAS and vNAS of DNAEs with AAA Server
are very import in High Availability scenarios, this shall help to
push Dynamic-policies to new DNAEs directly for end-users.
5. vNAS role in AAA Server for DNAS
AAA Server shall maintain NAS-Client information whenever respective
NAS Clients are UP/DOWN by receiving Accounting On/Off messages, so
that it is easy to maintain accounting records for end-users belong
to that particular DNAE.
AAA Server must record the Accounting Records by mapping the NAS-IP-
Address and NAS-Identifier (vNAS value) of each end-user received
from NAS-Client based. This approach shall help to push dynamic-
policies for end-user by including vNAS in Dynamic-Authorization
messages towards DNAE which are part of DNAS. The following cases
requires to update the information,
- Whenever NAS-Client (DNAE) is UP/DOWN in a given DNAS. - DNASs and
DNAEs are located geographically in HSRP environment.
Earlier, whenever NAS-Client is going down is capable of sending
Accounting Off or individual end-user Accounting Request with Acct-
Status-Type with STOP to AAA Server. And also, Whenever NAS-Client
is going down or Redundancy Roles are changed, old NAS-Client is
going to send Accounting Off and New NAS-Client is going to send
Accounting-On messages. In redundancy role exchange, old NAS-Client
is used to generate Accounting-Request with Acct-Status-Type as STOP
and new NAS-Client shall generate Accounting-Request with Acct-
Status-Type as START for end-user accounting transactions. This is
how AAA can close earlier transactions and maintain new transactions
for end-user under HSRP scenarios.
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Accounting Off messages are having significance role whenever NAS-
Client is DOWN, this shall eventually help AAA Server to close all
outstanding accounting transactions records that are maintained for
end-users from each NAS-Client and with this approach, old NAS-Client
no need to generate Accounting-Request with Acct-Status-Type with
STOP for individual end-users.
6. Formal Syntax
The following syntax specification uses the augmented Backus-Naur
Form (BNF) as described in RFC-2234 [RFC2234].
7. Acknowledgements
This template was derived from an initial version written by Pekka
Savola and contributed by him to the xml2rfc project.
8. IANA Considerations
vNAS is a Virtual-NAS defined for DNAS and shall leverage the
existing Radius NAS-Identifier attribute to include the vNAS value in
Radius Messages. Based on review, may define a new attribute for
vNAS in Radius Protocol.
9. Security Considerations
Because this document describes the problem space associated with the
need for virtualization of networks in complex, large-scale, data-
center networks, it does not itself introduce any security risks.
However, it is clear that security concerns need to be a
consideration of any solutions proposed to address this problem
space. Solutions will need to address both data-plane and control-
plane security concerns.
10. Informative References
[RFC1321] Rivest, R., "The MD5 Message-Digest Algorithm", RFC 1321,
DOI 10.17487/RFC1321, April 1992,
<https://www.rfc-editor.org/info/rfc1321>.
[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>.
[RFC2234] Crocker, D., Ed. and P. Overell, "Augmented BNF for Syntax
Specifications: ABNF", RFC 2234, DOI 10.17487/RFC2234,
November 1997, <https://www.rfc-editor.org/info/rfc2234>.
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Internet-Draft Virtual NAS (vNAS) Support for DNAS December 2017
[RFC2865] Rigney, C., Willens, S., Rubens, A., and W. Simpson,
"Remote Authentication Dial In User Service (RADIUS)",
RFC 2865, DOI 10.17487/RFC2865, June 2000,
<https://www.rfc-editor.org/info/rfc2865>.
[RFC2866] Rigney, C., "RADIUS Accounting", RFC 2866,
DOI 10.17487/RFC2866, June 2000,
<https://www.rfc-editor.org/info/rfc2866>.
[RFC2869] Rigney, C., Willats, W., and P. Calhoun, "RADIUS
Extensions", RFC 2869, DOI 10.17487/RFC2869, June 2000,
<https://www.rfc-editor.org/info/rfc2869>.
[RFC3162] Aboba, B., Zorn, G., and D. Mitton, "RADIUS and IPv6",
RFC 3162, DOI 10.17487/RFC3162, August 2001,
<https://www.rfc-editor.org/info/rfc3162>.
[RFC3575] Aboba, B., "IANA Considerations for RADIUS (Remote
Authentication Dial In User Service)", RFC 3575,
DOI 10.17487/RFC3575, July 2003,
<https://www.rfc-editor.org/info/rfc3575>.
[RFC5176] Chiba, M., Dommety, G., Eklund, M., Mitton, D., and B.
Aboba, "Dynamic Authorization Extensions to Remote
Authentication Dial In User Service (RADIUS)", RFC 5176,
DOI 10.17487/RFC5176, January 2008,
<https://www.rfc-editor.org/info/rfc5176>.
Authors' Addresses
Raghunadha Reddy Pocha (editor)
Cisco Systems
Cessna Business Park, Kadubeesanahalli
Bengaluru 560103
India
Phone: +91 9731 203 806
Email: pragredd@cisco.com
Chandrashekhar Jamadarkhani (editor)
Cisco Systems
Cessna Business Park, Kadubeesanahalli
Bengaluru 560103
India
Phone: +91 9972 039 140
Email: cjamadar@cisco.com
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Satyanarayana Danda
Cisco Systems
Cessna Business Park, Kadubeesanahalli
Bengaluru 560103
India
Phone: +91 9741 732 155
Email: sdanda@cisco.com
Nishad M
Cisco Systems
Cessna Business Park, Kadubeesanahalli
Bengaluru 560103
India
Phone: +91 9482 538 306
Email: nism@cisco.com
Nagappa Chinnannavar
Cisco Systems
Cessna Business Park, Kadubeesanahalli
Bengaluru 560103
India
Phone: +91 9742 489 050
Email: nchinnan@cisco.com
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