Internet Engineering Task Force Alexandre Cassen
Internet-Draft Freebox S.A.
Intended status: Informational May 25, 2009
Expires: November 26, 2009
Access Right Distribution Protocol (ARDP)
<draft-cassen-access-right-distribution-protocol-06.txt>
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Abstract
This document describes a protocol using multicast to securely
distribute IPTV management elements such as IPTV customer's access
rights. The protocol typically runs on any piece of equipments to
locally store owned customers IPTV service access right. This design
provides access control at aggregation level.
Table of Contents
1. Introduction .............................................. 4
1.1. Scope ................................................. 5
1.2. Definitions ........................................... 5
2. ARDP framework ............................................ 7
2.1. NSP/CP Hierarchy ...................................... 7
2.2. Using Multicast to convey ARDP datagrams .............. 7
2.3. An ID and attributes oriented protocol ................ 8
2.4. CP Service Plane ...................................... 8
2.5. ClientID ............................................. 10
2.6. Conditional Access Right ............................. 10
2.7. Attributes inheritance ............................... 11
3. ARDP Architecture ........................................ 11
3.1. Interface with NE routing stack ...................... 13
3.2. Adaptive zapping ..................................... 14
3.3. Confidentiality and security considerations .......... 15
3.4. NSP ARDP Server ...................................... 16
3.5. CP ARDP Server ....................................... 17
3.6. NE ARDP Client ....................................... 17
3.7. NSP ARDP Report ...................................... 18
3.8. NSP ARDP Accounting .................................. 18
3.9. Make it reliable ! ................................... 19
3.10. ARDP stream bitrate ? ............................... 20
3.11. Global Operation workflow ........................... 20
4. Multicast Protocol Part .................................. 21
4.1. IP/UDP packet field descriptions ..................... 21
4.2. ARDP header Packet Format ............................ 21
4.3. ARDP AVP Packet Format ............................... 24
5. ARDP Base Protocol AVPs .................................. 24
6. Unicast Protocol Part .................................... 30
7. ARDP Server Operations ................................... 30
8. NE ARDP Client Operations ................................ 31
8.1. Initialize State ..................................... 31
8.2. Learning State ....................................... 33
9. Sending and receiving ARDP datagram ...................... 34
9.1. Sending .............................................. 34
9.2. Receiving ............................................ 34
10. Acknowledgments ......................................... 34
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11. References ............................................... 35
12. Authors' Address ......................................... 36
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1. Introduction
Standard digital TV security models are based on smartcard
intelligence at the end user CPE side. We will not present global
goal and design of Conditional Access System since this is not the
scope of this document. We can simply remind that digital pay TV is
based on such a system where EMM (Entitlement Management Message), an
encrypted message, provides private conditional access information
concerning the broadcast services one viewer is allowed to receive.
The challenge of such an architecture is to provide strong
cryptographic systems to protect EMM messages against piracy since
EMM are stored directly into the CPE/smartcard. If this system can be
considered as good for regular broadcasting design where no upstream
(on CPE side) is available, this design can be enhanced on network
(xDSL, FTTx) offering upstream feedback channel.
The very first security consideration rely more on trust aggregation
network or any routing equipements and reduce end user CPE
intelligence/complexity. Networking architecture provides a way to
dissociate Conditionnal Acces and video content protection. While
stream can still use standard DVB-CSA scrambling design, EMM
equivalent can be stored into aggregation equipment. CPE is
considered as no trust equipement and the idea is to reduce to the
max the action it may have. CPE intelligence and operations on
security side can be emulated which open the door to reverse
engineering. For services like IPTV, this design offers a secure
conditional access design by physically dissociating both security
components. Stream access is controled during stream subscribtion
stage. The CPE simply requests for a video stream and the aggregation
equipment grants or not access according to its local access database
(local access right cache).
The challenge for now is to find a secure and scalable way to
populate aggregation equipments access database. We can be inspired
from the broadcasting model by using multicast transmission to
distribute access rights over a network backbone. The following
document will present a protocol used on top of IP to securely
distribute those access rights.
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1.1 Scope
The remainder of this document describes the features, design goals,
and theory of operation of Access Right Distribution Protocol - The
message format, protocol processing rules and state machine that
guarantee safe and secure operations.
1.2 Definitions
In this document we will use same Definitions/Abbreviations as
present in [AAA] document.
ChannelID An abstraction modelizing a CP pieces of
informations identifying a CP IPTV streaming
service (multicast group and any other
low-level related attributes).
ServiceID An abstraction modelizing a CP pieces of
informations identifying a CP IPTV set of
ChannelID.
ClassID An abstraction modelizing a CP pieces of
informations identifying a CP IPTV set of
ServiceID.
Service Plane An abstraction modelizing the CP set of
ClassID / ServiceID.
ClientID An abstraction modelizing association between
customer Identification number and physical
IP address (or MAC address or phone number).
Each IP address (or MAC or phone number) can
have multiple ClientID, each one is unique to
each CP namespace.
Access Right An abstraction modelizing a customer
conditional access on a specific ServiceID or
ClassID. It determines whether or not a
ClientID
can access a specific ServiceID or ClassID.
CP Content Provider is in charge of multicast
content streaming. Each CP is also in charge
of distributing Service Plane, ClientID,
Access Right over ARDP backbone.
ARDP Backbone A Wide Area Network made of lot of ARDP
clients.
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NSP Network Service Provider owns ARDP Backbone
and is in charge of any administration related
operations over it.
NE Network Equipment is runing an ARDP Client and
is storing Access Right. It controls and
maintains multicast subscription.
ARDP Client A Software component running ARDP protocol on
network aggregation routing equipments. It is
responsible for NE local right cache
management and is interacting with NSP ARDP
Server. It stores all CP Service Plane,
ClientID, associated security elements (RSA
public key) and customer Access Right.
CP ARDP Server Each CP stores an RSA keypair and uses RSA
private key to sign all ARDP protocol
datagrams sent to ARDP Backbone. The RSA
public key is exported to all NE ARDP Clients.
It manages Service Plane and Access Right
flooding.
NSP ARDP Server A server running ARDP protocol and acting as
root authority. This server distributes
ClientID over ARDP backbone and forwards ARDP
requests to CP ARDP servers.
ARDP Session A connection issued by NSP ARDP Server to
CP ARDP Server to request Access Right
flooding for a set of CP ClientID.
NSP Accounting Srv A server listening and handling any
accounting reports sent by NE.
NSP Report Srv A server acting as a proxy between
NE and Back-office management systems.
Use to fetch/verify Access Right
bound to a specific ClientID.
CDS Content Delivery Services.
CPE Customer Premise Equipment.
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2. ARDP framework
ARDP provides secure, scalable and reliable facilities to distribute
IPTV management elements. Those elements are :
. CP Service Plane (ClassID/ServiceID)
. ClientID
. Access Right
2.1. NSP/CP Hierarchy
ARDP design tend to create a hierarchy between NSP and CP. NSP trust
CP with point of presence in its ARDP Backbone, but for
security/maintenability reasons NSP MUST protect/hide its low-level
topology. NSP is in charge with administration and operations all
over its backbone, each NE can change/migrate to a different routing
plane, each customer can roam from NE to NE and consequently change
their routing related elements and path (change of IP address for
example).
NSP is responsible for keeping accurate association between ClientID
and IP Address in all CP namespace.
CP operations are CDS centralized, it manages informations needed to
run its business : ServiceID/ClassID/Access Right.
2.2. Using Multicast to convey ARDP datagrams
ARDP is running over multicast. ARDP Servers are a only multicast
sending source while NE ARDP Client are a only multicast receiver.
Every CP are network low-level topology agnostic, using multicast
provides a simple and scalable answer to offer a full and realtime
distribution of Access Right to each CP.
IPTV makes extensive use of multicast, using multicast for ARDP and
localizing it into same networking plane as other regular streamed
contents will provide an accurate feedback on multicast reliability
until NE. As presented in section 4.5, ARDP architecture defines an
accounting server used to handle ARDP protocol reliability, any
trouble occuring on ARDP multicast flow can be extrapolated to other
multicast flows into the same networking plane.
Finally, using multicast as distribution vector offers to ARDP
protocol a very short convergence time since one change will be
learnt and affect every NE at a time. For example, changing any
Service Plane piece of informations (multicast group, ...) will be
quite realtime.
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2.3. An ID and attributes oriented protocol
ARDP is network topology agnostic by making extensive use of ID for
addressing every low-level elements. IDs are key-elements just like
those found in DVB satellite architecture. Using IDs create an
abstraction between managed and target elements leading to a very
short (optimum) convergence time needed while updating those target
elements.
CP Service Plane is the ARDP fundation element. Every CP are
permanently flooding over ARDP backbone all of their ServiceID and
ClassID elements. On its own, NSP is flooding ClientID elements.
Service Plane and ClientID open the road to CP Access Right flooding,
in other words: setting an Access Right for a ServiceID or ClassID to
a target ClientID. An Access Right is thus a binding between a
ClientID and a ServiceID or a ClassID.
The others ARDP key-elements are attributes. Every IDs are filled
with a set of attributes like presented in section 4.3.1. ServiceID,
ClassID, ClientID are a set of attributes.
Creating ID abstraction provides flexibility while managing
attributes. Attributes values updates (over ClassID, ServiceID,
ClientID, ....) will not impact any ARDP operations since Access
Right binding is made on ID.
2.4. CP Service Plane
Service Plane is managed by a CP, it defines low-level elements CP
will use to run its business. A Service Plane is thus a set of
ServiceID and ClassID learnt by NE ARDP Client. Service Plane brings
an important flexibility for CP since it can change any elements in
quite realtime. It provides functional flexibility like defining
playlist based ServiceID, adaptive zapping, ...
2.4.1. ServiceID
A ServiceID is compounded by a set of ChannelID and is unique in CP
ARDP namespace. Its management representation is an ID and is filled
using the following ABNF notation as in [RFC4234]:
ServiceID ::= { Auth-Service-Id }
* [ AVP ]
{ Service-Profile }
[ Channel-Id [ AVP ] ]
{ Service-Profile-fallback }
[ Channel-Id [ AVP ] ]
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Detailed AVPs declaration and specifications can be found in section
5.
A live IPv4 only example can be :
SvcID | Service Attributes
---------+---------------------------------------
201 | . Service Name : IETF IPTV Room1
| . PC Redirect : 1
| . Number of Decoder : 2
| . Accounting-Zap : 192.168.200.10
| . Profile :
| . ChannelID : 419
| . Service Name : IETF IPTV HD
| . Multicast Group : 239.1.2.3
| . Unicast Source : 192.168.200.1
| . Capabilities : 0x0002
| . Bitrate : 5500
| . ChannelID : 32
| . Service Name : IETF IPTV SD
| . Multicast Group : 239.1.2.4
| . Unicast Source : 192.168.200.2
| . Capabilities : 0x0004
| . Bitrate : 3600
| . ChannelID : 347
| . Service Name : IETF IPTV H264
| . Multicast Group : 239.1.2.5
| . Unicast Source : 192.168.200.3
| . Capabilities : 0x0008
| . Bitrate : 2000
| . Profile Fallback :
| . ChannelID : 519
| . Service Name : IETF FB HD
| . Multicast Group : 239.1.2.6
| . Unicast Source : 192.168.200.4
| . Capabilities : 0x0002
| . Bitrate : 5500
| . ChannelID : 132
| . Service Name : IETF FB SD
| . Multicast Group : 239.1.2.7
| . Unicast Source : 192.168.200.5
| . Capabilities : 0x0004
| . Bitrate : 3600
| . ChannelID : 447
| . Service Name : IETF FB H264
| . Multicast Group : 239.1.2.8
| . Unicast Source : 192.168.200.6
| . Capabilities : 0x0008
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| . Bitrate : 2000
In this example ServiceID 201 defines "IETF IPTV Room1" service.
2.4.2. ClassID
A ClassID is managed by a CP, it defines a set of ServiceID and is
filled using the following ABNF notation as in [RFC4234]:
ClassID ::= { Auth-Class-Id }
* [ AVP ]
[ Auth-Service-Id ]
A live example can be :
ClassID | Class Attributes
---------+---------------------------------------
74 | . Class Name : IETF IPTV Area
| . Number of Decoder : 3
| . Service :
| 201 202 203 204 205 206 207 208
2.5. ClientID
A ClientID defines an NSP low-level binding between Client networking
informations and its ARDP representation. A ClientID is filled using
the following ABNF notation as in [RFC4234]:
ClientID ::= { Auth-Client-Id }
* [ AVP ]
A live IPv4 only example can be :
ClientID | Client Attributes
----------+---------------------------------------
100 | . IP-Address : 10.1.1.1
| . Number of Decoder : 5
| . Accounting-Zap : 192.168.200.150
2.6. Conditional Access Right
A conditional Access Right defines a binding between
(ClientID,ServiceID) or (ClientID,ClassID). CP is setting those
bindings for every ClientID it manages. If a Client is subscribing to
a marketing offer modelized in ARDP by ClassID 74 then CP simply send
an ARDP datagram to set/create this binding.
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2.7. Attributes inheritance
ARDP provides attributes inheritance design between every element it
manages. Inheritance tree is :
ServiceID
^
|
ClassID
^
|
ClientID
ServiceID is surcharging ClassID attributes surcharging ClientID
attributes.
If we use the live example presented in previous sections, "Number of
Decoder" attributes will finally have the value of 2.
3. ARDP Architecture
We can localize each ARDP architecture component on the following
diagram :
+-----------+ +-----------+
| | | |
__________| CP ARDP 1 |________| CP ARDP 2 |________________
/ | | | | \
/ +-----------+ +-----------+ \
| |
| ARDP Backbone |
| |
\ +-------+ +------+ +------+ +------+ /
\__| NSP |_______________| NE 1 |___| NE 2 |..| NE n |_____/
| ARDP | +------+ +------+ +------+
+-------+ ^ ^ ^ ^
................ . . .
. . . .
+--------- v + +---------- v + . .
| NSP ARDP | | NSP ARDP |<...... .
| Accounting | | Report |<...............
+------------+ +-------------+
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NSP ARDP : NSP ARDP Server
CP ARDP 1 : CP 1 running CP 1 ARDP Server
CP ARDP 2 : CP 2 running CP 2 ARDP Server
NE 1 : NE 1 running NE 1 ARDP Client
NE 2 : NE 2 running NE 2 ARDP Client
NE n : NE n running NE n ARDP Client
NSP ARDP Accounting : NSP Accounting Server
NSP ARDP Report : NSP Back-Office Report Server
All customer ClientID are flooded from NSP ARDP Server. All customer
Access Right are flooded from CP ARDP Server. Every CP ARDP Server
are flooding Service Plane and Access Right for ServiceID/ClassID
they manage. NE ARDP Client is then filtering received multicast
datagrams to only store Access Right, for customers it hosts
(ClientID).
ARDP finality is then to maintain Access Right cache integrity on NE
ARDP Client side and to offer any CP the ability to flood directly
Service Plane and Access Right over ARDP Backbone.
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3.1. Interface with NE routing stack
In IPTV architectures, stream subscription is most of the time done
through IGMP (as described in [RFC3376]) since streaming is done via
multicast. In IGMP there is a lake of feedback while performing JOIN
or LEAVE operation, in this document we will not use IGMP as
subscription protocol, we will rather use SUBSP acronym to identify
this subscription protocol. SUBSP MUST be a protocol offering
feedback/error reporting and using transactionnal design to benefit
any ARDP features and flexibilities. SUBSP can be :
- RTSP as described in [RFC2326]
- SIP/RTSP as descibed in [SIPRTSP]
ARDP operates close to aggregation equipment stack at subscription
protocol level. The diagram below shows general ARDP operations :
+--------------------------------------------------------+
| NE Routing Software |
| +--------------------+ |
| | ARDP | |
| | Information Base | |
| +------------------------+ +----------^---------+ |
| | CORE Routing Stack | | |
| | +-------+ +------v-----+ |
| | | SUBSP |<------>| ARDP Stack | |
| +----------------+---^---+ +------------+ |
+------------------------|-------------------------------+
|
|
+------v------+
| CPE |
+-------------+
When CPE requests for a ServiceID, it generates an Access Request
caught by NE routing stack. Before processing the subscription
operation, SUBSP stack requests authorisation to ARDP Stack. If
access is granted by ARDP then SUBSP stack proceeds to perform stream
subscription and any routing related task. SUBSP is thus sending
Access Request to ARDP Stack.
Authentication workflow between CPE and NE Routing Software is
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defined as :
+------+ +-------+ +------+
| CPE | | SUBSP | | ARDP |
+------+ +-------+ +------+
| | |
| JOIN / LEAVE | |
|-------------------->| Access-Request |
| |-------------------->|
| | |
| | Access-Response |
| |<--------------------|
| ACK / NAK | (DENY / ACCEPT) |
|<--------------------| |
| | |
Using ABNF notation as in [RFC4234] SUBSP Access-Request and Access-
Response can be specified as :
Access-Request ::= { Namespace }
{ Auth-Client-Id / IP-Address }
{ Auth-Service-Id }
Access-Response ::= { DENY / ACCEPT }
[ Channel-Id [ AVP ] ]
While handling Access-Response ARDP stack will append ServiceID's
Profile or Profile Fallback rather it is an ACCEPT or a DENY.
3.2. Adaptive zapping
An important feature provided by ARDP Service Plane is to offer
adaptive zapping. As described in section 3.1 customer zapping in
translated into sending an Access Request to ARDP for a specific
ServiceID. As described in section 2.4.1, ServiceID is a set of
ChannelID filled with a set of attributes. While performing
conditionnal Access Right operations, NE routing software can
adaptively select a ChannelID based on attribute matching.
A specific use case of this feature is to select a ChannelID based on
bitrate attribute value so that zapping will be dynamic/adaptive
according to available bandwitdh between CPE and NE. If a CPE is
feeded with multiple streams at a time then this mecanism can
optimize bandwidth usage.
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3.3. Confidentiality and security considerations
First of all, ARDP operates in a separate/dedicated network plane
without any physical link with the CPE network. It is mandatory to
separate the ARDP network plane from the CPE network plane. Only
aggregation equipment can access the ARDP plane and CPE plane;
however no routings or forwardings rules may exist between the two
planes.
ARDP protocol is disigned to operate in a multi-operator fashion.
From the networking point of view it is running multiple multicast
sending sources at a time. One of the goals of the protocol is to
give CP full control of Service Plane and Access Right for running
its business. NSP provides a Namespace and a point of presence in
ARDP backbone to each CP. Using ARDP, a CP can manage Service Plane
and Access Right through head-end in realtime using flexibility of
multicast.
ARDP architecture defines a hierarchy between NSP and CP. On the one
hand NSP, formerly an IPTV operator owning network infrastructure,
has a role of arbitration and root authority :
- Distributes all CP ClientID over ARDP Backbone. Each CP
has its own namespace for ClientID but the association
between a CP ClientID and a physical client (customer)
identification (IP address, MAC address, phone number, ...) is
only known by NSP.
- Requests CP ARDP Server to distribute Access Right to
a particular ClientID.
On the other hand, CP is a supervisor authority for distributing ARDP
Service Plane and Access Right it manages :
- Handles NSP ClientID request by flooding in response
the associated ARDP Access Right.
- Permanently flood Service Plane.
A RSA signature is used to guaranty protocol datagram authenticity
and integrity using a RSA keypair. Each ARDP Server stores its RSA
private key and CP ARDP Client stores all RSA exported public key. A
Public Key Infrastructure can be used to distribute RSA pubkey, we
will not detail this part since it is out of the scope of this
document.
On the other hand ARDP is using sequence numbers in every datagram
and generated at server side which prevent against any kind of replay
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attack. ARDP protocol replay attack is not intrinsec possible since
ARDP message contains validity range. If a malicious source try to
replay any previously recorded datagrams, the final effect will just
be a forced update at NE side, that will end on a no effect
injection. The benefit brought by sequence number, when used with
authenticated datagrams (HMAC-MD5-96bit or RSA), resides in the key
decision it provides to drop any incoming malicious datagram and thus
prevent against any time consuming task induced by datagram handling.
In addition ARDP AVPs can be encrypted.
3.4 NSP ARDP Server
The main goal of this server is to distribute CP ClientID over ARDP
backbone and issue ARDP Sessions with CP ARDP Server. Main functional
elements blocks can be represented as following :
. . . . . . . . . . . . . . . . . . . . . . . . . . . .
. .
. .
. .
| ARDP Backbone |
| |
| |
| +-----------+ ^(MCAST) |
\ | | . +------+ +------+ +------+ /
\___| CP ARDP |______._______| NE 1 |___| NE 2 |..| NE n |__/
| | . +------+ +------+ +------+
+-----------+ . . .
^ . . (TCP) .(TCP)
.(TCP) . ............. ....
. . . .
+----- . --------------- . -------------- v -- v -------+
| +--------------+ +----------------+ +-------------+ |
| | ARDP Session | | ClientID Flood | | NE Listener | |
| +--------------+ +----------------+ +-------------+ |
| +------------------+ |
| | Subscribers's DB | |
| | Interface | |
| NSP ARDP Server +------------------+ |
+-------------------------------------------------------+
NSP ARDP Server fonctionnalities are :
- ARDP Session : Peering, using TCP, ClientID to CP ARDP Server
to request CP Access Right flooding accordingly.
- ClientID Flooding : Flooding, using multicast, ClientID of every
CP.
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- NE Listener : Listening, on TCP, to any NE flooding requests.
- Subscriber's DB Interface : It is closely linked to subscriber's
database to fetch accurate informations
for ClientID flooding and Session
with every CP ARDP Servers.
3.5 CP ARDP Server
This server is managed by CP and operates two major tasks:
- Autonomous ARDP flooding : Any CP back-office MUST and NEED to send
Access Right whenever it is needed.
- Sollicited ARDP flooding : Any CP ARDP Server MUST send Access
Right over ARDP Backbone upon NSP ARP Server request received by ARDP
session.
3.6 NE ARDP Client
Is running on NE and is managing NE ARDP information base. Main
functional elements blocks can be represented as following :
. . . . . . . . . . . . . . . . . . . . . . . . . . .
. .
. .
| ARDP Backbone |
| |
\ +------+ +------+ /
\___| CP |_| NSP |________________________________.______/
| ARDP | | ARDP |<.................. .
+------+ +------+ . .
. .
+-------------+ +--------------- . ----------- . ------+
| NSP ARDP | | +----------+ +-.----+ +----v-----+ |
| Report |<........>| Report | | NSP | | MCAST | |
+-------------+ | | Listener | | Req. | | Listener | |
| +----------+ +------+ +----------+ |
+-------------+ | |
| NSP ARDP | | +------------+ +------------------+ |
| Accounting |<.........| Accounting | | Routing Software | |
+-------------+ | | Notifier | | Interface | |
| +------------+ +------------------+ |
| |
| NE ARDP Client |
+--------------------------------------+
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NE ARDP Client fonctionnalities are :
- MCAST Listener : Multicast listener handling incoming ARDP
datagram received from ARDP Backbone.
- NSP Requester : Send ARDP flooding request to NSP ARDP Server.
ARDP ClientID and Access Right flooding requests.
- Routing Software interface : A TCP listener handling Access-Request
coming from SUBSP (as presented in
section 3.1.)
- Report Listener : A TCP listener, listening to NSP ARDP Report
server Access Right fetching request.
- Accounting notifier : Periodically notify, using TCP, NSP
Accounting
Server to internal informations and states.
3.7 NSP ARDP Report
The main goal of this server is to provide an interface to customer's
management back-office in order to fetch ClientID Access Right
bindings and thus providing an accurate feedback on internal ARDP NE
storage. For exemple it can provides facilities to customer's hotline
in order to verify customer Access Right.
3.8 NSP ARDP Accounting
The main goal of this server is to provide ARDP protocol accounting
facilities. NE ARDP Client push periodically internal informations to
this central node. This accounting server offers a centralized
consolidation point. NE ARDP Client can push informations like :
- ARDP Stream discontinuity.
- Customer zapping request rate.
- ServiceID zap auditing.
- ...
In this document we will not detail protocol framing used to push
accounting informations to NSP ARDP Accounting server, but it is
mainly using the ARDP protocol header with ARDP AVPs append.
Due to its push design fashion, NE ARDP Client needs to add a skew
factor to its internal timer pushing informations to workaroung any
flooding side-effect. IPTV customer's uses are impulsive and
periodical, pushing timer needs to be short in order to consider and
consolidate accurate informations.
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3.9 Make it reliable !
ARDP is using multicast to distribute protocol datagrams. The main
constraint using multicast is to make it reliable since it is not
connected. Any datagram can be lost in transit especially when
running on a very large network. There is multiple way found into
litterature to handle reliability of multicast stream.
The very first design is to retransmit lost sequences. As presented
in section 4.2.7, ARDP datagrams are sequenced so that ARDP Client
can learn how many ARDP datagrams have been lost and request for
retransmission. Retransmission can also be operated by agnostic
protocol like presented into [RMT] IETF Working Group. The main side
effect of such an architecture is to lead to massive restransmission
flooding. Actually, on large operator network it is most likely any
operationnal actions on routings or network equipments will lead to
lost datagram into network regions where operations took place. It
can be extrapolated to a massive retransmission request if drops are
localized close to multicast streaming source. This design can be
considered for multicast stream where lost of datagram is critical
and irreversible, if lost datagram can be recomputed and
retransmitted later on then we can investigate others alternatives
offering flexibility of delayed operations.
An alternative to previous design would be to completely ignore lost
datagrams and, instead, periodically flood global ARDP protocol
informations (ClientID + Access Right). The main advantage with this
approach is its simplicity but its cost resides in flooding time
increase accordingly to number of ARDP datagram to be sent. On one
hand we have the flexibility of delayed operations, on the other hand
we increase convergence time and impact scalability.
Another alternative would be to mix both approaches. NE ARDP Client
is periodically pushing back to NSP ARDP Accounting Server protocol
stream discontinuity so that if NSP ARDP Server is notified
accordingly it can flood back to NE any ARDP protocol related
informations (ClientID + Access Right). NSP ARDP Server can
selectively flood ARDP protocol informations by NE. This approch will
scale and provide flexibility of mass flooding. This document will
prefer this approach.
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3.10. ARDP stream bitrate ?
ARDP is a multicast streamed protocol so that its bitrate will
directly impact receiving processing, even more since it is using
crypto. Controlling ARDP sending source will control any NE ARDP
Client time computing ressources. Making ARDP stream Constant BitRate
will transitively induce a maximum time computing threshold tweakable
at sending source.
3.11. Global Operation workflow
The following diagram gives the general workflow of ARDP protocol.
+-----------+ +-----------+
| | | |
__________| CP ARDP 1 |________| CP ARDP 2 |________________
/ +---->| | | | \
/ | +-----------+ +-----------+ \
| | \ |
| | \(d) |
| | \ |
| |(c) ^ v ARDP Backbone |
| | / |
| | /(b) |
| | / |
\ +-------+ +------+ +------+ +------+ /
\__| NSP |______________| NE 1 |___| NE 2 |..| NE n |______/
| ARDP | +------+ +------+ +------+
+---^---+ |
+----------------------+
(a)
This sample configuration illustrates ARDP operation workflow from ARDP
protocol boot-up state (a) through ClientID and Access Right flooding stage
(b), (c) and (d). Protocol operates at both Multicast and
Unicast levels such as follows :
(a) Unicast message : NE 1 informs NSP ARDP Server of its
initialization state. It requests for ClientID and right
flooding.
(b) Multicast message : NSP ARDP Server floods ClientID for each
customer hosted by NE 1 in each CP ClientID namespace.
(c) Unicast message : NSP ARDP Server requests Access Right flooding
to each remote CP ARDP Server for given ClientID in each
CP ClientID namespace.
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(d) Multicast message : In response to (c) each CP ARDP Server
floods Access Right requested by NSP ARDP Server.
4. Multicast Protocol Part
ARDP protocol operates at multicast level and runs over UDP.
ARDP packet are encapsulated in IP/UDP packets and sent to a
routed multicast IPv4 address over ARDP Backbone. Multicast offers
a many-to-many entities discussion. Using UDP encapsulation offers
the ability to run multiple ARDP plane using the same multicast
routing ressource.
4.1. IP/UDP packet field descriptions
For the current ARDP version 1 there is no layer3/4 restrictions.
Multicast TTL must be set with a proper value permitting
backbone traversal.
4.2. ARDP header packet format
Each ARDP protocoal datagram starts with ARDP header as follows.
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Ver | Hl | Msg Type | Size |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Count Msg |E| Auth Type | Sequence Number |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Source CP ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Namespace |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| NE ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| . |
| CP Signature |
| . |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ARDP AVPs...
+-+-+-+-+-+-+-+-+-+-+-+-+-
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4.2.1. Version field
Specifies the ARDP protocol version a packet belongs to. Our current
document describes Version 1.
4.2.2. Header Length field
Specifies the length of the ARDP header.
4.2.3. Message Type field
Specifies the type of ARDP packet data part following the ARDP
header. ARDP message types are :
- 0x01 : CP Conditional Access Attributes message
- 0x02 : CP ServiceID Attributes message
- 0x03 : CP ClassID Attributes message
- 0x04 : ClientID Attributes message
4.2.4. Size field
Specifies the total size of the ARDP packet including ARDP header and
message data.
4.2.5. Count Messages field
Specifies the number of ARDP message data included in the global ARDP
packet.
4.2.6. Encryption flag
Specifies, if set to 1, that ARDP AVPs are encrypted using [AES].
4.2.6. Authentication Type field
Specifies kind of authentication used to sign the ARDP packet.
Mandatory Authentication Type are :
- 0x01 : No authentication signature
- 0x02 : Use HMAC-MD5-96bit signature as described in [RFC2104]
- 0x03 : Use RSA signature as described in [RFC2437]
4.2.8. Sequence Number field
This 16-bit field contains a monotonically increasing counter value
managed at ARDP Server side. Each ARDP Server maintains a sequence
counter for every ARDP Message Types it may send. This sequence
number is legitimated by 2 points.
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4.2.9. Source CP ID field
Specifies the CP origin of the ARDP packet. This gives ARDP Client
side the possibility to select authentication to be used as sanity
check. An Operator ID is a 32bit value identifying in a unique way
any CP. This can be an IPv4 IP address used as point of presence in
ARDP Backbone.
4.2.10. Namespace field
This field is used during ClientID flooding to indicate which CP the
ClientID flooding message belongs to.
4.2.11. NE ID field
This field is used during flooding to indicate which NE the
ClientID/Access Right flooding messages belongs to. This field
prevent against filtering every AVPs in every datagram while
processing. NE will process datagram if NE ID field found in ARDP
header is matching its locally configured ID. If field is zeroed then
NE will process inconditionnally datagram.
4.2.12. CP Signature field
Includes the digital signature (if used) to authenticate ARDP packet.
On ARDP Client side, Source CP ID field indicates which CP secret or
key to be used. Depending on authentication type used, this field is
96bit length long for HMAC-MD5-96bit signature or larger for RSA
signature.
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4.3. ARDP AVP Packet Format
ARDP AVPs carry specific authentication, accounting, authorization,
routing and security information as well as configuration details for
a specific ServiceID, ClassID and ClientID. This message refers to
format and paradigm as presented in [RFC3588]. Every ARDP AVPs are
using the following Header specification as described in section 4.1
of [RFC3588]:
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| AVP Code |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|V M P r r r r r| AVP Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Vendor-ID (opt) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Data ...
+-+-+-+-+-+-+-+-+
In following sections we will define specifics AVPs for use in ARDP
protocol using Basic AVP data formats and Derived/Grouped AVP data
formats as in section 4.2 and 4.3 of [RFC3588].
5. ARDP Base Protocol AVPs
The following table describes the ARDP AVPs defined in the base
protocol, their AVP Code Values, types, possible flag values and
whether the AVP MAY be encrypted. For the the originator of a ARDP
message, "Encr" (Encryption) means that if a message containing that
AVP is to be sent via an ARDP server then the message MUST NOT be
sent unless there is a end-to-end security between the originator and
the recipient (eg: between ARDP Server and ARDP Client).
+---------------------+
| AVP Flag rules |
|----+-----+----+-----|----+
AVP Section | | |SHLD| MUST| |
Attribute Name Code Defined Data Type |MUST| MAY | NOT| NOT|Encr|
-----------------------------------------|----+-----+----+-----|----|
Auth-Service- 65536 3.3.3 Unsigned32 | M | P | | V | N |
Id | | | | | |
Auth-Class- 65537 3.3.4 Unsigned32 | M | P | | V | N |
Id | | | | | |
Auth-Client- 65538 3.3.5 Unsigned32 | M | P | | V | N |
Id | | | | | |
Auth-Client- 65539 3.7.3 Address | M | P | | V | N |
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Address | | | | | |
Auth-Begin- 65540 3.3.6 Time | M | P | | V | N |
Validity | | | | | |
Auth-End- 65541 3.3.7 Time | M | P | | V | N |
Validity | | | | | |
Accounting- 65542 3.3.8 Address | M | P | | V | N |
Server | | | | | |
Multicast- 65543 3.5.3 Address | M | P | | V | N |
Group | | | | | |
Unicast- 65544 3.5.4 Address | M | P | | V | N |
Source | | | | | |
Bitrate 65545 3.5.7 Unsigned32 | M | P | | V | N |
Capabilities 65546 3.5.8 Unsigned32 | M | P | | V | N |
Service-Name 65547 3.5.9 UTF8String | M | P | | V | N |
Version-Code 65558 3.5.10 Unsigned32 | M | P | | V | N |
-----------------------------------------|----+-----+----+-----|----|
ARDP Grouped AVPs are set of Base Protocol AVPs:
+---------------------+
| AVP Flag rules |
|----+-----+----+-----|----+
AVP Section | | |SHLD| MUST| |
Attribute Name Code Defined Data Type |MUST| MAY | NOT| NOT|Encr|
-----------------------------------------|----+-----+----+-----|----|
Access-Right- 65580 3.4.1 Grouped | M | P | | V | N |
Add | | | | | |
Access-Right- 65581 3.4.2 Grouped | M | P | | V | N |
Delete | | | | | |
Accounting- 65582 3.4.3 Grouped | M | P | | V | N |
Zap | | | | | |
ServiceID-Add 65583 3.5.1 Grouped | M | P | | V | N |
ServiceID- 65584 3.5.2 Grouped | M | P | | V | N |
Delete | | | | | |
ClassID-Add 65587 3.6.1 Grouped | M | P | | V | N |
ClassID-Delete 65588 3.6.2 Grouped | M | P | | V | N |
ClientID-Add 65589 3.7.1 Grouped | M | P | | V | N |
ClientID- 65590 3.7.2 Grouped | M | P | | V | N |
Delete | | | | | |
-----------------------------------------|----+-----+----+-----|----|
5.1. AVP Auth-Service-Id
The Auth-Service-Id AVP (AVP code 65536) is of type Unsigned32 and
refers to an ARDP ServiceID.
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5.2. AVP Auth-Class-Id
The Auth-Class-Id AVP (AVP code 65537) is of type Unsigned32 and
refers to an ARDP ClassID.
5.3. AVP Auth-Client-Id
The Auth-Client-Id AVP (AVP code 65538) is of type Unsigned32 and
refers to an ARDP ClientID.
5.5. AVP Auth-Begin-Validity
The Auth-End-Validity AVP (AVP code 65540) is of type Time and
identifies begin of a validity of Access right.
5.6. AVP Auth-End-Validity
The Auth-End-Validity AVP (AVP code 65541) is of type Time and
identifies end of a validity of Access right.
5.7. AVP Accounting-Server
The Accounting-Server AVP (AVP code 65542) is of type Address and
informs to ARDP client the remote accounting server it MUST send
recorded zapping events (join, leave).
5.8. AVP Access-Right-Add
The Access-Right-Add AVP (AVP code 65580) is of type Grouped. It adds
a positive access right for a ClientID to a specific ServiceID into
ARDP Conditional Access cache. If received by NE then ClientID will
have ability to zap and receive specified ServiceID (CP IPTV
streaming service: multicast group) stream until its CPE.
The Grouped Data field has the following ABNF grammar as in
[RFC4234]:
Access-Right-Add ::= < AVP Header: 65580 >
{ Auth-Client-Id }
{ Auth-Service-Id } / { Auth-Class-Id }
{ Auth-Begin-Validity }
{ Auth-End-Validity }
* [ AVP ]
This AVP allow ARDP sending source to append optional AVPs.
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5.9. AVP Access-Right-Delete
The Access-Right-Delete AVP (AVP code 65581) is of type Grouped. It
removes access right for a ClientID to a specific ServiceID from ARDP
Conditional Access cache. If received by NE then ClientID will no
longer have ability to zap and receive specified ServiceID.
The Grouped Data field has the following ABNF grammar as in
[RFC4234]:
Access-Right-Delete ::= < AVP Header: 65581 >
{ Auth-Service-Id }
{ Auth-Client-Id }
5.10. AVP Accounting-Zap
The Accounting-Zap AVP (AVP code 65582) is of type Grouped. It
defines accounting server for zapping event accounting. Every Zap
events for a specified ClientID to a specific ServiceID or ClassID or
set of ServiceID/ClassID will be traced to the specified Server.
The Grouped Data field has the following ABNF grammar as in
[RFC4234]:
Accounting-Zap ::= < AVP Header: 65582 >
{ Auth-Client-Id }
{ Accounting-Server }
* [{ Auth-Service-Id } / { Auth-Class-Id }]
5.11. CP ServiceID Attributes message format
This message type refers to a unary CP service definition and apply
to ARDP header message Type as presented in section 3.2.3.
5.12. AVP ServiceID-Add
The ServiceID-Add AVP (AVP code 65583) is of type Grouped. It adds
into CP namespace a ServiceID with its optional attributes.
The Grouped Data field has the following ABNF grammar as in
[RFC4234]:
ServiceID-Add ::= < AVP Header: 65583 >
{ Auth-Service-Id }
{ Version-Code }
{ Multicast-Group }
* { Unicast-Source }
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* { Multicast-Fallback-Group }
* { Unicast-Fallback-Source }
* { Bitrate }
* { Capabilities }
* { Service-Name }
This AVP allow ARDP sending source to append ServiceID and optional
AVPs.
5.13. AVP ServiceID-Delete
The ServiceID-Delete AVP (AVP code 65584) is of type Grouped. It
removes from CP namespace a ServiceID.
The Grouped Data field has the following ABNF grammar as in
[RFC4234]:
ServiceID-Add ::= < AVP Header: 65584 >
{ Auth-Service-Id }
{ Version-Code }
5.14. AVP Multicast-Group
The Multicast-Group AVP (AVP code 65543) is of type Address and is
specific to ServiceID AVPs (Add and Delete). It specifies a unique ID
into the TV Operator namespace.
5.15. AVP Unicast-Source
The Multicast-Group AVP (AVP code 65544) is of type Address and is
specific to ServiceID AVPs (Add and Delete). It specifies an IPv4 IP
address source of streaming refering to Multicast Group field. This
is useful information when using SSM for wide-area multicast as
described in [RFC3569].
5.16. AVP Capabilities
The Capabilities AVP (AVP code 65548) is of type Unsigned32 and is
specific to ServiceID AVPs (Add and Delete). It specifies ServiceID
capabilities.
5.17. AVP Service-Name
The Service-Name AVP (AVP code 65549) is of type UTF8String and is
specific to ServiceID AVPs (Add and Delete). It specifies Service
description.
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5.18. AVP Version-Code
The Version-Code AVP (AVP code 65550) is of type Unsigned32 and is
specific to ServiceID AVPs (Add and Delete). It specifies a version
number to identify the service plan this Service ID belongs to.
5.19. CP ClassID Attributes message format
This message type refers to a unary CP Class definition and apply to
ARDP header message Type as presented in section 3.2.3.
5.20. AVP ClassID-Add
The ServiceID-Add AVP (AVP code 65587) is of type Grouped. It adds
into CP namespace a ClassID.
The Grouped Data field has the following ABNF grammar as in
[RFC4234]:
ClassID-Add ::= < AVP Header: 65587 >
{ Auth-Class-Id }
{ Version-Code }
{ Auth-Service-Id }
This AVP allow ARDP sending source to append ClassID AVPs.
5.21. AVP ClassID-Delete
The ServiceID-Add AVP (AVP code 65588) is of type Grouped. It removes
from CP namespace a ClassID.
The Grouped Data field has the following ABNF grammar as in
[RFC4234]:
ClassID-Add ::= < AVP Header: 65588 >
{ Auth-Class-Id }
5.22. ClientID Attributes message format
This message type refers to a unary ClientID association and apply to
ARDP header message Type as presented in section 3.2.3.
5.23. AVP ClientID-Add
The ClientID-Add AVP (AVP code 65589) is of type Grouped. It adds
into CP namespace a ClientID.
The Grouped Data field has the following ABNF grammar as in
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[RFC4234]:
ClientID-Add ::= < AVP Header: 65589 >
{ Auth-Client-Id }
{ Auth-Client-Address }
* [ AVP ]
This AVP allow ARDP sending source to append any optional AVPs.
5.24. AVP ClientID-Delete
The ClientID-Delete AVP (AVP code 65590) is of type Grouped. It
removes from CP namespace a ClientID.
The Grouped Data field has the following ABNF grammar as in
[RFC4234]:
ClientID-Delete ::= < AVP Header: 65590 >
{ Auth-Client-Id }
5.25. AVP Auth-Client-Address
The ClientID-Delete AVP (AVP code 65539) is of type Address. It
specifies the NE Client IP Address.
6. Unicast Protocol Part
ARDP Unicast datagrams are used by NE ARDP Client to request ARDP NSP
Server for right cache feeding. Those messages are using general ARDP
protocol header presented in section 3.2. Authentication is not
mandatory since flows are local to private ARDP Backbone from NE to
NSP ARDP Server. Unicast messages are vehiculed over IP/TCP and are :
- 0x01 : NE Access Right populate request
- 0x02 : NE ClientID populate request
NE ARDP Client fills the NE ID field with its own ID. Formerly it
used the IPv4 IP Address provided for ARDP Backbone point of
presence.
7. ARDP Server Operations
The global goal of ARDP architecture is to focus protocol complexity
onto the ARDP server instead of ARDP client. ARDP protocol reduce CPE
complexity by deporting conditional access to aggregation equipment.
The same statement is used for ARDP Server. It is responsible for
ARDP protocol messages flooding and scheduled flooding jobs. In this
many-to-many networking scheme it is convenient to centralize
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complexity onto the server side for maintenance and scalability
reasons.
ARDP Server MUST perform the following operations :
- MUST permanently flood CP Service ID plane. If new
Service ID plane is flooded then send all Access Right
(of this CP).
- If ARDP server is NSP ARDP Server then:
o Only accept Unicast requests from NE ARDP Client
o Only send Unicast request to remote CP ARDP Server
Else
o Only accept unicast requests from NSP ARDP Server
Endif
- MUST periodically flood whole Access Right
- MUST flood ClientID before any Access Right related to this
ClientID.
- MUST monotonically increment sequences counters for every
message type while sending ARDP datagrams.
8. NE ARDP Client Operations
ARDP Client side manages local access right cache. Its finite state machine
is divided into 2 states as follows :
+------------------+ +------------------+
| |------------------------>| |
| Initialize | | Learning |
| |<------------------------| |
+------------------+ +------------------+
8.1. Initialize State
The purpose of this state is to boot up ARDP protocol. While in this
state, ARDP client MUST perform the following operations :
- If Authentication is used then MUST load CP secrets
for HMAC-MD5-96bit authentication or load RSA public key if
RSA authentication is used. In addition it load CP secrets
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for AVPs AES encryption.
- MUST wait until CP Service IDs are received. While receiving
Service IDs update local ServiceID sequence counter.
- MUST wait until CP Class IDs are received. While receiving
Class IDs update local ClassID sequence counter.
- MUST connect to NSP ARDP Server only to request for
ClientID flooding.
- If ClientID table is empty then:
o Re-schedule a new ClientID flooding request to
NSP ARDP Server.
o If ClientID table still empty until max_retry then:
. Disable scheduling ClientID flooding retry.
. Re-schedule a new ClientID request with a longer
delay
Endif
Else
o Schedule Access Right flooding request to NSP ARDP Server.
Endif
- If Access Right Table is empty then:
o Re-schedule a new Access Right flooding request to
NSP ARDP Server.
o If Access Right table still empty until max_retry then:
. Disable scheduling Access Right flooding retry.
. Re-schedule a new Access Right request with a longer
delay
Endif
Else
o Transit to Learning state.
Endif
In this pseudo code we can note that "Re-schedule" can mean inhibit
flooding request since NSP ARDP Server can schedule any request since
it has the knowledge of the whole ARDP Backbone point of presence.
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8.2. Learning State
The purpose of this state is to enter a long time listening stage.
While in this state, ARDP client MUST perform the following
operations :
- If Authentication is used then MUST drop any datagram
received with a lower sequence number than currently
stored sequence counter related to incoming ARDP
message type.
- When receiving ARDP datagram then MUST update local ARDP message
type sequence counter with ARDP header sequence number field.
- When receiving ClientID message, if ClientID is refering to a
local NE IP Address then store this new correspondance.
- When receiving ClientID message then MUST remove any Access
Right associated if already exists.
- When receiving Access Right message then MUST replace any Access
Right related to the same ClientID/ServiceID.
- When receiving new ServiceID, means when "Version Code" field is
different from current ARDP Client Service version code then
remove any Access Right related to the CP source of the message.
- If Access Right Table is empty then:
o Transit to Initialize state.
Endif
- When NE ARDP stack is looking for Access Right or TimeSlot
in Access Right cache as describe in section 2.1, it MUST
expire CP Access Right and CP Free Access TimeSlot according
to Validity learnt during ARDP message flooding as presented in
section 3.3.5/3.3.6 for CP Access Right and 3.7.3/3.7.4 for
CP Free Access TimeSlot. If Access Right or Free Access TimeSlot
has expired, then it is removed from local Access Right cache.
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9. Sending and receiving ARDP datagram
9.1. Sending
Any ARDP sending source MUST perform the following operations:
- MUST fill ARDP protocol header in accordance with protocol
specification in section 3.
- If Authentication is used then sign ARDP datagram.
- If E-flag is set then encrypt ARDP AVPs.
9.2. Receiving
Any ARDP received datagram MUST perform the following operations:
- MUST perform sanity check over datagram to conform ARDP header
elements with real data content.
- If Authentication is used then:
o MUST verify HMAC-MD5-96bit or RSA signature. If signature
is not valid then:
. Drop incoming datagram.
Endif
Endif
- If E-flag is set then:
o MUST Decrypt AVPs.
Endif
10. Acknowledgments
Funding for the RFC Editor function is provided by the IETF
Administrative Support Activity (IASA).
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11. References
[HMAC] Madson, C., and R. Glenn, "The Use of HMAC-MD5-96 within
ESP and AH", Work in Progress.
[AES] NIST, FIPS PUB 197, "Advanced Encryption Standard
(AES)," November 2001.
http://csrc.nist.gov/publications/fips/fips197/
fips-197.{ps,pdf}
[RFC2104] H. Krawczyk, M. Bellare, R. Canetti, "HMAC: Keyed-Hashing
for Message Authentication", RFC 2104, February 1997.
[RFC2437] B. Kaliski, J. Staddon, "PKCS #1: RSA Cryptography
Specifications Version 2.0", RFC 2437, October 1998.
[RFC3588] P. Calhoun, J. Loughney, E. Guttman, G. Zorn, J. Arkko
"Diameter Base Protocol", RFC 3588, September 2003.
[RFC4234] D. Crocker Ed., P. Overell, "Augmented BNF for Syntax
Specifications: ABNF", RFC 4234, October 2005.
[RFC3376] B. Cain, S. Deering, I. Kouvelas, B. Fenner,
A. Thyagarajan, "Internet Group Management Protocol,
Version 3", RFC 3376, October 2002.
[RFC3569] S. Bhattacharyya, Ed., "An Overview of Source-Specific
Multicast (SSM)", RFC 3569, July 2003.
[RFC2326] H. Schulzrinne, A. Rao, R. Lanphier, "Real Time Streaming
Protocol (RTSP)", RFC 2326, April 1998.
[SIPRTSP] X. Marjou, J. Lindquist, P. Rajagopal, M. Said, S. Ganesan
"Session Description Protocol (SDP) Offer/Answer Model For
Media Control Protocol", Internet Draft.
[AAA] Hiroaki Satou, Hiroshi Ohta, Christian Jacquenet,
Tsunemasa Hayashi, Haixiang He,
"AAA Framework for Multicasting", Internet Draft.
Cassen Expires November 26, 2009 [Page 35]
Internet-Draft Access Right Distribution Protocol(ARDP) May 2009
12. Authors' Address
Alexandre Cassen
Freebox S.A.
8, Rue de la Ville l Eveque
75008 Paris
FR
EMail: acassen@freebox.fr
Cassen Expires November 26, 2009 [Page 36]