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[802SEC] FW: [New-work] WG Review: Access Node Control Protocol (ancp)

IEEE 802 WG Chairs,

The following New Work announcement from the IETF may be of interest to
your WG members. Please forward as appropriate.


-----Original Message-----
From: IESG Secretary [] 
Sent: Monday, June 12, 2006 12:39 PM
Subject: [New-work] WG Review: Access Node Control Protocol (ancp) 

A new IETF working group has been proposed in the Internet Area. The
IESG has not made any determination as yet.  The following draft charter
was submitted, and is provided for informational purposes only.  Please
send your comments to the IESG mailing list ( by June


Access Node Control Protocol (ancp)

Current Status: Proposed Working Group


Internet Area Director(s):
Mark Townsley <>
Jari Arkko <>

Technical Advisor(s):


Area Specific Mailing List:

Mailing Lists:
General Discussion:
To Subscribe:
In Body: subscribe your_email_address


The purpose of the ANCP WG is to standardize an IP based Access Node
Control Protocol (ANCP) for use in service provider Digital Subscriber
Line (DSL) access and aggregation networks. ANCP operates between an
Access Node (AN) and Network Access Server (NAS). 

Necessary Terminology:

Access Node (AN) - Network device, usually located at a service provider
central office or street cabinet, that terminates acess loop connections
from Subscribers. In DSL, this is often referred to as a Digital
Subscriber Line Access Multiplexer (DSLAM)

Network Access Server (NAS) - Network device which aggregates
multiplexedSubscriber traffic from a number of Access Nodes. The NAS
plays a central role in per-subsciber policy enforcement and QoS. Often
referred to as an Broadband Network Gateway (BNG) or Broadband Remote
Access Server (BRAS). A detailed definition of the NAS is given in


ANCP is intended to address the requirement for a bidirectional, IP-
based, control protocol that operates across multiple types (i.e.,
Ethernet, ATM) of DSL access and aggregation networks. The goal of an
ANCP message exchange is to convey status and control information
between one or more ANs and one or more NASs without going through
intermediate element managers. 

The ANCP WG will address the following four use-cases:

1. Dynamic Access Loop Attributes
Various queuing and scheduling mechanisms are used in access networks to
avoid congestion while dealing with multiple flows and distinct QoS
profiles. Communicating the access-loop status, attributes and current
DSL synchronization rate between the AN and Subscriber up to the NAS is
desirable, particularly when the NAS is providing QoS for individual
flows and subscribers. ANCP will provide a mechanism to communicate
dynamic access-loop attributes from the AN to the NAS.

2. Access Loop Configuration
In additional to reporting Access Loop characteristics from the AN to
the NAS, ANCP will allow a NAS to send loop-specific configuration
information to an AN based on the results of subscriber authentication
and authorization (e.g., after AAA responses have been received at the

3. Remote Connectivity Test
Traditional DSL access and aggregation networks employ point-to-point
ATM circuits between the AN and NAS for each subscriber, allowing
troubleshooting of the local loop from the NAS via ATM OAM tools. With
the increasing deployment of Ethernet in the access and aggregation
network, operators require consistent methods to test and troubleshoot
connectivity for mixed Ethernet and ATM access networks (including the
local loop). ANCP will allow a remote procedure for a local loop
connectivity test to be triggered from the NAS with results communicated
back to the NAS. 

4. Multicast
When multicast replication for subscriber-bound traffic is performed at
the AN, it offloads the network between the AN and NAS. However, a
subscriber's policy and configuration for multicast traffic may only be
known at the NAS. ANCP will provide a mechanism to communicate the
necessary information exchange between the AN and NAS so as to allow the
AN to perform subscriber bound multicast group replication in line with
the subscriber's policy and configuration, and also allow the NAS to
follow each subscriber's multicast group membership.


ANCP is an IP-based protocol that operates between the AN and NAS, over
a DSL access and aggregation network. It will not address setup or
configuration of circuits or connections in the access and aggregation
network itself.

The focus of this WG is on one very specific application space. While
the design of the protocol must be general as to not preclude other uses
in the future should a need arise, it is not a goal of this WG to
address specific requirements outside of DSL access and aggregation


The ANCP working group will provide a threat analysis and address the
associated security aspects of the control protocol. 

Resiliency and Scalabilty: 

A graceful restart mechanism will be defined to enable the protocol to
be resilient to network failures between the AN and NAS.

Scalability at the NAS is of primary concern, as it may be aggregating
traffic from a large number of ANs, which in turn may be serving a large
number of Subscribers. ANCP traffic should not become a denial of
service attack on the NAS control plane. Format of messages, pacing,
transport over UDP or TCP, etc. will be considered with this in mind.

For reasons of aggregation network scalability, some use cases require
that aspects of NAS or AN functionality may be distributed in nodes in
the aggregation network. In these cases, ANCP can run between these


The working group will define a basic framework and requirements
document intended for Informational publication, focusing on the four
use-cases outlined in this charter. This document will include a
security threat analysis and associated requirements. The WG will then
investigate and define a solution for an IP based control protocol
meeting these requirements. 

There are early interoperable implementations of an ANCP-like protocol
which are based on an extended subset of the GSMPv3 protocol. This
running code will be the the starting point for the working group
solution, and will be abandoned only if the WG determines it is not
adequate to meet requirements going forward.

Coordination with other Working Groups or Organizations:

The working group will coordinate with the ADSL MIB working group so the
the management framewoirk and MIB modules are consistent for DSL access
environments. The working group will re-use, as far as possible,
standard MIB modules that have already been defined.

The remote connectivity test use case may require coordination with
ITU-T Ethernet OAM work, and with IEEE 802.1ag.

Goals and Milestones:

November 2006 Accept WG I-D for ANCP Framework and Requirements January
2007  Accept WG I-D for Access Node Control Protocol (ANCP) January 2007
Framework and Requirements last call
March 2007    Accept WG I-D for ANCP MIB
April 2007    Access Node Control Protocol (ANCP) Last Call
May 2007      ANCP MIB Last Call
July 2007     Re-charter or conclude Working Group

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