Data Classes


Revision: 2012-08-08

This MIB defines objects describing subscriber sessions, or more specifically, subscriber sessions terminated by a RAS. A subscriber session consists of the traffic between a CPE and a NAS, as illustrated in the diagram below.


Access Provider Network Network

+–+ +—+ +–+ { } +—+ { } |PC+–+CPE+–+AN+–{ }–+NAS+–{ } +–+ +—+ +–+ { } +—+ { }


A subscriber session behaves according to the FSM illustrated below.

+—>| DISCONNECTED |<——-+ | +——–+——–+ | | | | | failed | initiated | disconnect | V | | +—————–+ | +—-+ PENDING +——–+

+——–+——–+ |
established |

V |

+—————————-+ | | UP | | | +—+ | +—————–+ | | | UNAUTHENTICATED | | | +——–+——–+ | | | | | | authenticated | | V | | +—————–+ | | | AUTHENTICATED | | | +—————–+ | | | +—————————-+

A subscriber session in the DISCONNECTED state technically doesn’t exist; that is, the system does not maintain a context to describe a disconnected subscriber session.

Once the system detects the initiation of a subscriber session, then it creates a context and places the subscriber session in the PENDING state. The initiation of a subscriber session can occur either through provisioning or the reception of a packet. In the PENDING state, a system does not forward subscriber traffic.

A pending subscriber session can become DISCONNECTED if it fails to come up (e.g., a timeout) or if the system or the subscriber explicitly terminates the subscriber session.

A pending subscriber session can become UP if the system successfully configures and applies any relevant policies. Once in the UP state, a system forwards subscriber traffic.

A operationally UP subscriber session can become DISCONNECTED if either system or the subscriber terminates it.

A operationally UP subscriber session can either be UNAUTHENTICATED or AUTHENTICATED. When the system is in the process of checking a the credentials associated with a subscriber session, it is in the UNAUTHENTICATED state. When the system successfully completes this process, it transitions the subscriber session to the AUTHENTICATED state. If the process fails, then the system terminates the subscriber session.

Besides describing individual subscriber sessions, this MIB module provides an EMS/NMS with the means to perform the following functions:

  1. Enumerate subscriber sessions by ifIndex.
  2. Enumerate subscriber sessions by subscriber session type and ifIndex.
  3. Monitor aggregated statistics relating to subscriber sessions:
    1. System-wide
    2. System-wide by subscriber session type
    3. Per node
    4. Per node by subscriber session type
  4. Collect 15-minute aggregated performance data history relating to subscriber sessions:
    1. System-wide
    2. System-wide by subscriber session type
    3. Per node
    4. Per node by subscriber session type
  5. Submit a query for a report containing those subscriber sessions that match a specified identity match criteria.
  6. Terminate those subscriber session that match a specified identify match criteria.


Access Concentrator
See NAS.
Access Network
The network that provides connectivity between a AN and NAS. An access network may provide L2 or L3 connectivity. If the access network provide L2 connectivity, it may switch traffic or tunnel it through a MPLS or IP network.
AN (Access Node)
A device (e.g., a DSLAM) that multiplexes or switches traffic between many CPEs and an access network.
BRAS (Broadband Remote Access Server)
See NAS.
CPE (Customer Premise Equipment)
A device (e.g., a DSL modem) that connects a customer’s network to an AN.
DHCP (Dynamic Host Configuration Protocol)
The protocol that provides a framework for transacting configuration information to devices on an IP network, as specified by RFC-2131.
NAS (Network Access Server)
A device that switches or routes traffic between subscriber sessions and service provider networks.
Network Service
Access to the Internet backbone, voice, video, or other content.
A physical entity capable of maintaining a subscriber session within a distributed system. The notion of a node is not applicable to a centralized system.
PADI (PPPoE Active Discovery Initiation)
A subscriber broadcasts a PADI packet to start the process of discovering access concentrators capable of serving it.
PADO (PPPoE Active Discovery Offer)
The packet sent by an access concentrator to a subscriber indicating that it can serve the subscriber.
PADR (PPPoE Active Discovery Request)
The packet sent by a subscriber to an access concentrator requesting a PPPoE connection.
PADS (PPPoE Active Discovery Session-confirmation)
The packet sent by an access concentrator to a subscriber confirming the request for a PPPoE connection. Once this packet has been sent, then the PPP can proceed as specified by RFC-1661.
PADT (PPPoE Active Discovery Terminate)
The packet indicating that a PPPoE connection has been terminated. Either the subscriber or the access concentrator can send this packet.
PPP (Point-to-Point Protocol)
The standard method for transporting multi-protocol datagrams over point-to-point links, as defined by RFC-1661. The PPP specifies the encapsulation for these datagrams and the protocols necessary for establishing, configuring, and maintaining connectivity.
PPPoE (Point-to-Point Protocol over Ethernet)
The protocol and encapsulation necessary to support a PPP connection over an Ethernet connection, as defined by IETF RFC-2516.
Service Provider Network
The network that provides connectivity between a NAS and a network service.
A customer of a network service.
Subscriber Session
A context maintained by a NAS for the purpose of classifying a subscriber’s traffic, maintaining a subscriber’s identity, applying configuration and policies, and maintaining statistics. For more information on the types of subscriber sessions, see the CISCO-SUBSCRIBER-SESSION-TC-MIB.