Cisco Cisco IOS Software Release 12.0(19)S
IP Services Engine Line Cards
Feature Overview
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Cisco IOS Release 12.0(19)S
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Automatic Protection Switching (APS) and Multiplexed Switching Protection (MSP)
The APS feature allows switchover of packet-over-SONET (POS) circuits in the event of circuit failure.
APS uses a 1+1 redundancy architecture: a “protect” POS interface in the network is configured as a
backup for each “working” POS interface. When the working interface fails, the protect interface quickly
assumes the traffic load. Normally, the protect and working interfaces are connected to a SONET ADM
(add-drop multiplexer), which sends the same signal payload to the working and protect interfaces. For
APS functionality on the channelized ISE line cards, the working line is configured under the working
controller, and the protect line is configured under the protect controller.
APS uses a 1+1 redundancy architecture: a “protect” POS interface in the network is configured as a
backup for each “working” POS interface. When the working interface fails, the protect interface quickly
assumes the traffic load. Normally, the protect and working interfaces are connected to a SONET ADM
(add-drop multiplexer), which sends the same signal payload to the working and protect interfaces. For
APS functionality on the channelized ISE line cards, the working line is configured under the working
controller, and the protect line is configured under the protect controller.
This APS network survivability scheme is known in SDH networks as multiplexed switching protection
(MSP). APS and MSP are fundamentally similar.
(MSP). APS and MSP are fundamentally similar.
Note
In channelized ISE line cards configured for APS, the channelizations for the working and protect
ports must be identical. If the channel configuration is changed for a working port, those same
changes must be made to the protection port (and vice versa). If the channelization configurations on
the working and protect ports are different when a protection switch occurs, the traffic carried by any
mis-matched interface will be lost.
ports must be identical. If the channel configuration is changed for a working port, those same
changes must be made to the protection port (and vice versa). If the channelization configurations on
the working and protect ports are different when a protection switch occurs, the traffic carried by any
mis-matched interface will be lost.
for additional information on feature capability and configuration. See
for instructions to configure APS for ISE line
cards.
Encapsulation
The WAN data link layer (Layer 2), defines how data is formatted, or framed, for transmission to remote
sites. This formatting is referred to as encapsulation. Each interface on an ISE line card can be
configured with one of the encapsulations described in this section.
sites. This formatting is referred to as encapsulation. Each interface on an ISE line card can be
configured with one of the encapsulations described in this section.
See
for instructions to configure an interface encapsulation.
See
for additional information on feature capability and configuration.
High-Level Data Link Control (HDLC)
HDLC is a bit-oriented, data link layer protocol derived from the Synchronous Data Link Control
(SDLC) encapsulation protocol. HDLC encapsulation is configured as the default encapsulation method
on all ISE interfaces.
(SDLC) encapsulation protocol. HDLC encapsulation is configured as the default encapsulation method
on all ISE interfaces.
See the section on HDLC in the Cisco Systems publication Synchronous Data Link Control and
Derivatives for additional information. This document is part of the Internetworking Technology
Overview.
Derivatives for additional information. This document is part of the Internetworking Technology
Overview.