Cisco Cisco IOS Software Release 12.0(10)S
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Cisco IOS Release 12.0(10)S
Signaling IS-IS When dCEF Is Disabled
Feature History
This feature module describes the Signaling IS-IS When dCEF Is Disabled feature and includes the
following sections:
following sections:
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Feature Overview
The Intermediate System-to-Intermediate System (IS-IS) routing protocol uses the International
Organization for Standardization (ISO) Connectionless Network System (CLNS) protocol as its
transport mechanism for distributing link-state information across the network. CLNS operates as a
network layer protocol and does not depend on IP services including Cisco Express Forwarding (CEF).
IS-IS builds and maintains adjacencies on an interface independently of the status of CEF. When
distributed Cisco Express Forwarding (dCEF) is configured, dCEF sometimes can be disabled on an
interface. IS-IS processes on adjacent routers continue to forward IP routing information to the interface
where dCEF is disabled because CLNS operates independently of the status of CEF or dCEF. IS-IS needs
the ability to tear down the adjacencies to an interface where dCEF is disabled because some platforms
are incapable of forwarding IP traffic through the interface unless dCEF is enabled. A new command,
external overload signalling, has been implemented to ensure that IS-IS will tear down adjacencies
when dCEF is disabled on an interface, even though the interface may still be up. IS-IS does not rebuild
adjacencies for the interface until it receives a signal from dCEF.
Organization for Standardization (ISO) Connectionless Network System (CLNS) protocol as its
transport mechanism for distributing link-state information across the network. CLNS operates as a
network layer protocol and does not depend on IP services including Cisco Express Forwarding (CEF).
IS-IS builds and maintains adjacencies on an interface independently of the status of CEF. When
distributed Cisco Express Forwarding (dCEF) is configured, dCEF sometimes can be disabled on an
interface. IS-IS processes on adjacent routers continue to forward IP routing information to the interface
where dCEF is disabled because CLNS operates independently of the status of CEF or dCEF. IS-IS needs
the ability to tear down the adjacencies to an interface where dCEF is disabled because some platforms
are incapable of forwarding IP traffic through the interface unless dCEF is enabled. A new command,
external overload signalling, has been implemented to ensure that IS-IS will tear down adjacencies
when dCEF is disabled on an interface, even though the interface may still be up. IS-IS does not rebuild
adjacencies for the interface until it receives a signal from dCEF.
Release
Modification
12.0(10)S
This feature was introduced.
12.0(10)ST
This command was integrated into Cisco IOS Release 12.0(10)ST.