Cisco Nexus 5000 Series Switch Fabric Manager Software Configuration Guide, NX-OS 4.0 (OL-16598-01, June 2008)

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7-6
Nexus 5000 Series Switch Fabric Manager Software Configuration Guide
OL-16598-01
Chapter 7 Using Cisco Fabric Services
CFS Support for Applications
• Physical topology level (physical scope)
Some applications (such as NTP) need to distribute the configuration to the entire physical topology.
• Between two selected switches
Some applications operate only between selected switches in the network.
CFS Merge Support
CFS Merge is supported for CFS distribution over Fibre Channel.
An application keeps the configuration synchronized in a SAN fabric through CFS. Two such fabrics
might merge as a result of an ISL coming up between them. These two fabrics could have two different
sets of configuration information that need to be reconciled in the event of a merge. CFS provides
notification each time an application peer comes online. If a fabric with M application peers merges with
another fabric with N application peers, and if an application triggers a merge action on every
notification, a link-up event results in M*N merges in the fabric.
CFS supports a protocol that reduces the number of merges required to one by handling the complexity
of the merge at the CFS layer. This protocol runs per application per scope. The protocol involves
selecting one switch in a fabric as the merge manager for that fabric. The other switches do not have a
role in the merge process.
During a merge, the merge manager in the two fabrics exchange their configuration databases with each
other. The application on one of them merges the information, decides if the merge is successful, and
informs all switches in the combined fabric of the status of the merge.
In case of a successful merge, the merged database is distributed to all switches in the combined fabric
and the entire new fabric remains in a consistent state. You can recover from a merge failure by starting
a distribution from any of the switches in the new fabric. This distribution restores all peers in the fabric
to the same configuration database.
CFS Support for Applications
The following topics describe the CFS capabilities that support applications:
• CFS Application Requirements, page 7-6
• Enabling CFS for an Application, page 7-7
• Locking the Network, page 7-8
• Committing Changes, page 7-8
• Discarding Changes, page 7-9
• Saving the Configuration, page 7-10
• Clearing a Locked Session, page 7-10
CFS Application Requirements
All switches in the network must be CFS capable. Switches that are not CFS capable do not receive
distributions and result in part of the network not receiving the intended distribution.