- Preface
- Overview
- Using Cisco Fabric Services
- Configuring PTP
- Configuring User Accounts and RBAC
- Configuring Session Manager
- Configuring Online Diagnostics
- Configuring System Message Logging
- Configuring Smart Call Home
- Configuring DNS
- Configuring SNMP
- Configuring RMON
- Configuring SPAN
- Configuring ERSPAN
- Index
Contents
- Using Cisco Fabric Services
- Information About CFS
- CFS Distribution
- CFS Distribution Modes
- Uncoordinated Distribution
- Coordinated Distribution
- Unrestricted Uncoordinated Distributions
- Verifying CFS Distribution Status
- CFS Support for Applications
- CFS Application Requirements
- Enabling CFS for an Application
- Verifying Application Registration Status
- Locking the Network
- Verifying CFS Lock Status
- Committing Changes
- Discarding Changes
- Saving the Configuration
- Clearing a Locked Session
- CFS Regions
- About CFS Regions
- Example Scenario
- Managing CFS Regions
- Creating CFS Regions
- Assigning Applications to CFS Regions
- Moving an Application to a Different CFS Region
- Removing an Application from a Region
- Deleting CFS Regions
- Configuring CFS over IP
- Enabling CFS over IPv4
- Enabling CFS over IPv6
- Verifying the CFS Over IP Configuration
- Configuring IP Multicast Address for CFS over IP
- Configuring IPv4 Multicast Address for CFS
- Configuring IPv6 Multicast Address for CFS
- Verifying IP Multicast Address Configuration for CFS over IP
- Default CFS Settings
Using Cisco Fabric Services
This chapter contains the following sections:
- Information About CFS
- CFS Distribution
- CFS Support for Applications
- CFS Regions
- Configuring CFS over IP
- Default CFS Settings
Information About CFS
Some features in the Cisco Nexus Series switch require configuration synchronization with other switches in the network to function correctly. Synchronization through manual configuration at each switch in the network can be a tedious and error-prone process.
Cisco Fabric Services (CFS) provides a common infrastructure for automatic configuration synchronization in the network. It provides the transport function and a set of common services to the features. CFS has the ability to discover CFS capable switches in the network and discovering feature capabilities in all CFS capable switches.
Cisco Nexus Series switches support CFS message distribution over IPv4 or IPv6 networks.
CFS provides the following features:
- Peer-to-peer protocol with no client-server relationship at the CFS layer.
- CFS message distribution over IPv4 or IPv6 networks.
-
Three modes of distribution.
- Coordinated distributions: Only one distribution is allowed in the network at any given time.
- Uncoordinated distributions: Multiple parallel distributions are allowed in the network except when a coordinated distribution is in progress.
- Unrestricted uncoordinated distributions: Multiple parallel distributions are allowed in the network in the presence of an existing coordinated distribution. Unrestricted uncoordinated distributions are allowed to run in parallel with all other types of distributions.
The following features are supported for CFS distribution over IP:
CFS Distribution
The CFS distribution functionality is independent of the lower layer transport. Cisco Nexus Series switches support CFS distribution over IP. Features that use CFS are unaware of the lower layer transport.
CFS Distribution Modes
CFS supports three distribution modes to accommodate different feature requirements:
Only one mode is allowed at any given time.
Uncoordinated Distribution
Uncoordinated distributions are used to distribute information that is not expected to conflict with that from a peer. Parallel uncoordinated distributions are allowed for a feature.
Coordinated Distribution
Coordinated distributions allow only one feature distribution at a given time. CFS uses locks to enforce this. A coordinated distribution is not allowed to start if locks are taken for the feature anywhere in the network. A coordinated distribution consists of three stages:
- A network lock is acquired.
- The configuration is distributed and committed.
- The network lock is released.
Coordinated distribution has two variants:
- CFS driven —The stages are executed by CFS in response to an feature request without intervention from the feature.
- Feature driven—The stages are under the complete control of the feature.
Coordinated distributions are used to distribute information that can be manipulated and distributed from multiple switches, for example, the port security configuration.
Unrestricted Uncoordinated Distributions
Unrestricted uncoordinated distributions allow multiple parallel distributions in the network in the presence of an existing coordinated distribution. Unrestricted uncoordinated distributions are allowed to run in parallel with all other types of distributions.
Verifying CFS Distribution Status
The show cfs status command displays the status of CFS distribution on the switch.
switch# show cfs status Distribution : Enabled Distribution over IP : Enabled - mode IPv4 IPv4 multicast address : 239.255.70.83 IPv6 multicast address : ff15::efff:4653 Distribution over Ethernet : Enabled
CFS Support for Applications
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. CFS has the following requirements:
- Implicit CFS usage—The first time you issue a CFS task for a CFS-enabled application, the configuration modification process begins and the application locks the network.
- Pending database—The pending database is a temporary buffer to hold uncommitted information. The uncommitted changes are not applied immediately to ensure that the database is synchronized with the database in the other switches in the network. When you commit the changes, the pending database overwrites the configuration database (also known as the active database or the effective database).
- CFS distribution enabled or disabled on a per-application basis—The default (enable or disable) for CFS distribution state differs between applications. If CFS distribution is disabled for an application, then that application does not distribute any configuration nor does it accept a distribution from other switches in the network.
- Explicit CFS commit—Most applications require an explicit commit operation to copy the changes in the temporary buffer to the application database, to distribute the new database to the network, and to release the network lock. The changes in the temporary buffer are not applied if you do not perform the commit operation.
Enabling CFS for an Application
All CFS-based applications provide an option to enable or disable the distribution capabilities.
Applications have the distribution enabled by default.
The application configuration is not distributed by CFS unless distribution is explicitly enabled for that application.
Verifying Application Registration Status
The show cfs application command displays the applications that are currently registered with CFS. The first column displays the application name. The second column indicates whether the application is enabled or disabled for distribution (enabled or disabled). The last column indicates the scope of distribution for the application (logical, physical, or both).
 Note | The show cfs application command only displays applications registered with CFS. Conditional services that use CFS do not appear in the output unless these services are running. |
switch# show cfs application
----------------------------------------------
Application Enabled Scope
----------------------------------------------
ntp No Physical-all
fscm Yes Physical-fc
rscn No Logical
fctimer No Physical-fc
syslogd No Physical-all
callhome No Physical-all
fcdomain Yes Logical
device-alias Yes Physical-fc
Total number of entries = 8
The show cfs application name command displays the details for a particular application. It displays the enabled/disabled state, timeout as registered with CFS, merge capability (if it has registered with CFS for merge support), and lastly the distribution scope.
switch# show cfs application name fscm
Enabled : Yes
Timeout : 100s
Merge Capable : No
Scope : Physical-fc
Locking the Network
When you configure (first time configuration) a feature (or application) that uses the CFS infrastructure, that feature starts a CFS session and locks the network. When a network is locked, the switch software allows configuration changes to this feature only from the switch holding the lock. If you make configuration changes to the feature from another switch, the switch issues a message to inform the user about the locked status. The configuration changes are held in a pending database by that application.
If you start a CFS session that requires a network lock but forget to end the session, an administrator can clear the session. If you lock a network at any time, your user name is remembered across restarts and switchovers. If another user (on the same machine) tries to perform configuration tasks, that user’s attempts are rejected.
Verifying CFS Lock Status
The show cfs lock command displays all the locks that are currently acquired by any application. For each application the command displays the application name and scope of the lock taken.
The show cfs lock name command displays the lock details for the specified application.
Committing Changes
A commit operation saves the pending database for all application peers and releases the lock for all switches.
In general, the commit function does not start a session, only a lock function starts a session. However, an empty commit is allowed if configuration changes are not previously made. In this case, a commit operation results in a session that acquires locks and distributes the current database.
When you commit configuration changes to a feature using the CFS infrastructure, you receive a notification about one of the following responses:
- One or more external switches report a successful status—The application applies the changes locally and releases the network lock.
- None of the external switches report a successful state—The application considers this state a failure and does not apply the changes to any switch in the network. The network lock is not released.
You can commit changes for a specified feature by entering the commit command for that feature.
Discarding Changes
If you discard configuration changes, the application flushes the pending database and releases locks in the network. Both the abort and commit functions are only supported from the switch from which the network lock is acquired.
You can discard changes for a specified feature by using the abort command for that feature.
Saving the Configuration
Configuration changes that have not been applied yet (still in the pending database) are not shown in the running configuration. The configuration changes in the pending database overwrite the configuration in the effective database when you commit the changes.
 Caution | If you do not commit the changes, they are not saved to the running configuration. |
Clearing a Locked Session
You can clear locks held by an application from any switch in the network to recover from situations where locks are acquired and not released. This function requires Admin permissions.
Caution | Exercise caution when using this function to clear locks in the network. Any pending configurations in any switch in the network is flushed and lost. |
CFS Regions
About CFS Regions
A CFS region is a user-defined subset of switches for a given feature or application in its physical distribution scope. When a network spans a vast geography, you may need to localize or restrict the distribution of certain profiles among a set of switches based on their physical proximity. CFS regions allow you to create multiple islands of distribution within the network for a given CFS feature or application. CFS regions are designed to restrict the distribution of a feature’s configuration to a specific set or grouping of switches in a network.
Example Scenario
The Call Home application triggers alerts to network administrators when a situation arises or something abnormal occurs. When the network covers many geographies, and there are multiple network administrators who are each responsible for a subset of switches in the network, the Call Home application sends alerts to all network administrators regardless of their location. For the Call Home application to send message alerts selectively to network administrators, the physical scope of the application has to be fine tuned or narrowed down. This is achieved by implementing CFS regions.
CFS regions are identified by numbers ranging from 0 through 200. Region 0 is reserved as the default region, and contains every switch in the network. You can configure regions from 1 through 200. The default region maintains backward compatibility.
If the feature is moved, that is, assigned to a new region, its scope is restricted to that region; it ignores all other regions for distribution or merging purposes. The assignment of the region to a feature has precedence in distribution over its initial physical scope.
You can configure a CFS region to distribute configurations for multiple features. However, on a given switch, you can configure only one CFS region at a time to distribute the configuration for a given feature. Once you assign a feature to a CFS region, its configuration cannot be distributed within another CFS region.
Managing CFS Regions
Creating CFS Regions
You can create a CFS region.
1.
switch#
configure terminal
2.
switch(config)#
cfs region
region-id
DETAILED STEPS
| Command or Action | Purpose |
|---|
Assigning Applications to CFS Regions
You can assign an application on a switch to a region.
1.
switch#
configure terminal
2.
switch(config)#
cfs region
region-id
3.
switch(config-cfs-region)#
application
DETAILED STEPS
The following example shows how to assign applications to a region:
switch# configure terminal
switch(config)# cfs region 1
switch(config-cfs-region)# ntp
switch(config-cfs-region)# callhome
Moving an Application to a Different CFS Region
You can move an application from one region to another region.
1.
switch#
configure
2.
switch(config)#
cfs region
region-id
3.
switch(config-cfs-region)#
application
DETAILED STEPS
| Command or Action | Purpose | |||
|---|---|---|---|---|
| Step 1 |
switch#
configure
|
Enters configuration mode. | ||
| Step 2 |
switch(config)#
cfs region
region-id
|
Enters CFS region configuration submode. | ||
| Step 3 |
switch(config-cfs-region)#
application
|
Indicates application(s) to be moved from one region into another.
|
The following example shows how to move an application into Region 2 that was originally assigned to Region 1:
switch# configure terminal
switch(config)# cfs region 2
switch(config-cfs-region)# ntp
Removing an Application from a Region
Removing an application from a region is the same as moving the application back to the default region (Region 0). This brings the entire network into the scope of distribution for the application.
1.
switch#
configure
2.
switch(config)#
cfs region
region-id
3.
switch(config-cfs-region)#
no
application
DETAILED STEPS
| Command or Action | Purpose |
|---|
Deleting CFS Regions
Deleting a region nullifies the region definition. All the applications bound by the region are released back to the default region.
1.
switch#
configure
2.
switch(config)#
no cfs region
region-id
DETAILED STEPS
| Command or Action | Purpose |
|---|
Configuring CFS over IP
Enabling CFS over IPv4
You can enable or disable CFS over IPv4.
Note | CFS cannot distribute over both IPv4 and IPv6 from the same switch. |
1.
switch#
configure
2.
switch(config)#
cfs ipv4 distribute
3.
(Optional)
switch(config)#
no cfs ipv4 distribute
DETAILED STEPS
| Command or Action | Purpose |
|---|
Enabling CFS over IPv6
You can enable or disable CFS over IPv6.
Note | CFS cannot distribute over both IPv4 and IPv6 from the same switch. |
1.
switch#
configure
2.
switch(config)#
cfs ipv6 distribute
3.
(Optional)
switch(config)#
no cfs ipv6 distribute
DETAILED STEPS
| Command or Action | Purpose |
|---|
Verifying the CFS Over IP Configuration
To verify the CFS over IP configuration, use the show cfs status command.
switch# show cfs status
Distribution : Enabled
Distribution over IP : Enabled - mode IPv4
IPv4 multicast address : 239.255.70.83
IPv6 multicast address : ff15::efff:4653
Configuring IP Multicast Address for CFS over IP
All CFS over IP enabled switches with similar multicast addresses form one CFS over IP network. CFS protocol-specific distributions, such as the keepalive mechanism for detecting network topology changes, use the IP multicast address to send and receive information.
Note | CFS distributions for application data use directed unicast. |
Configuring IPv4 Multicast Address for CFS
You can configure a CFS over IP multicast address value for IPv4. The default IPv4 multicast address is 239.255.70.83.
1.
switch#
configure
2.
switch(config)#
cfs ipv4 mcast-address
ipv4-address
3.
(Optional)
switch(config)#
no cfs ipv4 mcast-address
ipv4-address
DETAILED STEPS
| Command or Action | Purpose | |
|---|---|---|
| Step 1 |
switch#
configure
|
Enters configuration mode. |
| Step 2 |
switch(config)#
cfs ipv4 mcast-address
ipv4-address
|
Configures the IPv4 multicast address for CFS distribution over IPv4. The ranges of valid IPv4 addresses are 239.255.0.0 through 239.255.255.255 and 239.192/16 through 239.251/16. |
| Step 3 |
switch(config)#
no cfs ipv4 mcast-address
ipv4-address
| (Optional)
Reverts to the default IPv4 multicast address for CFS distribution over IPv4. The default IPv4 multicast address for CFS is 239.255.70.83. |
Configuring IPv6 Multicast Address for CFS
You can configure a CFS over IP multicast address value for IPv6. The default IPv6 multicast address is ff13:7743:4653.
1.
switch#
configure
2.
switch(config)#
cfs ipv6 mcast-address
ipv4-address
3.
(Optional)
switch(config)#
no cfs ipv6 mcast-address
ipv4-address
DETAILED STEPS
| Command or Action | Purpose | |
|---|---|---|
| Step 1 |
switch#
configure
|
Enters configuration mode. |
| Step 2 |
switch(config)#
cfs ipv6 mcast-address
ipv4-address
|
Configures the IPv6 multicast address for CFS distribution over IPv6. The range of valid IPv6 addresses is ff15::/16 (ff15::0000:0000 through ff15::ffff:ffff) and ff18::/16 (ff18::0000:0000 through ff18::ffff:ffff). |
| Step 3 |
switch(config)#
no cfs ipv6 mcast-address
ipv4-address
| (Optional)
Reverts to the default IPv6 multicast address for CFS distribution over IPv6. The default IPv6 multicast address for CFS over IP is ff15::efff:4653. |
Verifying IP Multicast Address Configuration for CFS over IP
To verify the IP multicast address configuration for CFS over IP, use the show cfs status command:
switch# show cfs status
Fabric distribution Enabled
IP distribution Enabled mode ipv4
IPv4 multicast address : 10.1.10.100
IPv6 multicast address : ff13::e244:4754
Default CFS Settings
The following table lists the default settings for CFS configurations.
|
Parameters |
Default |
|---|---|
|
CFS distribution on the switch |
Enabled. |
|
Database changes |
Implicitly enabled with the first configuration change. |
|
Application distribution |
Differs based on application. |
|
Commit |
Explicit configuration is required. |
|
CFS over IP |
Disabled. |
|
IPv4 multicast address |
239.255.70.83. |
|
IPv6 multicast address |
ff15::efff:4653. |
The CISCO-CFS-MIB contains SNMP configuration information for any CFS-related functions. See the Cisco Nexus 3000 Series MIBs Reference available at the following URL: http://www.cisco.com/en/US/docs/switches/datacenter/nexus3000/sw/mib/reference/n3k_mib_ref.html for more information on this MIB.