Cisco Nexus 7000 Series NX-OS SAN Switching Configuration Guide
Advanced Fibre Channel Features and Concepts
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Advanced Fibre Channel Features and Concepts

Advanced Fibre Channel Features and Concepts

This chapter contains the following sections:

Advanced Fibre Channel Features and Concepts

Fibre Channel Timeout Values

You can modify Fibre Channel protocol-related timer values for the switch by configuring the following timeout values (TOVs):


  • Distributed services TOV (D_S_TOV)—The valid range is from 5,000 to 10,000 milliseconds. The default is 5,000 milliseconds.

  • Error detect TOV (E_D_TOV)—The valid range is from 1,000 to 10,000 milliseconds. The default is 2,000 milliseconds. This value is matched with the other end during port initialization.

  • Resource allocation TOV (R_A_TOV)—The valid range is from 5,000 to 10,000 milliseconds. The default is 10,000 milliseconds. This value is matched with the other end during port initialization.


Note


The fabric stability TOV (F_S_TOV) constant cannot be configured.


Timer Configuration Across All VSANs

You can modify Fibre Channel protocol related timer values for the switch.


Caution


The D_S_TOV, E_D_TOV, and R_A_ TOV values cannot be globally changed unless all VSANs in the switch are suspended.



Note


If a VSAN is not specified when you change the timer value, the changed value is applied to all VSANs in the switch.


To configure Fibre Channel timers across all VSANs, perform this task:

SUMMARY STEPS

1.    switch# configure terminal

2.    switch(config)# fctimer R_A_TOV timeout


DETAILED STEPS
  Command or Action Purpose
Step 1 switch# configure terminal
 

Enters configuration mode.

 
Step 2 switch(config)# fctimer R_A_TOV timeout
 

Configures the R_A_TOV timeout value for all VSANs. The units is milliseconds.

This type of configuration is not permitted unless all VSANs are suspended.

 

Timer Configuration Per-VSAN

You can also issue the fctimer for a specified VSAN to configure different TOV values for VSANs with special links such as Fibre Channel. You can configure different E_D_TOV, R_A_TOV, and D_S_TOV values for individual VSANs. Active VSANs are suspended and activated when their timer values are changed.


Note


This configuration must be propagated to all switches in the fabric. Be sure to configure the same value in all switches in the fabric.


To configure per-VSAN Fibre Channel timers, perform this task:

SUMMARY STEPS

1.    switch# configuration terminal

2.    switch(config#)# fctimer D_S_TOV timeout vsan vsan-id


DETAILED STEPS
  Command or Action Purpose
Step 1 switch# configuration terminal
 

Enters configuration mode.

 
Step 2 switch(config#)# fctimer D_S_TOV timeout vsan vsan-id
 

Configures the D_S_TOV timeout value (in milliseconds) for the specified VSAN. Suspends the VSAN temporarily. You have the option to end this command, if required.

 

The following example configures the timer value for VSAN 2:

switch(config#)# fctimer D_S_TOV 6000 vsan 2
Warning: The vsan will be temporarily suspended when updating the timer value This
configuration would impact whole fabric. Do you want to continue? (y/n) y
Since this configuration is not propagated to other switches, please configure the same
value in all the switches

About fctimer Distribution

You can enable per-VSAN fctimer fabric distribution for all Cisco SAN switches in the fabric. When you perform fctimer configurations, and distribution is enabled, that configuration is distributed to all the switches in the fabric.

You automatically acquire a fabric-wide lock when you enter the first configuration command after you enabled distribution in a switch. The fctimer application uses the effective and pending database model to store or commit the commands based on your configuration.

Enabling or Disabling fctimer Distribution

To enable or disable fctimer fabric distribution, perform this task:

SUMMARY STEPS

1.    switch# configuration terminal

2.    switch(config)# fctimer distribute

3.    switch(config)# no fctimer distribute


DETAILED STEPS
  Command or Action Purpose
Step 1 switch# configuration terminal
 

Enters configuration mode.

 
Step 2 switch(config)# fctimer distribute
 

Enables fctimer configuration distribution to all switches in the fabric. Acquires a fabric lock and stores all future configuration changes in the pending database.

 
Step 3 switch(config)# no fctimer distribute
 

Disables (default) fctimer configuration distribution to all switches in the fabric.

 

Committing fctimer Changes

When you commit the fctimer configuration changes, the effective database is overwritten by the configuration changes in the pending database and all the switches in the fabric receive the same configuration. When you commit the fctimer configuration changes without implementing the session feature, the fctimer configurations are distributed to all the switches in the physical fabric.

To commit the fctimer configuration changes, perform this task:

SUMMARY STEPS

1.    switch# configuration terminal

2.    switch(config)# fctimer commit


DETAILED STEPS
  Command or Action Purpose
Step 1 switch# configuration terminal
 

Enters configuration mode.

 
Step 2 switch(config)# fctimer commit
 

Distributes the fctimer configuration changes to all switches in the fabric and releases the lock. Overwrites the effective database with the changes made to the pending database.

 

Discarding fctimer Changes

After making the configuration changes, you can choose to discard the changes by discarding the changes instead of committing them. In either case, the lock is released.

To discard the fctimer configuration changes, perform this task:

SUMMARY STEPS

1.    switch# configuration terminal

2.    switch(config)# fctimer abort


DETAILED STEPS
  Command or Action Purpose
Step 1 switch# configuration terminal
 

Enters configuration mode.

 
Step 2 switch(config)# fctimer abort
 

Discards the fctimer configuration changes in the pending database and releases the fabric lock.

 

Fabric Lock Override

If you have performed a fctimer fabric task and have forgotten to release the lock by either committing or discarding the changes, an administrator can release the lock from any switch in the fabric. If the administrator performs this task, your changes to the pending database are discarded and the fabric lock is released.

The changes are only available in the volatile directory and are subject to being discarded if the switch is restarted.

To use administrative privileges and release a locked fctimer session, use the clear fctimer session command.

switch# clear fctimer session

Fabric Database Merge Guidelines

When merging two fabrics, follow these guidelines:


  • Be aware of the following merge conditions:


    • The merge protocol is not implemented for distribution of the fctimer values. You must manually merge the fctimer values when a fabric is merged.

    • The per-VSAN fctimer configuration is distributed in the physical fabric.

    • The fctimer configuration is only applied to those switches containing the VSAN with a modified fctimer value.

    • The global fctimer values are not distributed.

  • Do not configure global timer values when distribution is enabled.


Note


The number of pending fctimer configuration operations cannot be more than 15. After 15 operations, you must commit or abort the pending configurations before performing any more operations.


Verifying Configured fctimer Values

Use the show fctimer command to display the configured fctimer values. The following example displays the configured global TOVs:

switch# show fctimer
F_S_TOV   D_S_TOV   E_D_TOV   R_A_TOV
----------------------------------------
5000 ms   5000 ms   2000 ms   10000 ms

Note


The F_S_TOV constant, though not configured, is displayed in the output of the show fctimer command.


The following example displays the configured TOV for VSAN 10:

switch# show fctimer vsan 10
vsan no.  F_S_TOV   D_S_TOV   E_D_TOV   R_A_TOV
-------------------------------------------------
10        5000 ms   5000 ms   3000 ms   10000 ms

World Wide Names

The world wide name (WWN) in the switch is equivalent to the Ethernet MAC address. As with the MAC address, you must uniquely associate the WWN to a single device. The principal switch selection and the allocation of domain IDs rely on the WWN.

Cisco SAN switches support three network address authority (NAA) address formats. (see the following table).

Table 1 Standardized NAA WWN Formats

NAA Address

NAA Type

WWN Format

IEEE 48-bit address

Type 1 = 0001b

000 0000 0000b

48-bit MAC address

IEEE extended

Type 2 = 0010b

Locally assigned

48-bit MAC address

IEEE registered

Type 5 = 0101b

IEEE company ID: 24 bits

VSID: 36 bits


Caution


Changes to the world-wide names should be made by an administrator or individual who is completely familiar with switch operations.


Verifying WWN Information

Use the show wwn commands to display the status of the WWN configuration. The following example displays the status of all WWNs:

switch# show wwn status
Type    Configured     Available    Resvd.  Alarm State
----    ----------  --------------  ------  -----------
   1           64        48 ( 75%)      16    NONE
 2,5       524288    442368 ( 84%)   73728    NONE

The following example displays the information for block ID 51:

switch# show wwn status block-id 51
WWNs in this block: 21:00:ac:16:5e:52:00:03 to 21:ff:ac:16:5e:52:00:03
Num. of WWNs:: Configured: 256 Allocated:    0 Available: 256 
Block Allocation Status: FREE

The following example displays the WWN for a specific switch:

switch# show wwn switch
Switch WWN is 20:00:ac:16:5e:52:00:00

Link Initialization WWN Usage

Exchange Link Protocol (ELP) and Exchange Fabric Protocol (EFP) use WWNs during link initialization. ELPs and EFPs both use the VSAN WWN by default during link initialization. However, the ELP usage changes based on the peer switch’s usage:


  • If the peer switch ELP uses the switch WWN, then the local switch also uses the switch WWN.

  • If the peer switch ELP uses the VSAN WWN, then the local switch also uses the VSAN WWN.

Configuring a Secondary MAC Address

To allocate secondary MAC addresses, perform this task:

SUMMARY STEPS

1.    switch# configuration terminal

2.    switch(config)# wwn secondary-mac wwn-id range value


DETAILED STEPS
  Command or Action Purpose
Step 1 switch# configuration terminal
 

Enters configuration mode.

 
Step 2 switch(config)# wwn secondary-mac wwn-id range value
 

Configures the secondary MAC address. This command cannot be undone.

 

The following example shows how to configure the secondary MAC address:

switch(config)# wwn secondary-mac 00:99:55:77:55:55 range 64
This command CANNOT be undone.
Please enter the BASE MAC ADDRESS again: 00:99:55:77:55:55
Please enter the mac address RANGE again: 64
From now on WWN allocation would be based on new MACs. Are you sure? (yes/no) no
You entered: no. Secondary MAC NOT programmed

FC ID Allocation for HBAs

Fibre Channel standards require a unique FC ID to be allocated to an N port attached to an F port in any switch. To conserve the number of FC IDs used, Cisco SAN switches use a special allocation scheme.

Some HBAs do not discover targets that have FC IDs with the same domain and area. The switch software maintains a list of tested company IDs that do not exhibit this behavior. These HBAs are allocated with single FC IDs. If the HBA can discover targets within the same domain and area, a full area is allocated.

To allow further scalability for switches with numerous ports, the switch software maintains a list of HBAs that can discover targets within the same domain and area. Each HBA is identified by its company ID (also known as Organizational Unique Identifier, or OUI) used in the pWWN during a fabric log in. A full area is allocated to the N ports with company IDs that are listed and for the others, a single FC ID is allocated. Regardless of the type (whole area or single) of FC ID allocated, the FC ID entries remain persistent.

Default Company ID List

All Cisco SAN switches contain a default list of company IDs that require area allocation. Using the company ID reduces the number of configured persistent FC ID entries. You can configure or modify these entries using the CLI.


Caution


Persistent entries take precedence over company ID configuration. If the HBA fails to discover a target, verify that the HBA and the target are connected to the same switch and have the same area in their FC IDs, then perform the following procedure:


  1. Shut down the port connected to the HBA.
  2. Clear the persistent FC ID entry.
  3. Get the company ID from the port WWN.
  4. Add the company ID to the list that requires area allocation.
  5. Bring up the port.

The list of company IDs have the following characteristics:


  • A persistent FC ID configuration always takes precedence over the list of company IDs. Even if the company ID is configured to receive an area, the persistent FC ID configuration results in the allocation of a single FC ID.

  • New company IDs added to subsequent releases are automatically added to existing company IDs.

  • The list of company IDs is saved as part of the running and saved configuration.

  • The list of company IDs is used only when the fcinterop FC ID allocation scheme is in auto mode. By default, the interop FC ID allocation is set to auto, unless changed.


    Tip


    We recommend that you set the fcinterop FC ID allocation scheme to auto and use the company ID list and persistent FC ID configuration to manipulate the FC ID device allocation.


    Use the fcinterop FCID allocation auto command to change the FC ID allocation and the show running-config command to view the currently allocated mode.

  • When you enter a write erase, the list inherits the default list of company IDs shipped with a relevant release.

To allocate company IDs, perform this task:

SUMMARY STEPS

1.    switch# configuration terminal

2.    switch(config)# fcid-allocation area company-id value

3.    switch(config)# no fcid-allocation area company-id value


DETAILED STEPS
  Command or Action Purpose
Step 1 switch# configuration terminal
 

Enters configuration mode.

 
Step 2 switch(config)# fcid-allocation area company-id value
 

Adds a new company ID to the default list.

 
Step 3 switch(config)# no fcid-allocation area company-id value
 

Deletes a company ID from the default list.

 

The following example adds a new company ID to the default list:

switch(config)# fcid-allocation area company-id 0x003223

Verifying the Company ID Configuration

You can view the configured company IDs by entering the show fcid-allocation area command. Default entries are listed first and the user-added entries are listed next. Entries are listed even if they were part of the default list and you later removed them.

The following example displays the list of default and configured company IDs:

switch# show fcid-allocation area
FCID area allocation company id info:
00:50:2E <--------------- Default entry
00:50:8B
00:60:B0
00:A0:B8
00:E0:69
00:30:AE + <------------- User-added entry
00:32:23 +
 
        
00:E0:8B * <------------- Explicitly deleted entry (from the original default list)
Total company ids: 7
+ - Additional user configured company ids.
* - Explicitly deleted company ids from default list.

You can implicitly derive the default entries shipped with a specific release by combining the list of Company IDs displayed without any identification with the list of deleted entries.

You can also view or obtain the company IDs in a specific WWN by entering the show fcid-allocation company-id-from-wwn command. Some WWN formats do not support company IDs. In these cases, you many need to configure the FC ID persistent entry.

The following example displays the company ID for the specified WWN:

switch# show fcid-allocation company-id-from-wwn 20:00:00:05:30:00:21:60
Extracted Company ID: 0x000530

Switch Interoperability

Interoperability enables the products of multiple vendors to interwork with each other. Fibre Channel standards guide vendors towards common external Fibre Channel interfaces.

Not all vendors follow the standards in the same way, which results in the need for interoperability modes. This section briefly explains the basic concepts of these modes.

Each vendor has a regular mode and an equivalent interoperability mode, which specifically turns off advanced or proprietary features and provides the product with a standards-compliant implementation.

About Interop Mode

The software supports the following four interop modes:


  • Mode 1— Standards-based interop mode that requires all other vendors in the fabric to be in interop mode.

  • Mode 2—Brocade native mode (Core PID 0).

  • Mode 3—Brocade native mode (Core PID 1).

  • Mode 4—McData native mode.

The following table lists the changes in switch operation when you enable interoperability mode.

Table 2  Changes in Switch Operation When Interoperability Is Enabled

Switch Feature

Changes if Interoperability Is Enabled

Domain IDs

Some vendors cannot use the full range of 239 domains within a fabric.

Domain IDs are restricted to the range 97 to 127, to accommodate McData’s nominal restriction to this same range. Domain IDs can either be static or preferred, which operate as follows:


  • Static: Cisco switches accept only one domain ID; if a switch does not get that domain ID it isolates itself from the fabric.

  • Preferred: If the switch does not get its requested domain ID, it accepts any assigned domain ID.

Timers

All Fibre Channel timers must be the same on all switches as these values are exchanged by E ports when establishing an ISL. The timers are F_S_TOV, D_S_TOV, E_D_TOV, and R_A_TOV.

F_S_TOV

Verify that the Fabric Stability Time Out Value timers match exactly.

D_S_TOV

Verify that the Distributed Services Time Out Value timers match exactly.

E_D_TOV

Verify that the Error Detect Time Out Value timers match exactly.

R_A_TOV

Verify that the Resource Allocation Time Out Value timers match exactly.

Trunking

Trunking is not supported between two different vendor’s switches. This feature may be disabled on a per port or per switch basis.

Default zone

The default zone operation of permit (all nodes can see all other nodes) or deny (all nodes are isolated when not explicitly placed in a zone) may change.

Zoning attributes

Zones may be limited to the pWWN and other proprietary zoning methods (physical port number) may be eliminated.

Note   

On a Brocade switch, use the cfgsave command to save fabric-wide zoning configuration. This command does not have any effect on Cisco SAN switches if they are part of the same fabric. You must explicitly save the configuration on each Cisco SAN switch.

Zone propagation

Some vendors do not pass the full zone configuration to other switches, only the active zone set gets passed.

Verify that the active zone set or zone configuration has correctly propagated to the other switches in the fabric.

VSAN

Interop mode only affects the specified VSAN.

TE ports and SAN port channel s

TE ports and SAN port channels cannot be used to connect Cisco switches to non-Cisco SAN switches. Only E ports can be used to connect to non-Cisco SAN switches. TE ports and SAN port channels can still be used to connect a Cisco switch to other Cisco SAN switches even when in interop mode.

FSPF

The routing of frames within the fabric is not changed by the introduction of interop mode. The switch continues to use src-id, dst-id, and ox-id to load balance across multiple ISL links.

Domain reconfiguration disruptive

This is a switch-wide impacting event. Brocade and McData require the entire switch to be placed in offline mode and/or rebooted when changing domain IDs.

Domain reconfiguration nondisruptive

This event is limited to the affected VSAN. Cisco SAN switches have the capability to restart only the domain manager process for the affected VSAN and not the entire switch.

Name server

Verify that all vendors have the correct values in their respective name server database.

Configuring Interop Mode 1

The interop mode1 in Cisco SAN switches can be enabled disruptively or nondisruptively.


Note


Brocade’s msplmgmtdeactivate command must explicitly be run prior to connecting from a Brocade switch to either Cisco SAN switches or to McData switches. This command uses Brocade proprietary frames to exchange platform information, which Cisco SAN switches or McData switches do not understand. Rejecting these frames causes the common E ports to become isolated.


To configure interop mode 1, perform this task:

SUMMARY STEPS

1.    Place the VSAN of the E ports that connect to the OEM switch in interoperability mode.

2.    Assign a domain ID in the range of 97 (0x61) through 127 (0x7F).

3.    Change the Fibre Channel timers (if they have been changed from the system defaults).

4.    When making changes to the domain, you may or may not need to restart the domain manager function for the altered VSAN.


DETAILED STEPS
Step 1   Place the VSAN of the E ports that connect to the OEM switch in interoperability mode.
switch# configuration terminal
switch(config)# vsan database
switch(config-vsan-db)# vsan 1 interop 1
switch(config-vsan-db)# exit
 
Step 2   Assign a domain ID in the range of 97 (0x61) through 127 (0x7F).
Note   

This is an limitation imposed by the McData switches.

In Cisco SAN switches, the default is to request an ID from the principal switch. If the preferred option is used, Cisco SAN switches request a specific ID, but still join the fabric if the principal switch assigns a different ID. If the static option is used, the Cisco SAN switches do not join the fabric unless the principal switch agrees and assigns the requested ID.

Note   

When changing the domain ID, the FC IDs assigned to N ports also change.

Step 3   Change the Fibre Channel timers (if they have been changed from the system defaults).
Note   

The Cisco SAN switches, Brocade, and McData FC Error Detect (ED_TOV) and Resource Allocation (RA_TOV) timers default to the same values. They can be changed if needed. The RA_TOV default is 10 seconds, and the ED_TOV default is 2 seconds. Per the FC-SW2 standard, these values must be the same on each switch within the fabric.

switch(config)# fctimer e_d_tov ?
  <1000-100000> E_D_TOV in milliseconds(1000-100000) 
switch(config)# fctimer r_a_tov ?
  <5000-100000> R_A_TOV in milliseconds(5000-100000)
 
Step 4   When making changes to the domain, you may or may not need to restart the domain manager function for the altered VSAN.
  • Force a fabric reconfiguration with the disruptive option.
    switch(config)# fcdomain restart disruptive vsan 1
     

or


  • Do not force a fabric reconfiguration.
    switch(config# fcdomain restart vsan 1
     

Default Settings for Advanced Features

The following table lists the default settings for the features included in this chapter.

Table 3  Default Settings for Advanced Features

Parameters

Default

CIM server

Disabled

CIM server security protocol

HTTP

D_S_TOV

5,000 milliseconds

E_D_TOV

2,000 milliseconds

R_A_TOV

10,000 milliseconds

Timeout period to invoke fctrace

5 seconds

Number of frame sent by the fcping feature

5 frames

Remote capture connection protocol

TCP

Remote capture connection mode

Passive

Local capture frame limits

10 frames

FC ID allocation mode

Auto mode

Loop monitoring

Disabled

Interop mode

Disabled