Connectrix Cisco MDS: How to configure Domain ID on a VSAN switch
Summary: Domain IDs uniquely identify a switch in a Virtual Storage Area Network (VSAN). A switch may have different domain IDs in different VSANs. The domain ID is part of the overall Fibre Channel (FC) ID. The configured domain ID can be preferred or static. By default, the configured domain ID is 0 (zero) and the configured type is preferred. Domain IDs can range from 1 to 239. The 0 (zero) value can be configured only if you use the preferred option. ...
Instructions
When a switch boots up or joins a new fabric, it can request a specific domain ID (statically configured) or take any available domain ID.
The Fibre Channel domain (fcdomain) feature performs principal switch selection, domain ID distribution, FC ID allocation, and fabric reconfiguration functions as described in the FC-SW-2 standards. The domains are configured on a per-VSAN basis. If you do not configure a domain ID, the local switch uses a random ID.
This section describes each fcdomain phase:
- Principal switch selection —This phase guarantees the selection of a unique principal switch across the fabric.
- Domain ID distribution —This phase guarantees that each switch in the fabric obtains a unique domain ID.
- FC ID allocation —This phase guarantees a unique FC ID assignment to each device attached to the corresponding switch in the fabric.
- Fabric reconfiguration —This phase guarantees a resynchronization of all switches in the fabric to ensure they simultaneously restart a new principal switch selection phase.
By default, the Fibre Channel domain feature is enabled on each switch. If you disable the Fibre Channel domain feature in a switch, that switch can no longer participate with other switches in the fabric.
If the configured domain ID is static, the switch requests a particular domain ID. If it does not get that domain ID, the assigned domain ID is discarded. All local interfaces are isolated, and the local switch assigns itself the configured domain ID, which becomes the runtime domain ID.
If the configured domain ID is preferred, the local switch accepts the domain ID the principal switch assigns. The assigned domain ID then becomes the runtime domain ID.
To configure a switch with a preferred or static domain ID, use the following steps:
switch # configure terminal switch (config) # fcdomain domain domain-id [preferred | static] vsan vsan-id
Fibre Channel domains can be started disruptively or non-disruptively.
If performing a disruptive restart, Reconfigure Fabric (RCF) frames are sent to other switches in the fabric. Data traffic is then disrupted on all the switches in the VSAN. This includes remotely segmented Inter-Switch Links (ISLs).
If you perform a non-disruptive restart, build fabric (BF) frames are sent to other switches in the fabric, and data traffic is disrupted only on the switch whose configured domain is static and numerically not the same as its runtime domain (for example, the configured domain is 11 static and the runtime domain is 99).
To restart the fabric non-disruptively in VSAN, use the following configuration steps:
switch # configure terminal switch (config) # fcdomain restart vsan vsan-id
To restart the fabric disruptively, use the fcdomain restart disruptive vsan vsan-id command. Irrespective of how many switches in that VSAN are configured, this command causes all devices of all switches to log out, causing data traffic disruption.