Fibre channel Addressing - Storage 10

1. World Wide Node Name (WWNN):- Sometimes it is also called as NWWN (Node World Wide Name).It is an 8-byte address used to identify device in the fabric.Every device in Fabric has its own WWNN.

No device can have two WWNN. Each node or HBA has one WWNN. If a server has two HBA then they have two WWNN.

2. World Wide Port Name (WWPN):- Also known as PWWN (Port World Wide Name). It is used to identify port on a device (switch or HBA card). Each port on a device has its own PWWN. It is also 8-Byte address.

3. Fabric Assigned Port World Wide Name (FAPWWN):-Some vendors like IBM also support Virtual PWWN called FAPWWN. These can be used to pre-configure the Zoning in order to increase the deployment efficiency.

4. Fabric Channel ID:- Referred to as FCID. Since there is a potential problem if 64 bits PWWN is used for routing, FC has used another address scheme.  FCID is used by the data plane to switch the traffic. FCID persistence is enabled by default to make sure it will not change after the device reboot.

FCID is 24 bit or 3 byte address assigned automatically to each port by switch. A switch can have different FCIDs for different VSANs.

FCID can be manually or dynamically assigned. Some HBAs doesn't allow the targets in the same area, static assignment can be useful in such scenario.

MDS-01# config t MDS-01(config)# fcdomain fcid database MDS-01(config-fcid-db)# vsan 100 wwn 00:00:00:00:00:00:00:01 fcid 0x010101

FCID is made up of three fields:-

• Domain ID: - It is the most significant byte that is a unique identifier assigned to each switch in a fabric. We can have 2 ^8 = 256 address available but few addresses are reserved and hence only 239 addresses can be used. It can either be assigned manually or dynamically.

   Domains ID are assigned by the Principle switch. PS is nothing but a general switch in the fabric that is responsible to assign the Domain IDs. Please refer to the below blog to find the more details about the Domain ID.

• Area ID: - It gives 2^8=256 addresses. In director switches there can be more than 256 switchport. And hence Area ID is the shared between the groups of ports. It cannot be configured and automatically configured by switches. 

• Port ID: - It is used to identify individual ports connected to N or NL port.