Fibre Channel Addressing and Routing Fabric Configuration Process
Stage 3: Domain ID Assignment
• Domain ID Assignment:
– Automatic - Principal Switch will assign a domain ID
–Preferred - Principal Switch can override preferred domain ID – Static - Principal Switch cannot override static domain ID
• Static Domain IDs are generally recommended:
– Speeds up fabric configuration process – Less impact to connectivity of attached ports – But can result in isolation when fabrics are merged
Most switches allow administrators to configure either preferred or static Domain IDs. When the Principal Switch assigns Domain IDs, switches request their preferred domain ID. The Principal Switch will assign the requested ID if that ID is available, and will assign a different ID if the requested ID is not available. This takes time, especially in a large fabric. In addition, the FCIDs of all devices attached to the switch will change if the Domain ID changes. Some servers, such as AIX and HP-UX servers, use FCIDs for device mapping, so administrators try to avoid changing Domain IDs.
However, when static Domain IDs are assigned, Domain IDs conflicts can result. There is a trade-off between the two methods.