Back to: FC (Fibre Channel) fundamentals
Fibre Channel (FC) protocols are communication standards used primarily in Storage Area Networks (SANs) for high-speed data transfer between servers and storage devices. Here’s a breakdown of the key aspects of FC protocols:
1. Fibre Channel Protocol (FCP)
- FCP is the primary protocol for transmitting SCSI commands over Fibre Channel networks.
- It allows block-level data transfer between storage and servers.
- Works similarly to SCSI but over a Fibre Channel fabric.
Key Features:
- Low latency and high throughput.
- Supports both optical and copper mediums.
- Uses World Wide Names (WWN) for addressing.
2. Fibre Channel over Ethernet (FCoE)
- FCoE allows Fibre Channel frames to be carried over Ethernet networks.
- Eliminates the need for separate FC and Ethernet networks.
- Uses Data Center Bridging (DCB) to ensure lossless Ethernet transport.
Key Features:
- Reduces hardware costs by converging networking and storage.
- Requires FCoE-capable switches and Converged Network Adapters (CNAs).
- Works only within the same Layer 2 domain.
3. Internet Fibre Channel Protocol (iFCP)
- iFCP is a gateway-to-gateway protocol used to transport FC traffic over IP networks.
- Provides remote SAN connectivity over long distances.
- Replaces FCIP in some cases.
Key Features:
- Uses TCP/IP for transport.
- Allows for FC storage to be accessed over WAN.
4. Fibre Channel over IP (FCIP)
- FCIP, also called FC tunneling, enables SANs to extend over IP networks.
- Encapsulates FC frames within TCP/IP for transmission.
Key Features:
- Used for remote replication and disaster recovery.
- Requires FCIP gateways.
- Adds latency due to TCP overhead.
5. NVMe over Fibre Channel (FC-NVMe)
- FC-NVMe enables NVMe protocol over Fibre Channel fabric.
- Designed for high-speed SSD storage in enterprise environments.
Key Features:
- Lower latency compared to FCP (SCSI-based).
- Supports parallel I/O processing.
- Ideal for all-flash storage arrays.
6. SCSI (Small Computer System Interface)
SCSI is a protocol used for communication between computers and storage devices. It defines how data moves between servers and storage devices.
Key Features:
- Block-level storage protocol.
- Used in DAS (Direct Attached Storage), SAN, and NAS.
- Can operate over different transport mediums like Parallel SCSI, SAS, FC, and iSCSI.
SCSI Variants:
- Parallel SCSI (legacy)
- Serial Attached SCSI (SAS)
- Fibre Channel Protocol (FCP) – SCSI over FC.
- iSCSI – SCSI over IP.
7. iSCSI (Internet Small Computer System Interface)
iSCSI is a storage protocol that allows SCSI commands to be transmitted over TCP/IP networks.
Key Features:
- Works over Ethernet instead of Fibre Channel.
- Allows remote storage access using IP.
- More cost-effective compared to Fibre Channel SANs.
- Used in enterprise and cloud storage.
Advantages of iSCSI over FC:
| Feature | iSCSI | Fibre Channel |
|---|---|---|
| Transport | TCP/IP (Ethernet) | Fibre Channel |
| Cost | Lower (uses standard network) | Higher (requires FC switches & HBAs) |
| Performance | Depends on network | Generally higher |
| Complexity | Easier to deploy | More complex |
iSCSI Components:
- iSCSI Initiator: Client (server) that sends SCSI commands.
- iSCSI Target: Storage device or SAN that receives commands.
- iSCSI LUN: Logical storage unit assigned to the server.
8. Fibre Channel Protocols (FCP, FCIP, FCoE, iFCP, FC-NVMe)
Fibre Channel is a high-speed networking protocol designed for connecting servers to storage.
Key FC-based Protocols:
| Protocol | Transport | Use Case | Key Benefit |
|---|---|---|---|
| FCP | Fibre Channel | Traditional SAN | High performance |
| FCoE | Ethernet | Unified network | Cost-effective |
| iFCP | IP | Remote SAN access | Long-distance connectivity |
| FCIP | IP | SAN extension | Disaster recovery |
| FC-NVMe | Fibre Channel | NVMe storage | Ultra-low latency |
Comparison of iSCSI vs. FCP (FC-SCSI)
| Feature | iSCSI | FCP (Fibre Channel-SCSI) |
|---|---|---|
| Transport | IP (Ethernet) | Fibre Channel |
| Performance | Lower | Higher |
| Cost | Lower (Ethernet-based) | Higher (FC-based) |
| Complexity | Easier | More complex |
9. Summary of Storage Protocols
| Protocol | Transport Medium | Common Use Case | Key Benefit |
|---|---|---|---|
| SCSI | Various (SAS, FC, iSCSI) | General storage | Block-level storage |
| iSCSI | TCP/IP (Ethernet) | Cloud, remote storage | Cost-effective, flexible |
| FCP | Fibre Channel | Enterprise SAN | High speed, low latency |
| FCoE | Ethernet | Converged network | Reduces infrastructure cost |
| FCIP | IP (WAN) | Remote SAN, DR | Extends SAN over distances |
| NVMe-over-FC | Fibre Channel | NVMe storage | Ultra-fast SSD access |