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Fiber Channel over Ethernet

Currently we have in data centres 2 major environments, 2 cabling standards, 2 interface adapters; differences:

  • LAN - focus on Ethernet connectivity interfacing with NIC - Network Interface Card
    • can deal with packet loss
  • SAN - focus on Fibre Channel connectivity interfacing using HBA - Host Bus Adapter
    • does not support packet loss
FCoE utilizes
  • interface CNA - Converged Network Adapter that can understand LAN and SAN traffic
  • uses 10Gbps Ethernet cable
  • takes advantage of layer 2 domains with multipath support using vpc - virtual port channels and FB - Cisco fabric path technology
FCoE adapted following solutions to overcome converging problems of 2 technologies
  • Entire F.C frame needs to carry full payload of Ethernet frame therefore we have Ethernet Jumbo Frames
  • map WWN to MAC addresses of Ethernet environment
  • FIP - Fibre Channel over Ethernet Initialization Protocol created to handle login of FC devices across of unified fabric
  • No packet-loss - using minimum 10Gbps Ethernet cable; there is no packet recovery/delivery mechanism in FCoE

We encapsulate FC frame into Ethernet frame with EtherType=0x8906 HEX

                                encapsulated        EtherType=0x8906
 [ Fibre Channel frame ]  ----------------------> [ Ethernet frame ]
   36B header
   2112B data
   2148 bytes max frame 

  FCoE uses default MTU=2240 bytes for this unified fabric.