Tag: FC

FCoE is short for Fibre Channel over Ethernet.

Fibre Channel over Ethernet (FCoE) solves the problem of organizations having to run parallel network infrastructures for their local area networks (LANs) and their storage area networks (SANs). As a result, they have to operate separate switches, host bus adapters (HBAs), network interface cards (NICs) and cables for each of these networks. Even utilizing a virtualization solution like VMware can actually increase the number of network adapters required to carry traffic out of the servers.

https://www.cisco.com/c/en/us/products/collateral/switches/nexus-7000-series-switches/white_paper_c11-560403.html

• FIP – FCOE Initialization Protocol
• FLOGI – Fabric login
• FcF – FibreChannel Forwarder
• FSPF – FibreChannel Shortest Path First

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LAN and SAN Separation

• Security  Ensures protection from hacking
• Bandwidth – SAN needs more bandwidth than LAN
• Flow Control – SAN is lossless and LAN is lossy
  • Ethernet Flow control ( LAN ):
    • Source transmits packets untill receiver buffer overflow, then sends a “Pause” frame
    • Lost packets are retransmitted
  • Fibre Channel ( SAN ):
    • Credit based mechanism – Receiver has control
    • Source does not send a frame until the receiver telsl the source it can receive a frame by sending “Ready” signal Back
• Performance – SAN provides more performance than LAN enviorments

LAN vs SAN flow control

• Flow control is how data is controlled in a network
• Ethernet Flow control ( LAN )
  • Source transmits packets until receiver buffers overflow, then sends a “Pause” frame
  • Lost packets are retransmitted
• Fibre Channel ( SAN )
  • Credit based mechanism – Receiver has control
  • Source does not send a frame until the receiver tells the source it can receive a frame by sending “Ready” signal back.
  • “Lossless Fabric”

FibreChannel

• San Topologies
  • Point-to-Point
    • Initiator (server) and Target (Storage) directly connected
  • Arbitraded Loop (FC-AL) (Legacy)
    • Logical ring topology, similar to token ring
    • Implies connection is required on the ring
  • Switched Fabric ( FC-SW ) ( Standard)
    • Logical equivalent to a switched ethernet LAN
    • Switches manage the fabric allowing any-to-any communication
    • Support more than 16 million device addresses
• FibreChannel Port types
  • N_port – Node Port
  • NL_port – Node Loop Port
  • F_port – Fabric Port
  • FL_port – Fabric Loop Port
  • E_port – Expansion Port ( ISL )
  • TE_port – Trunking Expansion Port
• FC Addressing is analogous to IP over Ethernet
  • IP addresses are logical and manually assigned
  • Ethernet MAC Addresses are physical and burned in
  • FC World Wide Names ( WWNs )  / MAC / Zoning
    
    • 8 byte address burned in by manufacturer
    • Word Wide Node Name
    • World Wide Port Name
  • FC Identifier ( FCID )  / IP / Routing
    
    • 3 byte logical address assigned by fabric
    • FCID is subdevided into three fields:
      • Domain ID
        • Each switch gets a domainID
      • Area ID
        • Group of ports on a switch have an Area ID
      • Port ID
        • End station connected to switch gets a Port ID
• FibreChannel Nameserver ( FCNS)
  • analogous to ARP cache
  • Used to resolve WWN ( pysical address ) to FCID ( logical address )
  • Like FSPF, FCNS requires no configuration
• FibreChannel Logins
  • Ethernet networks are connectionless
  • Fibre Channel networks are connection oriented
    • All end stations must first register with the control plane of the fabric before sending any traffic.
  • Fabric Registration has three parts
    • Fabric Login ( FLOGI)
    • Port Login ( PLOGI)
    • Process Login ( PLRI )
  • sh flogi database
  • sh fcns database
• VSANs
  • Logical seperation of SAN traffic
• Zoning
  • like an ACL in the IP world