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
- Ethernet Flow control ( LAN ):
- 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
- Point-to-Point
- 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
- Domain 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