Datacenter Design VII ( Datacenter Interconnects )

https://www.cisco.com/c/dam/en/us/solutions/collateral/data-center-virtualization/data-center-interconnect/at_a_glance_c45-493703.pdf

• Types of Data Center Interconnections
  • Layer 1 DCI
    • Physical connection between Data Centers
      • Dark Fiber ( MetroE)
      • Fibrechannel
    • Not as flexible
  • Layer 2 DCI
    • Carrier appears as L2 Bridge
    • MPLS options
    • VPLS options
    • IP Mobility
  • Layer 3 DCI
    • IP Based connection
      • iSCSI
      • Routing
      • ATOMoGRE

Layer 2 datacenter Interconnects

• Layer 2 DCI provides the best advantages
  • Seamless migration between datacenters  ( AWS )
  • VM Mobility, IP Address Mobility.
  • Single physical circuit between multiple sites.
  • Count the cost of failure.
    • “What if X goes down?”
    • “What if a link goes down between datacenters?
• Layer 2 DCI Design options:
  • MPLS psuedowire
  • https://www.cisco.com/c/en/us/td/docs/wireless/mwr_2941_dc/software_config/guide/3_3/2941_33_Config_Guide/Pseudowire.pdf
  • Ethernet Over MPLS ( EOMPLS – ELAN )
  • Virtual Private Lan Private Service ( VPLS )

Layer 3 datacenter Interconnects

The challenge is how to make Layer3 DCI act like Layer2 DCI.

• Basic IP Routing, Always an option, combined with overlay networks for layer2.
• Any transport over MPLS over GRE ( ATOMoGRE ).
• Overlay Transport Virtualization ( OTV ).
  • Developed by Cisco.
  • No pseudowires, MPLS, STP
  • No Mac Flooding, OTV Edge devices use IS-IS to advertise MACs.
• Virtual Extensible LAN ( VxLAN ).
  • Original overlay
  • Mac Flooding, Learning, Requires 1600 Byte Packet Size