[DC] Datacenter Interconnects (DCI, OTV)

Distributed Data center Goals

• Ensure business continuity
• Distributed applications
• Seamless workload mobility
• Maximize compute resources

Challenges in traditional Layer 2 VPN:

• Flooding Behavior
  • Unknown unicast for mac propagation
  • Unicast Flooding reaches all sites
• Pseudo-wire Maintenance
  • Full mesh of Pseudo-wire is complex
  • Head-End replication is a common problem
• Multi-Homing
  • Requires additional protocols and extends STP
  • Malfunctions impact multipe sites

https://www.quisted.net/index.php/2018/02/15/data-center-design-vii-datacenter-interconnects/

DCI vs Network Interconnectivity

Network Interconnectivity

• Using traditional LAN technologies to connect multiple datacenters
• Typically use Layer3
  • Some applications require L2 Extensions
    • Clustering
    • Workload mobility
    • Replication

Datecenter Interconnect

• Loop-free LAN extention stretching across the datacenter WAN.
• Issuess to be concerned with:
  • Limited by physical standards for media
  • STP convergence
  • Broadcast storms
  • Failure isolation (sites should be independent)
  • Number of sites
  • Scalability (Max numbers of VLANs and MAC addresses)
  • Confidentiality ( Encryption )
  • Operational complexity

OTV  ( Overlay Transport Virtualization )

• Ethernet LAN Extension over any Network
  • Works over darkfiber, MPLS, or IP Network
  • Multi-datacenter scalability
• Simplified Configuration and Operation
  • Seamless overlay – no network redesign
  • Single touch site configuration
• High Resilency
  • Failure domain isolation
  • Seamless Multi-homing
• Maximizes available bandwith
  • Automated Multipathing
  • Optimal multicast replication

• Unknown Unicast Supression
  • No flooding storm over DCI
• Spanning tree Seperation
  • Reduce failure domains
• Controlling ARP
  • ARP cache
• Multihoming
  • Per-VLAN loadbalancing
• Path optimization
  • FHRP Localization

NVGRE