A brief introduction to FabricPath

FabricPath is a technology which combines the benefits of Routing protocols, here will be Intermediate-System-to-Intermediate-System (IS-IS), and Layer 2 Network Ethernet environments.

To list some of FabricPath advantages:

  • MAC Address scalability by Conversational Learning
  • No spanning-tree anymore, hurray! Each switch will have its own view of Layer 2 topology and calculates the L2 topology using SPF calculation.
  • Equal cost multipath forwarding for Unicast Layer 2 traffic!
  • Makes any kind of topology possible!
  • Configuration/Administration is not a hassle anymore
  • Loop prevention/mitigation by having a TTL field in the frames

Switch-ID

We can refer to FabricPath as “Routing MAC Addresses” or “Layer 2 over Layer 3”, but it doesn’t mean that FabricPath ports have an IP Address! In a FabricPath topology, each device is dynamically assigned a “switch-id” via Dynamic Resource Allocation Protocol (DRAP), and L2 forwarding table is populated based on reachability to each switch-id.

Function types in FabricPath

  • Leaf: This is where Classic Ethernet devices are connected to. It’s the point of “MAC to switch-id” mapping. Traffic is looked up in the L2 forwarding table and then encapsulated into a MAC-in-MAC frame whose destination switch-id is the switch which the destination host is connected to. FabricPath is only supported on Cisco Nexus 5500 with NX-OS 5.1(3)N1(1) and higher as the edge (access) device in FabricPath topology.
  • Spine: Cisco Nexus 7000 is supported as the aggregation device in FabricPath topology with NX-OS 5.1(1) and higher, but only based on F1 line cards. Layer 3 forwarding could be gained by adding M1 series cards.

Continue reading “A brief introduction to FabricPath”

Share this!

Cisco DCI Design & Implementation

Being involved in different Data Center design projects requires you knowing how to interconnect Data Centers. Below you’ll find my notes from Cisco Data Center Design & Implementation Guide, System Release 1.0.

DCI Business Driversclip_image0014_thumbHA Clusters/Geoclusters
  • Microsoft MSCS
  • Veritas Cluster Server (Local)
  • Solaris Sun Cluster Enterprise
  • VMware Cluster (Local)
  • VMware VMotion
  • Oracle Real Application Cluster (RAC)
  • IBM HACMP
  • EMS/Legato Automated Availability Manager
  • NetApp Metro Cluster
  • HP Metrocluster
Active/Standby Migration, Move/Consolidate Servers
  • VMware Site Recovery Manager (SRM)
  • Microsoft Server 2008 Layer 3 Clustering
  • VMware Vmotion

The applications above drive the business and operation requirement for extending the Layer 2 domain across geographically dispersed data centers. Extending Layer 2 domains across data centers present challenges including, but not limited to:

  • Spanning tree isolation across data centers
  • Achieving high availability
  • Full utilization of cross sectional bandwidth across the Layer 2 domain
  • Network loop avoidance, given redundant links and devices without spanning tree

Continue reading “Cisco DCI Design & Implementation”

Share this!