• VDC
  • VPC
  • Fabricpath
  • Fabric Extenders (FEX)
  • OTV

VDC ( Virtual Device Context )



A VDC can be used to virtualize the device itself, presenting the physical switch as multiple logical devices. Within that VDC it can contain its own unique and independent set of VLANs and VRFs. Each VDC can have assigned to it physical ports, thus allowing for the hardware data plane to be virtualized as well. Within each VDC, a separate management domain can manage the VDC itself, thus allowing the management plane itself to also be virtualized.

Create a new VDC:

N7k1(config)# vdc N5K1
N7k1# switchto vdc N5K1

Show allocated interfaces:

switch# show vdc membership

vdc_id: 0 vdc_name: switch interfaces:

        Ethernet2/1           Ethernet2/2           Ethernet2/3
        Ethernet2/4           Ethernet2/5           Ethernet2/6
        Ethernet2/7           Ethernet2/8           Ethernet2/9
        Ethernet2/10          Ethernet2/11          Ethernet2/12
        Ethernet2/13          Ethernet2/14          Ethernet2/15
        Ethernet2/16          Ethernet2/17          Ethernet2/18
        Ethernet2/19          Ethernet2/20          Ethernet2/21
        Ethernet2/22          Ethernet2/23          Ethernet2/24
        Ethernet2/25          Ethernet2/26          Ethernet2/27
        Ethernet2/28          Ethernet2/29          Ethernet2/30
        Ethernet2/31          Ethernet2/32          Ethernet2/33
        Ethernet2/34          Ethernet2/35          Ethernet2/36
        Ethernet2/37          Ethernet2/38          Ethernet2/39
        Ethernet2/40          Ethernet2/41          Ethernet2/42
        Ethernet2/43          Ethernet2/44          Ethernet2/45

vdc_id: 1 vdc_name: N5K1


Allocate interfaces:

N7k1(config)#vdc N5K1
N7k1(config-vdc)#allocate interface e2/1 - 12

VPC ( Virtual Port Channel )


LAB IV ( vPC – virtual Port-channels )

  • vPC overview
    • vPC made up of only 2 physical switches
      • vPC peers
    • vPC Peers each have
      • Same Domain #
      • vPC Peer link
        • Layer 2 trunk link to sync control plane between peers
        • MAC table, ARP cache, IGMP Snooping DB
        • Uses Cisco Fabcric Service over Ethernet ( CFSoE )
        • Used to elect a vPC primarty and vPC Secondary Role
        • Normally not used for the Dataplane
          • vPC Peer link generally much lower BW than aggregate of vPC member ports
      • vPC Peer Keepalive Link
        • Layer 3 used as heartbeat in the control plane.
        • Used to prevent active/active or “Split Brain” vPC roles
        • Not used in the vPC dataplane.
      • vPC Member Ports
        • Dataplane portchannel towards the downstream neighbor
        • Each vPC Peer has at least one memberport per vPC
        • From the perspective of the downstream neighbor, upsteam vPC peers are one switch
        • VLANs on vPC member ports must be allowed on vPC Peer link trunks
    • vPC orphans
      • Servers or switches connected to only one vPC peer
    • vPC Loop Prevention
      • Goal of vPC is to hide redundant links from STP
        • Could result in layer2 flooding loops
      • Loops are prevented via vPC check behavior
        • Frames received in the vPC Peer Link cannot flood out a vPC Member Port while the remote vPC Peer has active vPC Members Ports in the same vPC.


Datacenter Design V ( TRILL, Fabric Path )



  • Classic Ethernet ( CE )
    • Regular internet with regular flooding, regular STP, etc.
  • Leaf switch
    • Connects CE domain to FP domain
  • Spine switch
    • FP backbone switch all ports in the FP domain only
  • FP Core Ports
    • Links on leaf up to Spine, or Spine to Spine
    • i.e. the switchport mode fabricpath links
  • CE Edge Ports
    • Links of leaf connecting to regular CE domain (to servers / switches)
    • i.e. NOT the switchport mode fabricpath links

Activating the fabricpath feature set.

For the activation is the “ENHANCED_LAYER2.PK” license needed, or the grace-period of 120 days:


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