Category: Various

LAB IV ( vPC – virtual Port-channels )

vPC Domain Includes the vPC Peers, KeepAlive Links and the PortChannels that use the vPC technology.
vPC Peer SwitchThe other switch within the vPC domain. Each switch is connected via the vPC peer link. Its also worth noting that one device is selected as primary and the other secondary.
vPC Member PortPorts included within the vPCs.
vPC Peer Keepalive LinkConnects both vPC peer switches and carries monitoring traffic to/from each peer switch. Monitoring is performed to ensures the switch(s) is both operational and running vPC.
vPC Peer LinkConnects both vPC peer switches. And carries BPDUs, HSRPs, and MAC addresses to its vPC peer. In the event of vPC member port failure it also carries unicast traffic to the peer switch.
Orphan PortAn orphan port is a port that is configured with a vPC VLAN (i.e a VLAN that is carried over the vPC peer link) and is not configured as a vPC member port.

A virtual PortChannel (vPC) allows links that are physically connected to two different Cisco Nexus™ 5000 Series devices to appear as a single PortChannel to a third device. The third device can be a Cisco Nexus 2000 Series Fabric Extender or a switch, server, or any other networking device. A vPC can provide Layer 2 multipathing, which allows you to create redundancy by increasing bandwidth, enabling multiple parallel paths between nodes and load-balancing traffic where alternative paths exist.

After you enable the vPC function, you create a peer keepalive link, which sends heartbeat messages between the two vPC peer devices.

The vPC domain includes both vPC peer devices, the vPC peer keepalive link, the vPC peer link, and all the PortChannels in the vPC domain connected to the downstream device. You can have only one vPC domain ID on each device.


LAB I ( OSPF over GRE with and without IPsec )


  • R1 functions as the internet.
  • R2 is the first location with Public IP
  • R3 is the second location with Public IP

There must be a GRE tunnel configured between R2 and R3 so that OSPF can be used between them. In the example we will use a tunnel with and without IPsec.

Configuration without IPsec:



interface FastEthernet0/0
 ip address
 duplex auto
 speed auto

interface Tunnel0
 ip address
 tunnel source
 tunnel destination

interface Loopback0
 ip address

router ospf 1
 network area 0
 network area 0

ip route



SNMP – Simple network management protocol

  • Manager – Monitoring device
  • Agent – Devices being monitored
  • MIB – management information Base
  • UDP port 161
  • Uses GETs and SETs
  • SNMP Traps
    • Agent informs the manager.
  • SNMPv1 and 2c have community strings.
  • SNMPv3 has encryption and authentication.
    • auth – Group using the AuthNoPriv Security Level
      • Authentication: yes
      • Privacy ( encryption ): no
    • noauth – Group using the noAuthNoPriv Security Level
      • Authentication: no
      • Privacy ( encryption ): no
    • Priv – Group using the AuthPriv Security Level
      • Authentication: yes
      • Privacy ( encryption ): yes
  • If no read view is defined , all objects can be read.
  • If no write view is defined , no objects can be written.
  • If no notify view is defined , group members are not sent notifications.




  • Point-to-multipoint layer 3 overlay VPN
  • Logical hub and spoke topology
  • Direct spoke to spoke is support

DMVPN uses a combination of:

  • Multipoint GRE tunnels (mGRE)
  • Next Hop Resolution Protocol ( NHRP )
  • IPsec Crypto Profiles
  • Routing



  • Virtual Private Network
    • Route exchange privacy
    • Path determination for packets
    • Data Security
      • IPSec IP security
    • Collection of standized protocols that provide
      • Confidentiality
      • Integrity
      • Authentication
      • Anti-Reply



  • Transition technique designed to allow native IPv6 hosts to access IPv4-only content.
    • (Translation technique not a tunneling technique).
  • Primarily used to allow v6 hosts to initiate connections to IPv4 content.
    • Mechanisms do exist to allow the reverse.
  • Stateful and stateless versions.
    • stateful can use any prefix
    • stateless has restriction on prefix

NAT64 and DNS64 co-existance.

  1. IPv6 host sends AAAA DNS Query
  2. DNS64 server tries AAAA lookup and fails
  3. DNS64 server successfully resolves IPv4 address
  4. DNS64 server generates AAAA DNS response of <IPv6 prefix:IPv4 adress> and sends it back to the client.


IPv6 Tunnels

  • point-to-point tunnels
  • MCT ( manually configured tunnel )
  • GRE ( Generic Routing Encapsulation )
  • Virtual point-to-point between two IPv4 routers
  • IPv6 iGP routing protocols can run over these virtual links.


Policy Based Routing

  • PBR intercepts packets before regular routing
  • PBR overwrites the router’s natural destination
  • PBR is tied to route-maps
    • Define the match criteria
    • Define the action for the packets
  •  Packet forwarding
    • Outgoing interface
    • IP Next-Hop



  • Can be used by various
    • PBR
    • Static route
    • HSRP
  • Feature to monitor destination
    • Cpu creates data to monitor
    • Operations
    • Different operations can be monitored at the same time
  • The receiver can be a router or host
    • Might be configured as a SLA Responder