TOC

  1. General Snippets
  2. General notes
    1. Virtual Routing & Forwarding
    2. Generic Routing Encapsulation

General Snippets

Get time/timezone bash show clock

Show all VRF Interfaces ```bash show vrf

show ip vrf 
``` Ping IP through VRF interface 
```bash
ping vrf <vrf-name> <ip> 
```

Filter logging bash sh logging | include May 16

General notes

Virtual Routing & Forwarding

  • used to facilitate MPLS
  • VRF-lite is VRF without MPLS
  • used by service providers to allow one device to carry traffic from multiple customers
  • Allows you to split physical router into multiple virtual routers , “vlans for routers”
  • Separate routing tables for each instance
  • TCP / IP layer 3 interfaces can be configured to use VRF
  • interfaces and routes are configured to a specified VRF
  • cannot be applied to layer 2 interfaces
  • traffic in one VRF cannot be forwarded out of an interface in another VRF without VRF leaking
  • Router intefaces , SVI’s and routed ports on multilayered switches can be configured in a VRF

Generic Routing Encapsulation

  • Layer 2 adjacency between two routers separated by cloud
  • IPSec implements encryption , GRE does not implement encryption by default
  • Encapsulation in GRE packets , both multicast or unicast
  • Pipe GRE packets into IPSec tunnel
  • GRE tunnels creates a virtual link and as a consequence , lowers the hop count