Tag: devices

Windows 10: Opening Program management tools and features from command prompt

by Samuel Mitchell, posted in Microsoft, windows

Sometimes you may want to run open Programs and Features without searching for it in the Control Panel. Another reason to require these commands is to run them with administrative privileges.

You can open the Run using [Windows KEY] + [R] or the cmd or even in PowerShell ISE

appwiz.cpl – open the Programs and Features window.

appwiz

devmgmt.msc – open the device manager

devmgmt

compmgmt.msc – open the computer management

compmgmt

diskmgmt.msc – opens the disk management

diskmgmt

lusrmgr.msc – opens the local users and groups management

lusrmgr

I will update this article with more useful commands as I identify them.

 

CCNP R&S Switch: First Hop Redundancy Protocol Inner Workings

by Samuel Mitchell, posted in Cisco, Routing & Switching

This article is to identify the important information to know about the the three (3) First Hop Redundancy Protocols (FHRP) supported on a Cisco devices.

The three FHRP are:

  • HSRP – Hot Standby Redundancy Protocol
  • VRRP – Virtual Router Redundancy Protocol
  • GLBP – Gateway Load Balancing Protocol

HSRP

  • The virtual mac address are as follows based on version:
    • v1: 0000.0c07.acXX
    • v2 : 0000.0c9f.f000 – 0000.0c9f.ffff
  • sends hello message every 3 seconds to multicast address on port UDP 1985:
    • 224.0.0.2 (v1)
    • 224.0.0.102 (v2)
  • Preemption is disabled by default
  • The HSRP virtual IP address cannot be the same as any of the devices in the group
  • The group number can be the same on the different interfaces on a device
    • v1 group range 0 – 255
    • v2 group range 0 – 4095
  •  If the priority is equal on all devices in a group, the device with the highest IP address wins.
  • v1 and v2 are not interoperable
  • Router state are either Active or Standby

VRRP

  • This protocol is an IEEE standard
  • The virtual mac address is 0000.5e00.01RR (R represents the virtual router identifier)
  • sends hello message every 1 second to multicast address 224.0.0.18 via IP protocol 112
  • Preemption is enabled by default
  • Router state are either Master or Backup
  • Protocol has the option to learn timer from the Master
    • vrrp # timer learn

GLBP

  • the virtual MAC address is 0007.b400.GGFF (G is the GLBP group number and R is the AVF number)
  • sends hello message every 3 seconds to multicast address on port UDP 3222:
    • 224.0.0.102
  • All devices will be an AVF (Active Virtual Forwarder)
  • Only one AVG (Active Virtual Gateway) will be elected
  • The AVG assign a virtual MAC address to the AVF
  • AVG is responsible for responding to ARP requests for the virtual IP address
  • load balancing methods
    • round-robin (default)
    • host-dependent
    • weighted
  • preemption is disabled by default
  • GLBP uses 3 packet types: Hello, Request and Reply

The detail listed is not exhausted but it will be updated in the future.