Network Time Protocol

Network Time Protocol (NTP)

NTP is an internet protocol used to synchronize the clock of computer to some time reference. It developed by Professor David L. Mills at the University of Delaware.  

NTP uses co-ordinated universal Time to synchronize computer clock times to a millisecond. NTP is run over the User datagram protocol (UDP), using port No. 123 as both the source and destination. An NTP network usually gets its time from an authoritative time source, such as radio clock and an atomic clock attached to a time server.

Each cisco switch has an internal time clock that runs continuously without any intervention. However, do not assume that a switch already has its internal clock set to the correct date and time.  We can use the show clock command to find time:

Router# show clock

We can use the following commands as a guideline to define the  time zone and summer time and to set the clock:

Switch(config)# clock timezone <name,any> <offset-hours> <offset-minutes>

Offset-hours means if we can set offset -5 than it calculate time 19 means 7:00.

 Offset-minute same as but in minutes.

Switch(config)# clock summer-time <name> date <start date> <start-month> <start-year><hh:mm> <end-date> <end-month> <end-year> <hh:MM>

Or

Switch(config)#clock summer-time <name> recurring <start-week> <start-day> <start-month> <hh:mm> <end-week> <end-day> <end-month> <hh:mm>

If we want donn’t set any other parameters

Switch(config)# clock summer-time <name> recurring

NTP With Server Configuration

Router(config)# ntp server <server ip address>

 

Check NTP Server Status

Router# show ntp status  

Securing NTP

On NTP enable authentication key and password and on router

Router(config)# ntp authentication-key <key-no.> md5 <key-string>

Router(config)# ntp  authenticate

Router(config)# ntp trusted-key <key-no.>

Router(config)#ntp server <ip address> key <key-no>

 

 

 

 

  

 

Open Shortest Path First - Part 1

Open Shortest Path First (OSPF)

1.) It is link state protocol, which elect best way from source to destination base on highest bandwidth.
2.) It support both FLSM and VLSM subnetting.
3.) Every ospf router interface work in single area, which represent in area-id.
4.) It use Dijkstra algorithm.
5.) OSPF is fast convergency protocol as camper to eigrp.
6.) It support unlimited hope count.
7.) It also use PID (process ID) number for identification of each ospf process.
8.) It use wildcard mask for network adjacency.

   

     

9.) OSPF Router:
       In OSPF environment following  router work:

       A.) Designated Router (DR) :
              Every single area have DR, the router that keeps the highest database for the subnet, it
                 became DR.
 
       B.) Backup Designated Router (BDR) :
              Which router have second highest ip address, became BDR.

       C.) Area Border Router (ABR) :
              This types of router have entry of multiple areas. Its one interface connected with the area 0
               (Backbone Area) and another is with different area.

       D.) Autonomous System Border Router (ASBR) :
              It is placed on ISP. It is use to create connection between multiple different areas. It always
              represent area 0.
              Note: Area 0 (Backbone area) is must be require to create connection different multiple
                         area.

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