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To move the BCMSN examination and earn your CCNP, you have got to learn HSRP inside and out! Part of the is knowing how the MAC address of the virtual router is made, and yet another part is knowing how to change this address. We'll take a look at both features in this training. We have got two routers on a part running HSRP, therefore first we should discover what the MAC address of the HSRP virtual router is. The show command for HSRP is show stand-by, and it's the first command you should work while configuring and troubleshooting HSRP. Let's run it on both routers and compare results. R2#show stand-by Ethernet0 - Group 5 Local state is Stand-by, concern 10-0 Hellotime 3 sec, holdtime 10 sec Next hi submitted 0.776 Virtual IP address is 172.12.23.10 designed  [http://www.haodonggt.com/how-do-you-keep-in-touch-with-my-online-assistant/ business productivity]  Active hub is 172.12.23.3, priority 100 finishes in 9.568 Life router is local  [http://carterservicesplus.com/Portal/node/211785 The World of Virtual Gambling | Carter Services Plus Portal]  1 state changes, last state change 00:00:22 R3#show standby Ethernet0 - Group 5  [http://www.smosh.com/forum/general/do-i-need-assistant Do I Need a Assistant | SMOSH]  Regional state is Active, goal 10-0 Hellotime 3 sec, holdtime 10 sec Next hello sent in 2.592 Virtual IP is 172.12.23.10 configured Effective modem is local Standby modem is 172.12.23.2 expires in 8.020 Electronic mac address is 0000.0c07.ac05 2 state changes, last state change 00:02:08 R3 is in Active state, while R2 is in Standby. The hosts are employing the 172.12.123.10 address as their gateway, but R3 is clearly managing the workload. R2 will require over if R3 becomes unavailable. An IP address was statically assigned to the virtual router, but not a MAC address. However, there is a MAC address underneath the show stand-by production on R3, the active router. How did the HSRP approach get to a MAC of 00-00-0c-07-ac-05? Well, a lot of the work is done prior to the arrangement is even begun. The MAC address 00-00-0c-07-ac-xx is reserved for HSRP, and xx is the class number in hexadecimal. That's a great skill to own for the exam, so make sure you are comfortable with hex conversions. The group number is 5, which will be expressed as 05 with a two-bit hex character. We'd see 1-1 at the end of the MAC address - one unit of 16, one unit of 1, when the class number had been 17. On rare occasions, you may have to change the MAC address assigned to the virtual router. This can be done with the standby mac-address order. Just ensure you are not duplicating a MAC address that's already in your network! R2( config-if )#standby 5 mac-address 0000.1111.2222 1d12h: %STANDBY-6-STATECHANGE: Ethernet0 Group 5 state Active -&gt; Learn R2#show standby Ethernet0 - Group 5 Regional state is Active, priority 150, might pre-empt Hellotime 4 sec, holdtime 12 sec Next hi submitted 3.476 Virtual IP is 172.12.23.10 designed Active switch is local Stand-by modem is 172.12.23.3 finishes in 10.204 Personal mac address is 0000.1111.2222 designed 4 state changes, last state change 00:00:00 1d12h: %STANDBY-6-STATECHANGE: Ethernet0 Group 5 state Listen -&gt; Active The MAC address will have a few seconds to alter, and the HSRP modems will get into state for that time period. A real-world HSRP troubleshooting note: If you see constant state changes with your HSRP setup, do what you should always do when troubleshooting - check the physical layer first. Most useful of luck on your own BCMSN test!