[c-nsp] Question on HSRT and MST protocol

[Juan Angel Menendez]

         Agreed, but some platforms don't support this feature (ie my 3550-12G)

         router#
         router#interface vlan 5
         router(config-if)#standby 5 mac-address ?
         % Unrecognized command

At 12:41 07/09/2006, Ed Ravin wrote:

>On Thu, Sep 07, 2006 at 11:57:38AM -0300, Juan Angel Menendez wrote:
> >          Each HSRP group will use a different "Virtual MAC address'".
> > So if you're using different physical interfaces or VLANs in a
> > switched environment you can reuse the HSRP group numbers. This is
> > useful when you reach the max HSRP group limitation (which varies on
> > each platform).
>
>But don't forget, by default, each HSRP group uses the SAME Virtual
>MAC address - if you re-use an HSRP group number on a different
>VLAN without changing the default virtual MAC address, you'll have
>the same MAC address appearing twice on your network, though in
>different VLANs.  Some switches (notably the ancient but otherwise
>venerable HP4000m/HP2424m/HP8000m series) can't handle that.  And
>you may have other systems in place (like arpwatch) that might complain
>about it.
>
>So if you reuse an HSRP group number, you should take a close look
>at the MAC address implications, and consider using the "standby N 
>mac-address"
>command to change the virtual MAC address.