HSRP via direct trunk or via L2 switch?

FrankGuthrieFrankGuthrie Member Posts: 245
in CCNA & CCENT
HRSP-trunk-SW.png
See example above



Would there be any different as to how HSRP should work if it would be connected via a direct Trunk or via a SW. I'm guessing not. In situation 3, Will R2 get the multicast from both the SW and R1 (directly over the trunk)? I think yes?



I guess Multicast, like broadcast is send out of all interface, or will the R1/R2 make a decision as to on which interface it will send out multicast/HSRP pakcets?


Is there a way to see if if HSRP message are received over an interface?
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Comments

  • d4nz1gd4nz1g Member Posts: 464
    debug condition interface Typex/y
    debug standby packets
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  • FrankGuthrieFrankGuthrie Member Posts: 245
    d4nz1g wrote: »
    debug condition interface Typex/y
    debug standby packets

    Are there no show command to show this? Debug command in production is always threading on thin ice.
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  • 636-555-3226636-555-3226 Member Posts: 975 ■■■■■□□□□□
    Unrelated, but since you're playing with HSRP anybody who's taken SANS SEC660 might suggest reading up on a related topic re: HSRP security

    https://www.dshield.org/diary/Network%2BReliability,%2BPart%2B2%2B-%2BHSRP%2BAttacks%2Band%2BDefenses/10120
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  • networker050184networker050184 Mod Posts: 11,962 Mod
    There wouldn't be any difference in the behavior assuming your router supports L2 switching.

    As far as the second part think STP here.
    An expert is a man who has made all the mistakes which can be made.
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  • OctalDumpOctalDump Member Posts: 1,722
    FrankGuthrie wrote: »
    Are there no show command to show this? Debug command in production is always threading on thin ice.

    This is why you try theoreticals and hypotheticals in the lab :)

    But if HSRP is properly configured, there shouldn't be too much traffic to debug, and you'd only need to run it for a couple of minutes tops.
    2017 Goals - Something Cisco, Something Linux, Agile PM
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  • FrankGuthrieFrankGuthrie Member Posts: 245
    networker050184 wrote: »
    There wouldn't be any difference in the behavior assuming your router supports L2 switching.

    Are you saying that a "pure" router doesn't support L2 switching? I know it does a layer 2 rewrite, but then again, decision are made on IP (Layer 3)
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  • networker050184networker050184 Mod Posts: 11,962 Mod
    In the pure sense, no a router doesn't switch. You'd need to front them with a switch for HSRP to function.
    An expert is a man who has made all the mistakes which can be made.
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  • FrankGuthrieFrankGuthrie Member Posts: 245
    networker050184 wrote: »
    In the pure sense, no a router doesn't switch. You'd need to front them with a switch for HSRP to function.

    And if there is a trunk between 2x L3? switches
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