Switchport block unicast

[J_Rega]

Should switchport block unicast be set on trunk ports? There is plenty of documentation about setting it in general and what it does with regards to not flooding unknown unicast traffic, but, I cannot find anything in specific about setting it on trunk ports. Does it negatively impact the ability of a switch to pass traffic if the destination MAC is not know by the switch?

[Reza Sharifi]

You usually control broadcast and multicast at that access level.

here is an example for access ports: 

storm-control broadcast include multicast

storm-control broadcast level x.00

storm-control action trap

you set the level to whatever you are comfortable with and work for your environment. You can start with 1% or 2% and raise it as needed. Usually, 1% works fine on a gig port.

HTH

[J_Rega]

Thank you for the quick response. Setting the controls at the access level makes sense to me and I understand storm-control settings, but I am looking specifically for how block unicast will affect a trunk port. There is an organizational requirement to set block unicast on ports, but not specifically access or trunk ports. I want to understand how this setting will impact a trunk port before I engage with my organization about excluding trunk ports from this requirement if it is detrimental.

[Reza Sharifi]

I want to understand how this setting will impact a trunk port before I engage with my organization about excluding trunk ports from this requirement if it is detrimental.

I think, in order to really understand the impact, you would have to test it first during off-hours and then in a limited production segment and tun as you go because every environment is different.

HTH