Can't disable Unknown multicast blocked: enabled on a Nexus 5596

[rafise]

Hello All,

I've been trying to disable Unknown multicast blocked: enabled for some reason can't get it to change on any port, is happening on all 96 ports, not sure if there's a global setting or feature that needs to be activated perhaps a license would appreciate the help thanks.

commands used

config t

int e1/1

no switchport block  multicast

# show interface ethernet 1/1 switchport
Name: Ethernet1/1
  Switchport: Enabled
  Switchport Monitor: Not enabled
  Operational Mode: trunk
  Access Mode VLAN: 1 (default)
  Trunking Native Mode VLAN: 2610 (INFRA)
  Trunking VLANs Allowed: 1-4094
  Pruning VLANs Enabled: 2-1001
  Voice VLAN: none
  Extended Trust State : not trusted [COS = 0]
  Administrative private-vlan primary host-association: none
  Administrative private-vlan secondary host-association: none
  Administrative private-vlan primary mapping: none
  Administrative private-vlan secondary mapping: none
  Administrative private-vlan trunk native VLAN: none
  Administrative private-vlan trunk encapsulation: dot1q
  Administrative private-vlan trunk normal VLANs: none
  Administrative private-vlan trunk private VLANs: none
  Operational private-vlan: none
  Unknown unicast blocked: disabled
  Unknown multicast blocked: enabled

[Mark Elsen]

 - Why do you want to disable this ? The reason for the question is that if the requirements are known, then the community may provide alternatives or further insights.

 M.

[rafise]

I'm having issue pxe booting servers over trunk cant get any server to pxe boot when the port is trunk only. want to see if unblocking the multicast fix the issue on the switch.

[Mark Elsen]

                - Check and scrutinize the threads mentioned below :

   https://community.cisco.com/t5/switching/pxe-boot-on-a-trunk-port/td-p/3922404

   https://community.cisco.com/t5/switching/pxe-boot-requests-fail-across-vlan-s/td-p/2485239

   https://community.cisco.com/t5/switching/trunk-ports-and-dhcp/td-p/1890308

 M.

[rafise]

Marce1000 - Thanks for the links.
The first link was my last year and I checked the other ones and there's no solution. Not sure if there's a bug on the ios series 7.3 I already tried 7.3(6) and 7.3(5) with no change.

[rafise]

2 cisco engineer looked at them and they suggested to get rid of them and get new switches this is happening on 2 switches, not 1. I'll open a ticket with cisco to see if I get them to replace if not will get a different brand.