Nexus, NLB, Static MAC Issues

[mfarrenkopf]

I am working on a migration of server chassis from 6500 10 gig ports to Nexus.  Of course, we're using Microsoft NLB in IGMP multicast mode.  I was really looking forward to NX-OS 5.2 on the 5548s, but it's just not working out.

I can configure the ARP entry without issue, but when I try to configure anything else I get errors:

DCRdn5kAA1# conf t

Enter configuration commands, one per line.  End with CNTL/Z.

DCRdn5kAA1(config)# int vlan 800

DCRdn5kAA1(config-if)# ip arp 10.76.20.250 0100.5e7f.19fa

DCRdn5kAA1(config-if)# exit

DCRdn5kAA1(config)# mac address-table ?

  aging-time    Aging Time

  notification  User notification of an event via log message

  static        Static Entry

DCRdn5kAA1(config)# mac address-table static 0100.5e7f.19fa vlan 800 int po11 po12

ERROR: mac address is an ip multicast mac

DCRdn5kAA1(config)# vlan configuration 800

DCRdn5kAA1(config-vlan-config)# ip igmp snooping static-group 239.255.20.250 int po1,po11,po12

Interface information not available, configuration cached

DCRdn5kAA1(config-vlan-config)#

IGMP snooping is enabled.  Not sure what else to do.  Can't go very far if the configuration doesn't even want to apply.  As can be seen, I don't have a "multicast" keyword option to the mac address-table command.  I don't understand what "Interface information not available, configuration cached" means.  The interfaces are already configured and live; I'm passing other traffic on that subnet/VLAN without issue.

Running NX-OS 5.2(1)N1(3) on two 5548UP switches with routing enabled.

Any direction toward resolution appreciated, as this has become a major stumbling block in this migration.

[Reza Sharifi]

Have a look at this doc with example on configuring Nexus with static MAC

http://www.fryguy.net/2010/10/28/static-arp-entries-on-nx-os/

HTH

[mfarrenkopf]

No help there.  The ARP entry works just fine.  It's trying to statically define the MAC that's an issue.  One workaround I'd seen is trying to statically join a multicast group with an identical IGMP multicast address, but that's where I get the "Interface information not available" error.

[Rolf Fischer]

Hi,

I may be wrong, but to my best knowledge you don't need static MAC bindings when using the IGMP-Option in Multicast-Mode (MM).

The ARP entry is needed because the combination Unicast IP address <> Multicast MAC in ARP replies will be dropped by Cisco Routers (RFC 1812 3.3.2).

The MAC bindings in MM without IGMP option is only needed for limiting the NLB traffic, otherwise it would be flooded over all ports in that VLAN.

With the IGMP option enabled this should be done by IGMP snooping (that's why an IANA reserverd MC MAC 01-00-5e-xx-xx-xx is used by this mode) - as far as I understand it.

Without limiting the NLB traffic to particular interfaces it should work anyway but of course you don't want the traffic to be flooded and your switch acting like a hub.

I did some further reading in this document: http://www.cisco.com/en/US/products/hw/switches/ps708/products_tech_note09186a008059a9df.shtml which gives good explanation and various solutions beside static MAC entries. The problem with IGMP snooping is not limining traffic flooding (like in "normal" MM) but the requirement of mrouter-ports on all relevant switches. 

Hope that helps

Rolf

P.S.: Found this discussion:

https://supportforums.cisco.com/thread/2058501