Cannot add Static ARP entry to HP A5800 switch for multicast MAC - Windows 2003 NLB

Posted on 2011-10-31
Last Modified: 2012-10-17
We made some "basic" changes to our core network on Saturday and one of the surprising fallouts is that we can't connect to our NLB - network load balance - IP address anymore across routed vlans.  We have 8-10  vlans in our network and unless I'm on the specific vlan I can't get back to the cluster IP address anymore.  The rest of the vlan in question is routing into and out of the switch just fine.  We are running an HP A5800 (H3C) stacked switch pair as our core networking equip.

We have had this config working fine within VMware ESXi 4.1 for the last 6 months.  Our changes Saturday somehow knocked out whatever it was that made this work in the past.  We've tried adding a static ARP entry but get an error that says that it's an invalid MAC.  I understand that the switch supports static ARP entries for Unicast IP addresses with multicast MAC's - but it doesn't appear so.  we are running Comware Software, Version 5.20, Release 1206 on the switch stack.  This connects into our HP virtual connect mezzanine on an HP C7000 chassis.

Like I mentioned-  this has been working fine for the last 6 months after P2V's of all of these Win2k3 terminal servers and now it's broke.
Question by:Shadow_knows
    LVL 17

    Expert Comment


    What were the basic changes?

    Accepted Solution

    We had our original vlan on the flat network setup using our ASA as the default gateway before we had layer 3 routing.  We removed that interface configuration and put in a small /29 network between our ASA, web content filter and our HP core.  The original DFGW address no longer exists.  Our hunch is that the ARP table on the ASA had the MAC address for the NLB cluster IP and passed it along to the HP core.  Now that the HP doesn't have that "upstream" network setup - must be the reason why that ARP value is gone.

    We're under the impression that we probably need to upgrade the code on the HP A5800 switch in order to execute the ARP command for the multicast MAC entry.  We're putting on newer code tonight to test with.
    LVL 17

    Expert Comment

    Yes it seems that some vendors don't like the arp to multicast mac address. I guess the ASA was ok with it.

    Author Closing Comment

    We had to tell the A5800 not to inspect for Multicast.  We upgraded the code and we also enabled settings so that we could put in static ARP entries to the switch for multicast MACs.

    Expert Comment

    We are having a similar issue with the A5800.  The switch will not pass the static ARP entries to other VLANs and IP subnets.  Were you successful to get your virtual IP to work across all your VLANs and routed network?  Would you mind sharing a sample configuration?  We have the newer code,  the undo arp check enable command, and a static ARP.

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