[j-nsp] MX960 ARP issues

[John Neiberger]

On Tue, Jan 28, 2014 at 8:42 AM, Marcel Plug <marcelplug at gmail.com> wrote:
> If packet captures on the servers don't show the arp packets getting there,
> its a good bet they aren't getting there.  Have you ruled out the switch as
> the culprit?  At least monitor the server's port on the switch to confirm
> the arp packets are leaving the port because to me it seems like they
> aren't.  I don't have any suggestions as to why that would happen but it
> would be good to rule it out...
>

It's very unusual. The servers receive broadcasts from other devices
in the vlan including RouterA. RouterB can send broadcast ARP requests
and receive responses from other devices on the subnet, like the other
router and the switch. RouterB says that it is sending the ARP
request. I don't see anything unusual about it.

15:33:35.097423 Out
        Juniper PCAP Flags [Ext], PCAP Extension(s) total length 22
          Device Media Type Extension TLV #3, length 1, value: Ethernet (1)
          Logical Interface Encapsulation Extension TLV #6, length 1,
value: Ethernet (14)
          Device Interface Index Extension TLV #1, length 2, value: 284
          Logical Interface Index Extension TLV #4, length 4, value: 97
          Logical Unit Number Extension TLV #5, length 4, value: 1
        -----original packet-----
        5c:5e:ab:5f:6a:bb > ff:ff:ff:ff:ff:ff, ethertype 802.1Q
(0x8100), length 46: vlan 8, p 0, ethertype ARP, arp who-has
10.2.47.149 tell 10.2.47.147

If other devices on the vlan are seeing broadcasts from RouterB, I
don't see why these servers wouldn't, as well. I just got some
additional information from one of the people reporting the problem.
It sounds like this server does respond correctly while it's booting
until a second interface comes up. They said it is the "Primary C2"
interface, but I have no idea what that means. I need to get a better
picture for how this server is connected to the network. I don't think
I have the full story.