Isilon: IP conflict. Error: "arp: <MAC> is using my IP address <IP> on <interface>"

Summary: Issues in accessing SMB shares and mount NFS exports using IP addresses. The IP's on Isilon interface are pingable and also has a valid ARP entry with the mac address in the output of netstat -ni. ...

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Symptoms



The following error appears in /var/log/messages:
 
2018-08-05T23:58:00-05:00 <0.3> isilon-1 /boot/kernel.amd64/kernel: arp: <MAC:ec> is using my IP address 10.232.5.50 on ix1!
2018-08-05T23:57:17-05:00 <0.3> isilon-2 /boot/kernel.amd64/kernel: arp: <MAC:58> is using my IP address 10.232.5.51 on ix1!

Issue accessing SMB shares and mount NFS exports using the above IP addresses seen in messages. The respected IP's are on Isilon interface and are pingable. Also has a valid ARP entry with the mac address in netstat -ni:

$ cat isilon-1/ifconfig
ix1: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> metric 0 mtu 1500        options=e407bb<RXCSUM,TXCSUM,VLAN_MTU,VLAN_HWTAGGING,JUMBO_MTU,VLAN_HWCSUM,TSO4,TSO6,LRO,VLAN_HWTSO,RXCSUM_IPV6,TXCSUM_IPV6>
        ether <MAC:cd>
        inet 10.232.5.90 netmask 0xffffff00 broadcast 10.232.5.255 zone 1
        inet 10.232.5.78 netmask 0xffffff00 broadcast 10.232.5.255 zone 1
        inet 10.232.5.50 netmask 0xffffff00 broadcast 10.232.5.255 zone 4
        inet 10.232.5.66 netmask 0xffffff00 broadcast 10.232.5.255 zone 4
        inet 10.232.5.67 netmask 0xffffff00 broadcast 10.232.5.255 zone 4
        inet 10.232.5.68 netmask 0xffffff00 broadcast 10.232.5.255 zone 4
        inet 10.232.5.69 netmask 0xffffff00 broadcast 10.232.5.255 zone 4
        nd6 options=29<PERFORMNUD,IFDISABLED,AUTO_LINKLOCAL>
        media: Ethernet autoselect (10Gbase-SR <full-duplex,rxpause>)
        status: active

$ cat isilon-2/ifconfig
ix1: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> metric 0 mtu 1500        options=e407bb<RXCSUM,TXCSUM,VLAN_MTU,VLAN_HWTAGGING,JUMBO_MTU,VLAN_HWCSUM,TSO4,TSO6,LRO,VLAN_HWTSO,RXCSUM_IPV6,TXCSUM_IPV6>
        ether <MAC:69>
        inet 10.232.5.91 netmask 0xffffff00 broadcast 10.232.5.255 zone 1
        inet 10.232.5.79 netmask 0xffffff00 broadcast 10.232.5.255 zone 1
        inet 10.232.5.51 netmask 0xffffff00 broadcast 10.232.5.255 zone 4
        inet 10.232.5.61 netmask 0xffffff00 broadcast 10.232.5.255 zone 4
        inet 10.232.5.64 netmask 0xffffff00 broadcast 10.232.5.255 zone 4
        nd6 options=29<PERFORMNUD,IFDISABLED,AUTO_LINKLOCAL>
        media: Ethernet autoselect (10Gbase-SR <full-duplex,rxpause>)
        status: active

Cause

The IP addresses which have issues accessing SMB shares and NFS exports are assigned/used by another external host/server/machine in customer's environment leading to the IP conflict.

IP's: 10.232.5.50 and 10.232.5.51

1) Run the following command on the cluster to find a valid ARP entry for the IP which has issue:
isilon-1# isi_for_array -s arp -an | grep <IP>

Or identify the arp entries on the Isilon for the above IPs in the log file:
 
isilon-1$ cat arp | grep -i 10.232.5.50
? (10.232.5.50) at <MAC:cd> on ix1 permanent [ethernet]
 
isilon-2$ cat arp | grep -i 10.232.5.51
? (10.232.5.51) at <MAC:69> on ix1 permanent [ethernet] 
 
MAC address <MAC:cd> and <MAC:69> belongs to Isilon nodes 1 and 2 ix1 interfaces 

 
2) Entry in /var/log/messages suggest that the IP's are on MAC address which does not belong to Isilon (different host):

Run the following command on the cluster:
 
# isi_for_array -s cat /var/log/messages | grep -i "is using my IP address <IP addr>"

Or look for for the error in messages log file:
 
messages$ tail -n100 isilon-*-messages | grep -i arp
2018-08-05T23:58:00-05:00 <0.3> isilon-1 /boot/kernel.amd64/kernel: arp: <MAC:ec> is using my IP address 10.232.5.50 on ix1!
2018-08-05T23:57:17-05:00 <0.3> isilon-2 /boot/kernel.amd64/kernel: arp: <MAC:58> is using my IP address 10.232.5.51 on ix1!


Search for the above MAC address is var/log/messages on Isilon (both nodes):

2018-08-06-001$ grep '' isilon-*/ifconfig | grep -i <MAC:ec>
2018-08-06-001$
 
2018-08-06-001$ grep '' isilon-*/ifconfig | grep -i <MAC:58>
2018-08-06-001$
 
MAC address <MAC:ec> and <MAC:58> does not belong to Isilon

The above IP's are being used on a NetApp Server which led to an IP conflict.

HOST02#show arp|incl 10.232.5.50
10.232.5.50           N/A  <MAC:ec>  Vlan5, Ethernet8/2
HOST02#

HOST02#show arp|incl 10.232.5.51
10.232.5.51           N/A  <MAC:58>  Vlan5, Ethernet8/1
HOST02#

Resolution

If IP conflict persists, suggest checking with the network team.
Find the Server/Machine which has the MAC address as seen in /var/log/messages.
Contact Isilon Support to remove the IP addresses from the Isilon network pool.
or
Contact your Network team to remove the IP from the Client's server/Machine.

Validation:
  1. Remove the interface from the network pool so the affected IP's are no longer on Isilon interfaces or edit the IP range in the network pool.
  2. After removing the interface, ping the IP address and check if they are pingable.
  3. If its pingable, then the IP's are assigned to a different machine/server in the environment.
  4. A packet capture tells the MAC address of the Server on which the IP's are assigned. 

Affected Products

Isilon

Products

Isilon
Article Properties
Article Number: 000052761
Article Type: Solution
Last Modified: 11 Oct 2024
Version:  3
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