cancel
Showing results for 
Search instead for 
Did you mean: 
cancel
4616
Views
3
Helpful
4
Replies

Vm Hosts are not getting IP once its restarted VMWare is suggesting to diable gratuitous ARP to resolve.

Hi,

 

I would like to know the effect of disabling gratuitous arp in server farm switches(model : WS-C3560X-24T-S IOS:15.0(2)SE4 ) as the VM's are  connected to this switches are not getting IP when they restarted when we check with VMware they are suggesting to disable this option.

 

Thanks & Regards,

Pradeep Dhanasekaran

1 Accepted Solution

Accepted Solutions

Hi Pradeep,

The VMware KB is useful. Presumably you've gone through the Cisco Duplicate IP Address 0.0.0.0 Error Message Troubleshoot document they reference, or are not able to follow any of those recommendations due to not having the correct IOS release?

If you have VMs connected to other VMware vSphere servers that are not exhibiting this problem, then I'd try and understand the difference between the two different vSphere server types before making any significant changes to the router/switch configurations.

I'm generally wary of changing settings such as gratuitous ARP as there may be some other impact that is not immediately obvious. For example gratuitous ARP is used by HSRP to update switch CAM tables when an HSRP state change occurs. If the switch is not able to send the ARP, this may slow convergence in the event of a failure.

Regards

View solution in original post

4 Replies 4

Steve Fuller
Level 9
Level 9

Hi Pradeep,

The command enables and disables the sending of gratuitous ARP from the switch. I think before disabling I'd ask VMware to explain exactly how having gratuitous ARP enabled on the switch is stopping the VMs getting an IP address. We have 1000s of VM connected to Catalyst switches and have never disabled this feature.

Can you provide a little more background as to how you arrived at this point i.e., the troubleshooting you've already undertaken that has led to VMware's recommendation? Have you been able to do packet capture on the network or DHCP server to check whether the DHCP request is reaching the server etc.

Regards

Hi Steve,

Thanks for your reply we are facing this issue with particular model only(VSphere 5.1) other VM's connected on the same switch is working fine please find the below link we referred, 

http://kb.vmware.com/selfservice/microsites/search.do?language=en_US&cmd=displayKC&externalId=1028373

Regards,

Pradeep Dhanasekaran

Hi Pradeep,

The VMware KB is useful. Presumably you've gone through the Cisco Duplicate IP Address 0.0.0.0 Error Message Troubleshoot document they reference, or are not able to follow any of those recommendations due to not having the correct IOS release?

If you have VMs connected to other VMware vSphere servers that are not exhibiting this problem, then I'd try and understand the difference between the two different vSphere server types before making any significant changes to the router/switch configurations.

I'm generally wary of changing settings such as gratuitous ARP as there may be some other impact that is not immediately obvious. For example gratuitous ARP is used by HSRP to update switch CAM tables when an HSRP state change occurs. If the switch is not able to send the ARP, this may slow convergence in the event of a failure.

Regards

Hi Steve,

I will check the difference between  two servers and thanks for sharing the impacts.

Thanks & Regards,

Pradeep Dhanasekaran

Getting Started

Find answers to your questions by entering keywords or phrases in the Search bar above. New here? Use these resources to familiarize yourself with the community: