Do i need to send gratuitous ARP request after restarting network service after online migration.

Hi all,

What i am trying out here is online migration of server process
which has active client connections.
When i move this server process to new node , i want to change IP
address of destination host
to that of source so that clients doesn't know about migration.
I think after migration , and setting new IP address on
destination , i should send gratuitous ARP
request with new ip address and the MAC address of the device on
destination. This should update
arp cache entry for this IP address in all neighbors. And next packet
form client destined to this IP
will be sent to migrated one and not the source one. (which will be
suing different IP now).

Or restarting network service after changing IP address on
destination side would do this for me and i don't need to send any
extra ARP request ?? or i will need to ??

Thanks,
Rohit

If i need to send ARP request , how to send one ?? is there a utility
that will do it for me or library-call which i can use ?? I have a
kernel module inserted , so can i directly use send_arp function in
linux kernel ?? What is the way to send gratuitous ARP , in much
cleaner way on platforms like linux , Solaris, AIX and BSD ??

http://su2.info/doc/arpspoof.php

Im not responsible for anything that my incurr after reading this post.
But, im pretty sure that reading the sources of the above link will
help you further your investigation.

Good luck.
will_u_tellmemore wrote:
> If i need to send ARP request , how to send one ?? is there a utility
> that will do it for me or library-call which i can use ?? I have a
> kernel module inserted , so can i directly use send_arp function in
> linux kernel ?? What is the way to send gratuitous ARP , in much
> cleaner way on platforms like linux , Solaris, AIX and BSD ??

On Thu, 21 Dec 2006 06:35:06 -0800, will_u_tellmemore wrote:

> Hi all,
>
> What i am trying out here is online migration of server process
> which has active client connections.
> When i move this server process to new node , i want to change IP
> address of destination host
> to that of source so that clients doesn't know about migration.
> I think after migration , and setting new IP address on
> destination , i should send gratuitous ARP
> request with new ip address and the MAC address of the device on
> destination. This should update
> arp cache entry for this IP address in all neighbors. And next packet
> form client destined to this IP
> will be sent to migrated one and not the source one. (which will be
> suing different IP now).
>
> Or restarting network service after changing IP address on
> destination side would do this for me and i don't need to send any
> extra ARP request ?? or i will need to ??

Here is what I would do if moving a service from one server to another.

1. Edit DNS record for service and change TTL to 30
(this ensure that the record isn't cached too long so once services are
moved the clients will goto the correct server)

2. Move said service to new server

3. Edit DNS record and change IP Address to new server and set default
TTL

You don't need to do anything with ARP that will happen automatically.


--

Regards
Robert

Smile... it increases your face value!


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