From: Jack Tsai (jacknew2005@gmail.com)
Date: Tue Jun 03 2008 - 09:44:46 ART
Dear Study Group:
>
> We have two LVS servers running linux that we want them to do fail-over.
> One server, 172.16.28.37, has one NIC, and 172.16.28.44 has been
> assigned to the same NIC as the secondary IP address.
> 172.16.28.44 is the server address of the LVS service.
> The other server, 172.16.28.20, has two NIC's, and 172.16.28.44 would
> be assigned to the second NIC when the first LVS server dies.
> Both servers have the same default gateway, 172.16.28.1, which is the
> server switch, Cisco 4503.
> The server switch's default gateway is 172.16.28.2, a cisco 6509. IP
> routing is enabled on both 4503 and 6509 switches.
>
> When we disable the second IP setup on the first server and enable the
> second NIC on the second server, the following are observed:
> (1) show arp | include 28.44 on the server switch (4503) still shows
> the MAC address of the first server's NIC.
> (2) ping 172.16.28.44 is not successful within the subnet or outside
> the subnet.
> (3) after clear arp-cache on the server siwtch, ping 172.16.28.44
> within the subnet is successful, but cannot ping it from outside.
> (4) show arp | include 28.44 on the 6509 switch shows the MAC address
> of the first server NIC, before and after the clear arp-cache on the
> server switch (4503).
>
> After swapping 172.16.28.44 back from the second sever to the first
> server, the following are observed:
> (5) ping 172.16.28.44 is successful from everywhere.
> (6) show arp | include 28.44 on the server switch (4503) still shows
> the MAC address of the SECOND server's NIC.
> (7) had to clear arp-cache on the server siwtch (4503) three times
> before show arp | include 28.44 could show the FIRST server's NIC.
>
> Could someone shed a light on the dark area between (5) and (6)?
>
> Thanks,
>
> Jack Tsai
> study very hard for the CCIE R&S lab
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