From: Luca Hall (lhall@setnine.com)
Date: Tue Jun 03 2008 - 12:03:09 ART
heres my guess:
(1)
once the change happens do you have some type of script or
something sending out traffic (from .44) all the way to the 6500
to let the switches know of the mac change?
(2)
assuming your not doing 1, and theres no gratious arps send out
they see they have the mac (old downed first) and wont arp, keeping the old mac
then everything will fail
(3)
now local will arp and get the correct mac and work locally
(4)
no traffic or notification of change so it will use the old downed first mac
(5)
pings from local are most likely going to lvs2 while pings from your
6500 are most likely going to lvs1 now
(6)
why wouldnt it? how does it know to change?
(7)
i assume at this point lvs1 is sending traffic, and has taken about
the same time it takes to clear the arp cache 3 times
tcpdump locally should show you all this in action
----- Original Message -----
From: Jack Tsai <tsai@eng.fsu.edu>
To: ccielab@groupstudy.com
Sent: Tue, 3 Jun 2008 08:35:19 -0400 (EDT)
Subject: Re: CCIE LAb permission
test.
Recently I sent a message as follows to ccielab@groupstudy.com, but
never got posted.
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
This archive was generated by hypermail 2.1.4 : Tue Jul 01 2008 - 06:23:20 ART