In
RQ said:
Thanks Pillips,
I suggested to do that way, but I'd like to know why 2-nic 2-IP same
LAN is not allowed and what could be happen in the network if apply
this configuration?
My take on this is if you have two IPs with the same name, then there will
be a conflict with NetBIOS names (duplicate names, same IP). This is the
basis of MS networking that's difficult to circumvent. Many applications
rely on NetBIOS support. Assuming you will be wanting this for 'failover', I
can understand but to make two IPs work on the same network (same segment or
enterprise) you need to disable NetBIOS, MS CLient Service and the F&P
service on one of them. But considering its for a database, and IIRC, you
are using SQL, SQL requires NetBIOS name resolution, so this automatic
failover solution will fail. Exchange behaves the same way, since MAPI
clients REQUIRE NetBIOS resolution.
You can fudge this by trying two DNS A entries with the same name and give
it the two different IPs, but the issue comes down to, since Round Robin is
in effect, that the server will offer one IP to one client, and then the
other to the next query. If the one NIC is down, it will not stop DNS from
giving that IP to a querying client and hence the client cannot connect
since the NIC is down. This still does NOT address the duplicate name issue
with the two IPs for the same name. This also does not work with Subnet
Prioritization, since both IPs are on the same subnet.
As previously posted, its highly suggested to use Clustering to achieve this
effect. Or use NIC Teaming (based on the NIC manufacturer's software) that
gives both NICs the same IP and they work in conjunction. meant for load
balancing, but IIRC with teaming, that should one fail, the other continues
servicing, but warnings are giving. You would need to read up on the
vendor's product sheet for more info on this.
Now if I missed something else on this, Phillip, or anyone else that reads
this, please do add ro comment on this. I just want the poster to understand
the mechanisms behind this in order to realize what is occuring and why.
--
Regards,
Ace
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Ace Fekay, MCSE 2000, MCSE+I, MCSA, MCT, MVP
Microsoft Windows MVP - Active Directory
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