Dual Network Cards

[Amiel Tutolo]

Sorry about that first one, a return key got in the way. Here is my question:

I have an N4000 with two NIC's. We are running a production Oracle 8.0.5 DB.

Under normal daily circumstances most people are doing inquire only against the database but here is where my confusion starts. My lan0 card is doing all the packet receives while my lan1 card is doing all the packet xmits. Since I have defined everyones NT machine to use a sqlnet connection through my lan0 card I would expect to see very little traffic on lan1. Also if I leave lan1 enabled the overall performance of the network seems slower. Also it appears that lan0 and lan1 are mirroring each other in respect to the number of packets being sent (lan1) or being received (lan0). I would expect more xmits than receives given the nature of the application running but not for the 2 to be equal. Also I not only see this through glance but with a switch monitoring tool on an NT machine. Can anybody explain why I might be seeing this or a good paper to read? My UNIX networking knowledge is limited. Thanks in advance for any help.

[Kofi ARTHIABAH · Accepted solution]

I am assuming that you have two different IP address for each of the cards. If this is the case then is it possible that your default gateway is through the lan1? check with netstat -rn. if that is the case then you will have to modify your default routes to use the lan0 IP address as the default route...

[Joseph T. Wyckoff]

IP address determines routing...but name resolution maps to IP address.

What you MIGHT be seeing is a new connection to your clients, rather than a reply on the same connection.

1. NT client sends message, hey, I want some data, send it to me (ntbox) when you get a chance...(maybe this is UDP, or maybe it is a very simple TCP send message and close transaction)

2. UX Listener gets message, starts query, resolves the client name (NTBOX) and sends a message to the ntbox, using default routing.

IF the name NTBOX resolves to the subnet attached to your UX lan 1 - the default routing will go out that card...assuming this is a new connection.

It is really hard to avoid traffic on your primary network card...you really have to understand name resolution and routing...and even then, if there is a router (or several) in the middle...well thats out of my depth...

Good Luck...it should prove an interesting puzzle...

[John Bolene]

Each of the network cards should be on a different network segment , such as having one on a FDDI or 100 base segment for high speed transfers and the other on a 10 base segment for management traffic. There should be a central DNS that all users get information from to resolve.
What may be happening is that the request comes in on one IP address due to the default gateway for the user and the default gateway for the server is set up to return requests thru the 2nd IP address.
It would help to know more about your setup. At a minimum to know what the IP addresses and gateways of the client and each server card.