network cards, virtual interface and performace

[Shivkumar]

Hi,

We are using PA-RISC servers. Servers has more than one physical lan cards installed.

Are different lan cards connected through cat5 cable to different ports of the switch ?

I was thinking to use different physical lan card (lan interface) for a new application so that i can use separate network traffic path. This way i will get more network speed.

The other option was to use the virtual network interface (IP aliasing) for the new application. But my apprehension is if we use different virtual interfaces for old and new applications on same physical NIC then network traffic will go through the same physical card, cable and switch port and performance would be impacted because of sharing the traffic by various applications.

Am i thinking in right correction ? Appreciate your viewpoint.

Shall i use different NIC for different application having different subnet ?

Thanks,
Shiv

[A. Clay Stephenson · Accepted solution]

If on different subnets then you must use another NIC (or at least another physical port in the same multi-port NIC). If you really want to increase network throughput through a given IP address, the HP-UX way is Auto Port Aggregation (APA). APA combines several physical NIC ports into 1 logical IP connection. It also, seamlessly, allows a physical port, cable, or switch port to fail without losing the connection. APA is not supported on all ethernet switches nor is it free but it is very powerful and robust.

[Chauhan Amit]

Hello Shiv,

You should use different NIC for different application having different subnet . Even if it is same application and the subnet is different then also you should use different NIC as it will affect the throughput of the Card managing two different subnets.

As Clay suggested you should also consider APA , Check the link below for more informtion on the same:

HP APA Configuration Examples

http://docs.hp.com/en/J4240-90033/ch01s08.html

-Amit

[Steven E. Protter]

Shalom Shiv,

Virtual networking does not do anything for performance. The total performance of the NIC card and all of its virtual addresses will equal that of the NIC card by itself.

Things to think about:

1) If you add a NIC card and its on the same Switch as the existing one, it can't have the same network, and its probably not going to perform well. To boost performance on a busy switch, you will need to connect to a new switch that is capable of high performance.

2) I've seen a lot of folks wonder why their GB NIC cards performed poorly. The number one reason is that they were plugged into 100 BaseT switches or GB switch ports manually configured for 100 BaseT. To get a performane boost, you need to analyze your network environmetn.

Conclusion: If you get a new NIC and a better swtich you should get a boost from another NIC card. If your current core switch is saturated, there is no benefit in either of your plans.

Some research and coordintion with your networking team is in order.

SEP

[rick jones]

A couple things - one can configure multiple logical interfaces into separate IP subnets. Also, one can configure multiple physical interfaces into the same IP subnet - it just means using something like ip_strong_es_model ==2 to get it to do what most people ass-u-me it would do by default.

However, for multiple NICs, APA is a good way to go as it increases aggregate throughput and availability.

If a switch is bottlenecked adding one more link, it is either _really_ busy, or really low-end.

While I'm sure that HP would be more than happy to sell you another NIC and/or a copy of APA, you might want to first look at your network utilization - just how loaded is it already? If not all that loaded, adding the second application probably won't do all that much to it. (Well, if the second application was netperf... :)

[Chauhan Amit]

Check out these threads as well for NIC Throughput:
http://forums1.itrc.hp.com/service/forums/bizsupport/questionanswer.do?threadId=625391

http://forums1.itrc.hp.com/service/forums/questionanswer.do?threadId=945761

http://forums1.itrc.hp.com/service/forums/bizsupport/questionanswer.do?threadId=592349

-Amit