Two Network Cards Query

[Ryan Ma]

I have two network card config with two IP.
Say 192.168.0.1 and 192.168.0.2 in HP-UX 11.0

How can I control using which IP to telnet / ping to other host? Is there any Primary / Secondary concept on these two IP?

Can I config one network card to be a stand-by of another?

Can I config to use two network cards for load balancing? (2 NIC using the same IP)

[Patrick Wallek]

If you have 2 NICs on the same machine it is highly recommended to have them on different subnets.

As far as load balancing or having the 2 cards behave as one, you should check HPs Auto Port Aggregation software. It is a product you have to purchase separately.

http://www.software.hp.com/cgi-bin/swdepot_parser.cgi/cgi/displayProductInfo.pl?productNumber=J4240AA

[Ravi_8]

Hi,

if you have 2 network cards, you can assign 2 different IP's with same or different subnetmask. you can force ftp/telnet/ping to use particular interface by downing the another one(ifconfig lanx down). anyway the load balancing on both interfaces i haven't heard till now.

[Ryan Ma]

Thanks for your information.

To force establishing connection by dowing another interface is not a good way.

As for example, if I run two web services using two IP, the method is not pratical.

[Rainer von Bongartz]

Ryan,

as far as know there is no 'build in' functionality to use one nw-card as a stand-by for another.

The HP Product MC/Service Guard allows you to build high available applications and one of the functioinalites of MC/SG allows you to configure hot stand-by network cards.

Regards
Rainer

[Ryan Ma]

Rainer von Bongartz,

Just as you say, MC/Service Guard is used for cluster of application. It seems no one will use it just for a stand-by network card. :)

[Santosh Nair_1]

Ryan,

Just an FYI, you don't need to have two cards to have two IP addresses...you can bind multiple IP addresses to the same card using the ifconfig : command, i.e. in your case:

ifconfig lan0 192.168.0.1
ifconfig lan0:1 192.168.0.2

Having multiple NICs on the same subnet doesn't really buy you much. If you're looking to get the extra bandwidth, look into the APA product from HP. This product allows you combine multiple NICs into one "supre" NIC. For example, you can combine 3 100BT lan cards to get an effect 300BT lan card.

You c an get more info on APA from the following links:

http://docs.hp.com/hpux/onlinedocs/netcom/hp_apa_using11i.pdf
http://docs.hp.com/hpux/onlinedocs/J4240-90005/J4240-90005.html

-Santosh

[Christopher Caldwell]

HP's networking implementation won't load balance in the 'Cisco' sense. If you have multiple NIC cards and you add more than one default route, HP uses the last default route to push traffic.

(If you add more than one default route to a Cisco router where the default routes point out different interfaces, Cisco will load balance on a packet by packet basis or on a destination by destination basis).

[Christopher Caldwell]

When using multiple IPs on a given interface, it's up to the application to select which IP traffic comes from.

Many modern IP servers (httpd, ftpd, etc.) bind to specific, configurable IPs in multiple IP configurations; that's how many of the "virtual" servers work. Older implementations use the IN_ADDR_ANY constant to bind/listen to ANY IP available on that host.

Outbound traffic will look like it's coming from the systems base IP.