[TriLUG] multiple IP from the same network card?
Jason Tower
jason at cerient.net
Wed Jun 18 14:00:36 EDT 2003
subnets are a IP (layer 3) thing, a switch operates at layer 2. the switch
only cares about the MAC (layer 2) address. you can have lots of different
subnets running through a layer 2 switch, but you won't be able to
communicate between subnets without routing (at layer 3) between them.
jason
On Wednesday 18 June 2003 13:56, lfwelty wrote:
> How do the virtual interfaces work w/ different subnets if you are
> connected via the same physical interface?
>
> ie. Do you have to be plugged into a switch that can handle different
> subnets on the same interface?
>
> Jason Tower wrote:
> > what you are describing is a virtual interface, and it's a snap. for a
> > quick and dirty setup, you can simply run the following:
> >
> > [root at bigtoe root]# ifconfig eth0:0 10.1.1.1
> >
> > which results in something like the following:
> >
> > [root at bigtoe root]# ifconfig
> > eth0 Link encap:Ethernet HWaddr 00:A0:C9:5A:DF:F7
> > inet addr:10.0.0.100 Bcast:10.0.0.255 Mask:255.255.255.0
> > UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
> > RX packets:454545 errors:0 dropped:0 overruns:0 frame:0
> > TX packets:311037 errors:0 dropped:0 overruns:0 carrier:0
> > collisions:0 txqueuelen:100
> > RX bytes:94017376 (89.6 Mb) TX bytes:31798276 (30.3 Mb)
> > Interrupt:10 Base address:0xdc00 Memory:ef201000-ef201038
> >
> > eth0:0 Link encap:Ethernet HWaddr 00:A0:C9:5A:DF:F7
> > inet addr:10.1.1.1 Bcast:10.1.1.255 Mask:255.255.255.0
> > UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
> > RX packets:0 errors:0 dropped:0 overruns:0 frame:0
> > TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
> > collisions:0 txqueuelen:100
> > RX bytes:0 (0.0 b) TX bytes:0 (0.0 b)
> > Interrupt:10 Base address:0xdc00 Memory:ef201000-ef201038
> >
> > to make this permanent, copy /etc/sysconfig/network-scripts/ifcfg-eth0 to
> > ifcfg-eth0:0 and modify the file contents with the desired info. you can
> > have several virtual interfaces, all on different subnets. good luck!
> >
> > jason
> >
> > On Wednesday 18 June 2003 13:29, Michael Winslow Czeiszperger wrote:
> >>Hi--
> >>
> >>I'm working on a new feature for our load testing product and have been
> >>stumped on a Linux configuration issue. The product needs to send out
> >>HTTP requests from multiple IP addresses in order to fake out IP-based
> >>load balancers. To do this I need to configure a Linux box to have
> >>multiple IP addresses on the same network card, but for the life of me
> >>I can't find the HOWTO or docs to do this. Strangely enough it seemed
> >>fairly easy on Windows :-(
> >>
> >>Any pointers to the right documentation would be greatly appreciated...
> >>
> >>Thanks,
> >>
> >>--------------------------------
> >>Michael Czeiszperger
> >>czei at webperformanceinc dot com
> >>Web Performance, Inc.
> >>9207 Baileywick Road, Suite 203
> >>Raleigh, NC 27615
> >>919-845-7601
> >>
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> >
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