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Old 11-09-2003, 04:40 PM   #1
h/w
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ethernet and wireless


what exactly happens when u have an ethernet and a wireless interface up together?
i have eth0 (ethernet), and eth1 (wireless).
im a bit confused bout how things work here. each by themselves work fine.

if i have eth0 up first, and it gets an ip addr to use, then i insert my wireless card, and it gets an ip addr, its like theres a conflict as to which one to use or some.

anyone can clarify this for me?
thanks.
 
Old 11-09-2003, 09:19 PM   #2
akaBeaVis
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Well, there's really no "conflict" here, but unless they are connected to different routers or access points, only one of them is going to do any work, and typically that will be the last one configured. take a look at the route command before and after inserting the 2nd card, before insertion, eth0 has the route to your access point/router, after insertion, eth1 is going to have it.

in other words, if both cards are trying to reach the same destination, the last one assigned the route to it will do the work.

ps: if you were thinking (like me) that you could somehow "gang" 2 cards together and use their aggregate bandwidth, so far all I can figure is that one needs to do all the transmitting and the other all the receiving, assuming both are connected to the same access point or router. this sounds like something that would have to be hacked in the card's driver

Last edited by akaBeaVis; 11-09-2003 at 09:25 PM.
 
Old 11-09-2003, 09:53 PM   #3
h/w
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hmm i havent checked 'route' (on win32 right now) ... will look tomorrow.
but im sure what ur saying is whats happening. and yeah, the two routers/gateways are different.

but im not too sure about your idea of totalling the b/w using 2 cards though. have you tried it and seen it work? wouldnt things to be done on http have to be on 80,? even if the supposed X'fer rate for a card is 11Mbps, it would never reach it, possibly cos of the signal quality?
as for telling which interface to do the X'mission, and which to receive, can something like netfilter do it, if this is possible?

hey, did you check out my other post titled 'iwpriv'? its got to do with my orinoco card, and i would appreciate any suggestions from you.

thanks again.
 
Old 11-09-2003, 11:01 PM   #4
akaBeaVis
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I'm not familiar with netfilter, what is it? As for telling which card to do what, that's where route comes in. So, you're wired card is connected to one router, and your wireless card to a different one, this is interesting, what do each of these routers connect to? Do they both act as internet gateways also? Does each one have a valid internet ip address?

Last time I read anything about wireless throughput, I believe they said that after overhead, the actual speed was like 3.3Mbps. If I can find the link I'll post it. I think it was over on extremetech.com or pcmag.com

as for aggregating the bandwidth of 2 cards, I haven't tried it, seems like it would require some kind of additional driver or hacking the actual driver modules for the cards.

I don't have an orinoco card yet, but post the link and I'll try.
 
Old 11-10-2003, 01:01 AM   #5
h/w
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netfilter = iptables.
well, i was sitting in school. and i was connected to the lan, and i had my wlan card in my bag, which i inserted to see what happens ... and i posted.

i cant yet imagine what to look at in the case of running 2 interfaces (either connected to one router, or to multiple ones). not really a networking/systems guy although its what i kinda like doing. if one app is using port 80, i dont see how it will send on one interface, and receive on another. 2 different mac and n/w layers (thats how im thinking ...).

as for the 'iwpriv' question, here it is:
http://www.linuxquestions.org/questi...hreadid=113582

thanks again.
 
Old 11-10-2003, 01:31 AM   #6
akaBeaVis
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ok, iptables I've heard of

So you were sitting in school and were connected to the lan via the wired card, you stuck in your wireless card and were able to post, but the question is: after you stuck in your wireless card, which interface (wired or wireless) was used for your post? Only one of them was used, but which?

I'm betting it was the wired interface, but the only way to know for sure is to do it again, but before sticking in your wireless card, check route, and ifconfig, see what eth0 is doing, then stick in the wireless card, check route and ifconfig again, see if the wireless card has a valid ip address for the same network the the wired card had, see if the routing has changed so that eth1 is mapped to the default gateway, I don't think you're going to see that both cards have a route at that point, one will, the other won't.

re: the iwpriv's, I've a few cards that also say via iwpriv that you can use certain things, yet same as you they don't respond to it. Beyond that I don't know *why* they would report it but not respond, but indeed they do.
 
Old 11-10-2003, 12:42 PM   #7
Patrick Bulteel
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It's possible to use mutiple network cards to increase your bandwidth but it has do be aggregated at the head end too... what you CAN do is have multiple interfaces to go out through different gateways and if you're lucky enough (or if you run routing protocols like RIP, OSPF, GBP, etc) you could use the gateway that is the least congested or the that your destination is the closest (least number of hops.)

At home I have DSL and cable going to the firewall and all the internal machines can use both interfaces. One advantage is that when one goes down, the other one takes over.

One thing I noticed is that I might go to a site and get the content through one interface and the images from a different interface. This works if it's like www.yahoo.com and images.yahoo.com... not if images and content are served from the same server.

You can read about it here http://lartc.org/
 
Old 11-10-2003, 12:51 PM   #8
h/w
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interesting.

akabeavis : you;re right about the last interface being brought up being the one that is used.
thanks for lookin at my other post too.

patrick : thnx for the input. ill chk out the lartc link soon.
 
Old 11-10-2003, 12:53 PM   #9
h/w
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akabeavis : i first had my ethernet card up, and then the wlan. they both use different routers/gateways (the wlan was picking up a local verizon wi-fi which i cant use cos im not registered for it).
 
  


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