LinuxQuestions.org
Visit Jeremy's Blog.
Go Back   LinuxQuestions.org > Forums > Linux Forums > Linux - Networking
User Name
Password
Linux - Networking This forum is for any issue related to networks or networking.
Routing, network cards, OSI, etc. Anything is fair game.

Notices


Reply
  Search this Thread
Old 04-20-2004, 07:46 AM   #1
kayser
LQ Newbie
 
Registered: Apr 2004
Posts: 10

Rep: Reputation: 0
using 2 ethernet cards one Tx and one Rx


I want to use a card to transmit data and one to recieve data

i don't know how to do it

If someone can help me

Thanks
 
Old 04-20-2004, 08:22 AM   #2
demian
Member
 
Registered: Apr 2001
Location: Bremen, Germany
Distribution: Debian
Posts: 303

Rep: Reputation: 30
Why would you want to do that? The way the TCP protocol works this isn't possible. The sending host expects ACK responses from the receiving host to know that the data actually arrived. Now two different interfaces would be bound to two different IP addresses and ultimately there's some switch or bridge that maps the IP address to the MAC address of the card. So even if you could instruct an interface to only send/receive data the sending host would get confused cause the ACK packets don't originate from where they should.

If all this is to increase throughput here's a better solution:
http://heroinewarrior.com/firehose.php3

firehose let's you combine multiple ethernet cards and scales linearly (not just in theory).
 
Old 04-20-2004, 08:26 AM   #3
jcookeman
Member
 
Registered: Jul 2003
Location: London, UK
Distribution: FreeBSD, OpenSuse, Ubuntu, RHEL
Posts: 417

Rep: Reputation: 33
Why would you want to do this? A 100 Mbps+ full duplex connection can send/receive at the same time. This coupled with streaming data over a TCP duplex socket would render two seperate NICs grossly ineffective (that's the way I perceive it).

I've heard talk of people wanting to explore this in the past, but I don't even know if the code exists to do this. Essentially this would be multilinking two interfaces. You would have to support this on the other end of the connection (switch).

Maybe there is some extreme high performance stuff out there that does this.
 
Old 04-21-2004, 04:50 AM   #4
kayser
LQ Newbie
 
Registered: Apr 2004
Posts: 10

Original Poster
Rep: Reputation: 0
I would like to use a dvb-s card in reception and an ethernet card in transmission.

Before that i would like to try with two ethernet cards.

I think i can do this with a bridge and some routes which could give the good direction of data

But how to install this bridge

I heard about Ebtables and Brctl ??

what 's the difference

Thanks
 
Old 04-21-2004, 06:56 AM   #5
leckie
Member
 
Registered: Dec 2003
Location: Australia
Distribution: Mandrake 9.2
Posts: 151

Rep: Reputation: 30
well, a point to mention if you assign 2 adapters the same ip address linux will always send data to the adapter first added to the routing table. so generally the second adapter is unusable. But who is to say the second adapter will not receive data.



So give it a try and see if it works.


Ok how
get 2 computers fired up with 2 ethernet cards and use 2 cross over cables. First plug one of the cross over cables into eth0 on both machines. assign ip's and check you can ping.

second assign eth1 on both machines with the same ip address as eth0's. also check you can still ping.

finally plug eth0 into eth1 of both machines, using both cables.

and see what happens. if all goes to plan eth0 will transmit and eth1 will receive.

i would test it but i have to much thesis crap to do.
 
Old 04-21-2004, 07:10 AM   #6
kayser
LQ Newbie
 
Registered: Apr 2004
Posts: 10

Original Poster
Rep: Reputation: 0
ok i'll try this .

Thanks a lot .
 
Old 04-21-2004, 10:43 AM   #7
demian
Member
 
Registered: Apr 2001
Location: Bremen, Germany
Distribution: Debian
Posts: 303

Rep: Reputation: 30
Quote:
Originally posted by kayser
I would like to use a dvb-s card in reception and an ethernet card in transmission.

Before that i would like to try with two ethernet cards.

I think i can do this with a bridge and some routes which could give the good direction of data

But how to install this bridge

I heard about Ebtables and Brctl ??

what 's the difference

Thanks
ebtables is a userspace tool that let's you filter on the link layer. Much like iptables inspects ip packets on a firewall ebtables inspects ethernet frames to do the filtering. Commonly this is used to set up a transparent bridge firewall. This is handy when you want to shield part of your network from other parts without the clients knowing about this, ie you don't have to change any routing tables. brctl is the tool you use to set up the bridge interfaces, ie tell the kernel which interface belong to the bridge, and optionally asign an IP address to the bridge interface.

When using linux 2.4.x you need to patch the kernel using the patch from ebtables.sf.net This code is included in the 2.6.x branch so no need for patching there.

I still don't understand why you think this is a good idea but hopefully I could shed some light on the ebtables thingy.

Good luck.
 
Old 04-21-2004, 12:20 PM   #8
digi_com_lb
LQ Newbie
 
Registered: Apr 2004
Location: Lebanon
Distribution: RH9
Posts: 5

Rep: Reputation: 0
hello m8s

am after something like this but between nic & sat dvb card to make nic as uplink & the dvb card as downlink .

can ebtables help ?

P.S : i want these to be routed with a third parity which is nic that provide my lan with internet connection .

kind regards
 
Old 04-22-2004, 08:33 AM   #9
kayser
LQ Newbie
 
Registered: Apr 2004
Posts: 10

Original Poster
Rep: Reputation: 0
Hi digi_com_lb !!

I m' trying to test if ebtables could help us !!

Maybe we should have a discussion on our project . It seems to be near of mine.

Dvb-s card --> Rx and ethernet-->Tx for me

Dvb-s card --Rx and Nic --> Tx for you

thanks
 
Old 04-26-2004, 03:16 AM   #10
kayser
LQ Newbie
 
Registered: Apr 2004
Posts: 10

Original Poster
Rep: Reputation: 0
maybe using ebtables could help me ?

do you know how to use ebtables with MAC @ ??

thanks
 
Old 05-03-2004, 11:00 AM   #11
kayser
LQ Newbie
 
Registered: Apr 2004
Posts: 10

Original Poster
Rep: Reputation: 0
Final round

I succeed in using the two cards like i wanted.

I just needed to use EBTABLES and BRCTL.

Brctl to make a bridge beetwin the cards and configure the direction of data by using the chains and rules given by ebtables.
 
Old 05-03-2004, 02:03 PM   #12
jcookeman
Member
 
Registered: Jul 2003
Location: London, UK
Distribution: FreeBSD, OpenSuse, Ubuntu, RHEL
Posts: 417

Rep: Reputation: 33
Ok...nice to see you succeeded. Can you give us some performance data to explain why this would be worth employeeing?
 
  


Reply


Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is Off
HTML code is Off



Similar Threads
Thread Thread Starter Forum Replies Last Post
Two ethernet cards Scorper Linux - Hardware 1 06-05-2005 07:38 AM
2 ethernet cards.. Nyybai Slackware 8 04-12-2004 11:49 AM
2 Ethernet Cards matt80 Linux - Networking 14 12-01-2003 03:19 PM
Old ethernet cards rsbecker007 Linux - Networking 1 07-31-2002 10:21 PM
Ethernet Cards and Sound Cards SchizoIV Linux - Newbie 2 07-05-2002 09:10 PM

LinuxQuestions.org > Forums > Linux Forums > Linux - Networking

All times are GMT -5. The time now is 06:03 PM.

Main Menu
Advertisement
My LQ
Write for LQ
LinuxQuestions.org is looking for people interested in writing Editorials, Articles, Reviews, and more. If you'd like to contribute content, let us know.
Main Menu
Syndicate
RSS1  Latest Threads
RSS1  LQ News
Twitter: @linuxquestions
Open Source Consulting | Domain Registration