[Bridge] Monitor the status of two ethernet interface

[Bridge] Monitor the status of two ethernet interface

[Jie Chen]

Hi everybody,

Just have myself added into the maillist. I have a few linux boxes with 
Kernel 2.6.9. Each box has 2 ethernet interfaces, one 3COM, one Intel. I 
connected one with Power Line Modem, and one with Wifi Modem. They form a 
nice network with bridge. I have a few questions here.

Suppose I have two path from box A to box D, which path will packets go 
through? If I want to monitor the condition (throughput) of each interface, 
and pick the better one, how do I do it? If I want to use both interfaces to 
transfer data, how do I do it?

Thanks in advance for your answers,
cj

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Re: [Bridge] Monitor the status of two ethernet interface

[Stephen Hemminger]

On Wed, 20 Dec 2006 21:26:18 +0000
"Jie Chen" <cj70286@hotmail.com> wrote:

> Hi everybody,
> 
> Just have myself added into the maillist. I have a few linux boxes with 
> Kernel 2.6.9. Each box has 2 ethernet interfaces, one 3COM, one Intel. I 
> connected one with Power Line Modem, and one with Wifi Modem. They form a 
> nice network with bridge. I have a few questions here.
> 
> Suppose I have two path from box A to box D, which path will packets go 
> through? If I want to monitor the condition (throughput) of each interface, 
> and pick the better one, how do I do it? If I want to use both interfaces to 
> transfer data, how do I do it?

With STP it will choose the "least cost" which is determined by the port
cost variable. In 2.6, it automatically sets the cost based on link speed. but
then you can change it later with brctl

> 
> Thanks in advance for your answers,
> cj
> 
> _________________________________________________________________
> Type your favorite song.  Get a customized station.  Try MSN Radio powered 
> by Pandora. http://radio.msn.com/?icid=T002MSN03A07001
> 

Re: [Bridge] Monitor the status of two ethernet interface

[Jie Chen]

Thank you, Stephen.


I'm reading the codes. The software uses ioctl a lot. I'm new to ioctl, is 
it an interface between register values of the ethernet card and user 
application?


We use ioctl to add a bridge, add an interface to the bridge, which ioctl 
file do we use for that? I greped the whole file system of my linux box, I 
found some ioctl files, but when I try to match the cases (The second 
parameter such as SIOCSIFBR, SIOCBRADDBR) it handles, it seems none of those 
files match our cases.


Another question I had is about my understanding on ioctl. Since I think 
ioctl is just to set physical register values of ethernet cards, once it's 
set, all the functions should be automatic, when packets come, the bridge 
automatically routes, is Kernel involved in those functions?


About STP, seems like everything is set by a function br_set, and eventually 
by ioctl. Is there any daemon to maintain STP?


Thanks again for your valuable time.
Jie

>From: Stephen Hemminger <shemminger@osdl.org>
>To: "Jie Chen" <cj70286@hotmail.com>
>CC: bridge@lists.osdl.org
>Subject: Re: [Bridge] Monitor the status of two ethernet interface
>Date: Wed, 20 Dec 2006 14:32:09 -0800
>
>On Wed, 20 Dec 2006 21:26:18 +0000
>"Jie Chen" <cj70286@hotmail.com> wrote:
>
> > Hi everybody,
> >
> > Just have myself added into the maillist. I have a few linux boxes with
> > Kernel 2.6.9. Each box has 2 ethernet interfaces, one 3COM, one Intel. I
> > connected one with Power Line Modem, and one with Wifi Modem. They form 
>a
> > nice network with bridge. I have a few questions here.
> >
> > Suppose I have two path from box A to box D, which path will packets go
> > through? If I want to monitor the condition (throughput) of each 
>interface,
> > and pick the better one, how do I do it? If I want to use both 
>interfaces to
> > transfer data, how do I do it?
>
>With STP it will choose the "least cost" which is determined by the port
>cost variable. In 2.6, it automatically sets the cost based on link speed. 
>but
>then you can change it later with brctl
>
> >
> > Thanks in advance for your answers,
> > cj
> >
> > _________________________________________________________________
> > Type your favorite song.�� Get a customized station.�� Try MSN Radio 
>powered
> > by Pandora. http://radio.msn.com/?icid=T002MSN03A07001
> >

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Re: [Bridge] Monitor the status of two ethernet interface

[Stephen Hemminger]

On Thu, 21 Dec 2006 13:50:31 +0000
"Jie Chen" <cj70286@hotmail.com> wrote:

> Thank you, Stephen.
> 
> 
> I'm reading the codes. The software uses ioctl a lot. I'm new to ioctl, is 
> it an interface between register values of the ethernet card and user 
> application?
> 
> 
> We use ioctl to add a bridge, add an interface to the bridge, which ioctl 
> file do we use for that? I greped the whole file system of my linux box, I 
> found some ioctl files, but when I try to match the cases (The second 
> parameter such as SIOCSIFBR, SIOCBRADDBR) it handles, it seems none of those 
> files match our cases.

Download bridge-utilities source code:
	http://sourceforge.net/project/showfiles.php?group_id=26089
And look at libbridge code there.

> 
> Another question I had is about my understanding on ioctl. Since I think 
> ioctl is just to set physical register values of ethernet cards, once it's 
> set, all the functions should be automatic, when packets come, the bridge 
> automatically routes, is Kernel involved in those functions?

The architecture is more like:

      Applications      | brctl |
                        +-------+
user                        |
----------------------------|-----------------
kernel                      |
              +----------------+
              |   Bridge       |
              |   driver       |
              +----------------+
                |              |
        +--------+            +--------+
        |Ethernet|            |Ethernet|
        | Driver |            | Driver |
        +--|-----+            +----|---+
-----------|-----------------------|---------
physical
         LAN1                     LAN2                            


> About STP, seems like everything is set by a function br_set, and eventually 
> by ioctl. Is there any daemon to maintain STP?

No. But the long term plan is to do STP in userspace with a daemon
since that allows for more flexibility

> 
> Thanks again for your valuable time.
> Jie
> 
> >From: Stephen Hemminger <shemminger@osdl.org>
> >To: "Jie Chen" <cj70286@hotmail.com>
> >CC: bridge@lists.osdl.org
> >Subject: Re: [Bridge] Monitor the status of two ethernet interface
> >Date: Wed, 20 Dec 2006 14:32:09 -0800
> >
> >On Wed, 20 Dec 2006 21:26:18 +0000
> >"Jie Chen" <cj70286@hotmail.com> wrote:
> >
> > > Hi everybody,
> > >
> > > Just have myself added into the maillist. I have a few linux boxes with
> > > Kernel 2.6.9. Each box has 2 ethernet interfaces, one 3COM, one Intel. I
> > > connected one with Power Line Modem, and one with Wifi Modem. They form 
> >a
> > > nice network with bridge. I have a few questions here.
> > >
> > > Suppose I have two path from box A to box D, which path will packets go
> > > through? If I want to monitor the condition (throughput) of each 
> >interface,
> > > and pick the better one, how do I do it? If I want to use both 
> >interfaces to
> > > transfer data, how do I do it?
> >
> >With STP it will choose the "least cost" which is determined by the port
> >cost variable. In 2.6, it automatically sets the cost based on link speed. 
> >but
> >then you can change it later with brctl
> >
> > >
> > > Thanks in advance for your answers,
> > > cj
> > >
> > > _________________________________________________________________
> > > Type your favorite song.  Get a customized station.  Try MSN Radio 
> >powered
> > > by Pandora. http://radio.msn.com/?icid=T002MSN03A07001
> > >
> 
> _________________________________________________________________
> Get FREE Web site and company branded e-mail from Microsoft Office Live 
> http://clk.atdmt.com/MRT/go/mcrssaub0050001411mrt/direct/01/
> 

Re: [Bridge] Monitor the status of two ethernet interface

[Jie Chen]

Hi Stephen,

I've been reading the source code for a few days. I can locate these two 
files:
/usr/include/linux/sockios.h
/usr/include/sys/ioctl.h
and I want to look at the codes for the function ioctl(), since there are so 
many files includes ioctl() under /usr/ folder. Do you have any idea which 
specific one we are using? For example, does the one in following file look 
the correct one?
/usr/src/linux-2.6.15_gz/net/socket.c


Thanks for the nice architecture drawing. What is the relationship between 
TCP/IP architecture and the architecture you showed me? The bridge driver 
should be considered as physical layer and IP layer is above that?


For STP, if there's no Daemon running behind, who's maintaining the STP 
table and who decide which interface to go with?


Thanks for everything you have done, I really appreciate your help. Have a 
nice holiday.

Jie




>From: Stephen Hemminger <shemminger@osdl.org>
>To: "Jie Chen" <cj70286@hotmail.com>
>CC: bridge@lists.osdl.org
>Subject: Re: [Bridge] Monitor the status of two ethernet interface
>Date: Thu, 21 Dec 2006 07:51:18 -0800
>
>On Thu, 21 Dec 2006 13:50:31 +0000
>"Jie Chen" <cj70286@hotmail.com> wrote:
>
> > Thank you, Stephen.
> >
> >
> > I'm reading the codes. The software uses ioctl a lot. I'm new to ioctl, 
>is
> > it an interface between register values of the ethernet card and user
> > application?
> >
> >
> > We use ioctl to add a bridge, add an interface to the bridge, which 
>ioctl
> > file do we use for that? I greped the whole file system of my linux box, 
>I
> > found some ioctl files, but when I try to match the cases (The second
> > parameter such as SIOCSIFBR, SIOCBRADDBR) it handles, it seems none of 
>those
> > files match our cases.
>
>Download bridge-utilities source code:
>	http://sourceforge.net/project/showfiles.php?group_id=26089
>And look at libbridge code there.
>
> >
> > Another question I had is about my understanding on ioctl. Since I think
> > ioctl is just to set physical register values of ethernet cards, once 
>it's
> > set, all the functions should be automatic, when packets come, the 
>bridge
> > automatically routes, is Kernel involved in those functions?
>
>The architecture is more like:
>
>       Applications      | brctl |
>                         +-------+
>user                        |
>----------------------------|-----------------
>kernel                      |
>               +----------------+
>               |   Bridge       |
>               |   driver       |
>               +----------------+
>                 |              |
>         +--------+            +--------+
>         |Ethernet|            |Ethernet|
>         | Driver |            | Driver |
>         +--|-----+            +----|---+
>-----------|-----------------------|---------
>physical
>          LAN1                     LAN2
>
>
> > About STP, seems like everything is set by a function br_set, and 
>eventually
> > by ioctl. Is there any daemon to maintain STP?
>
>No. But the long term plan is to do STP in userspace with a daemon
>since that allows for more flexibility
>
> >
> > Thanks again for your valuable time.
> > Jie
> >
> > >From: Stephen Hemminger <shemminger@osdl.org>
> > >To: "Jie Chen" <cj70286@hotmail.com>
> > >CC: bridge@lists.osdl.org
> > >Subject: Re: [Bridge] Monitor the status of two ethernet interface
> > >Date: Wed, 20 Dec 2006 14:32:09 -0800
> > >
> > >On Wed, 20 Dec 2006 21:26:18 +0000
> > >"Jie Chen" <cj70286@hotmail.com> wrote:
> > >
> > > > Hi everybody,
> > > >
> > > > Just have myself added into the maillist. I have a few linux boxes 
>with
> > > > Kernel 2.6.9. Each box has 2 ethernet interfaces, one 3COM, one 
>Intel. I
> > > > connected one with Power Line Modem, and one with Wifi Modem. They 
>form
> > >a
> > > > nice network with bridge. I have a few questions here.
> > > >
> > > > Suppose I have two path from box A to box D, which path will packets 
>go
> > > > through? If I want to monitor the condition (throughput) of each
> > >interface,
> > > > and pick the better one, how do I do it? If I want to use both
> > >interfaces to
> > > > transfer data, how do I do it?
> > >
> > >With STP it will choose the "least cost" which is determined by the 
>port
> > >cost variable. In 2.6, it automatically sets the cost based on link 
>speed.
> > >but
> > >then you can change it later with brctl
> > >
> > > >
> > > > Thanks in advance for your answers,
> > > > cj
> > > >
> > > > _________________________________________________________________
> > > > Type your favorite song.�� Get a customized station.�� Try MSN Radio
> > >powered
> > > > by Pandora. http://radio.msn.com/?icid=T002MSN03A07001
> > > >
> >
> > _________________________________________________________________
> > Get FREE Web site and company branded e-mail from Microsoft Office Live
> > http://clk.atdmt.com/MRT/go/mcrssaub0050001411mrt/direct/01/
> >

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Re: [Bridge] Monitor the status of two ethernet interface

[Cameron Schaus]

Jie Chen wrote:
> Hi Stephen,
>
> I've been reading the source code for a few days. I can locate these 
> two files:
> /usr/include/linux/sockios.h
> /usr/include/sys/ioctl.h
> and I want to look at the codes for the function ioctl(), since there 
> are so many files includes ioctl() under /usr/ folder. Do you have any 
> idea which specific one we are using? For example, does the one in 
> following file look the correct one?
> /usr/src/linux-2.6.15_gz/net/socket.c
The bridge ioctls are in net/bridge/br_ioctl.c, but some of the bridge 
functionality is done using the sysfs interface, whose code in is 
br_sys_{br,if}.c.

> Thanks for the nice architecture drawing. What is the relationship 
> between TCP/IP architecture and the architecture you showed me? The 
> bridge driver should be considered as physical layer and IP layer is 
> above that?
You will want to check out the netif_receive_skb function in 
net/core/dev.c and note the bridge hooks used to pass packets to the 
bride code.  This is done prior to IP processing.

> For STP, if there's no Daemon running behind, who's maintaining the 
> STP table and who decide which interface to go with?
This is done by the kernel bridge code, using timers and incoming 
packets to trigger STP state changes.  The code of interest is in 
/usr/src/linux/net/bridge/br_stp.*, with some of the timer creation/init 
done when bridge entities are created.  Search for br_stp_timer_init and 
br_stp_port_timer_init.

All of the bridge code is in net/bridge/ and I would recommend the 
"Understanding Linux Network Internals" book published by O'Reilly 
publishing.  This book has several chapters that explain in detail the 
linux bridge and STP implementation, as well as a chapter that explains 
STP in detail.

Cam

Re: [Bridge] Monitor the status of two ethernet interface

[Jie Chen]

Hi Cam,

Thank you very much. The book is a very good one, it cleared out all 
problems I had in implementation. I also located those source codes, which 
are also very helpful.

For guys who are trying to cross compile v1.2, actually I have the same 
problem, and I just gave up and use v1.1. Anybody can clear it up?

Thanks and have a wonderful long weekend.

Jie


>From: Cameron Schaus <cam@schaus.ca>
>To: Jie Chen <cj70286@hotmail.com>, bridge@lists.osdl.org
>Subject: Re: [Bridge] Monitor the status of two ethernet interface
>Date: Thu, 21 Dec 2006 13:17:16 -0500
>
>Jie Chen wrote:
>>Hi Stephen,
>>
>>I've been reading the source code for a few days. I can locate these two 
>>files:
>>/usr/include/linux/sockios.h
>>/usr/include/sys/ioctl.h
>>and I want to look at the codes for the function ioctl(), since there are 
>>so many files includes ioctl() under /usr/ folder. Do you have any idea 
>>which specific one we are using? For example, does the one in following 
>>file look the correct one?
>>/usr/src/linux-2.6.15_gz/net/socket.c
>The bridge ioctls are in net/bridge/br_ioctl.c, but some of the bridge 
>functionality is done using the sysfs interface, whose code in is 
>br_sys_{br,if}.c.
>
>>Thanks for the nice architecture drawing. What is the relationship between 
>>TCP/IP architecture and the architecture you showed me? The bridge driver 
>>should be considered as physical layer and IP layer is above that?
>You will want to check out the netif_receive_skb function in net/core/dev.c 
>and note the bridge hooks used to pass packets to the bride code.  This is 
>done prior to IP processing.
>
>>For STP, if there's no Daemon running behind, who's maintaining the STP 
>>table and who decide which interface to go with?
>This is done by the kernel bridge code, using timers and incoming packets 
>to trigger STP state changes.  The code of interest is in 
>/usr/src/linux/net/bridge/br_stp.*, with some of the timer creation/init 
>done when bridge entities are created.  Search for br_stp_timer_init and 
>br_stp_port_timer_init.
>
>All of the bridge code is in net/bridge/ and I would recommend the 
>"Understanding Linux Network Internals" book published by O'Reilly 
>publishing.  This book has several chapters that explain in detail the 
>linux bridge and STP implementation, as well as a chapter that explains STP 
>in detail.
>
>Cam
>

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Re: [Bridge] Monitor the status of two ethernet interface

[Jie Chen]

Hi all,

I hope everybody had a great holiday.

I got a question in applying ethernet bridge in Linux boxes. The scenario 
I'm trying to simulate is like this:  I have 3 linux boxes in total, 
everyone has 2 ethernet ports, one port is connected to Power line modem, 
and the other to wifi modem. The power line modem failed, so it's the same 
as I have just one port for each. I put them apart, Box A is in one end, and 
Box C is in another end, and Box B in the middle, so that Box A can talk to 
B but not C. Box B can talk to A and C. Box C and talk to B but not A. Now I 
set bridge on, the question is am I able to let A and C talk?

The reason I have this question is according to bridge, B get packets from A 
on one port, and suppose to deliver to C from the other port, but the other 
port didn't work. So I would think the packets can't be delivered from A to 
C, is that the case?

Thanks a lot,
Jie


>From: Cameron Schaus <cam@schaus.ca>
>To: Jie Chen <cj70286@hotmail.com>, bridge@lists.osdl.org
>Subject: Re: [Bridge] Monitor the status of two ethernet interface
>Date: Thu, 21 Dec 2006 13:17:16 -0500
>
>Jie Chen wrote:
>>Hi Stephen,
>>
>>I've been reading the source code for a few days. I can locate these two 
>>files:
>>/usr/include/linux/sockios.h
>>/usr/include/sys/ioctl.h
>>and I want to look at the codes for the function ioctl(), since there are 
>>so many files includes ioctl() under /usr/ folder. Do you have any idea 
>>which specific one we are using? For example, does the one in following 
>>file look the correct one?
>>/usr/src/linux-2.6.15_gz/net/socket.c
>The bridge ioctls are in net/bridge/br_ioctl.c, but some of the bridge 
>functionality is done using the sysfs interface, whose code in is 
>br_sys_{br,if}.c.
>
>>Thanks for the nice architecture drawing. What is the relationship between 
>>TCP/IP architecture and the architecture you showed me? The bridge driver 
>>should be considered as physical layer and IP layer is above that?
>You will want to check out the netif_receive_skb function in net/core/dev.c 
>and note the bridge hooks used to pass packets to the bride code.  This is 
>done prior to IP processing.
>
>>For STP, if there's no Daemon running behind, who's maintaining the STP 
>>table and who decide which interface to go with?
>This is done by the kernel bridge code, using timers and incoming packets 
>to trigger STP state changes.  The code of interest is in 
>/usr/src/linux/net/bridge/br_stp.*, with some of the timer creation/init 
>done when bridge entities are created.  Search for br_stp_timer_init and 
>br_stp_port_timer_init.
>
>All of the bridge code is in net/bridge/ and I would recommend the 
>"Understanding Linux Network Internals" book published by O'Reilly 
>publishing.  This book has several chapters that explain in detail the 
>linux bridge and STP implementation, as well as a chapter that explains STP 
>in detail.
>
>Cam
>

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Re: [Bridge] Monitor the status of two ethernet interface

[Stephen Hemminger]

On Thu, 04 Jan 2007 20:39:12 +0000
"Jie Chen" <cj70286@hotmail.com> wrote:

> Hi all,
> 
> I hope everybody had a great holiday.
> 
> I got a question in applying ethernet bridge in Linux boxes. The scenario 
> I'm trying to simulate is like this:  I have 3 linux boxes in total, 
> everyone has 2 ethernet ports, one port is connected to Power line modem, 
> and the other to wifi modem. The power line modem failed, so it's the same 
> as I have just one port for each. I put them apart, Box A is in one end, and 
> Box C is in another end, and Box B in the middle, so that Box A can talk to 
> B but not C. Box B can talk to A and C. Box C and talk to B but not A. Now I 
> set bridge on, the question is am I able to let A and C talk?
> 
> The reason I have this question is according to bridge, B get packets from A 
> on one port, and suppose to deliver to C from the other port, but the other 
> port didn't work. So I would think the packets can't be delivered from A to 
> C, is that the case?
> 
> Thanks a lot,
> Jie
> 
>

True bridging to Wifi won't usually work see the http://linux-net.osdl.org/index.php/Bridge

The problem is that internally Wifi is not a Bus network like Ethernet, but
is really point-to-point from host to access point.


-- 
Stephen Hemminger <shemminger@osdl.org>

Re: [Bridge] Monitor the status of two ethernet interface

[Jie Chen]

Just to make my question clearer, I don't use wireless card, I use regular 
ethernet card, and then plugged in wifi modem.


I have tested the case of 4 linux boxes with one wireless modem on each box. 
I can check which is root bridge and the rest the designated bridge. I did 
it with 4 linux boxes together. I haven't done the scenario I asked. In 
order to make box A and C talk, packets from A to B have to be sent out to C 
through the same ethernet port. So my question is will B deliver the packet 
through the same port as it received?

Thanks,
Jie


>From: Stephen Hemminger <shemminger@osdl.org>
>To: "Jie Chen" <cj70286@hotmail.com>
>CC: cam@schaus.ca, bridge@lists.osdl.org
>Subject: Re: [Bridge] Monitor the status of two ethernet interface
>Date: Thu, 4 Jan 2007 13:03:16 -0800
>
>On Thu, 04 Jan 2007 20:39:12 +0000
>"Jie Chen" <cj70286@hotmail.com> wrote:
>
> > Hi all,
> >
> > I hope everybody had a great holiday.
> >
> > I got a question in applying ethernet bridge in Linux boxes. The 
>scenario
> > I'm trying to simulate is like this:  I have 3 linux boxes in total,
> > everyone has 2 ethernet ports, one port is connected to Power line 
>modem,
> > and the other to wifi modem. The power line modem failed, so it's the 
>same
> > as I have just one port for each. I put them apart, Box A is in one end, 
>and
> > Box C is in another end, and Box B in the middle, so that Box A can talk 
>to
> > B but not C. Box B can talk to A and C. Box C and talk to B but not A. 
>Now I
> > set bridge on, the question is am I able to let A and C talk?
> >
> > The reason I have this question is according to bridge, B get packets 
>from A
> > on one port, and suppose to deliver to C from the other port, but the 
>other
> > port didn't work. So I would think the packets can't be delivered from A 
>to
> > C, is that the case?
> >
> > Thanks a lot,
> > Jie
> >
> >
>
>True bridging to Wifi won't usually work see the 
>http://linux-net.osdl.org/index.php/Bridge
>
>The problem is that internally Wifi is not a Bus network like Ethernet, but
>is really point-to-point from host to access point.
>
>
>--
>Stephen Hemminger <shemminger@osdl.org>

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