[Bridge] Problem with Routed mode using br2684ctl tool

Stephen Hemminger shemminger at osdl.org
Thu Aug 4 09:33:27 PDT 2005


On Thu, 4 Aug 2005 05:37:05 -0700 (PDT)
Zoran s <s_zoran at yahoo.com> wrote:

> Hi,
> 
> I am writing this email in sincere hope that somebody
> experienced similar/same problem and found solution to
> it.
> 
> The classical bridge setup could be achieved using
> brctl tool, which could be found at:
> http://home.regit.org/br2684.html
> 
> I have an ADSL CO line card Linux based [2.4.24
> kernel] with 8 nas interfaces and eth0. Rather than
> having bridge, the decision was to have a router,
> which does routing functionality between nasx
> interfaces and eth0.
> 
> >From user space, setting up a bridge connection is
> quite simple. First, the linking an ATM VC with an
> interface should be done followed by configuring this
> interface.
> 
> The syntax of the command is the following:
> 
> br2684ctl [-c n -e 0|1 -b 0|1 -s buf_size -a
> [itf].vpi.vci ]+
> 
> -a [itf].vpi.vci : ATM PVC number, VPI and VCI.
> Mandatory
> -c n             : BR2684 interface number such as
> nas0,
>                    nas1,... Mandatory
> -e 0|1           : Encapsulation method. 0=LLC, 1=VC
> mux.
>                    default is 0, LLC
> -b 0|1           : Running background. 1=background,
>                    0=foreground. Default is 0
> -s buf_size      : send buffer size. Default is 8192.
> 
> The problem with setting bridge with brctl tool is
> lack of option p 0|1 [bridged or routed
> functionality]. I'm using more advanced tool based on
> brctl with additional option p:
> 
> -p 0|1           : Bridged or routed. 0=routed,
> 1=bridged
>                    Default is 0 [routed].
> 
> In other words using ADSL CO line card as IP router
> makes every nasx and eth0 interfaces to have their own
> IP addresses. The example of setting a nas0 interface:
> 
> br2684ctl -b -c 0 -e 0 -p 0 -a 0.0.40, where p is used
> as Routed mode option.
> 
> When there is need to configure a WAN connection on
> CPE side [ADSL modem on other side of twisted pair],
> there are 5 possible options for WAN connection
> creation:
> 
> [1] RFC1483 Bridge
> [2] RFC1483 Route
> [3] PPP over ATM
> [4] PPP over Ethernet
> [5] IP over ATM [CLIP]
> 
> Choosing option 2 [RFC1483 Route] as an option follows
> usage of brctl tool for nas0 interface creation on CO
> side in routed mode.
> 
> The actual problem is that routed mode does NOT work
> after setting the parameters as shown [CPE modem
> receives packets on WAN, but discards them, finding
> them as bad].
> 
> The problem is solved by creating [on CO side] nasx
> interfaces in bridged mode. As example, the nas0
> interface creation syntax looks a bit different:
> 
> br2684ctl -b -c 0 -e 0 -p 1 -a 0.0.40, where -p is
> used as Bridged mode option.
> 
> On other [CPE] side, the option 1 is used [RFC1483
> Bridge (with NAT)] for creating the WAN interface.
> This works perfectly, albeit both CO and CPE sides are
> set as routers!
> 
> Any ideas why RFC1483 Route mode does NOT work? I'll
> apprecate any ideas which can show me some direction.
> 
> Best Regards,
> 
>

This list is about the IEEE 802 based bridging and your
questions is about ATM based bridging.  Perhaps you should ask on
the ATM list linux-atm-general at lists.sourceforge.net

Also see: http://home.regit.org/br2684.html




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