bridge-utils and ppp
Hi Folks-
Forgive the newbie question, but my attempts to answer this through google have left me confused.
I'm trying to bridge between a pair of ppp and eth interfaces in an embedded linux distribution called SlugOS. The kernel is 2.6.21 and my understanding was that the 2.6 kernels have the mods to support ppp interfaces. When I try to add my ppp0 interface to a bridge, I get:
Quoted 2 lines
$ brctl addif test ppp0 can't add ppp0 to bridge test: Invalid argument
MTUs are set the same for all interfaces. Is there a specific version of the bridge-utils package I need? The version packed for my distribution claims to be 1.2-r0
Thanks in advance,
Lou
Quoted 11 lines · Lou Steinberg
Hi Folks-
Forgive the newbie question, but my attempts to answer this through google have left me confused.
I'm trying to bridge between a pair of ppp and eth interfaces in an embedded linux distribution called SlugOS. The kernel is 2.6.21 and my understanding was that the 2.6 kernels have the mods to support ppp interfaces. When I try to add my ppp0 interface to a bridge, I get:
Quoted 2 lines
$ brctl addif test ppp0 can't add ppp0 to bridge test: Invalid argument
Does a bridge "test" exist? What is the output of brctl show?
Quoted 14 lines
MTUs are set the same for all interfaces. Is there a specific version of the bridge-utils package I need? The version packed for my distribution claims to be 1.2-r0
Thanks in advance,
Lou_______________________________________________
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https://lists.linux-foundation.org/mailman/listinfo/bridge
Hi Richard-
[snip]
Quoted 3 lines
Does a bridge "test" exist? What is the output of brctl show?
[snip]
Yes, the bridge exists. brctl shows:
Quoted 7 lines
root@wan-bridge:~$ brctl addif test ppp0 can't add ppp0 to bridge test: Invalid argument root@wan-bridge:~$ echo $? 1 root@wan-bridge:~$ brctl show bridge name bridge id STP enabled interfaces test 8000.000000000000 no
Thanks,
Lou
Quoted 18 lines · On Sun, 09 Mar 2008 09:58:57 -0400 Lou Steinberg <[email protected]> wrote:
Hi Richard-
[snip]
Quoted 3 lines
Does a bridge "test" exist? What is the output of brctl show?
[snip]
Yes, the bridge exists. brctl shows:
Quoted 7 lines
root@wan-bridge:~$ brctl addif test ppp0 can't add ppp0 to bridge test: Invalid argument root@wan-bridge:~$ echo $? 1 root@wan-bridge:~$ brctl show bridge name bridge id STP enabled interfaces test 8000.000000000000 no
The bridging code only works for devices that have Ethernet headers. That is the way the bridging 802.2 standard works, it is a Layer 2 bridge and it uses the address information from Ethernet to do routing.
PPP does not use Ethernet level framing so it can't be bridged. What were you trying to do? there are plenty of other ways to get the same effect.
Stephen-
Quoted 8 lines · Stephen Hemminger
The bridging code only works for devices that have Ethernet headers. That is the way the bridging 802.2 standard works, it is a Layer 2 bridge and it uses the address information from Ethernet to do routing.
PPP does not use Ethernet level framing so it can't be bridged. What were you trying to do? there are plenty of other ways to get the same effect.
Makes sense, I suppose (The forwarding is complicated by a p-p link without a destination mac addr that looks like ethernet). I expected that someone had built a table to do the mappings because the docs I referenced in the original post specifically say that ppp can be bridged.
What I'm trying to do is a simple/low latency forward from a vpn concentrator/firewall/router out to a cellular WAN modem that attaches to a USB. My firewall lacks the USB interface so I simply need to forward packets between the USB and ethernet. Am doing it now at layer 3 (using iptables to do NAT) but that adds a lot of complexity and my firewall already does NAT (so it's happening twice). I haven't yet tested an ipsec tunnel over the link, but am concerned that I may also need to add ipsec passthrough if I do this at layer 3.
All in all, a simple layer 2 forward between eth0 and ttyUSB0 is what I really need.
/Lou