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Brad Fitzpatrick

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Xen3 question [Jun. 3rd, 2006|12:50 pm]
Brad Fitzpatrick
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I know Xen2. New to Xen3.....

Loving all the improvements (one U/0 kernel, improved balloon, primary eth not in bridget, ...) but trying to understand that last one.

What is this peth0 device that's in the xenbr0 bridge now?
sammy:/etc/xen# brctl show
bridge name     bridge id               STP enabled     interfaces
xenbr0          8000.feffffffffff       no              vif5.0
                                                        peth0
                                                        vif0.0
sammy:/etc/xen# ifconfig 
eth0      Link encap:Ethernet  HWaddr 00:0C:F1:79:11:8D  
          inet addr:10.0.0.81  Bcast:10.0.0.255  Mask:255.255.255.0
          inet6 addr: fe80::20c:f1ff:fe79:118d/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:45185 errors:0 dropped:0 overruns:0 frame:0
          TX packets:30229 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:0 
          RX bytes:53881559 (51.3 MiB)  TX bytes:2913325 (2.7 MiB)

lo        Link encap:Local Loopback  
          inet addr:127.0.0.1  Mask:255.0.0.0
          inet6 addr: ::1/128 Scope:Host
          UP LOOPBACK RUNNING  MTU:16436  Metric:1
          RX packets:489 errors:0 dropped:0 overruns:0 frame:0
          TX packets:489 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:0 
          RX bytes:47785 (46.6 KiB)  TX bytes:47785 (46.6 KiB)

peth0     Link encap:Ethernet  HWaddr FE:FF:FF:FF:FF:FF  
          inet6 addr: fe80::fcff:ffff:feff:ffff/64 Scope:Link
          UP BROADCAST RUNNING NOARP MULTICAST  MTU:1500  Metric:1
          RX packets:45460 errors:0 dropped:0 overruns:0 frame:0
          TX packets:30491 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000 
          RX bytes:54092321 (51.5 MiB)  TX bytes:3142684 (2.9 MiB)
          Base address:0xac00 Memory:ff4e0000-ff500000 

vif0.0    Link encap:Ethernet  HWaddr FE:FF:FF:FF:FF:FF  
          inet6 addr: fe80::fcff:ffff:feff:ffff/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:30252 errors:0 dropped:0 overruns:0 frame:0
          TX packets:45231 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:0 
          RX bytes:2915659 (2.7 MiB)  TX bytes:53885585 (51.3 MiB)

vif5.0    Link encap:Ethernet  HWaddr FE:FF:FF:FF:FF:FF  
          inet6 addr: fe80::fcff:ffff:feff:ffff/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:161 errors:0 dropped:0 overruns:0 frame:0
          TX packets:357 errors:0 dropped:347 overruns:0 carrier:0
          collisions:0 txqueuelen:0 
          RX bytes:93615 (91.4 KiB)  TX bytes:36520 (35.6 KiB)

xenbr0    Link encap:Ethernet  HWaddr FE:FF:FF:FF:FF:FF  
          inet6 addr: fe80::200:ff:fe00:0/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:1642 errors:0 dropped:0 overruns:0 frame:0
          TX packets:6 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:0 
          RX bytes:144659 (141.2 KiB)  TX bytes:468 (468.0 b)
LinkReply

Comments:
(Deleted comment)
[User Picture]From: askbjoernhansen
2006-06-03 08:44 pm (UTC)

Doesn't work with more than one interface ...

If you have more than one interface and/or aliases it might not work. At least on fedora it doesn't.
(Reply) (Parent) (Thread)
[User Picture]From: xlerb
2006-06-03 11:17 pm (UTC)
Am I to infer that this a result of a certain design decision of Linux bridging where the bridge intercepts all traffic from the member interfaces, rather than letting traffic directed to the host be delivered normally?
(Reply) (Parent) (Thread)
(Deleted comment)
[User Picture]From: tijuanacartel
2006-06-04 06:06 am (UTC)
The "suck" part is all the major changes taking place in point releases, that from their perspective arent so major but cause a major headache to the rest of us.
(Reply) (Parent) (Thread)
[User Picture]From: edm
2006-06-03 09:54 pm (UTC)

peth0

This confused me too when I started trying to figure out where I got peth0. It's not explained as clearly as I'd have liked.

What happens in the default bridge scripts is that one of the Xen virtual devices is linked into a bridge (xenbr0 by default) with the real ethernet device, and then the real ethernet device is renamed peth0, and the virtual interface is renamed eth0. This allows the same startup scripts, etc, to be used before and after starting up the xen bridge, but to refer to the Xen virtual interface (and hence the bridge) when that's appropriate.

The shorewall guide to firewalling on Xen 3 is quite useful in understanding what's going on:

http://www.shorewall.net/Xen.html

and the Xen My Way document by the shorewall author was also useful for hints:

http://www.shorewall.net/XenMyWay.html

Ewen
(Reply) (Thread)