Jean-Christophe Guillain
2005-Aug-15 11:09 UTC
[Xen-users] Constructor code in MAC address does matter ?
I observed a strange networking behaviour of my Debian virtual host in function of the MAC address I use. It seems that when I use an existing constructor code, networking works without any problem, but is impossible in the other case... Ex. : - vif = [ ''mac=aa:00:00:00:00:55, bridge=xen-br0'' ] -> no problem - vif = [ ''mac=df:00:00:00:00:55, bridge=xen-br0'' ] -> the bridge does not transmit my packets apparently. No DHCP possible, and when I used a static address I can''t ping the bridge from the guest... Is it normal ? Is it really related to constructor code ? I use a Xen 2.0.6 on a Debian Sarge host with kernels 2.6.11.12-xen0/u... *** Jean-Christophe Guillain jcg@adviseo.fr - 06 61 52 20 76 http://www.adviseo.fr - http://www.open-sp.fr _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
Derrik Pates
2005-Aug-15 18:36 UTC
Re: [Xen-users] Constructor code in MAC address does matter ?
On Mon, Aug 15, 2005 at 01:09:15PM +0200, Jean-Christophe Guillain wrote:> > I observed a strange networking behaviour of my Debian virtual host in > function of the MAC address I use. It seems that when I use an existing > constructor code, networking works without any problem, but is impossible > in the other case... > Ex. : > - vif = [ ''mac=aa:00:00:00:00:55, bridge=xen-br0'' ] -> no problem > - vif = [ ''mac=df:00:00:00:00:55, bridge=xen-br0'' ] -> the bridge does not > transmit my packets apparently. No DHCP possible, and when I used a static > address I can''t ping the bridge from the guest...Yes, this actually makes sense. Bit 0 of the first hex byte of the MAC address indicates the packet is going to a broadcast address, but in a source MAC address, it''s nonsensical. I''m not surprised other TCP stacks would squash it. Provide a MAC address that doesn''t have that bit set. (I.e., de:00:00:00:00:55 should work; df:00:00:00:00:55 won''t.) Note that this has nothing to do with the domain builder, and everything to do with the behavior of Ethernet networking. -- Derrik Pates demon@devrandom.net _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
Marcus Brown
2005-Aug-16 01:32 UTC
Re: [Xen-users] Constructor code in MAC address does matter ?
Hi, Jean-Christophe Guillain wrote:> > I observed a strange networking behaviour of my Debian virtual host in > function of the MAC address I use. It seems that when I use an existing > constructor code, networking works without any problem, but is > impossible in the other case... > Ex. : > - vif = [ ''mac=aa:00:00:00:00:55, bridge=xen-br0'' ] -> no problem > - vif = [ ''mac=df:00:00:00:00:55, bridge=xen-br0'' ] -> the bridge does > not transmit my packets apparently. No DHCP possible, and when I used a > static address I can''t ping the bridge from the guest... > Is it normal ? Is it really related to constructor code ? > I use a Xen 2.0.6 on a Debian Sarge host with kernels 2.6.11.12-xen0/u...Have you seen http://wiki.xensource.com/xenwiki/XenNetworking ? Which says: Whehn choosing MAC addresses to use, ensure you choose a unicast address. That is, one with the low bit of the first octet set to zero. For example, an address starting aa: is OK but ab: is not. It is best to keep to the range of addresses declared to be "locally assigned" (rather than allocated globally to hardware vendors). These have the second lowest bit zero in the first octet. For example, aa: is OK, a8: isn''t. In summary, an address of the following form should be OK: XY:XX:XX:XX:XX:XX where X is any hexadecimal digit, and Y is one of 2, 6, A or E. Marcus _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
yang jianguo
2005-Aug-16 06:38 UTC
[Xen-users] Problem in domains communication without ethernet card
Hi list: My computer didnot have an ethernet card. I installed xen-unstable in Federa Core 3. Of course the ifconfig only have lo device. I start a ttylinux dom-u with kernel vmlinuz-2.6.11.2-xenU, ip=10.100.1.179 How do the two domains communicate through tcp? And I use vnc=1 in "ttylinux.vmx" ,it did not work.I think the is the two domain cannot communicate throuth tcp. what should i do? I have read the maillist and wiki, they all have an ethernet card, but i have not.And the xenLinux said command"brctl" was not exsisted! --------------------------------- DO YOU YAHOO!? 雅虎免费G邮箱－No.1的防毒防垃圾超大邮箱 --0-1394216061-1124174306=:5856 Content-Type: text/html; charset=gb2312 Content-Transfer-Encoding: 8bit <P>Hi list:</P> <P>My computer didnot have an ethernet card.<BR>I installed xen-unstable in Federa Core 3. Of course the ifconfig only have lo device.<BR>I start a ttylinux dom-u with kernel vmlinuz-2.6.11.2-xenU, ip=10.100.1.179<BR>How do the two domains communicate through tcp?<BR>And I use vnc=1 in "ttylinux.vmx" ,it did not work.I think the is the two domain cannot communicate throuth tcp.</P> <P>what should i do? I have read the maillist and wiki, they all have an ethernet card, but i have not.And the xenLinux said command"brctl" was not exsisted!</P><p> <hr size=1>DO YOU YAHOO!?<br> <a href="http://cn.mail.yahoo.com" target=blank> 雅虎免费G邮箱－No.1的防毒防垃圾超大邮箱 </a> --0-1394216061-1124174306=:5856-- --===============0859912447=Content-Type: text/plain; charset="us-ascii" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Content-Disposition: inline _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users --===============0859912447==--