Untagged VLANs in qemu-kvm vm

Untagged VLANs in qemu-kvm vm

Post by Srinivasa T » Fri, 13 May 2011 18:16:48



Hi All,
   I have a FC14 host and 2 RHEL 6 systems running as VMs.  I am using
tap interface and have set up a private virtual bridge among the 3
machines (I have used 12.168.122.x).  Now when I configure the tagged
lans in both the VMs (using vconfig add eth0 <vlan-id>) and give IP
addresses to those virtual interfaces (192.168.2.2 in one VM and
192.168.2.3 in other VM), I am not able to ping each other.  tcpdump
is showing ARP is broadcast but there is no response.  What is the
step I am missing?

Regards,
Seenu.

 
 
 

Untagged VLANs in qemu-kvm vm

Post by Srinivasa T » Sat, 21 May 2011 22:17:51



Quote:> Hi All,
> ? ?I have a FC14 host and 2 RHEL 6 systems running as VMs. ?I am using
> tap interface and have set up a private virtual bridge among the 3
> machines (I have used 12.168.122.x). ?Now when I configure the tagged
> lans in both the VMs (using vconfig add eth0 <vlan-id>) and give IP
> addresses to those virtual interfaces (192.168.2.2 in one VM and
> 192.168.2.3 in other VM), I am not able to ping each other. ?tcpdump
> is showing ARP is broadcast but there is no response. ?What is the
> step I am missing?

This was solved by using -netdev instead of just -net option to qemu-
kvm.

FYR: http://fedoraproject.org/wiki/Features/VHostNet

Regards,
Seenu.

 
 
 

1. To vlan or not to vlan, that's the question

Hello everyone, 1st. post on this group here! (hope it's the right place)

Actually the network I administer, consists of actually 3 networks,
INTERNAL, DMZ, and EXTERNAL, that may be a familiar scenario for most of
you, simple and effective. The three networks, are interconnected with a
firewall (on a linux box, using netfilter). I was asked to literally
divide the network in two (phisically and/or logically), intending to
improve security & performance.

That's why we considered the option of a switch with VLAN support (but
we haven't done it in a serious way yet). Notice that we're talking
about a network with <100 hosts, counting servers and workstations.

The 1st. question is:
1) Why would I spend $$ on a switch that supports VLAN, among other
features(*), if (IMHO) I can implement the same thing with 2 common
switches (less money), and a firewall interconnecting them (managing
security & routing) ?

beside the -probable- answer is 'you just don't need vlan!!! Don't burn
money!', please let me write some additional questions:

2) in what environment is really worthy implement vlan?
Google took me here:
http://nislab.bu.edu/nislab/education/sc441/six/implementation.htm
"Why implement Vlan?" but, It'd be nice to see comments about some
real-life examples.

3) What can I do with a vlan switch than I CANNOT DO with 2 switches?

4) The firewall/router interconnecting both networks will have any
special issues to consider if the interconnected networks are a vlan
network, or are independient?

(*) there may be other features, that I don't know, and even I may not
need, but this can be gently answered in question 2 ;)

Regards,

pd: sorry for my eventual lack of knowledge, in that case, here go my
apologies in advance, and I'd be glad to be pointed to some "FMs"...so I
can RTFM  :P

--
Jose R. "Xous" Negreira
[ *xous*at*xouslab_dot_com* ]
XousLAB - http://www.xouslab.com
iptableslinux - http://www.iptableslinux.com

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