Software router

James Hess mysidia at
Wed Jun 2 07:08:26 UTC 2010

On Tue, Jun 1, 2010 at 3:50 PM, Andrey Khomyakov
<khomyakov.andrey at> wrote:
>Seems like to do that I'd have to run a software router on a VM that would
For a VM router  (for performance reasons is different than what i'd
suggest for a generic software router), I would suggest picking an
off-the-shelf OS that Vmxnet2 or Vmxnet3  drivers are available for,
see KB1001805, make sure to install the VM tools, change vNICs'  type
to vmx.    Standard OS + quagga, openbgpd, or other.    Vyatta should
be great, if you are able to compile the vmx drivers for it.

Hopefully you are not planning to forward high-PPS traffic through a
single VM;  vNICs are potentially a serious bottleneck in that

 If traffic is not trivial,   I would suggest using third-party
next-hop routing,  that is, with VM-based routers  removed from
forwarding path,  by acting as route server, or announcing as next-hop
another (real)  third-party router's   IP  instead one of its own IPs
(requiring all 3 routers to share a subnet).

Or investigate layer 2 extension of an upstream subnet via  L2TPv3
pseudo-wire service,  or Cisco OTV, etc....
then design failover scenario to not require a VM involvement.

Another thought is   OSPF /32  host advertisements on  some 'beacon'
VM(s),  with tracked routes for  'virtual subnet' selection, instead
of a "router" VM.

Those are some vague thoughts...   I'm just saying, almost anything,
other than having a VM forward packets for subnets, if it is
avoidable,  even  tunnelling -- on a non-VM router...    :)


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