Up: 4.4 Performance
VNET test configurations for the local area (a) and the wide area (b).
Local area is between two labs in the Northwestern CS Department.
Wide Area is between the first of those labs and a lab at Carnegie Mellon.
Although VNET is targeted primarily for wide-area distributed
computing, we evaluated performance in both a LAN and a WAN. Because
our LAN testbed provides much lower latency and much higher throughput
than our WAN testbed, it allows us to see the overheads due to VNET
more clearly. The Client, Proxy, and Host machines are 1 GHz Pentium
III machines with Intel Pro/100 adaptors. The virtual machine uses VMware GSX Server 2.5, with 256 MB of memory, 2 GB virtual disk and RedHat 7.3. The network driver used is vmxnet.
Our testbeds are illustrated in Figure 3. The LAN
and WAN testbeds are identical up to and including the first router
out from the Client. This portion is our firewalled lab in the
Northwestern CS department. The LAN testbed then connects, via a
router which is under university IT control (not ours), to another
firewalled lab in our department which is a separate, private IP
network. The WAN testbed instead connects via the same router to the
Northwestern backbone, the Abiline network, the Pittsburgh
Supercomputing Center, and two administrative levels of the campus
network at Carnegie Mellon, and finally to an lab machine there.
Notice that even a LAN environment can exhibit the network management
problem. It is important to stress that the only requirement that
VNET places on either of these complex environments is the ability to
create a TCP connection between the Host and Proxy in some way.
We measured the latency and throughput of the underlying ``physical''
IP network, VMWare's virtual networking options, VNET, and of SSH
- Physical: VNET transfers Ethernet packets over multiple
hops in the underlying network. We measure equivalent hops, and also
end-to-end transfers, excepting the VM.
VMWare: Here we consider the
performance of all three of VMWare's options, described earlier.
: Machine on the
Host's LAN to/from the Host.
: Analogous to the first hop for an outgoing
packet in VNET and the last hop for an incoming packet.
: Analogous to the TCP connection of
a Handler, the tunnel between the two VNET servers.
: End-to-end except for the VM.
: Internal transfer on the Host.
VNET: Here we use VNET to project the VM onto the Client's
: Host-only networking, which VNET builds
(Bridged): Bridged networking.
This leaves the network administration problem at the remote site.
(NAT): NAT-based networking.
This partially solves the network administration problem at the remote
site at the layer 3, but creates an asymmetry between incoming and
outgoing connections, and does not support VM migration. It's close
to VNET in that network traffic is routed through a user-level server.
SSH: Here we look at the throughput of an SSH connection
between the Client and the Host to compare with VNET with SSL.
(VNET): VNET without SSL
(VNET+SSL): VNET with SSL
Up: 4.4 Performance