		Frequently asked questions about VIF
		------------------------------------

1. How many virtual interfaces can I have?

I have never tried more than 32 interfaces myself, but I don't know of any
specific limit. I would *not* be surprised if the operating system refuses
more than 256 virtual interfaces per real interface, though.

2. netstat gives me garbage!

If you've tried to install vif with for instance 16 interfaces on SunOS
4.1.x, using #define NVIF 16 in vif.h, you'll find that the netstat output
looks strange.

netstat, at least on SunOS 4.1.x, has a bug for more than 10 interfaces.
The vif interfaces above vif9 will show up as 'vif:', 'vif;', etc. You
simply get the next characters in the ASCII character set. On HP-UX,
netstat works fine, and the interfaces show up as vif10, vif11 etc. as
they shoiuld.

ifconfig, however, does not have this bug. This means that the vif interface
which shows up as 'vif:' in the netstat output can be configured as vif10,
'vif;' can be configured as vif11 etc. Here is the netstat output from a
SunOS system with

#define NVIF 32

after I had done:

# ifconfig vif9 129.241.36.2 netmask 0xffffff00
# ifconfig vif10 129.241.36.3 netmask 0xffffff00
# ifconfig vif20 129.241.36.13 netmask 0xffffff00
# ifconfig vif30 129.241.36.23 netmask 0xffffff00

# netstat -ian
Name  Mtu  Net/Dest      Address        Ipkts  Ierrs Opkts  Oerrs Collis Queue 
le0   1500 129.241.1.0   129.241.1.16   34700992 42   14737736 1834 3350636 0     
lo0   1536 127.0.0.0     127.0.0.1      2480261 0    2480261 0    0      0     
vif0* 1536 none          none           0       0    0       0    0      0     
vif1* 1536 none          none           0       0    0       0    0      0     
vif2* 1536 none          none           0       0    0       0    0      0     
vif3* 1536 none          none           0       0    0       0    0      0     
vif4* 1536 none          none           0       0    0       0    0      0     
vif5* 1536 none          none           0       0    0       0    0      0     
vif6* 1536 none          none           0       0    0       0    0      0     
vif7* 1536 none          none           0       0    0       0    0      0     
vif8* 1536 none          none           0       0    0       0    0      0     
vif9  1536 129.241.36.0  129.241.36.2   0       0    0       0    0      0     
vif:  1536 129.241.36.0  129.241.36.3   0       0    0       0    0      0     
vif;* 1536 none          none           0       0    0       0    0      0     
vif<* 1536 none          none           0       0    0       0    0      0     
vif=* 1536 none          none           0       0    0       0    0      0     
vif>* 1536 none          none           0       0    0       0    0      0     
vif?* 1536 none          none           0       0    0       0    0      0     
vif@* 1536 none          none           0       0    0       0    0      0     
vifA* 1536 none          none           0       0    0       0    0      0     
vifB* 1536 none          none           0       0    0       0    0      0     
vifC* 1536 none          none           0       0    0       0    0      0     
vifD  1536 129.241.36.0  129.241.36.13  0       0    0       0    0      0     
vifE* 1536 none          none           0       0    0       0    0      0     
vifF* 1536 none          none           0       0    0       0    0      0     
vifG* 1536 none          none           0       0    0       0    0      0     
vifH* 1536 none          none           0       0    0       0    0      0     
vifI* 1536 none          none           0       0    0       0    0      0     
vifJ* 1536 none          none           0       0    0       0    0      0     
vifK* 1536 none          none           0       0    0       0    0      0     
vifL* 1536 none          none           0       0    0       0    0      0     
vifM* 1536 none          none           0       0    0       0    0      0     
vifN  1536 129.241.36.0  129.241.36.23  0       0    0       0    0      0     
vifO* 1536 none          none           0       0    0       0    0      0     

Since vif is entirely unsupported, and SunOS 4.1.x is not exactly the highest
priority for Sun these days, I do not expect this bug to be fixed.

3. I cannot ping one of the virtual addresses from other machines.

The most frequent problem here is forgetting to manually add a permanent,
published ARP entry. This is essential - the operating system will *not* do
it for you.

If you already have added a permanent, published ARP entry, please check the
routing tables on the machine you're trying to ping from. You may also wish
to use tcpdump, snoop or a similar packet sniffer to verify that packets are
being sent with the correct IP address *and* Ethernet address.

4. I cannot ping one of the virtual addresses from the host itself.

On SunOS this should work right away, without any more configuration. If it
doesn't, you probably have other problems as well.

On HP-UX you need to add a host route to the loopback interface in order to
ping the host from itself. Using the vif9 interface from the example above,
you would do:

# route add host 129.241.36.2 127.0.0.1 0
