[libvirt] need help: what should be supported?

[Gene Czarcinski]

I need some help/guidance as to what networking characteristics should 
be supported by libvirt.  Mostly, I am asking what should be valid for a 
prefix.

For IPv4:

The prefix can theoretically range from 0 to 32.  Typically, the values 
of 8, 16 or 24 is used.  For an IP specification, should I be able to 
specify prefix=32 (netmask 255.255.255.255)?  This is not a network 
specification but one for a specific guest-host ... but, what will the 
virtualization host have for the address on this interface?

Proposed: prefix (or equivalent netmask) must be
     8 < prefix < 29

For IPv6:  Similar to IPv4 but the range is (theoretically) 0 to 128.  
However, DHCPv6 and RA will **ONLY** work for prefix=64 ... nothing 
greater and nothing less.  For an network on an interface which is 
visible to the virtualization host, it must have an address for the 
host;  therefore, prefix <127.  I am not sure what an IP definition with 
prefix=0 means for a libvirt virtual network.

Proposed: Prefix=64 for DHCPv6 and/or RA support.  For other network 
addresses (such as static route),
     7 < prefix <= 64.

Most IPv6 software does not appear to handle subnets where prefix > 64 
except for prefix=128 for a specific host address.

That is not to say that prefix <64 prefix < 128 could not have a meaning 
and be useful.  But, if supported, how should it be specified so that 
user problems are minimized ... or do we just support it and what 
happens is a user problem?

Comments?  Suggestions??

Gene