[c-nsp] Pre-create virtual interfaces

[Gert Doering]

Hi,

On Tue, May 17, 2005 at 04:29:22PM +0200, Oliver Boehmer (oboehmer) wrote:
> > i'm running 12.3T; did i get this by default and not realize it?
> 
> Yes. If you're running 12.3T and still see users terminated on "real"
> virtual-access (i.e. Vi2, Vi3, Vi4, etc..), you're probably using a
> feature which is not supported on VAI sub-ifs. Use the "test
> virtual-template <n> subinterface" to identify the feature and evaluate
> removing/replacing it..

Indeed...

Subinterfaces cannot be created using Virtual-Template3
Interface specific commands:
 ip route-cache flow

(12.3(9a), but I don't think there is a way to get feature navigator to
tell me whether this has been added in more recent trains)

Time for a rant now.

<rant>
Cisco is promoting "move from IP accounting to netflow!!!" since how many
years now?  5 years?  More?

And on the other hand we get:
 
  - "ip accounting out" is VAI-subif compatible, "netflow" is not
    (and 12.3 does not have "ip flow egress", which would work around
    having to do "ip route-cache flow" on the virtual-templates)

  - "ip accounting out" can be switched on and off on a per-subinterface
    basis for 802.1q and ATM sub-interfaces.  "Netflow" always does it
    for the whole interface (at least in 12.2S and 12.3).

  - on some boxes, you only get global netflow export, not per-interface
    at all  (7600, as far as I understand from the comments on this list)

How shall I justify moving to netflow if it just means "more stupid things
to watch out for"?  Of course I can build a collector infrastructure that
will cope with all the extra flow records needlessly exported, and throw
them away, and of course I can get more powerful routers (to handle the
extra exporting load, or the extra VAI cloning load) - but why is it so
difficult to implement "you really want that!" things in a useful way?
</rant>

gert
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Gert Doering - Munich, Germany                             gert at greenie.muc.de
fax: +49-89-35655025                        gert at net.informatik.tu-muenchen.de