Cisco 6509 Sup2/MSFC2
Is there any performance difference in an interface that is straight
layer3 IP versus a VLAN Interface on the Sup?
Thanks,
Paul
cisco-nsp mailing list cisco-nsp (AT) puck (DOT) nether.net
archive at

Fri, Jul 22, 2005 at 08:39:00AM -0400, Paul Stewart wrote:
Cisco 6509 Sup2/MSFC2

Is there any performance difference in an interface that is straight
layer3 IP versus a VLAN Interface on the Sup?

No. There's also no difference in the underlying implementation -- the
ability to configure a layer 3 interface is for the convience of the
engineer and is purely cosmetic -- internally, it creates a VLAN, an
SVI, and puts the physical interface into that VLAN.

"show vlan internal usage" will show what VLAN number it used for the
Layer3 interface.

-- Brett

cisco-nsp mailing list cisco-nsp (AT) puck (DOT) nether.net

archive at

This is something that makes me wonder.

Is there a way to *change* that VLAN number, if you need to? Because
you have to use that VLAN number on another link, due to external
factors that you can't change?

The only thing I found is "vlan internal allocation policy
{ascending|descending}". I guess that for all other cases, you could
just use SVI's, instead of L3 interfaces, couldn't you?

Marko.

cisco-nsp mailing list cisco-nsp (AT) puck (DOT) nether.net

archive at

There is no way to reassign that vlan, except by de-configuring the L3
interface, assigning the (old) internal vlan to the SVI etc that you
wanted, and then redefining the L3 interface.

The vlan allocation policy is a good suggestion, though you could then end
up with some high numbered vlan that you need for on-wire use. But at least
the internal range is not taken right from the middle of the 4K range.

Note that changing the vlan allocation policy requires a reboot.

Tim

At 02:37 PM 7/22/2005, Gert Doering contended:
>Hi,
>
Fri, Jul 22, 2005 at 09:15:48PM +0000, Marko Milivojevic wrote:
This is something that makes me wonder.

Is there a way to *change* that VLAN number, if you need to? Because
you have to use that VLAN number on another link, due to external
factors that you can't change?

The only thing I found is "vlan internal allocation policy
{ascending|descending}". I guess that for all other cases, you could
just use SVI's, instead of L3 interfaces, couldn't you?
>
>Well, of course. You could clear an internal VLAN number by going
>to an explict VLAN+SVI, and then use that VLAN number for whatever
>you need it for. Sounds ugly
>
>gert
>

>USENET is *not* the non-clickable part of WWW!

>//www.muc.de/~gert/
>Gert Doering - Munich, Germany gert (AT) greenie (DOT) muc.de
>fax: +49-89-35655025 gert (AT) net (DOT) informatik.tu-muenchen.de
>
>cisco-nsp mailing list cisco-nsp (AT) puck (DOT) nether.net
>
>archive at

Tim Stevenson, tstevens (AT) cisco (DOT) com
Routing & Switching CCIE #5561
Technical Marketing Engineer, Catalyst 6500
Cisco Systems, http://www.cisco.com
IP Phone: 408-526-6759

The contents of this message may be *Cisco Confidential*
and are intended for the specified recipients only.

cisco-nsp mailing list cisco-nsp (AT) puck (DOT) nether.net

archive at