Re: Switch Virtual Interface (SVI)

From: ronnie.angello@gmail.com
Date: Sun Jul 20 2008 - 12:01:01 ART

Good explanation Petr... I thought I'd mention that on some platforms you can use the 'no autostate' command on the SVI. That will bring the SVI up without a port in the vlan in the forwarding state.

Ronnie
Sent from my Verizon Wireless BlackBerry

-----Original Message-----
From: "Petr Lapukhov" <petr@internetworkexpert.com>

Date: Sun, 20 Jul 2008 10:53:02
To: GAURAV MADAN<gauravmadan1177@gmail.com>
Cc: Anthony Sequeira<Anthony_Sequeira@skillsoft.com>; David Cruz<david@thecruzs.net>; <ccielab@groupstudy.com>
Subject: Re: Switch Virtual Interface (SVI)

In order for an SVI to become "up/up" the following conditions must be met
1) VLAN must exist in local database and be in "active" state (not
suspended, not shutdown).

2) VLAN must be in STP forwarding state for at least one port in the switch.
That splits into either one of two sub-conditions:

2.1 There exist an access port in this VLAN, which is in spanning-tree
forwarding state

2.2) There exist a trunk, where VLAN is allowed, not pruned, and is in STP
forwarding state.

3) If STP is disabled for a VLAN, the only additional condition to (1) is
for VLAN to be active on any of the switch ports (be it access or trunk).

HTH 

-- 
Petr Lapukhov, CCIE #16379 (R&S/Security/SP/Voice)
petr@internetworkexpert.com

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2008/7/20 GAURAV MADAN <gauravmadan1177@gmail.com>:

> One thing to remember is that SVI will come in UP state depending on
> whether the corresponding vlan is present in vlan database or not .
> Assosiating the port to vlan does not come in picture .
>
> Hope it helps
> Gaurav Madan.
>
> On Sun, Jul 20, 2008 at 11:49 AM, Anthony Sequeira
> <Anthony_Sequeira@skillsoft.com> wrote:
> > Hi David!
> >
> > Here we create an SVI and assign an IP address:
> >
> > interface vlan 10
> > ip address 172.16.1.10 255.255.255.0
> >
> > Here the SVI becomes active:
> >
> > interface fa0/9
> > switchport mode access
> > switchport access vlan 10
> > no shutdown
> >
> > -----Original Message-----
> > From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
> > David Cruz
> > Sent: Saturday, July 19, 2008 1:28 PM
> > To: ccielab@groupstudy.com
> > Subject: Switch Virtual Interface (SVI)
> >
> > Hello Everyone,
> >
> > In the "Catalyst 3750 Switch Software Configuration Guide, Rel.
> > 12.1(19)EA1"
> > it states the following:
> >
> > "When you create an SVI, it does not become active until it is
> > associated
> > with a physical port."
> >
> > Does this association happen dynamically? Is there a command that has to
> > be
> > input? Any claification will be greatly appreciated.
> >
> > Regards,
> >
> > David
> >
> >
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