Is Vlan1 still untagged if SVI was created for vlan1

[romanroma]

I have no way to model this in a Lab due to equipment; however, I understand that vlan1 is untagged traffic by default. But if you make a SVI for 'int vlan 1' on a upstream switch, is the traffic still classed as untagged on trunks on that local switch? Do down stream switches still behave as default with vlan1 being untagged?

Thank you

[Martin L]

Yes, vlan1 is untagged traffic by default and I don't think matters if you have SVI for vlan 1 or not.  By default Cisco switches have vlan1 as untagged; this matters on trunks between a pair of switches. So, if you want to change/add a tag to vlan other than vlan 1, you must match vlan x on both ends of a trunk link.  I think command is switchport trunk vlan 1 native

Regards, ML
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[Reza Sharifi]

Long post but have a look at Peter's explanation here.

https://community.cisco.com/t5/switching/native-vlan/td-p/1505169

HTH

[balaji.bandi · Accepted solution]

cisco environment VLAN 1 is by default, either you mentioned native VLAN means its vlan1, only if you do not like native VLAN 1, change to a different number, but it required to match both the side of trunks

[romanroma]

I appreciate you all for the help. I was a little taking back, since I need to introduce another vendor product as a router, and I noticed the person at this sight left everything in vlan1, which I know is already untagged and is really a BIG NO NO, but to many switches, and to many items to change, and the job was not spec for that. However, the other vendor doesn't relay on the term 'trunk' but enabling 802.1Q protocol, which more or less turns the interface into a trunk and then tag/untag the vlans that go across it (very similar to pro-curves). But, I was moving SVI off the out-of-date Cisco equipment, and noticed that a SVI was created for 'vlan1', and didn't know if that would have any impacts.

Thank you all for your help.

[balaji.bandi]

Layer 2 wise no impact, But when you Move Layer3 VLAN 1  SVI new switch, there is small network convergence to find a new gateway on the new switch.