<div>
Hi,<br />
switchport trunk native vlan 20<br />
will set vlan 20 as &quot;untagged&quot; ... that's it.<br />
Now you have the default, that is vlan 1 native.<br />
<br />
you probably want to shutdown vlan 1 and then set<br />
switchport trunk allowed vlan 100,20<br />
<br />
this way you lose any track of vlan1 (which is desirable from security point of view).<br />
You need to set that on all other uplinked switches.<br />
<br />
hope this helps<br />
max
</div>


<div>
Hi Max,<br />
<br />
A little bit confused about your statement. You said that setiing native vlan 20 will set vlan20 as untagged. But then you said that now I have the default which is native vlan 1.<br />
<br />
Is the config below correct if I move my data subnet from vlan1 to vlan20? Thx<br />
<br />
int gig1/0/1<br />
description NEC VOIP<br />
switchport trunk encapsulation dot1q<br />
switchport mode trunk<br />
switchport trunk native vlan 20<br />
switchport trunk allowed vlan 100,20
</div>


<div>
Yes,exactly<br />
<br />
i as well tried to explain that it is not mandatory to set native vlan as a used vlan. Cisco switches (and many others) have their default to default vlan1 and native vlan1.<br />
When you shut down and disable vlan1, you may want to set trunk native vlan with another one, but this is not a must.<br />
Basically, if you do, you're telling the switch that the frames traverse the trunk &quot;untagged&quot; for that particular vlan.<br />
Cisco recommends that you set tha native vlan as an unused vlan (e.g. you create a dummy vlan, ex. vlan 4090 and set that as native) for security reason.<br />
My opinion is that thare is no security breach and you can safely use native vlan 20 as you wrote above.<br />
<br />
hope this clarify<br />
max
</div>


<div>
I see. So from my understanding, when the VoIP phone boots up, it will go to the data vlan first to get the information necessary to get to the VoIP vlan. In my current case, the data vlan is in vlan 1. So it is working fine. So if I move my data subnet from vlan1 to vlan 20, I do not need to configure native vlan20 on my VoIP port configuration. Correct?
</div>


<div>
<div class="content wysiwyg-content">
Below is my current VoIP config on a Cisco 3750 with data vlan1 and voip vlan100<br />
int gig1/0/1<br />
description NEC VOIP<br />
switchport trunk encapsulation dot1q<br />
switchport mode trunk <br />
switchport trunk allowed vlan 1,100<br />
<br />
Now I want to move my data subnet from vlan1 to vlan20. So I have to add native vlan20 in my config.Correct?<br />
int gig1/0/1<br />
description NEC VOIP<br />
switchport trunk encapsulation dot1q<br />
switchport mode trunk <br />
switchport trunk native vlan 20<br />
switchport trunk allowed vlan 1,100,20
</div>
</div>


Below is my current VoIP config on a Cisco 3750 with data vlan1 and voip vlan100
int gig1/0/1
description NEC VOIP
switchport trunk encapsulation dot1q
switchport mode trunk 
switchport trunk allowed vlan 1,100

Now I want to move my data subnet from vlan1 to vlan20. So I have to add native vlan20 in my config.Correct?
int gig1/0/1
description NEC VOIP
switchport trunk encapsulation dot1q
switchport mode trunk 
switchport trunk native vlan 20
switchport trunk allowed vlan 1,100,20

voip vlan with data vlan moving from vlan1 to vlan10

Voice over IP (VoIP) is a methodology and group of technologies for the delivery of voice communications and multimedia sessions over Internet Protocol (IP) networks, such as the Internet. Other terms commonly associated with VoIP are IP telephony, Internet telephony, broadband telephony, and broadband phone service. The term specifically refers to the provisioning of communications services (voice, fax, SMS, voice-messaging) over the public Internet, rather than via the public switched telephone network (PSTN).  Examples of the VoIP protocols are H.323, Media Gateway Control Protocol (MGCP), Session Initiation Protocol (SIP), H.248 (also known as Media Gateway Control (Megaco)), Real-time Transport Protocol (RTP), Real-time Transport Control Protocol (RTCP), Secure Real-time Transport Protocol (SRTP), Session Description Protocol (SDP), and Inter-Asterisk eXchange (IAX).

Voice Over IP

A switch is a device that filters and forwards packets of data between LAN segments. Switches operate at the data link layer or the network layer of the Open Systems Interconnection (OSI) Reference Model and therefore support any packet protocol. LANs that use switches to join segments are called switched LANs or, in the case of Ethernet networks, switched Ethernet LANs. A hub is a connection point for devices in a network. Hubs are commonly used to connect segments of a LAN. A hub contains multiple ports; when a packet arrives at one port, it is copied to the other ports so that all segments of the LAN can see all packets.

Switches / Hubs

Cisco PIX is a dedicated hardware firewall appliance; the Cisco Adaptive Security Appliance (ASA) is a firewall and anti-malware security appliance that provides unified threat management and protection the PIX does not. Other Cisco devices and systems include routers, switches, storage networking, wireless and the software and hardware for PIX Firewall Manager (PFM), PIX Device Manager (PDM) and Adaptive Security Device Manager (ASDM).

Cisco

IP telephony (Internet Protocol telephony) is a general term for the technologies that use the Internet Protocol's packet-switched connections to exchange voice, fax, and other forms of information that have traditionally been carried over the dedicated circuit-switched connections of the public switched telephone network (PSTN). Using the Internet, calls travel as packets of data on shared lines, avoiding the tolls of the PSTN. The challenge in IP telephony is to deliver the voice, fax, or video packets in a dependable flow to the user.