When does 802.1q use a VLAN header?
altjx
Member Posts: 194
in CCNA & CCENT
I'm taking the Boson exam right now and I just realized that 802.q1 does not use a VLAN header if the native VLAN is other than 1. I thought, for some reason, that anything outside of native VLAN 1 (which is default), would require a VLAN header. Here's what I'm looking at.
http://dl.dropbox.com/u/2526790/Capture.PNG (for bigger image)
Can anyone please explain to me when 802.1q uses a VLAN header? The question basically wants to know which of the following are true based on the configuration displayed.
http://dl.dropbox.com/u/2526790/Capture.PNG (for bigger image)
Can anyone please explain to me when 802.1q uses a VLAN header? The question basically wants to know which of the following are true based on the configuration displayed.
CompTIA: A+, Security+, Network+
Microsoft: MCTS: Windows 7, Configuring, MCTS: Windows Server 2008 Applications Infrastructure, Configuring
Cisco: CCENT, CCNA
Microsoft: MCTS: Windows 7, Configuring, MCTS: Windows Server 2008 Applications Infrastructure, Configuring
Cisco: CCENT, CCNA
Comments
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QHalo Member Posts: 1,488802.1q uses a VLAN header for any VLAN tagged with anything but the Native VLAN. In this case, VLAN 3 is set as the native VLAN, thus no header.
HTH -
altjx Member Posts: 194802.1q uses a VLAN header for any VLAN tagged with anything but the Native VLAN. In this case, VLAN 3 is set as the native VLAN, thus no header.
HTH
Gotcha, so if two switches have native vlan 1 configured, but using dot1q, and sends traffic over to a host in another VLAN, it tags the frame with the header. To VLAN 1 hosts, it doesn't. right?CompTIA: A+, Security+, Network+
Microsoft: MCTS: Windows 7, Configuring, MCTS: Windows Server 2008 Applications Infrastructure, Configuring
Cisco: CCENT, CCNA -
altjx Member Posts: 194CompTIA: A+, Security+, Network+
Microsoft: MCTS: Windows 7, Configuring, MCTS: Windows Server 2008 Applications Infrastructure, Configuring
Cisco: CCENT, CCNA -
thedrama Member Posts: 291 ■□□□□□□□□□802.1q uses a VLAN header for any VLAN tagged with anything but the Native VLAN. In this case, VLAN 3 is set as the native VLAN, thus no header.
HTH
Not just 802.1q but also ISL can be used for this. This depends on your brand. If at least one of them is non-cisco, you should use 1q for frame tagging.
Why do we need these? Because, inter-switch VLAN communication occurs by this way. A host assigned to a VLAN other than VLAN1
wanna talk to the same VLAN on another switch. In this case, how switch determines to send the data to the correct VLAN is
defined as frame tagging.Monster PC specs(Packard Bell VR46) : Intel Celeron Dual-Core 1.2 GHz CPU , 4096 MB DDR3 RAM, Intel Media Graphics (R) 4 Family with IntelGMA 4500 M HD graphics.
5 year-old laptop PC specs(Toshiba Satellite A210) : AMD Athlon 64 x2 1.9 GHz CPU, ATI Radeon X1200 128 MB Video Memory graphics card, 3072 MB 667 Mhz DDR2 RAM. (1 stick 2 gigabytes and 1 stick 1 gigabytes) -
advanex1 Member Posts: 365 ■■■■□□□□□□ISL encapsulates everything, native or not.Not just 802.1q but also ISL can be used for this. This depends on your brand. If at least one of them is non-cisco, you should use 1q for frame tagging.
Why do we need these? Because, inter-switch VLAN communication occurs by this way. A host assigned to a VLAN other than VLAN1
wanna talk to the same VLAN on another switch. In this case, how switch determines to send the data to the correct VLAN is
defined as frame tagging.Currently Reading: CISM: All-in-One
New Blog: https://jpinit.com/blog -
Heero Member Posts: 486Also, there is an option to turn on tagging of the native vlan when using dot1q.
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SharkDiver Member Posts: 844In the CCNA Security materials, it is suggested that you should set the Native VLAN to an unused VLAN so that all packets are tagged. This prevents VLAN Hopping.