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TOPIC: VTP - question about daisy chained VLAN switches

VTP - question about daisy chained VLAN switches 11 years 11 months ago #6320

  • gl0bal
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Could some one please clarify a VTP question for me.

If you have 2 or more switches daisy chained and you have VTP pruning enabled, how will a down stream switch get its VLAN info if its immediate upstream switch does not have any of the same VLANs.

Firewall.cx material says
VTP Pruning as you might have already guessed solves the above problem by reducing the unnecessary flooded traffic described previously. This is done by forwarding broadcasts and unknown unicast frames on a VLAN over trunk links only if the receiving end of the trunk has ports in that VLAN.

For example (excuse the simplistic drawing)

SwitchA - VLAN 2
SwitchA - VLAN 4
|
SwitchB - VLAN 4
|
SwitchC - VLAN 2
SwitchC - VLAN 3

Because of VTP pruning would SwitchC therefore not receive VLAN info for VLAN 2?

Thanks for your help
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Re: VTP - question about daisy chained VLAN switches 11 years 11 months ago #6326

  • sahirh
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VTP info will still be passed between the switches, the only thing that will be filtered will be traffic.. think of it like routing protocols that will keep giving each other information to effectively manage the routed protocols.



Did I just confuse that ?
;)
Sahir Hidayatullah.
Firewall.cx Staff - Associate Editor & Security Advisor
tftfotw.blogspot.com
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Re: VTP - question about daisy chained VLAN switches 11 years 11 months ago #6336

  • gl0bal
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When will I learn - firewall.cx has all the answers

www.firewall.cx/vlans-vtp.php
The advertised information will firstly reach the two Catalyst 2950 switches directly connected to the 3550 and will then travel to the cascaded switches below and through the trunk links. If the link between the cascaded 2950's was not a trunk link but an access link, then the 2nd set of switches would not receive and VTP updates:

Just like you were saying sahirh.

By the way its amazing how often you come across firewall.cx when googling for networking info.

Keep up the good work firewall.cx!
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Re: VTP - question about daisy chained VLAN switches 11 years 11 months ago #6369

  • Chris
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Global,

One of the reasons you almost always find the answer to your questions when reading through our material is because we read through our material considering ourselves as visitors, and then try to cover any questions that might arise from the articles.

This tactic has proven to be a lot more time consuming, but the results as you and everyone else see, are well worth it.

Be sure that we will continue to enrich our site with the best possible information and present it in such a way, you will never need to go anywhere else - this is also why we are recommend by Cisco in their CCNA curriculum :)

....and if you thought our material is awesome.... wait until you get your hands on our Cisco lab :wink:


Cheers,
Chris Partsenidis.
Founder & Editor-in-Chief
www.Firewall.cx
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