Can "VTP" support Nortel switch?

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Apr 17th, 2006
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Can Cisco "VTP" support by Nortel switch? I have enable

all Cisco switches with VTP, when link with Nortel Switch with pass thru, it seem can't work and with error messages from Cisco switch "domain mismatch..."

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janusng2000 Mon, 04/17/2006 - 06:06
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not even "VTP" pass thru? can Nortel switches pass thru

"VTP" traffics?

ankurbhasin Mon, 04/17/2006 - 06:12
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Hi Friend,


No not even pass through as the destination mac address used by VTP is cisco multicast address and that will not be understood by any other vendor.


HTH, if yes please rate the post.


Ankur

Bobby Thekkekandam Mon, 04/17/2006 - 06:20
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Hi,


I have to disagree with Ankur. Although the nortel switch won't participate in VTP, it *should* pass VTP advertisements through the switch. VTP advertisements are sent as a layer 2 multicast. The nortel switch should receive the VTP advertisements and treat them as unknown multicast traffic, which will result in flooding the advertisement out of every port.


Now, if there is some multicast constraining mechanism on the nortel switch such as igmp snooping, it may not pass the traffic through without creating a static entry for that multicast MAC address (01-00-0C-CC-CC-CC).


HTH,


Bobby


*Please rate helpful posts.

ankurbhasin Mon, 04/17/2006 - 06:41
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Hi Bobby,


That was the understanding I was having few days back that when any vendor switch comes on way between 2 cisco switch and if they receive the unknown muticast address it should broadcast that multicast frame to all port on that switch and it should pass.


But few days back I faced the problem using a extreme switch in between 2 cisco 2950 switches and with no multicast address constraints on extreme VTP information was not passing from the extreme switch.


I did not tried adding a static entry as customer was not ready to make any changes on extreme as you know how customers are cautious in live network.


So I thaught this may be extreme related issue but same happened with entrasys switch. I am not sure if it was a VTP constraint or other vendor constraint but cause it happened with me twice.


Regards,


Ankur

janusng2000 Mon, 04/17/2006 - 06:48
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Hi all,


Thanks for your reply, now I have an idea and minimize the problem with compromise hardware.

Bobby Thekkekandam Mon, 04/17/2006 - 07:06
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Hi Ankur,


This brings up an interesting point.


Many vendors use proprietary protocols that operate by sending layer 2 multicasts (firewalls, load balancers, etc).


Whenever a switch receives a frame with a multicast destination MAC address, and no IGMP snooping or other L2 mcast constraining mechanism is configured, it must treat the multicast frame as a broadcast and flood that frame within the VLAN. If it does not do so, then the switch is not behaving correctly.


regards,


Bobby

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