switchport mode trunk ....

Answered Question
Apr 8th, 2007

if a swichport is set to trunking, ...

then, what would i use the phyiscal port for?, could i plug an end node into the port?... or is this trunk port virtual where it doesnt matter what port on a switch i assign as the trunk port in a vlan...

I have this problem too.
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Correct Answer by balajitvk about 9 years 9 months ago

Dear Davis,

A port can be set to trunk mode if there is a need to carry multiple VLANs. If you plug an end node to the port assigned in trunk mode, the port can't understoond the untagged vlan packets coming from end node, so it won't do the job for you.....

Switch ports run in either access or trunk mode. In access mode, the interface belongs to one and only one VLAN. Normally a switch port in access mode attaches to an end user device or a server. The frames transmitted on an access link look like any other Ethernet frame.

Trunks, on the other hand, multiplex traffic for multiple VLANs over the same physical link. Trunk links usually interconnect switches.

However, they may also attach end devices such as servers that have special adapter cards that participate in the multiplexing protocol.

Hope this will clear ur doubt!

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Correct Answer
balajitvk Sun, 04/08/2007 - 08:46

Dear Davis,

A port can be set to trunk mode if there is a need to carry multiple VLANs. If you plug an end node to the port assigned in trunk mode, the port can't understoond the untagged vlan packets coming from end node, so it won't do the job for you.....

Switch ports run in either access or trunk mode. In access mode, the interface belongs to one and only one VLAN. Normally a switch port in access mode attaches to an end user device or a server. The frames transmitted on an access link look like any other Ethernet frame.

Trunks, on the other hand, multiplex traffic for multiple VLANs over the same physical link. Trunk links usually interconnect switches.

However, they may also attach end devices such as servers that have special adapter cards that participate in the multiplexing protocol.

Hope this will clear ur doubt!

Rgs,

davisr651 Sun, 04/08/2007 - 09:04

so, say DTP was running on a cisco switch, does it automatically assign a switchport that is not populated as a trunk port?

Jon Marshall Sun, 04/08/2007 - 08:55

Hi

As stated by the previous poster a trunk link is used to carry multiple vlan information across it. The vlans are tagged with a vlan ID when they go across the trunk.

Generally trunks are used between switches to allow multiple vlans to exist on multiple switches.

You can connect an end point to a trunk link if you are running 802.1q tagging on the end host which most modern NIC's support but this is not the norm.

HTH

Jon

davisr651 Sun, 04/08/2007 - 09:02

so, for example, i have fa 0/4 configured as

a trunk port, then, should i not plug a device such as a pc (node) into this port?

I trunk ports are used for switch-to-switch communitation..

thanks

balajitvk Sun, 04/08/2007 - 09:09

Hi davis,

Yes, you shouldn't connect device such as PC to the trunk port until that device has special card which will support trunking.....

Normally, Trunks are used between Switch to Switch communcation, in generally where multiple vlans needs to be carried on the single link.

Rate if it does,

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davisr651 Sun, 04/08/2007 - 09:16

I guess i should make fellow IT staff aware of this... not to you the trunk ports.....

If i did plug in a pc, i assume it would not work, is this correct?

balajitvk Sun, 04/08/2007 - 09:18

Davis,

Yes, I thought my earlier postings might clear your doubt!

Rate if it does,

Rgs

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