trunk between switch and windows xp host

Answered Question
Nov 15th, 2008

hi every body!

I learned that if one statically configure trunking on switch port using " switchport mode trunk" , it will enable trunking on that port regardless of state of remote end switch 's port.

So does it mean if I confiure the trunk statically on a switch port and connect that port to windows xp host, will the switch send vlans frame say vlan 1,vlan 2 to windows xp host?

I understand that if encapsulation is dotiq, and native vlan is vlan 1 then host is able to communicate with other hosts which are in vlan1.

How about if encapsulation is isl which means vlan1 will now be tagged, will windows xp host drop the frame as it does not undestand it?

thank a lot!

I have this problem too.
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Correct Answer by Giuseppe Larosa about 8 years 2 weeks ago

Hello Sarah,

as Glen has noted ISL is cisco proprietary so it is not a viable option in connecting to a windows xp NIC.

There are some NICs that support IEEE 802.1Q trunking and this fact has been used recently in our network to connect PCs running VMware: one VM instance uses one vlan to connect to a VRF (MPLS VPN protected), one VM instance uses another vlan that is in the global routing table, the third vlan is the voice vlan used by the IP phone that sits between the switch port and the PC NIC.

Hope to help

Giuseppe

Correct Answer by mihanlin about 8 years 2 weeks ago

Hi,

Windows XP will be able to receive both ISL and dot1q encapsulated packets but it won't be able to do much with them.

You can try doing this by placing Wireshark and listen on the trunk port.

However, most NIC manufacturers will strip the vlan tag before passing it to the operating system and you'll need to modify your registry to tell the driver NOT to remove the tag.

For most Intel NICs you can follow the directions from their site to do this:

http://support.intel.com/support/network/sb/CS-005897.htm

Correct Answer by glen.grant about 8 years 2 weeks ago

It will say it is trunking as long as it has a layer 1 link , the one problem with forcing on a trunk. . Doesn't mean trunking is working unless the nic card has trunking capability . A windows client cannot talk ISL it is a cisco proprietary trunking protocol used between old cisco switches , they are slowly phasing out an the ISL connectivity option, some only support dot1q now .

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Correct Answer
glen.grant Sat, 11/15/2008 - 18:26

It will say it is trunking as long as it has a layer 1 link , the one problem with forcing on a trunk. . Doesn't mean trunking is working unless the nic card has trunking capability . A windows client cannot talk ISL it is a cisco proprietary trunking protocol used between old cisco switches , they are slowly phasing out an the ISL connectivity option, some only support dot1q now .

Correct Answer
mihanlin Sun, 11/16/2008 - 02:54

Hi,

Windows XP will be able to receive both ISL and dot1q encapsulated packets but it won't be able to do much with them.

You can try doing this by placing Wireshark and listen on the trunk port.

However, most NIC manufacturers will strip the vlan tag before passing it to the operating system and you'll need to modify your registry to tell the driver NOT to remove the tag.

For most Intel NICs you can follow the directions from their site to do this:

http://support.intel.com/support/network/sb/CS-005897.htm

Correct Answer
Giuseppe Larosa Sun, 11/16/2008 - 04:09

Hello Sarah,

as Glen has noted ISL is cisco proprietary so it is not a viable option in connecting to a windows xp NIC.

There are some NICs that support IEEE 802.1Q trunking and this fact has been used recently in our network to connect PCs running VMware: one VM instance uses one vlan to connect to a VRF (MPLS VPN protected), one VM instance uses another vlan that is in the global routing table, the third vlan is the voice vlan used by the IP phone that sits between the switch port and the PC NIC.

Hope to help

Giuseppe

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