Tagging vs Trunking

[skhirbash]

We have two Procurve switches that are currently stacked. One 1Gbps port is linked to another 1Gbps port on the other switch. We are using one VLAN besided the Defualt_VLAN and want to know if Tagging the ports is the way to go or Trunking them is the better method.

Thanks in advance,

SK

[naveen_b81]

Trunking is a better method as it allows both the VLANs to communicate on the single link.

Naveen B

[sourabhagarwal]

there are two ways to configure trunking on cisco devices.

One is called as tagging (802.1q) and second one is known as encapsulation (ISL).

ISL is cisco proprietory and 802.1q is open standard which can be used with non cisco devices.

check this URL to get more information on above mentioned trunking protocols.

http://www.cisco.com/en/US/tech/tk389/tk390/technologies_tech_note09186a0080094665.shtml

hope it helps ... rate if it does ...

[kamal-learn]

hi

i think you cannot tag without trunking, to tag you need a special field whatever the type of the frame ethernet or tokingring, that field is prepared by a trunk protocol such as 802.1q or ISL . within that field the trunk protocol tag the frame with an identifier that determinate its mebership to a specific vlan.

if you go with 802.1q there is a concept called native vlan by default is the vlan 1, where the frames belonging to that vlan are not tagged.

HTH

please do rate if it does help

[MATTHIAS SCHAERER]

Your question is a difficult one because the "Trunk"-word is something that causes confusion. To my knowledge there are at least three different meanings for trunking and the replies to your question show me that these differences are not widely known.

1. When Cisco talks of trunking in a Catalyst switch environment, they talk about transporting mulitple VLAN over the same cable. Other vendors call this mechanism tagging because 802.1q tags are normally used. Cisco did not call it tagging years ago because their proprietary protocol ISL did encapsulate ethernet frames instead of tagging the ethernet header.

2. When other vendors (or at least some of them) talk about trunking they are bundling more than one physical link into one logical link. Cisco calls this EtherChannel. For your Procurve trunking means bundling interfaces with LACP or proprietay Procurve trunking.

3. When Voice engineers talk about trunks they talk about one line between two telephone switches. This can be an analog line or it can be one 64/56 kbits channel on an E1/T1 facility.

HTH to avoid confusion

Mat