VTP vs 802.1Q

mguy

I'm not sure what the difference is between the two. I thought both propagates VLAN information?

What is the function and difference between these two technologies? Please help!

SubnetZero

Hello,

They are completely different. The comparison should be between ISL and 802.1q instead:

VLAN Trunk Protocol (VTP) is a Cisco-proprietary protocol that is available on most of the Cisco Catalyst series products. VTP reduces administration in a switched network. When you configure a new VLAN on one VTP server, the VLAN is distributed through all switches in the domain. This reduces the need to configure the same VLAN everywhere.

IEEE 802.1Q is the networking standard that supports Virtual LANs (VLANs) on an Ethernet network. The standard defines a system of VLAN tagging for Ethernet frames and the accompanying procedures to be used by bridges and switches in handling such frames. The standard also contains provisions for a quality of service prioritization scheme commonly known as IEEE 802.1p and defines the Generic Attribute Registration Protocol.

Cisco Inter-Switch Link (ISL) is a Cisco Systems proprietary protocol that maintains VLAN information in Ethernet frames as traffic flows between switches and routers, or switches and switches.ISL is Cisco's VLAN tagging protocol and is supported only on some Cisco equipment over Fast and Gigabit Ethernet links. It is offered as an option to the IEEE 802.1Q standard, a widely used VLAN tagging protocol, although the use of ISL for new sites is deprecated by Cisco

HTH

mguy

Thank you for that.

it_consultant

In the non cisco world VTP = GVRP. VTP is confusing because it has the word "trunk" in it. In non-cisco switches trunks are the equivalent to Cisco's etherchannel (LACP) function. In non-cisco switches we "tag" and "untag" switchports as opposed to "trunking" them.

SubnetZero

it_consultant wrote: »

In the non cisco world VTP = GVRP. VTP is confusing because it has the word "trunk" in it. In non-cisco switches trunks are the equivalent to Cisco's etherchannel (LACP) function. In non-cisco switches we "tag" and "untag" switchports as opposed to "trunking" them.

Years a go when I was working with both Foundry and Cisco I learned this the hard way, call it baptism by fire!

So a Cisco "trunk" port is the equivalent to a non-cisco "tagged" port and a Cisco "EtherChannel" is the equivalent to a non-cisco "Trunk"

For some reason Cisco is the only vendor that names them like this, Foundry/Brocade, Juniper, HP, and Extreme Networks all use the OTHER terminology (which makes more sense).

Hopefully this doesn't mess with mguy's mind too much!

it_consultant

SubnetZero wrote: »

Years a go when I was working with both Foundry and Cisco I learned this the hard way, call it baptism by fire!

So a Cisco "trunk" port is the equivalent to a non-cisco "tagged" port and a Cisco "EtherChannel" is the equivalent to a non-cisco "Trunk"

For some reason Cisco is the only vendor that names them like this, Foundry/Brocade, Juniper, HP, and Extreme Networks all use the OTHER terminology (which makes more sense).

Hopefully this doesn't mess with mguy's mind too much!

VLANS make MUCH more sense when you think of it in terms of tagging. I remember learning VLANs when I first took the CCNA in 2007 and they were cramming ISL as the answer to all of our problems. I work almost exclusively on HP pro curves now. When you see how the 802.1Q frame is inserted it starts making sense. I think on my pro curves my port can be untagged (port belongs to this VLAN, computers with no vlan intelligence will be in this network) and can tag (port can belong to that VLAN if the computer can and wants to me) 10 vlans per port.