port-based vlan and tag-based vlan

[aaab...@hotmail.com]

What is difference between them?
What i understand is
1. port-based vlan is old (before intrduce
802.3q) currently on the market every switch is tag-based vlan,
Is it right?

2. port-based vlan no pvid concept and can not suuport trunk
(talk between vlans)

Any opinion?

TIA,
st

[Albert Manfredi]

Haven't we already been over this? Port based VLANs are usually the
way VLANs are implemented between the switch and the end system.
802.1Q is typically used between switches, in the trunk segments.

You can also support multiple VLANs on a segment without depending on
the 802.1Q VLAN tag, though. Your would need some other mechanism than
just the switch port number, as a way of differentiating. For example,
even without a VLAN tag, you can use MAC addresses (source and
destination) or you can use IP addresses (source and destination) to
make VLAN decisions.

Bert

[aaab...@hotmail.com]

Thanks,
Yes, Vlan can based on port,mac and protocols.
What i like to know is switches on the market whether they still
support
port based vlan or not? To make things easy, the tag does not
only work between swiches also works between switch to end system.
Am i right? Do most vendors replace port based vlan to tag based
vlan? (based on new ethernet interface chips?)

st

[Albert Manfredi]

On Oct 21, 7:51 pm, aaabb...@hotmail.com wrote:

> Yes, Vlan can based on port,mac and protocols.
> What i like to know is switches on the market whether they still
> support
> port based vlan or not? To make things easy, the tag does not
> only work between swiches also works between switch to end system.
> Am i right? Do most vendors replace port based vlan to tag based
> vlan? (based on new ethernet interface chips?)

Oh, okay, yes, switches certainly do still support port-based VLANs.
As far as I can tell, they are still the most common way to get hosts
onto a particular VLAN.

Whether 802.1Q VLANs will eventually displace all port-based VLANs
between hosts and switches, I'm not sure. It's possible. You'd have to
start seeing VLAN IDs being provided via DHCP, for instance, or some
other dynamic means, before hosts go in a big way to 802.1Q, I would
think.

Bert

[aaab...@hotmail.com]

Thanks,
Cisco support two types ethernet interface on their switches.
access port and trunk port. Is the access port based on port vlan
or tag vlan? The trunk port should be based on tag.

st

[Albert Manfredi]

On Oct 22, 12:29 pm, aaabb...@hotmail.com wrote:

> Cisco support two types ethernet interface on their switches.
> access port and trunk port. Is the access port based on port vlan
> or tag vlan? The trunk port should be based on tag.

Access port is untagged, trunk port is tagged, would be my conclusion.

Bert

[aaab...@hotmail.com]

Thanks, some venders have one more interface type HYBRID port
(access,trunk and hybrid ), I think Cisco does not has this type
port,
how can cisco support "hybrid" port function which can forward
multliple
untag and tag frames..

st

[Albert Manfredi]

On Oct 23, 4:47 pm, aaabb...@hotmail.com wrote:

> Thanks, some venders have one more interface type HYBRID port
> (access,trunk and hybrid ), I think Cisco does not has this type
> port,
> how can cisco support "hybrid" port function which can forward
> multliple
> untag and tag frames..

Should probably try a cisco news group. In principle, of course, there
should be no problem. The Tag Protocol Type, 0x81-00, does not
conflict with any other Type code or Length. So there should be no
problem mixing up tagged and untagged frames over an Ethernet segment.
I would expect that untagged frames would be sent over whatever
default VLAN the switch establishes, at priority 0.

Bert

[aaab...@hotmail.com]

Right, untagged frames based on default vlan (or pvid),It means that
only
one untagged frames can forward for trunk port. How does it support
multiple untagged (multiple vlan)? frames.

st

[Albert Manfredi]

On Oct 23, 8:48 pm, aaabb...@hotmail.com wrote:

> Right, untagged frames based on default vlan (or pvid),It means that
> only
> one untagged frames can forward for trunk port. How does it support
> multiple untagged (multiple vlan)? frames.

Only responding to the question "in principle." Which is to say, I
don't know whether or how Cisco might do this.

In principle, a trunk link could assign frmaes to VLANs based on the
802.1Q tag and also based on other rules. For example, a trunk link
could also assign untagged frames to VLANs based on MAC or IP
addresses.

Bert

[Stephen]

On Thu, 23 Oct 2008 13:47:35 -0700 (PDT), aaab...@hotmail.com wrote:

having 1 vlan which doesnt include a tag is part of 802.1Q spec.

this is the "native vlan" in cisco speak on a tagged interface (trunk
in cisco speak again).

1 common application is where a switch is connected to an IP phone,
and a port for a PC etc is in the back of the phone.
Packets from the PC are not tagged, but phone packets are, and the
switch can drop them into different vlans.

Exactly how these are configured and addressed varies on whether you
have a switch (where a vlan number is global across the box) and a
router (where vlan numbers are local to each interface).

there are loads of examples in the product manuals - go to the cisco
site for the relevant device type in support and download the ones for
the code version you have and read it.

The cisco docs are pretty good at explaining what the hardware / s/w
can do and how, and why you might want to do that, and are all
publically available.
>
>st
--
Regards

stephe...@xyzworld.com - replace xyz with ntl

[aaab...@hotmail.com]

On 10月25日, 上午5时35分, Stephen <stephen_h...@xyzworld.com> wrote:

> stephen_h...@xyzworld.com - replace xyz with ntl- 隐藏被引用文字 -
>
> - 显示引用的文字 -

Thanks both of you!