MPLS is atricky thing to define as MPLS has many components and features, depending on what features you want. The biggest benefit of MPLS is it is a labeling system. Each packet gets labeled with a class, and that class can include many variables (destination, source, packet type/port, customer name, a few others, etc). This label is integrated into the packet and follows it. What you do with that label data depends. MPLS also includes components for distributing instruvtion on how to handle the various classes to its neighbors and routers across the network, as well how to have that labeling survive differnt network types (ATM, EThernet, Sonet). MPLS also has a VPN tunnelling feature, most advantageous because its abilty to survive dissimilar networks.

Many Believe Q in Q is a replacement for MPLS for local Metro Ethernet networks. VLANs are different in the sense that each packet may be tagged with a VLAN ID, but it also requires manual configuration of every switch that it crosses. So you physically map out the VLANs path via the Switch configuration. Or atleast, at what point the VLAN Switch stripps the tag and retags it. But this is defined per ethernet port across your network.

One of the benefits of VLAN, is that it is widely supported by many many many in place devices. And there are just a few simple bits changed in the header of each packet at Layer 2. So it is VERY fast. ZERO degregation to delivery of packet thats getting tagged and untagged. You can now buy Layer2 managed (VLAN) 100 mbps 24 pot switches for $160. (SMC).

MPLS is more involved because you now have to have more expensive routers and MPLS enabled devices. Its a big redesign to add MPLS. One of the reasons people only use it at the edge where it is most appropriate to use for large providers. A MPLS does nothing unless there is a router configured with a decission process on what to do with specific class packets. Its not just about the circuit ID. MPLS can forward it to a priority queue for example to control QOS.

But what one learns is that Ethernet is also starting to get QOS features added, without MPLS required, and there are many third party solutions like Diff Serv that can be integrated with VLAns to get addequate results for one network design to deliver QOS.

Mikrotik EoIP, not exactly sure. I know it has significantly more over head on the packet than VLAN, wasting bandwidth. BUt I'd like to learn more about what EoIP is.

I think the most valuable technology of the three for WISPs depends on which ones get implemented into radios. We gain ease and power, when the features are added to the radios. One of the things that gives MPLS a disadvantage is that there is not a good reliable open source version of it yet. VLAN is solid on OPEN source. You want a technology that works on your routers and your radios both. MPLS is more complex and needs more processing power and code than just VLAN so less likely to be added to radio firmwares.

I am no way dismissing MPLS, I'm just saying committing to MPLS may mean commiting to name brand routers and such. MPLS is more powerful and ideal in many ways, but if you do not require all the features you can accomplish many of the things using alternate solutions that can be delivered today.

Tom DeReggi
RapidDSL & Wireless, Inc
IntAirNet- Fixed Wireless Broadband

----- Original Message ----- From: "John Scrivner" <[EMAIL PROTECTED]>
To: "WISPA General List" <>
Sent: Friday, June 09, 2006 3:06 PM
Subject: Re: [WISPA] looking for a device

Thanks to all for the double VLAN explanation. That makes perfect sense to me now.

Can anyone describe any functional and/or technical differences between VLANs and say MPLS or Mikrotik's EoIP? It sounds to me like all three are functional equivalents of each other. Please correct me if this is an incorrect assumption. I have Googled it so spare me the obvious. I want to hear your thoughts.

Eric Rogers wrote:

It is also referred as 802.1q tagging... If it supports multiple layers,
you can have a customer VLAN tags within your network VLAN tags.  Just
need your equipment that takes off your tags before it gets to the

AT&T uses the Cisco 3750 switches to do it at the customer's premises.
Then the customer can have VLAN 10 at one location and VLAN 10 at
another, and it is completely transparent to the end user.

If that made sense.


-----Original Message-----
Behalf Of Charles Wu
Sent: Friday, June 09, 2006 11:34 AM
To: 'WISPA General List'
Subject: RE: [WISPA] looking for a device

Google (or Cisco) is your friend


Technology Architects

-----Original Message-----
Behalf Of John Scrivner
Sent: Friday, June 09, 2006 8:39 AM
To: WISPA General List
Subject: Re: [WISPA] looking for a device

Can you or someone explain what double VLAN is? I have never heard of such a thing. How can it be used to help us?

Yo may want to look at Alvarion. Alvarion does support VLAN. new
Firmware4 supports double VLAN also.
Alvarion used to have one model that was designed to have a second integrated radio into it.
I can't remember if it was a 900/2.4 combo, or a 5.8/2.4 combo.

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