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" <wireless@wispa.org>
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.
Thanks,
Scriv
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
customer.
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.
Eric
-----Original Message-----
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On
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
http://www.cisco.com/en/US/products/sw/iosswrel/ps5207/products_feature_
guid
e09186a00801f0f4a.html
-Charles
-------------------------------------------
CWLab
Technology Architects
http://www.cwlab.com
-----Original Message-----
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On
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?
Thanks,
Scriv
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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