How to Build a MAN
Last Update 2007.05.27
1.0.0
Copyright 2000-2007 Kenenth M. Chipps PhD
www.chipps.com
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Objectives of This Section
• Learn
– What a MAN looks like in general
Copyright 2000-2007 Kenenth M. Chipps PhD www.chipps.com
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What is a MAN
• A MAN connects sites that are too far to
walk to
• But you can drive there in a short while
• It uses some of the same technologies a
WAN uses
• It may require a WAN service provider to
be used
Copyright 2000-2007 Kenenth M. Chipps PhD www.chipps.com
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What is a MAN
• When we discussed the CAN just previous
to this presentation nothing was said about
right of way issues
• That is because most CANs stay on your
property
• In some cases a CAN must cross a street
but in general it stays in one location
• A MAN on the other hand by definition
must go through somebody else’s
backyard
Copyright 2000-2007 Kenenth M. Chipps PhD www.chipps.com
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Layouts for MANs
• A MAN is usually in one of two forms
– Point-to-Point
– Ring
• Although a star pattern as seen in a LAN
and CAN is in essence just a bunch of
point-to-point links, a star is not a normal
layout for a MAN
Copyright 2000-2007 Kenenth M. Chipps PhD www.chipps.com
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Layers in MANs
• An ongoing argument concerning MANs is
what to do about the data link layer
• As seen in the table a few slides down, the
lower part of the physical layer is pretty
well defined
• It consists of fiber optic cable carrying light
divided into wavelengths, with each
wavelength or lambda carrying a signal
Copyright 2000-2007 Kenenth M. Chipps PhD www.chipps.com
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Layers in MANs
• This is called DWDM – Dense Wave
Division Multiplexing
• The next layer up is where the argument
starts
Copyright 2000-2007 Kenenth M. Chipps PhD www.chipps.com
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Layers in MANs
• Right now everyone uses SONET for the
most part
• The argument is - is this the best way to
send data over long distances
• Some say no, just put IP directly on the
fiber
• But others say you must still have a layer
2, since IP is layer 3
Copyright 2000-2007 Kenenth M. Chipps PhD www.chipps.com
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Layers in MANs
• The argument then is what should this
layer 2 be or is it even needed
• Options include
– IP directly on fiber in some manner, such as
PPP
– MPLS used to organize IP
– 10 GB Ethernet
– POS – Packet Over SONET
– ATM
Copyright 2000-2007 Kenenth M. Chipps PhD www.chipps.com
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Layers in MANs
Traditional Ring
Point to Point
Discussed
IP
ATM
POS
SONET
SONET
IP
DWDM
DWDM
DWDM
Fiber
Fiber
Fiber
Copyright 2000-2007 Kenenth M. Chipps PhD www.chipps.com
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Point-to-Point MAN
• The simplest MAN just connects two
locations
Cable
Building A
Building B
Copyright 2000-2007 Kenenth M. Chipps PhD www.chipps.com
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Point-to-Point MAN Made
• To do this fiber optic cable is laid
underground from Building A to Building B
• At each end point a piece of equipment is
used to connect the fiber
Copyright 2000-2007 Kenenth M. Chipps PhD www.chipps.com
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Point-to-Point MAN
• Loose Tube SM – Single Mode Fiber Optic
Cable
Copyright 2000-2007 Kenenth M. Chipps PhD www.chipps.com
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Point-to-Point MAN
• As a MAN link normally carries a lot of
traffic, at each end point a fairly powerful
box is required
• Equipment of this sort may also require a
specialized external power supply, which
is shown at the bottom of the rack
• A rack is also a good place to terminate
the fiber that connects the two locations,
this is the job of the patch panel at the top
of the rack
Copyright 2000-2007 Kenenth M. Chipps PhD www.chipps.com
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Point-to-Point MAN
Copyright 2000-2007 Kenenth M. Chipps PhD www.chipps.com
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Point-to-Point MAN
• The Relay Rack
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Point-to-Point MAN
• Fiber Optic Cable Patch Panel
Copyright 2000-2007 Kenenth M. Chipps PhD www.chipps.com
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Point-to-Point MAN
• Fiber Optic Cable Patch Panel which
mounts in the cabinet in the two oval
openings
Copyright 2000-2007 Kenenth M. Chipps PhD www.chipps.com
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Point-to-Point MAN
• SM Fiber Optic Cable SC Connector which
mounts to the back side of the patch panel
Copyright 2000-2007 Kenenth M. Chipps PhD www.chipps.com
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Point-to-Point MAN
• Cisco 12000 Series Router/Switch with
POS – Packet over SONET module
Copyright 2000-2007 Kenenth M. Chipps PhD www.chipps.com
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Point-to-Point MAN
• Power Supply
Copyright 2000-2007 Kenenth M. Chipps PhD www.chipps.com
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Send Data Point-to-Point
• The reason for the big, expensive Cisco
Router/Switch is that we will be sending
the data over a long distance, in this
example say 30 kilometers
• This distance will require we use POS –
Packet Over SONET
• Recall the layers discussed above
Copyright 2000-2007 Kenenth M. Chipps PhD www.chipps.com
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Send Data Point-to-Point
• When just connecting two points there is
no need for the overhead ATM introduces,
just form up the IP packets and deliver
them to SONET at the physical layer
Copyright 2000-2007 Kenenth M. Chipps PhD www.chipps.com
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Ring MAN
Building B
Building C
Building A
Copyright 2000-2007 Kenenth M. Chipps PhD www.chipps.com
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Ring MAN
• Fiber optic cable is laid underground from
point to point to point around a ring with a
diameter of say 10 to 50 kilometers
• At each point a piece of equipment is used
to connect to the fiber
• This equipment adds signals or removes
signals, just like an on or off ramp for a
freeway
Copyright 2000-2007 Kenenth M. Chipps PhD www.chipps.com
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Ring MAN
• A freeway loop around a city like 635
around Dallas or 820 around Fort Worth is
a perfect example of what a Ring MAN
looks like and the size they often are
Copyright 2000-2007 Kenenth M. Chipps PhD www.chipps.com
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Ring MAN
Loop 820
around
Fort Worth
Copyright 2000-2007 Kenenth M. Chipps PhD www.chipps.com
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Why Use a Ring Shape
• The main reason for the ring and the
expensive and bother associated with it
and the access line methods used to send
data over it is the ability of this
combination to fix itself
• For example, notice that the ring above
has two fiber optic cables shown
• This allows one set of fibers to fail, with
the other taking over all of the load
Copyright 2000-2007 Kenenth M. Chipps PhD www.chipps.com
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Why Use a Ring Shape
• Further, both fibers can be cut and the ring
will wrap to keep working
Copyright 2000-2007 Kenenth M. Chipps PhD www.chipps.com
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Why Use a Ring Shape
Building B
Building C
Building A
Copyright 2000-2007 Kenenth M. Chipps PhD www.chipps.com
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Equipment for a Ring MAN
• The equipment used for a ring shaped
MAN is pretty much the same as that for a
point-to-point MAN
• The major difference is the type of box at
each point
• Rather than a Layer 3 Switch with a POS
module as shown above, each on and off
ramp or location on the ring MAN will use
a device called an ADM
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Equipment for a Ring MAN
• ADM - Add/Drop Multiplexor
Copyright 2000-2007 Kenenth M. Chipps PhD www.chipps.com
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Send Data on a Ring MAN
• ATM on top of SONET as seen in the
diagram a few slides back is the preferred
method right now for sending data for a
MAN as large as the one described here
• The main reason for this is the ability of
this combination to produce resiliency and
ease OA&M – Operations, Administration,
and Maintenance
Copyright 2000-2007 Kenenth M. Chipps PhD www.chipps.com
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Send Data on a Ring MAN
• As you should recall from the access line
presentations SONET has excellent fault
tolerance
• ATM makes excellent use of all available
bandwidth
Copyright 2000-2007 Kenenth M. Chipps PhD www.chipps.com
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Send Data on a Ring MAN
• With the amount of traffic sent over a MAN
of this size it makes sense to put up with
the complexity of SONET and ATM in
order to get back their administrative and
fault tolerance capabilities
Copyright 2000-2007 Kenenth M. Chipps PhD www.chipps.com
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Other Issues Peculiar to a MAN
• As described above the equipment and
method used to send the data over the
medium length distances that constitute a
MAN are no big deal
• The problem is ground – right of way – you
can use to bury the fiber optic cable
required to connect the sites
• This is the tricky part of making a MAN
Copyright 2000-2007 Kenenth M. Chipps PhD www.chipps.com
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Review
• What is a MAN
Copyright 2000-2007 Kenenth M. Chipps PhD www.chipps.com
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