Download Network Training 2008-05-25

Peavey Electronics
®2006
AV-IT
CONVERGENCE
IT’S WHAT THE WORLD IS COMING TO, ALFIE
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Ethernet or 802.3?
You may have heard the term 802.3 used in
conjunction with the term Ethernet.
"Ethernet" originally referred to a
networking implementation standardized by
Digital, Intel and Xerox. (it is also known as
the DIX standard). In February 1980, the
Institute of Electrical and Electronics
Engineers, or IEEE (pronounced "I triple E"),
created a committee to standardize network
technologies. This was named the 802
working group, named after the year and
month of its formation.
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Subcommittees of the 802 working group
separately addressed different aspects of
networking. The IEEE distinguished each
subcommittee by numbering it 802.X. The
802.3 group standardized the operation of a
CSMA/CD network that was functionally
equivalent to the DIX Ethernet.
Though Ethernet and 802.3 differ slightly,
the term Ethernet refers generically to both
the DIX Ethernet implementation and the
IEEE 802.3 standard.
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Ethernet Terminology
Ethernet follows a simple set of rules
that govern its basic operation. To
better understand these rules, it is
important to understand the basics of
Ethernet terminology.
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Ethernet Terminology
•Medium - Ethernet devices attach to a
common medium that provides a path
along which the signals will travel.
Originally, this medium was coaxial
copper cable, but today it is a twisted
copper pair, fiber optic cabling, and now
a new emerging transport, wireless (RF
and IR).
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•Segment - We refer to a single shared
medium as an Ethernet segment,
Network, or LAN. This segment would be
the entire run of coax back when that
was the standard media. You could
divide a segment by placing a “Bridge”
somewhere in the middle of the run. This
device would then bridge those now two
segments (but do not confuse this with
creating a vLAN). Bridges will be
important when discuss “Switches” later.
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•Node - The devices that attach to that
segment (such as a computers, printers,
Nions, CABs, etc.) are referred to as
nodes.
•Frame - The nodes communicate in
short messages called frames, which are
variably sized chunks of information.
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Frames are sometime referred to as
Packets, Tokens, and occasionally as
Data Segments, along with other names
depending on the Protocol.
The technically correct term for the
complete data package for 802.3 is
Frame.
But because all protocols use a
frame somewhere within the protocol,
frame is the most common name for
these “chunks of data”.
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Frames are analogous to sentences in
human language. In English, we have
rules for constructing our sentences: We
know that each sentence must contain a
subject and a verb.
Likewise, each Ethernet protocol
specifies a set of rules for constructing
frames. There are explicit minimum and
maximum lengths for frames, and a set of
required pieces of information that must
appear in the frame.
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Each frame must include, for example,
both a destination address and a source
address, which identify both the recipient
and sender, which uniquely identifies the
node, just as a name identifies a
particular person.
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The Basic IEEE 802.3 MAC Format
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This is a CSMA/CD network, which is
the basis of the 802.3 Ethernet standard.
Carrier Sense - Nodes listens to the
media to confirm that it is clear.
Multiple Access - Many nodes using
the same media.
Collision Detection - Detects if another
node starts to transmit at the same time.
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Nodes listen to the medium while
they transmit to ensure that they are the
only node transmitting at that time. If
the nodes hear their own transmission
returning in a garbled form, as would
happen if some other node had begun to
transmit its own message at the same
time, then they know that a collision
occurred.
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A single Ethernet segment is
sometimes called a collision domain
because no two nodes on the segment
can transmit at the same time without
causing a collision. When nodes detect a
collision, they cease transmission, wait a
random amount of time, and attempt to
transmit when they again detect silence
on the medium.
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If you have too many nodes on a
network (the result would be too many
collisions, slowing the network down),
you can use an “Ethernet Bridge” to create
two smaller networks segments.
We are not going into depth on
Bridges, as these are rarely seen
anymore.
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One last piece of information before
we leave the subject CSMA/CD networks.
A Switch creates an Ethernet
segment between the switch and each
node. This is sometimes called a
“collisionless domain” because no two
nodes are on the same segment.
But we will get back to Switches later.
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568A
Many may remember COAX as the
standard for networking cabling,
whether it was RG-11 (Thick-Net), or
RG-58 (Thin-Net). Most of the time, if a
simple problem occurred at only one
node, the entire network would stop
working.
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So, a new standard was created within
802.3 called 568A, which brought the
“Hub” or “Star” network into being. A
hub consists of multiple repeaters all in
one box, with a node connected to each
port, commonly called a star layout.
This solved so many of the original
problems from using coax, that most
other protocols adapted the star
architecture, including Token Ring.
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But 568A can be confusing because with
in this standard is two RG-45 pin-out
configurations, 568A and 568B. So, you
could be using 568B pin-out (which is the
more common), but you are still using the
568A standard. Confused yet? Don’t
worry, you are not alone, most IT
managers don’t know this stuff. Bottom
line, make sure you are using the
“building standard” (ask the cable
installer). But it is getting trickier....
More on that in a couple slides.
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At the center of the star is a device
known as a HUB, but the function of the
network remains the same, using
CSMA/CD. A hub is merely an active
repeater that restores the “square” to
the square wave. You must not confuse
hubs with a switch, as all connected hubs
(and all connected nodes) are on a single
collision domain--segment.
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568A
So along comes Category 1,
which was not much better than
POTS (Plain Old Telephone Service).
Cat 2, of which there is a little of
this still in use today, because IBM went
long on this one. It runs at 4 Mbps.
Cat 3, also know as 10baseT and as
Ethernet, and ran at 10Mbps.
Cat 4, didn’t last long and had very
limited installs, as it ran at 17Mbps, and
Cat 5 was out about 18 months later.
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568A
A quick sidebar.
The main difference between each
of the category “levels” is the amount of
“twists per inch” of the cable. Each pair
within a cable has a different rate of
twist, the blue from the orange, etc.
Also important is how the pairs run
inside the outer jacket in relationship
with each other.
This all impacts noise rejection and
crosstalk.
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568A
Cat 5, also known as 100baseT or
Fast Ethernet, and runs (we will change
to present sense here) at 100 Mbps.
Cat 5e and Cat 5E, were hardware
(cable and connectors) changes that
enabled higher bandwidth. These new
categories were addendums to 568A,
and not really new standards.
Cat 5=100MHz, Cat 5e=150MHz,
Cat 5E=350MHz
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568B
Cat 6, almost 10 years after the
original Cat 5, and was ratified in April
of 2002 as the 568B Standard.
I warned you it would get tricky!
FYI. When Cat 7 is finished, it will be
the 568C Standard, and supposed to run
at Ten-Gig.
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568B
So we finally have Cat 6, which
enables 1000baseT, or Gigabit Ethernet.
But remember this....
Just because the infrastructure
(cable and jacks) are Cat 6, doesn’t
mean you should use Gigabit copper. Be
wary of the electronics, most are
problematic at this time, but hardware is
improving all the time…..BUT!!!!!
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568B
Most AV content that is riding on
ethernet is mission critical, meaning
that lost packets are, well, exactly
that...LOST.
Gone forever.
It can’t be resent like “regular”
computer data.
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568B
For video, lost packets would create
“video noise” at a minimum, a blank
screen at worse.
With CobraNet, a few lost packets
will sound like distortion, a few more
will sound like scratching on a mic’s
windscreen, a few more and audio will
stop.
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568B
So again, and this is important, if
you need Giga-speed, go fiber!
Another issue with AV devices that
just use the cabling infrastructure (not
going thru the switches, just the cable),
they don’t always work with Cat 6.
The changes in twists of the cable
(in comparison to Cat 5) cause too much
“skew”, so the signals cannot be put back
together correctly.
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We mentioned earlier that a switch
creates a collisionless domain by creating
a separate segment between each port
on the switch and the attached node.
So though switches look similar to a
hub, they are functionally very different
from a hub. The biggest difference being
this dedicated segment for every node on
the network.
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Switched Ethernet
This is perhaps the most striking
advancement in contemporary Ethernet
networks is the use of “Switched
Ethernet”.
Many AV devices are requiring
switches instead of hubs, so we are
going to spend some time here.
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Switched Ethernet
Switched networks replace the
shared medium of legacy Ethernet
(coax, hubs, and repeaters) with a
dedicated segment for each node.
Remember we talked earlier about
the hub being just many repeaters in
one box? Well, a switch is many
Ethernet Bridges in one box.
And what did I say a bridge does?
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Switched Ethernet
It divides a network into separate
segments, creating a Collisionless
Domain.
When a node is connected to a port
on a switch, it creates a single, separate
segment between the switch and that
node.
Some interconnected switches can
support thousands of dedicated
segments, for example, the Internet.
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Switched Ethernet
Because switches have become so
affordable, we in tech support are
recommending that mission critical data
be on a separate physical network, or
“LAN” (Local Area Network), in most
installs.
This minimizes any conflicts that
can (and frequently do) occur.
We have always recommended this
for large installs, but with a different
twist. We’ll discuss this in a moment.
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Switched Ethernet
In a (very) small install, where
there are few nodes, and where few
broadcasts occur (which goes to all
ports of a switch), a single switch can be
used.
But with most installs, it makes
sense to create that separate network
for the mission critical data.
Lets take audio as an example.
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Switched Ethernet
During the design phase, put the
cost of two inexpensive (but not
“cheap”) switches in the quote. This
way, you have two “physical” LANs in
place.
Another sidebar; why would you put the
“mission critical” part of a tens of
thousand dollar project on a $35
switch????
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Switched Ethernet
On one LAN (switch), all of the
CobraNet related devices are connected.
And on the second LAN (switch),
any required CPU’s NIC (Network
Interface Card) are connected, along
with all the other “control” type devices,
such as Nion and Crestron/AMX.
So in a single closet install, there
would be two switches, one for the
control devices and the other for the
CobraNet devices (two physical LANs).
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Switched Ethernet
In a multiple closet install, any
audio closet where a control device and
a CobraNet device co-exist, there would
be two switches (the two physical
LANs).
Four good, low cost, simple switches,
and two 100 Mbps channels from one
closet to another will cost less than one
good low cost “managed” switch and
one 100 Mbps channel.
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Another sidebar;
Because A/V is sharing closets more
and more with the IT/Phone people, we
need to learn the jargon. A MDF (Main
Distribution Frame) is the “focal” point
of the star layout, an IDF (Intermediate
Distribution Frame) are the closets that,
because of distance restraints, gather up
outlaying stars and “relay” them back to
the MDF.
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The Managed Network
A big install is a different story. On
the last install that I was involved on
before coming to Peavey, ten separate
networks were required by the A-V and
lighting system!
Two for lighting, four for CobraNet,
three for control and admin, and one for
nodes that I wanted to keep contained
in their own little world.
A Managed Switch using “VLANs” is
the only answer for this type of install.
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The Managed Network
Managed switching (the heart of a
managed network) has been around for
a long time, and as with everything to
do with computers, has become much
more affordable.
One of the best things (among many
other fun stuff) about a managed switch
is that you can create “Virtual Local Area
Networks” or VLANs.
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The Managed Network
Virtual LANs divide up a switch into
two or more networks, on a port by port
basis. For example, ports 1 & 2 would
be in one network, ports 3 thru 6 in
another, 7 thru 12 in another, etc.
So a single managed switch can be
setup as if there were many switches,
dividing up and isolating any conflicts
with network traffic.
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The Managed Network
But there is one caveat, whether
you are using two physical networks or
VLANs.
Because the nodes on one network
(or VLAN) can't talk to another network,
a gateway may be required.
A gateway could be as simple as
putting in a second NIC in any device
that needs to talk to two VLANs, making
that device into a gateway.
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The Managed Network
A router is also a gateway device,
and is the most common way to route
data traffic from one network to
another.
Now some will say that you could
instead use Layer 3 or Smart Switches,
and that is true. But, Layer 3 switches
are running some type of router
software, somewhere. So it could be
less expensive to go with a router and a
Layer 2 switch solution.
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The Managed Network
A managed switch can also provide
a means to expedite time-critical
(CobraNet) network traffic by setting
transmission priorities for outgoing
frames. This can be critical if a 100Mbps
backbone is being used.
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Corporate
LAN Router
Switch
Switch
Switch
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Switch
Switch
Router
Switch
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Product
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5 Port Workgroup Switch
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16 Port Workgroup Switch
Linksys SR216
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24 Port Managed Switch
Linksys ProConnect II 2224
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24 Port (plus 2 GBIC Module) Layer 3 Switch
Cisco 2950g
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A configurable,
routing capable,
Switch
Cisco 4506
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802.3
Because it is still about
convergence
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Layer 7, Application:
This layer provides network
services directly to the user's
application such as a web browser,
email or NWare software. Other
protocol's that operate here are:
Telnet, which would connect to
HyperTerminal, HTTP to Window’s
Explorer, SMTP to Outlook, FTP,
TFTP, NTP, SNMP, and EDI.
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Layer 6, Presentation:
This layer formats the data
ready to be presented to the
Application layer. It defines
encryption, compression, conversion
and other coding functions. Good
examples of this are: GIF, TIFF,
JPEG, and MPEG.
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Layer 5, Session:
This layer establishes, maintains
and terminates end-to-end
connections (sessions) between two
network nodes. It controls the
dialogue between the source and
destination node, when the node can
send and how long for. This layer
also provides error reporting for the
Application, Presentation and
Session layer.
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Layer 4, Transport:
This layer is responsible for endto-end delivery of data and provides
services such as error checking and
flow control. Protocols that operate
on this layer: TCP, UDP, NETBEUI,
SPX.
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Beginning here at the transport
layer, the raw data streams start the
process of being divided into
Frames.
On this layer the data is divided
into segments, this process creates
the data/pad part.
Flow control is integrated into
the process to guarantee that each
segment is being delivered at the
correct rate.
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Here is an important analogy
that we will come back to later.
Think of a water hose (the raw
data stream) filling a defined size
bucket (the explicit length of data).
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The bigger the bucket, the
longer it will take the hose to fill the
bucket to capacity so it can be
handed off to the next layer.
So why is this important...The
latency that this adds, but more on
this later.
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Now, another important thing to
remember at the transport layer is
that the protocols are either
connectionless or connectionoriented:
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Connection-oriented means that a
connection must be established
before data can be exchanged (in
other words, you know which way to
go as you have a set of instructions).
This can guarantee that data will
arrive at it's destination, and in the
same order it was sent.
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It guarantees that delivery by
sending acknowledgements back to
the source when messages are
received. TCP is an example of an
connection-oriented transport
protocol!
Connectionless is when the sender
does not establish a connection
before it sends data. It just sends
without a guarantee of delivery.
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Here is an example of both;
Connection
FTP (File Transfer Protocol)--Each
packet sent is acknowledged by the
receiving node. This process is usually
windowed, 5 packets sent before an
acknowledgement is returned,
acknowledging all 5 of those packets.
Connectionless
TFTP (Trivial File Transfer Protocol)
Packets are not acknowledged,
which makes the process faster.
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Layer 3, Network:
This layer provides the logical
addressing of the node and network
segments, which is required if the
data needs routing, which enables
data to be passed from one network
to another.
Protocols used at this layer are:
IP, IPX, AppleTalk, RIP, BGP, IGRP.
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This is where many protocols
begin to become a stacked (such as
TCP/IP, SPX/IPX) packet.
These stacked protocols are
sometimes known as “Layer 3”
addressing. This address structure
determines which network the node
is on and the individual node
address on that network.
It is worth making clear that the
already mentioned Layer 3 switches
and Routers operate at this layer.
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The process of creating a Frame
contunies.
By adding Logical Addressing on
this layer, the segment becomes a
Packet.
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Layer 2, Data Link:
This layer actually consists of
two sub-layers: LLC at the upper
layer (Logical Link Control) and at
the lower level is the MAC (Media
Access Control).
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Have you heard the term MAC
address before? The MAC address
resides in the data link layer!
Devices that use this layer (layer 2)
are routers, switches, and bridges.
By adding MAC Addressing on
this layer, the Packet now becomes
a Frame.
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This is where much of CobraNet
magic occurs, which is why we are
taking the time to talk about the OSI
Model. More on that later.
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Layer 1, Physical:
This layer defines the actual
physical specifications, either copper
(UTP/sUTP/coax/etc), fiber, or
wireless.
It handles the raw bit stream by
creating either electrical, light, or RF
bit streams, placing it on the medium
to be picked up by the Physical layer
at the receiving node.
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It is responsible for activating,
maintaining and deactivating the
physical link.
The Physical Layer defines
electrical (voltage), light signaling
(wavelength), or radio signaling
(frequency). Transmission rates and
distances, mechanical specifications
(cable lengths, and type of
connector).
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Devices that operate on this
layer are hubs, repeaters, NIC's, and
interfaces such as RS-232, OC-3,
BRI, X.25 and Frame Relay.
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Here is another graphic to show
how it all works
Data Streaming from the
Application Layer to the
Session Layer
Divided into Segments on the
Transport Layer
Adding Logical Addressing
create Packets
Adding the MAC Address
create the Frame
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OSI Model
OK, why have you just poured
all this information into that hole in
my head, it is already leaking out!!!
Because the IT department lives
and breathes this stuff.
Because if you understand this
model, you can troubleshoot many
network problems.
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The Bottom Line
Take the time to learn the IT
department’s language
Understanding another’s language
Is the art of communicating.
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The OSI Model
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The TCP/IP Protocol Stack
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The CobraNet Stack
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Internet Protocol Suite
Application
BOOTP
Transport
Network
SNMP
TFTP
UDP
RARP*
ARP
ICMP*
IP
Logical
Link
802.3 Ethernet
Physical
Fast Ethernet Interface
* PARTIAL SUPPORT
CobraNet
Services
Cobra
Net
Audio
Serial
Bridge
Packet
Bridge
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CobraNet Conductor
A CobraNet network would consist of
at least one Nion, which will be
communicating with up to 24 devices.
Each additional Nion will add up to 24
additional devices.
With all this traffic, there needs to be
some type of rules to bring order to this
chaos.
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CobraNet Conductor
Hence the CobraNet Conductor,
which regulates all CobraNet devices,
assigning a “time to send” to each device.
This applies to all CABs, as well as the
CobraNet cards in the Nions.
The Conductor assignment is autonegotiated shortly after start-up for the
CABs and Nions, with Nions having a
higher priority than CABs.
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CobraNet Conductor
To understand how this works, let’s
use a classroom analogy.
If you had something to say, you
could raise your hand and wait to be
called. Of course this won’t work on a
network.
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CobraNet Conductor
So lets says that as the instructor, I
clap my hands once each 65 minutes (I
know this sounds odd, but bear with me)
and everyone has a clock that they lock
to this signal.
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CobraNet Conductor
Now if we pre-arraigned that Joe would
speak for 16 seconds on the beat.
Then John would speak for 16 seconds at
16 seconds after (or offset from) the
beat.
Then Charlie would speak for 16 seconds
at a offset of 32.
Then Greg would speak for 16 seconds at
a offset of 48.
Then back to Joe for 16 seconds at a
offset of 64 seconds after the beat.
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CobraNet Conductor
This is what the Conductor is doing.
The Conductor sends the “beat” to which
all nodes lock their clock. And then tells
each node how much to offset from this
beat to trigger the send.
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CobraNet Conductor
Now why did I use 65 minutes?
Because this is what happens about
every second on the network, and
illustrates how much bandwidth is
available.
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CobraNet Conductor
But what about other non-CobraNet
nodes on a network?
Collisions will not occur because we
are using a switch, but if any other type
of nodes that can’t listen to the
Conductor are in use, other conflicts can
occur.
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CobraNet Conductor
This is why we recommend a second
switch (a physical network), or use a
“managed switch” on which you can
create VLANs (virtual networks),
anytime you have much else on a
network.
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Packet Size
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The Basic IEEE 802.3 MAC Data Frame Format
The Data (and Pad as required) is an
Explicit Length as defined by the
Length/Type part of the Frame
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Lower Latency
We discussed explicit length as part of
transport layer topic, remember the water
hose and bucket.
But let’s say that we use a smaller
bucket, instead of a gallon bucket we use a
half-gallon. So now we wait half as long to
fill the bucket...Lower latency.
So let’s now use a quart size bucket,
half the size of the half-gallon. Again,
lower latency.
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Static IP
Vs
DHCP
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DHCP
Topics
Define DHCP
Define Static IP
Show DHCP with a Alt. Config Static IP
DHCP can assign IP Addresses via MAC address, but what
happens when defective equipment is replaced. How can
control equipment find replacement equipment.
DHCP can assign IP addresses via “Friendly Names”, but
friendly names not common in AV equipment.
Nion can do both, and DHCP is helpful for initial set-up,
but static IP is highly recommended for the finished
install.
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BroadCast
MultiCast
UniCast
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Broadcast
• By sending data to all possible destinations
permits the sender to send the data only
once, and all receivers can copy it.
• A network broadcast in the IP protocol is
done with 255.255.255.255, with a MAC
address network, ff.ff.ff.ff.ff.ff is a broadcast.
• Sub-net masking allows a directed (limited)
broadcast can be made by combining the
network prefix with the host suffix composed
entirely of binary 1s.
For example, to send to all addresses within a network with the
prefix 192.0.2, the directed broadcast IP address is 192.0.2.255
(assuming the netmask is 255.255.255.0).
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MultiCast
• A multicast address is associated with a
group of interested (subscribed) receivers.
• IP addresses 224.0.0.0 to 239.255.255.255
are designated as multicast addresses.
• The sender sends a single datagram (from
the sender's unicast address) to the multicast
address, and the routers take care of making
copies and sending them to all receivers that
have registered their interest in data from
that sender.
• Multicast packets are delivered by using the
Ethernet MAC address range
01:00:5e:00:00:00 - 01:00:5e:7f:ff:ff
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MultiCast
• Switches that cannot understand multicast
addresses will broadcast traffic sent to a
multicast group to all the members of a LAN.
In this case, the system's network card must
filter the packets sent to multicast groups to
which they are not subscribed.
• There are a few switches that listen to
multicast traffic, maintaining a table of which
network nodes are subscribed to a given
multicast group. This table is then used to
forward traffic only to subscrbers. This is
done through the use of IGMP
Peavey Electronics
®2006
UniCast
• The most common concept of an Ethernet
address.
• It normally refers to a single sender and a
single receiver.
• Usually, a unicast address (MAC or IP) is
associated with a single device or host, but is
not necessarily one-to-one correspondence.
• Some individual NICs can have several
distinct unicast (IP) addresses, each for its
own distinct purpose.
• Sending the same data to multiple unicast
addresses requires the sender to send all the
data many times over, once for each
recipient.
Peavey Electronics
®2006
Nion & CobraNet
uses all three types
(More info to come....)
Peavey Electronics
®2006
Bundle
Type
Number
0
Null
Bundle Numbering
Usage
Type
Addressing
Unused bundle.
N/A
Transmitted by a single
1-255
Multicast
CobraNet device and
Always multicast
received by all other devices.
Transmitted by a single
CobraNet interface.
Dependent on txUnicastMode
Generally unicast
and txMaxUnicast settings,
but may multicast
256-65279 Unicast may be received at a single
If txUnicastMode
(default case), a few (multiple
variable is adjusted
unicast case), or a large
number (multicast case) of
interfaces.
65280Private
Very Advanced
65535
Mode
N/A
Always
Transmitted
Only
transmitted
when at least
one receiver is
identified via
reverse
reservation
Peavey Electronics
®2006
SNMP
Peavey Electronics
®2006
Simple Network Management Protocol
Background
The Simple Network Management Protocol
(SNMP) is an application layer protocol
that facilitates the exchange of
management information between
network devices.
Peavey Electronics
®2006
Simple Network Management Protocol
It is part of the Transmission
Control Protocol/Internet Protocol
(TCP/IP) protocol suite. SNMP enables
network administrators to manage
network performance, find and solve
network problems, and plan for
network growth.
Peavey Electronics
®2006
NETWORK MANAGEMENT: AD-HOC APPROACHES
LOCAL SYSTEM - EXAMPLES:
• PING
• TRACEROUTE
• NETSTAT
• ...
REMOTE SYSTEM
• TELNET / RLOGIN (COMMAND LINE INTERFACE - CLI)
• WEB INTERFACE
EXAMPLES WEB INTERFACE:
• PING
• TRACEROUTE
• WHOIS
• NTOP
Peavey Electronics
®2006
SNMP GOALS
UBIQUITY
• PCs AND CRAYs
INCLUSION OF MANAGEMENT
SHOULD BE INEXPENSIVE
• SMALL CODE
• LIMITED FUNCTIONALITY
MANAGEMENT EXTENSIONS
SHOULD BE POSSIBLE
• NEW MIBs
MANAGEMENT SHOULD BE ROBUST
• CONNECTIONLESS TRANSPORT
Peavey Electronics
®2006
Two versions of SNMP exist: SNMP
version 1 (SNMPv1) and SNMP version
2 (SNMPv2).
Both versions have a number of
features in common, but SNMPv2 offers
enhancements, such as additional
protocol operations.
Standardization of yet another version
of SNMP—SNMP Version 3 (SNMPv3)—
is just now available.
Peavey Electronics
®2006
SNMP Basic Components
An SNMP-managed network
consists of three key components:
managed devices, agents, and
network-management systems (NMSs).
Peavey Electronics
®2006
SNMP Basic Components
A managed device is a network node that
contains an SNMP agent and that resides
on a managed network. Managed devices
collect and store management
information and make this information
available to NMSs using SNMP.
Managed devices, sometimes called
network elements, can be routers and
access servers, switches and bridges,
hubs, computer hosts, or printers.
Peavey Electronics
®2006
SNMP Basic Components
An agent is a network-management
software module that resides in a
managed device.
An agent has local knowledge of
management information and translates
that information into a form compatible
with SNMP.
Peavey Electronics
®2006
SNMP Basic Components
An NMS executes applications that
monitor and control managed devices.
NMSs provide the bulk of the processing
and memory resources required for
network management.
One or more NMSs must exist on any
managed network.
Peavey Electronics
®2006
SNMP Basic Components
Managed devices are monitored and
controlled using four basic SNMP
commands: read, write, trap,
and traversal operations.
Peavey Electronics
®2006
SNMP Basic Components
The read command is used by an NMS to
monitor managed devices.
The write command is used by an NMS to
control managed devices.
The trap command is used by managed
devices to asynchronously report
events to the NMS.
Peavey Electronics
®2006
SNMP Basic Components
Traversal operations are used by the NMS
to determine which variables a managed
device supports and to sequentially
gather information in variable tables,
such as a routing table.
SNMP Management Information Base
Peavey Electronics
®2006
A Management Information Base (MIB)
is a collection of information that is
organized hierarchically.
MIBs are accessed using a networkmanagement protocol such as SNMP.
They are comprised of managed objects
and are identified by object identifiers.
SNMP Management Information Base
Peavey Electronics
®2006
A managed object (sometimes called
a MIB object, an object, or a MIB)
is one of any number of specific
characteristics of a managed device.
Managed objects are comprised of
one or more object instances,
which are essentially variables.
SNMP Management Information Base
Peavey Electronics
®2006
Two types of managed objects exist:
scalar and tabular.
Scalar objects define a
single object instance.
Tabular objects, define
multiple related object instances
that are grouped in MIB tables.
Peavey Electronics
®2006
PRINCIPLE OPERATION
MANAGER
SNMP
AGENTS
MIB
Peavey Electronics
®2006
PRINCIPLE OPERATION
MANAGER
POLLING
TRAPS
AGENTS
MIB
Peavey Electronics
®2006
PRINCIPLE OPERATION
MANAGER
GET / SET
TRAP
AGENTS
MIB
Peavey Electronics
®2006
PRINCIPLE OPERATION
MANAGER
AGENTS
TABLES
VARIABLES
STANDARDS
Peavey Electronics
®2006
SMI
• STRUCTURE OF MANAGEMENT INFORMATION
• RFC 1155
MIB-II
• MANAGEMENT INFORMATION BASE
• RFC 1213
• A LARGE NUMBER OF ADDITIONAL MIBs EXIST
SNMP
• SIMPLE NETWORK MANAGEMENT PROTOCOL
• RFC 1157
• NAME IS USED IN A MORE GENERAL SENSE
Peavey Electronics
®2006
SNMP Support
MainFrames and MiniFrames
Support SNMP v1 ONLY
But could be upgraded to SNMP vX
CobraNet supports SNMP v1 ONLY
Nion supports SNMP v1 and v2
And SNMP v3 when available
OKAY, why do I care about any of this?
We will explain later when we talk about
ControlManager
Peavey Electronics
®2006
AV-IT
CONVERGENCE
BUT I DON’T WANT TO CONVERGE!!!
Peavey Electronics
®2006