Transcript Network/Ethernet Basics

Networking/Ethernet Training
Guy Walker
Training and A&E Manager
“Review”
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IP addressing scheme (class A, B, etc)
MAC address vs. IP address
TCP vs UDP
OSI layers
Topologies
Why is it hot?
 What solutions do you use?
 What issues are you seeing?
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Basic Network Components
Switches, hubs
Cabling
Edge devices
Protocols
00101101011100101001010101010100101101110000101
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 Language of packets
 Relates to network
 Relates to devices on network
00101101011100101001010101010100101101110000101
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Edge Device
Edge Device
100Mbps Network
Parking Lot
Edge Switch
Wireless Bridge
Bridge
Core Switch
Gigabit Network
Gateway
Remote Office Building
DVR
Corporate Office Building
WAN
Remote Client
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Security Architecture Example
INTERCOM
DVR
CARD ACCESS
MATRIX SWITCH
VIDEO
IP
CODEC
DATA
OVER
IP
VOIP
VOIP
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Types of Networks
 LAN – Local Area Network
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A network covering a small physical area, like a home, office, or small group of buildings, such as a
school, or an airport.
 MAN – Metro Area Network
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A MAN is a network larger than a LAN, ranging from several blocks of buildings to entire cities. A MAN
might be owned and operated by a single organization, but it usually will be used by many individuals and
organizations. MANs might also be owned and operated as public utilities.
 WAN – Wide Area Network
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A network that covers a broad area (i.e., any network whose communications links cross metropolitan,
regional, or national boundaries). Less formally, a WAN is a network that uses routers and public
communications links.
Source: IEEE Standards
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Types of Messages
 Unicast
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A one-to-one communication link. Packets are sent from one IP address to another IP address.
 Broadcast
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A one-to-everyone communication link. Packets are sent from one IP address to all ports and IP
addresses on the network.
 Multicast
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A dynamic, one-to-many communication link. Packets are sent from one IP address to any other IP
addresses that request the packets. Since this a dynamic relationship, devices can “subscribe” and
“un-subscribe” at will.
IGMP – Internet Group Multicasting Protocol
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001011010111001010010101010101001011011
Multicasting Example
Command Center
001011
001011
001011
0010110101110010100101010101010010110110010101000110101
001011
0010110101110010100101010101010010110111
Remote Client
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OSI Model
Layer 3
(Router)
Layer 2
(Switch)
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Application
6
Presentation
5
Session
4
Transport
3
Network
2
Data link
1
Physical
Mostly
software
Mostly
hardware
Layer 1 (Hub
and cables)
The Open Systems Interconnection model defines seven functional
layers of the overall system. A layer is a group of conceptually similar
functions that provide services to the layer above it and receives service from
the layer below it.
Source: Wikimedia Commons
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OSI Model - Examples
HTTP, Telnet
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Application
6
Presentation
5
Session
TCP, UDP
4
Transport
IP, IGMP
3
Network
802.3 (Ethernet),
VLAN, PPP
2
Data link
1
Physical
MPEG, SSL
Half/Full Duplex
Mostly
software
Mostly
hardware
RS-232, POTS,
802.11 (wireless),
10Base-T
Source: Wikimedia Commons
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Ethernet
Ethernet is a family of frame-based computer networking
technologies for local area networks (LANs).
 Packets
It defines a number of wiring and signaling standards for the
Physical Layer of the OSI networking model, through means
of network access at the MAC/Data Link Layer, and a
common addressing format.
 Layer 1 and 2
Ethernet is standardized as IEEE 802.3. This includes versions
for twisted pair cabling, fiber optics and wireless.
 10Base-T
 100Base-T (Fast Ethernet)
 1000Base-T (Gigabit)
 100Base-FX, etc. (fiber-based)
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Ethernet Packet
Source: Wikimedia Commons
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Connectors and Cabling
RJ-45
SC
LC
RJ45 – more correctly called the 8 Position 8 Contact (8P8C) connector.
SC – fiber optic cable connector
LC – fiber optic cable connector
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Connectors and Cabling
Category 5 UTP
 Four twisted pairs in a single cable jacket.
 Up to 100Mbps
 Typically has three twists per inch of each twisted pair of 24 gauge copper.
 NO Power Over Ethernet (POE).
Category 5e UTP
 Four twisted pairs in a single cable jacket, but more twists per inch to avoid
crosstalk.
 Up to 1000Mbps.
Category 6 UTP or STP
 Four twisted pairs.
 Up to 1000Mbps
Category 7 STP
 Four individually shielded pairs inside an overall shield.
 Up to 10Gig
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MAC Address
The Media Access Control layer of the OSI stack. This is
the lowest layer (Layer 1) and makes for an easier and
more simplified packet transfer.
A MAC address is a 48-bit address defined by the
manufacturer and the hardware. It is a hard-coded, unique
address that is burned onto the device during
manufacturing.
The first three bytes will define the manufacturer and the
last three bytes define the device.
00-2A-9Z-3C-78-05
Manufacturer
Hardware
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MAC Address
MAC Addresses essentially provide an
unchanging, unique network identifier for a
device.
This also adds another layer of security that may
be utilized within the network.
Switches convert IP addresses to MAC
addresses to deliver packets.
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Internet Protocol
TCP/IP
The Internet Protocol Suite (commonly TCP/IP) is the set of
communications protocols used for the Internet and other similar
networks. It is named from two of the most important protocols in it:
the Transmission Control Protocol (TCP) and the Internet Protocol
(IP), which were the first two networking protocols defined in this
standard.
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Internet Protocol
TCP - is responsible for verifying the correct delivery of data from
client to client, and to trigger retransmission until the data is
correctly and completely received.
IP - is responsible for moving packets of data from node to node. IP
forwards each packet based on the IP address. The IP scheme
operates through “gateway” machines that allows data to move
from department to organization to region and then around the
world.
Socket - is an end-point of a bidirectional process-to-process
communication flow across an IP based network. A socket is an
interface between an application process and the TCP/IP protocol
stack provided by the operating system.
Source: Wikimedia Commons
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IP Addressing
126.15.101.10
IP Version 4 (current)
IP Version 6 (future)
 32 bit binary code
 128 bit binary code
 4 sections of 8 bits each
 3ffe:1900:4545:3:200:f8ff:fe21:67cf
 Network ID, Host ID
 Backwards compatible
IP Addressing rules:
 The Network ID cannot start with a ZERO
 The Host ID cannot end with a ZERO
 No two systems, on the same network, can have the same Host ID
 No two systems on one network can have the same IP Address.
 An octet’s value will never exceed 255
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IP Addressing
Class A
n = network
h = host
nnnnnnnn.hhhhhhhh.hhhhhhhh.hhhhhhhh
Network ID
Host ID
First Octet range (1-127)
NOTES:
 The 127.1.1.1 address is reserved for MS Loopback.
 Over 16 million possible HOSTS
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IP Addressing
Class B
n = network
h = host
nnnnnnnn.nnnnnnnn.hhhhhhhh.hhhhhhhh
Network ID
Host ID
First Octet range (128-191)
NOTES:
Over 65,000 possible HOSTS
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IP Addressing
Class C
n = network
h = host
nnnnnnnn.nnnnnnnn.nnnnnnnn.hhhhhhhh
Network ID
Host ID
First Octet range (192-223)
NOTES:
Only 254 possible HOSTS
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IP Addressing
Class D
Multicast
224.0.0.0 to 239.255.255.255
Class E
Experimental
240.0.0.0 to 254.255.255.255
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IP Addressing
Private Addresses
 Three ranges assigned by Internet Assigned Numbers Authority (IANA):
10.0.0.0
To
10.255.255.255
172.16.0.0
To
172.31.255.255
192.168.0.0
To
192.168.255.255
 Computers not connected to the Internet do not need to have globally unique IP addresses.
These addresses are not routed on the Internet, and thus do not need to be coordinated with an IP
address registry.
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IP Addressing
Multicasting
 IGMP – Internet Group Management Protocol
 Reserved IP Addresses:
224.0.0.0
To
239.255.255.255
 Any Ethernet packet with an IP destination within this range will be treated
as a Multicast stream by network switches/routers that support IGMP.
 A multicast address is associated with a group of interested receivers. The
sender sends a packet to the multicast address, and the intermediary routers
take care of making copies and sending them to all receivers that have
registered their interest in data from that sender
 This range was formerly called "Class D."
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001011010111001010010101010101001011011
Multicasting Example
Command Center
001011
001011
001011
0010110101110010100101010101010010110110010101000110101
001011
0010110101110010100101010101010010110111
Remote Client
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IP Scheme
WAN switches
Workgroup switches
Workstations, cameras,
access
Source: Microsoft TechNet
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IP Addressing
Subnet Masking
A way of further segregating HOSTS in a network.
Subnetting allows the network to be logically divided regardless of the
physical layout of a network, since it is possible to divide a physical network
into several subnets by configuring different host computers to use different
routers
Class A – 255.0.0.0
Class C – 192.168.151.1
Class B – 255.255.0.0
Class C – 255.255.255.0
Class C – 255.255.255.0
masking
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VLAN
Virtual Local Area Network
802.1Q
A configuration scenario where hosts are separated into groups to
segment traffic on the network.
VLANs are created to provide the segmentation services traditionally
provided by routers in LAN configurations. VLANs address issues such as
scalability, security, and network management.
Switches may not bridge IP traffic between VLANs as it would violate the
integrity of the VLAN broadcast domain.
Virtual LANs are essentially Layer 2 constructs, compared with IP subnets
which are Layer 3 constructs.
Source: Wikimedia Commons
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VLAN
Emergency Phone (VLAN 1)
Video
(VLAN 2)
Card
Access
(VLAN 3)
Operations Center
(Operation Center belongs to all 3 VLANs)
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VLAN
IP Codecs
Port 1
VLAN 1
Port 2
VLAN 2
Emergency Phone Video
Port 5
VLAN 3
Card Access
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Protocols
Network protocols are a convention or standard that controls or
enables the connection, communication, and data transfer between
two computing endpoints.
Most protocols specify one or more of the following behaviors:
 Detection of the underlying physical connection (wired or
wireless), or the existence of the other endpoint or node
 Handshaking
 Negotiation of various connection characteristics
 How to start and end a message
 How to format a message
 What to do with corrupted or improperly formatted messages
 Termination of the session or connection
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Protocols
SNMP
Simple Network Management Protocol
SNMP is used to monitor network-attached devices for conditions that warrant
administrative attention. It consists of a set of standards for network management,
including an Application Layer protocol, a database schema, and a set of data
objects.
 MIB – Mgmt Information Base – a type of database that describes the
condition of a network device.
 MIB Library
 Agent
 TRAP
RMON
Remote MONitoring
 A MIB that uses SNMP to communicate
 “Flow based” monitoring versus SNMP’s “device based” monitoring
 A little easier to implement
RFC 3411 — An Architecture for Describing Simple Network Management Protocol (SNMP) Management Frameworks
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Protocols
Routing
A Layer 3 protocol
Routing is utilized to effectively manage data packets on the
network. The Router does this by the use of a preconfigured
“Routing Table”.
This can be accomplished a few different ways based on the level
of routing allowed by the Router.
The three common routing tools are as follows:
 IP Address
 MAC Address
 System Name
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Protocols
RIP – Routing Information Protocol - an older interior gateway
protocol (IGP) using the distance-vector routing algorithm.
Considered outdated.
IS-IS – Intermediate System to Intermediate System: is a linkbased routing protocol, meaning that it operates by flooding network
topology information throughout the routers. Each router will then
independently build a picture of the network's topology. Likewise, packets
are forwarded based on the best path through the network to the
destination address.
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Protocols
OSPF – Open Shortest Path First - is another dynamic routing
protocol for use in IP networks. Specifically, it is a link-state routing
protocol and falls into the group of interior gateway protocols,
operating within an autonomous system.
TCP versus UDP
TCP has error correction
UDP is “fire and forget”
 Implications for video streaming
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Spanning Tree Protocol
IEEE 802.1d
Defined as where two bridges are used to interconnect the
same two computer network segments, spanning tree is a
protocol that allows the bridges to exchange information so
that only one of them will handle a given message/packet
that is being sent between two computers within the
network.
The spanning tree protocol prevents the condition known as
a bridge loop.
Also provides redundancy capability when switches are
connected in a ring topology.
30 to 50 second response.
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Rapid Spanning Tree Protocol
IEEE 802.1w
Same purpose as STP, but with faster results – and it’s
backwards compatible to STP.
Less than 1 second response.
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Rapid Spanning Tree Protocol
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RSTP and IGMP
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RSTP and IGMP
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Protocols
QoS
Quality of Service is the ability to provide different priority to different applications,
users, or data flows, or to guarantee a certain level of performance to a data flow.
CoS
Class of Service is a field within a layer two Ethernet frame header. It specifies a
priority value of between 0 (signifying best-effort) and 7 (signifying priority real-time
data) that can be used by Quality of Service disciplines to differentiate traffic.
DHCP (Server)
Dynamic Host Configuration Protocol is used by networked devices (hosts) to obtain
the parameters necessary for operation in an IP network.
NTP
Network Time Protocol is a protocol for distributing the Coordinated Universal Time
(UTC) to computer systems across a network.
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Real Problems
Dropped Packets
Routers or switches might fail to deliver (drop) some packets. This is normal for most
networks and is not a concern unless it happens in large amounts.
Lost Packets
This is not good. This means packets were dropped but can’t be retransmitted.
Delay
It might take a long time for a packet to reach its destination because it gets held up in
long queues, or takes a less direct route to avoid congestion. In some cases,
excessive delay can render an application, such as video, unusable.
Jitter
Packets from the source will reach the destination with different delays. This can
seriously affect the quality of streaming audio and/or video. (UDP can solve this)
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Problems, Really?
Bad IP Scheme
Can cause lots of problems – like edge devices dropping off the network.
Edge Devices
These need to be configured properly, especially video. Are reduced frame rates
being used? Is it your recorder? etc
Multicast Support
All network devices need to support IGMP on large or busy systems.
Bandwidth
Are you exceeding limits? What is an appropriate limit?
Standard vs. Custom Protocols
Many big switch manufacturers customize standard protocols.
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Wireless
IEEE 802.11 is a set of standards for wireless local area
networks (WLAN), in the 5 GHz and 2.4 GHz public
spectrum bands (unlicensed).
802.11b and 802.11g – use 2.4GHz ISM band and gets
up to 54Mbps over up to 38 meters.
802.11n – not a standard yet, but up to 600Mbps by
utilizing MIMO.
 Point-to-Point
 Point-to-Multipoint
 Mesh
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Wireless Topologies
Point-to-Point
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Wireless Topologies
Point-to-Multipoint
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Wireless Topologies
Mesh
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Wireless
Pros
 Less expensive than running cable
 Indoor and outdoor
 Flexible
Cons
 Unreliable
 Interference
 Limitations
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Power Over Ethernet
PoE IEEE 802.3af
 DC power over Ethernet cable - CAT 5e or higher
 Supplies 48V at 350 mA max
 13 Watts max
PSE – Power Source Equip.
PD – Powered Device
Midspan Hub
Endspan Hub
Can you put a non-PoE
Device into a PoE switch?
 25k Ohm resistor
802.3at standard coming – supplies more power
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Summery / Review
Ethernet Advantages
- Flexible Open Architecture IEEE 802.x
- Not Vendor Specific
- Extremely Scalable
- Lost Cost Solution
- Designed for Reliability
- Bandwidth is only used when needed
- Variety of Topologies Available
- Widely Available Management Tools
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