It’s All About Networking

Presented by

Bryan Crisler – SR. Network Engineer

Time Warner Cable

bryan.crisler@twcable.com

February 18th, 2015

Housekeeping

• Take this time to locate: – Emergency Exits: out the door to the right

first hallway on your right … continue to the parking lot.

– Restrooms: out the door to the right –first hallway on your right

– Note taking utensils

• Put your Phones on Vibrate – If you need to take a call, feel free to step

out of the room.

About your Speaker

• Bryan Crisler

– Started in Cable @ Charter Communications, Riverside, CA in June 2005

– Currently a Senior Network Engineer @ Time Warner Cable

About your Speaker

• Held following positions:

– Broadband Technician I-IV (Charter)

– Network Operations Specialist (Charter)

– Network Technician (Charter)

– Network Engineer (Charter & TWC)

– SR Network Engineer (TWC)

Today’s Lesson Plan

• Session 1: The Basics of Networking – 9:10 am - 10:00 am

• Session 2: The Basics of Networking @ Cable Company – 10:10 am – 11:00 am

• Session 3: Troubleshooting Networking Issues – 11:10 am – 12:00 pm

Basics of Networking

Session 1

9:10 am – 10:00 am

What is Networking?

• Networking – a supportive system of sharing information and services among individuals and groups having a common interest (dictionary.com)

What is a Computer Network?

• Computer Network – a group of electronic devices interconnected for the sharing of information, resources (printers, scanners, etc), and services (internet, email, etc)

• Each device on the network will communicate with each other to share information.

It’s Video Time!!!

• Check it out on youtube:

• http://youtu.be/Ve7_4ot-Dzs

Network Wiring

• Unshielded Twisted Pair (UTP – CAT 5

• 4 pair (orange, green, blue, brown) • Rated for 100 MBit/sec

– CAT 5e • 4 pair (orange, green, blue, brown) • Rated for 1000 MBit/sec • More twists/inch than CAT5 – better noise reduction

– CAT 6 • 4 pair (orange, green, blue, brown) • Rated for 1000 MBit/sec • More twists/inch than CAT5e – best noise reduction

Network Wiring - cont

• Fiber

– Multi-mode (Orange)

• Short Range

• 1310 nano meters wavelength

– Single-mode (Yellow)

• Longer Range

• 1550 nano meters wavelength

• Capable of CWDM & DWDM

Different Types of Networks

• WAN (Wide Area Networks)

– A Network that spans geographical areas. The internet is made up of many WANs

• LAN (Local Area Network)

– Smaller Network that is more geographically focused.

– Most companies are made up of multiple LANs

Network Models

• A conceptual networking model helps to define the different functions of a network.

• Allows various vendors to build network devices while still keeping to the same standard

• The Two most used models are TCP/IP Model and the OSI Model

The OSI Model

The OSI Model – Host Layer

• Application (Layer 7) – User Interface – Used by services like Web (HTML), File Transfer Protocol, and

Telnet

• Presentation (Layer 6) – Used to control Data sets like ASCII or UTF-8

• Session (Layer 5) – Controls Session data and dialog control, if required. – Used to establish Mode of transfer such as Full Duplex or Half

Duplex

• Transport (Layer 4) – Provides end to end communication, error checking, and data

integrity – Used by TCP and UDP

OSI Model – Media Layers

• Network (Layer 3) – Used by Routers and some Multi-Layer Switches – IP Address use to identify Network interfaces – Encapsulates Data into Packet

• Data Link (Layer 2) – Used by Routers and Switches – MAC Address used to identify physical Hardware Interfaces – Encapsulates Packets into Frames

• Physical (Layer 1) – Used by the physical medium such as ethernet, fiber or coax

between all network devices. – Uses bits to transfer frames across medium (1s and 0s)

What can you find in a Network?

• Routers

• Switches

• Hubs

• Firewalls

• Workstations (End Device)

• Servers (End Device)

What is A Router?

• Layer 3 (Network Layer) Device

• Connects WAN and LAN together

• Allows access to Internet

• Uses IP Address to Identify Network Interface

• Shares routing information with other Routers to determine best path.

• Can use Copper Twisted Pair, Fiber, or Serial Connections to connect to other Routers or Switches

What is a Switch?

• Layer 2 (Data Link) Device • Connects End Devices (CPEs) to a LAN • Allows Access to Local Services • Uses MAC Address to identify Physical Hardware

Interface • Employs Collision Detection and Full Duplex

communication for faster data transfer • Stores Known MAC Address into table for faster

lookup • Connects to Routers Upstream for Internet Access • Can use Copper Twisted Pair or Fiber to connect to

other Routers, Switches, or End Devices

What is A Hub?

• Layer 1 (Physical) Device • Connects End Devices (CPEs) to a LAN • Boost signal and retransmits data on all ports. • Older Technology, hardly used today. • Allows Access to Local Services • Connects to Routers Upstream for Internet

Access • Can use Copper Twisted Pair or Fiber to

connect to other Routers, Switches, or End Devices

What is a Firewall?

• A Layer 4/7 (Transport/Application) Device

• Configured with an IP Address

• Security Appliance that can prevent unauthorized access by: – Blocking IP Address (Sender/Receiver)

– TCP/UDP Port Number

– Packet Inspection (Layer 7/Application) Device

• May provide intrusion detection/prevention

• Network Address Translation

What is a Workstation?

• Layer 7 (Application) Device • End Device (CPE) • Receives IP Dynamically (DHCP) or Statically • Has a MAC Address for every Network

Interface Card • Runs Windows, Linux, or MacOS • Can be either Wired (Ethernet) or Wireless • Can gain access to server as a client via

Application layer protocols such as Web, FTP, SSH, Telnet, DNS, etc.

What is A Server?

• Layer 7 (Application) Device

• End Device

• Receives IP Dynamically (DHCP) or Statically

• Has a MAC Address for every Network Interface Card

• Runs Windows Server, Linux/Unix, or MacOS Server

• Can be either Wired (Ethernet) using Copper or Fiber

• Can provide servicess to clients via Application layer protocols such as Web, FTP, SSH, Telnet, DNS, etc.

Network Topology Review

IP Addressing

• Layer 3 (Network) form of Addressing

• Two different forms of IP Address:

– IPv4

• Uses Dotted Decimal (192.168.0.1)

• Has 4,294,967,296 total address (public & private)

• 32 bit address

– IPv6

• Uses Hexidecimal Notation (FE80::1)

• Has 3.4×1038 total address (public & private)

• 128 bit address

IP Addressing - cont

• Both versions represent a real number

• For Instance:

– 0.0.1.0 = 256

– 10.0.0.4 = 16,777,220

– 0:0:0:0:0:0:0:1 = 1

– 0:0:0:0:1:0:0:0 = 281,462,092,005,375

IP Addressing - cont

• Blocks of IPs are called Subnets

• Each Subnet represents a network (either WAN or LAN)

• The range of each subnet is determined by the Subnet Mask

• Each Subnet has a Network (First IP address) and a Broadcast (Last IP Address) IP Address

• Subnet Range is calculated Subtracting Subnet Mask and from 255.255.255.255.

• For Example a Subnet Mask of 255.255.255.0 will have 256 IPs in the Subnet

IP Address Example

• A home wireless Router is configured with network address of 192.168.0.0 and a subnet mask of 255.255.255.0

• 255.255.255.255 – 255.255.255.0 = 0.0.0.255 = 256 total address

• 192.168.0.0 + 0.0.0.255 = 192.168.0.255 • Network Range: 192.168.0.0 to

192.168.0.255 • Network Address: 192.168.0.0 • Broadcast Address: 192.168.0.255

IP Address - cont

• Network Address: First IP in a Subnet used to identify the entire network

• Broadcast Address: Last IP in a Subnet used to communicate any device on the Useable IP Range.

• Gateway IP Address: The configured IP address on the next hop router, which contains a path towards a WAN/Internet

• Useable IP Range: Any IP in a subnet that except the Network and Broadcast

MAC Address

• Layer 2 (Data Link) Address

• 48 Bit Address

• Identifies the Physical Hardware Address on a Network Interface Card

• Uses a hexidecimal representation

• First 6 digits indicate a vendor oui.

• Example: – 00:15:A4:00:11

– 00:e9:af:12:34

Resolving IP Address

• ARP – Address Resolution Protocol is used to discover a MAC Address for a specific IP Address by broadcasting a message to everyone on a subnet using a broadcast IP.

• rARP – Reverse Address Resolution Protocol is used to discover the IP Address for a specific MAC Address.

Public vs Private IP Space

• RFC1918 – Prohibits the distribution of private IP Address space on WAN Links.

• Private Address Space includes: – 10.0.0.0 – 10.255.255.255 – 172.16.0.0 – 172.31.255.255 – 192.168.0.0 – 192.168.255.255

• This space is specially reserved for private use only. • Private space is was allocated to allow network

useable space, without having to allocate and waste large blocks of public space.

• With Network Address Translation (NAT), private space can be mapped to public space.

Dynamic Host Configuration Protocol (DHCP)

• Allows a DHCP server to assign/configure an IP Address to an end device

• Will also configure Subnet Mask, Gateway IP, as well as DNS Servers

• When an end device is configured for DHCP, the DORA begins.

DHCP - cont

• DORA – Discover – Client sends a message to DHCP Server – Offer – Server sends a message to client with an

IP Address Offer – Request – Client formally request IP Address

Offered, and sets Subnet Mask, gateway, DNS and lease time

– Acknowledge – Server Acknowledges client Request and reserves IP.

• Once lease is at half-life, DORA process is repeated.

Domain Name Service (DNS)

• DNS – Maps a domain name like google.com to an IP Address

• Multiple DNS servers are configured for redundancy

• DNS Servers must be reachable in order to be queried

Transmission Control Protocol (TCP) • Layer 4 (Transport) Protocol

– State Oriented Protocol – Reliable and Ordered Transmission – Provides Error Checking and Flow Control – Three Way Handshake to form socket

• Host A sends Syn • Host B Sends Syn-Ack • Host A send Ack

• TCP Port Numbers reserved for well known services – Web (HTTP) : 80 – FTP : 20 & 21 – POP : 110 – IMAP : 143 – SMTP : 25 – Telnet : 23 – SSH: 22

User Datagram Protocol (UDP)

• Simple transmission • Stateless protocol • No error checking or reliability • Used for Real-time transmissions such as

voice, streaming video, etc. • Unidirectional communication • UDP Port Numbers Reserved for Well known

services: – tftp : 69 – Ntp : 123

Session 1 Review

• How many Layers are in the OSI Model?

• How many bits are in an IPv6 Address?

• What method is used by DHCP?

• How is the Network Range determined?

• Which device works at Layer 3 (Network)?

• What is a Layer 2 Address?

• How does a Layer 2 Address resolve a layer 3 address?

• Give me an example of a private address

• What is a Gateway IP Address?

Session 1 Q&A

• Any Questions???

Basics of Networking at a Cable Company

Session 2

10:10 am – 11:00 am

What is DOCSIS?

• DOCSIS - Data Over Cable Service Interface Specification – Allows network connection over RF Cable using cable modems and a CMTS

History of DOCSIS

• DOCSIS was developed by CableLabs and a consortium of other vendors

• DOCSIS 1.0 – Released in March 1997

• DOCSIS 1.1 – Released in April 1999

• DOCSIS 2.0 – Released in December 2001

• DOCSIS 3.0 – Released in August 2006

• DOCSIS 3.1 – Release in October 2013

DOCSIS Terminology

• DS – Downstream • US – Upstream • CM – Cable Modem • CPE – Customer Premise Equipment • TDMA – Time Division Multiple Access

– Allows multiple modems to register to a single interface

• Mac Domain – a single service group of multiple DS and US channels. A single Mac Domain may feed one or multiple RF/Fiber Nodes

• Channel Width – The width of a single channel in Hertz. US Channel widths range from 200 kHZ to 6.4 MHz, whereas DS Channel width is fixed at 6MHz

• Channel Modulation – A specific way that a channel signal is transformed, typically either QAM or QPSK

DOCSIS 1.0/1.1

• Supported 1 DS Carrier – Channel Width: 6 MHz

– Channel Modulation: 64 QAM / 256 QAM

– Maximum Speed: 42.88 Mbits/sec

• Supported 1 US Carrier – Channel Width: 200 kHz – 3.2MHz

– Channel Modulation: QPSK / 16 QAM

– Maximum Speed: 10.24 Mbits/sec

DOCSIS 2.0

• Supported 1 DS Carrier

– Channel Width: 6 MHz

– Channel Modulation: 64 QAM / 256 QAM

– Maximum Speed: 42.88 Mbits/sec

• Supported 1 US Carrier

– Channel Width: 200 kHz – 6.4MHz

– Channel Modulation: QPSK / 8 QAM - 64 QAM

– Maximum Speed: 30.72 Mbits/sec

DOCSIS 3.0

• Supported 24 DS Carrier – Supports DS Channel Bonding – Channel Width: 6 MHz – Channel Modulation: 64 QAM / 256 QAM – Maximum Speed: 1029.12 Mbit/ sec

• Supported 8 US Carrier – Supports US Channel Bonding – Channel Width: 200 kHz – 6.4MHz – Channel Modulation: QPSK / 8 QAM - 64 QAM – Maximum Speed: 245.76 Mbits/sec

DOCSIS 3.1

• Supported Unlimited DS Carrier – Supports DS Channel Bonding – Channel Width: 20 kHz – 50 kHz OFDM – Channel Modulation: 256 QAM / 4096 QAM – Maximum Speed: 10 Gbit/ sec

• Supported Unlimited US Carrier – Supports US Channel Bonding – Channel Width: 200 kHz – 6.4MHz – Channel Modulation: QPSK / 8 QAM - 128 QAM – Maximum Speed: 1 Gbits/sec

What is a CMTS?

• CMTS – Cable Modem Termination System

• A Layer 3 (Network) Device

• Has similar functions to that of a Router

• Connects to other Routers using Fiber or Copper UTP

• Provides a shared RF Connection to a fiber-node (service group/mac-domain) that will service upto 250 customers (on average)

• Uses DS Frequencies between 85MHz – 1 GHz and US Frequencies between 5-85 MHz to communicate to Cable Modems (DOCSIS 3.0 Spec)

What is a CMTS? - cont

• CMTS in production:

– Cisco uBR 10012

– Arris C4

– Arris E6000

– Casa 10G

– Motorola BSR 64000

What is a Cable Modem?

• A network bridge that provides network access via RF channels. Delivers broadband access and speeds upto 1Gbit/sec and 200Mbit/s

• Layer 2 (Data link) Device

• 1 RF Connection, 1 Ethernet Connection

• May have CPE such as STB, VoIP or Home Wireless Router attached

How do modems connect to the CMTS?

Modem/CMTS Messaging

• SYNC – Timing Synchronization – sent every 200 ms

• UCD – Upstream Channel Descriptor – Provides the upstream frequency of which the

modem will reply back on, along with symbol rate, modulation, etc.

• MAP – Media Access Protocol – Allocates set communication interval for each

modem.

• RNG-REQ – Range Request • RNG-RSP – Range Response

Modem/CMTS Messaging - cont

How Modems Register

How Modems Register - cont

How Modems Register - cont

How Modems Register - cont

Cable Modem Addressing

• Each cable modem has two primary addresses:

– MAC Address (CMAC/RF/DOCSIS, etc)

– IP Address

• Typically will be a private IP Address

• Acts as a bridge for Inbound and Outbound network traffic

CPE Addressing

• Each CPE has two primary address:

– MAC Address

• If you CPE is attached to a modem it may be a STB, VoIP, MTA, CPE MAC

– IP Address

• Depending on the service, this may or may not be a private IP Address.

• This address will provide access to the necessary services

Session 2 Review

• When was Channel Bonding Introduced?

• What is TDMA?

• What is a UCD and what does it contain?

• What is a Cable Modem?

• What is the channel width of a DS Carrier?

• IS the ip address of a cable modem typically public or private?

• What three Layers of the OSI model does a CMTS Operate on?

Session 2 Q&A

• Questions?

Basic Network Troubleshooting

Session 3

11:10 am – 12:00 am

IPConfig

• Run cmd

• Type ‘ipconfig /all’

– Displays all IP Addresses

• Type ‘ipconfig /release’ & ‘ipconfig /renew’

– If you need to refresh the IP with the DHCP Server do a /release & /renew

• Type ‘ipconfig /flushdns’

– If you are having problems reaching some websites, run a /flushdns

Tracert (Traceroute)

• Run cmd • Shows latency and hopcount • Each hop is a router interface • Maximum hops on tracert is 30 • Type ‘tracert google.com’

– To see if you can reach google or any other domain name.

• Type ‘tracert 4.2.2.2’ – If you are unable to resolve any DNS, you can still traceroute using

an IP Address

• Type ‘tracert 192.168.1.1’ – If you are trying to reach your local router’s gateway ip address

• Type ‘tracert <cpe gateway ip>’ – If you are trying to reach your CPE gateway IP Address on the

CMTS.

Ping

• Run cmd

• Great test for packet loss

• Type ‘ping google.com’ – To see if you can reach google or any other domain name

• Type ‘ping –t <ip or domain name>’ – To test for packet loss on the internet. –t will continuosly

ping until cntr-c is pressed.

• Type ‘ping –n <count> <ip or domain name> – To test for packet loss with a specific amount of packets.

• Type ‘ping –l <size of packet> <ip/domain> – To test for packet loss with a greater packet size.

NSLookup

• Run cmd

• Used to query DNS Server and perform DNS Lookups

• Can be used to determine if DNS server is down or not reachable

• Type ‘nslookup google.com’ – Performs a standard lookup

• Type ‘nslookup <ip address>’ – Performs a reverse dns lookup to find domain name

• Type ‘nslookup <ip/domain> <server ip>’ – Performs a lookup using a different server

Network-tools.com

• Goto www.network-tools.com

– Many different network tools

– Allows you to ping from outside cable network

– Can check DNS Records

– Can also check email spam blacklists

• Goto www.network-tools.com

– Many different network tools

– Allows you to ping from outside cable network

– Can check DNS Records

– Can also check email spam blacklists

Wireless Troubleshooting

• Check SSID

• Verify Security is using WPA2

• Set DHCP leases to 10

• Setup MAC Filtering

Session 3 Q&A

• Any Questions???