it’s all about networking - scte san...
TRANSCRIPT
It’s All About Networking
Presented by
Bryan Crisler – SR. Network Engineer
Time Warner Cable
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
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 – 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.
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?
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
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
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?
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