IP Networking Part 6‐
An Introduction to
. Pecena, CPBE, CBNE
Texas A&M Information Technology Educational Broadcast Services
Copyright By PowCoder代写 加微信 powcoder
IP Multicast
“A webinar to help you prepare for the CBNETM Certification”
IP Networking Part 6‐ An Introduction to IP Multicast
“A webinar to help you prepare for the CBNETM Certification”
Advertised Presentation Scope:
IP Multicast is a unique aspect of IP Networking technology that provides “One-to- Many” communications between a source IP host and numerous subscriber IP hosts. The use of IP Multicast for delivery of real-time media content often finds widespread use in the broadcast facility.
This webinar will focus upon understanding Multicast terminology, the addressing utilized, and the basics of switching and routing in a multicast IP network. Practical implementation examples to deliver AoIP and IPTV content will be utilized to illustrate the theoretical concepts presented.
My Goals & Deliverables for This Afternoon:
‐ Provide an Awareness of IP Multicast Terminology & Concepts on IPv4 Networks
‐ Provide an Understanding of IP Multicast Implementation
‐ Provide Reference Material & Resources to Obtain Further Knowledge
• Introduction to IP Multicast Terminology • The Multicast Group
• Multicast Addressing
– Layer2Address
– ClassDLayer3Address
• Multicast Switching & Routing
• Broadcast Deployment Examples
– AoIPSystems
– IPTVSystems
• Acronym Glossary
• Reference Documents
• Takeaway Summary – Q&A
Multicast Introduction
• IP Networking is Founded on an “Unicast” Model – OneSendHosttoOneReceiveHost
• Or the “Broadcast” Model
– OneSendHosttoAllOtherHostsonthe IP Packet(s)
A Host Must Join
A Multicast Group To Receive Multicast Packets
• Multicast Adds a 3rd Packet Distribution Approach
– One Send Host to A Group of Receive Hosts on the Subnet
Types of IP Packets on an IPv4 Network
– One Send Host Communicates With One Receive
• Broadcast
– One Send Host Communicates With ALL Hosts on
the Subnet
• Multicast
– One Send Host Communicates With A Group of Specific Hosts
Why IP Multicast?
• IP Multicast is a Bandwidth Conserving Technology
• Provides Efficient Control of Network Traffic
• Server & CPU Load Decrease
• Eliminates Network Traffic Redundancy
Number of Clients
Key Terminology To Be Aware Of:
• MulticastGroups
• ClassDIPAddressSpace
• InternetGroupManagementProtocol–IGMP • MulticastDistributionTree
• ProtocolIndependentMulticast–PIM
• ReversePathForwarding–RPF
IP Multicast Addressing
• Layer 2 Addressing (physical address)
– 23Bitsof48BitMACAddressReservedforMulticast
– ByDefault:ALayer2SwitchWillForwardMulticastPacketsOutAll Ports (except origin port)
– ToEliminate“Flooding”–IGMPSnoopingisUtilized
• IP Group Addressing (virtual address)
– 28Bitsof32BitIPAddressReservedforMulticast
– ClassDIPAddressRangeReservedforMulticast • 224.0.0.0 to 239.255.255.255
– Layer2MulticastAddressDerivedFromLayer3IPAddress
IP Group Addressing
• Multicast Utilizes “Class D” Reserved IP Address Space – 224.0.0.0to239.255.255.255
• Ranges Reserved Within Class D Address Space:
– 224.0.0.0to224.0.0.255 LocalMulticast/RoutingProtocolUse
– 224.0.1.0to238.255.255.255 PublicUse(GloballyScoped) – 239.0.0.0to239.255.255.255 PrivateUse(LimitedScope)
• Common Multicast Addresses:
– 224.0.0.1 – 224.0.0.2 – 224.0.0.5 – 224.0.0.22
AllHostsonSubnet AllRoutersonSubnet All OSPF Routers IGMPTraffic
Deriving a Multicast Layer 2 Address
The OUI of a Multicast MAC Address is Always “01:00:5e”
The Last 3 Hex Digits of the MAC Address Are Calculated Off the
Last 23 Bits of the IP Address
Internet Group Management Protocol
• A Multicast Group is Identified by a Multicast Address.
• IGMP is the Protocol That Allows a Multicast Receive Client (Host) to Send a Request to Join a Multicast Group.
• Three Versions of IGMP Exist:
(RFC 1112)
(RFC 2236) (RFC 3376)
IGMP Message Types
• Membership “Query”
– ARequesttoIdentifyMembersofaMulticastGroup
• Membership “Report”
– ListofMembersofaMulticastGroup
• Leave Group
– Terminates Multicast Group Membership (Disconnect)
Multicast Enabled Router.
IGMP in More Detail
• Multicast Works by Having a Multicast Source Send Packets to a Specific Group of Host Clients That Belong to the Multicast Group.
• The Multicast Group is Assigned a Specific Multicast Address.
• IGMP Provides for Host Clients to Send a “Join” Request to a
• IGMP “Snooping” Allows a Layer 2 Switch to “Learn” the Multicast MAC Address of Multicast Groups.
• IGMP Snooping “Listens” to IGMP Membership Reports and Builds a Multicast MAC Entry in the Switch Table.
IP Multicast Distribution Tree
• An IP Multicast Distribution Tree is a Path Structure From a Multicast Source to a Multicast Destination.
Single Source Tree
“Graft” The Tree
“Trim” or “Prune”
Protocol Independent Multicast
– PIMDenseMode
– PIMSparseMode
– PIMSparse‐DenseMode(PIM‐SM‐DM“CiscoProprietary”)
• Key Difference Between PIM Modes?
– HowTheDistributionTreeisCreated
• PIM is Focused on Getting Multicast Packets to the Desired Destination
• PIM Creates the Multicast Tree & “Trims” the Tree
• 3‐Types of PIM:
• Which is Best?
– DenseModeUsedinLargeNetworks–QuickTreeCreation
– SparseModeUsedinSmallerNetworks–MoreEfficientBandwidthUse
PIM Dense Mode
• All Segments of the Multicast Tree Are “Flooded”.
• Branches Are “Pruned” if Multicast Traffic is Not needed.
PIM Sparse Mode
• Multicast Traffic is NOT Flooded.
• A “Rendezvous Point” is Designated.
• All Multicast Sources & Clients Register With the Rendezvous Point.
Multicast Packet
Multicast Packet
Multicast Packet
Multicast Packet
Multicast Forwarding (Routing)
• Unicast Routing Only Looks at the Destination Address
• Multicast Traffic is Forwarded Away From the Source Host or Downstream
• Reverse Path Forwarding (RPF) is Used to Prevent Loops
• A Router Only Forwards Traffic Received on an Upstream Interface
• RPF Check Used to Determine if an Interface is Valid
X Discarded
What About Multicast on an IPv6 Network?
• Multicast is Inherent to IPv6!
• But, You Still Must:
– Build the Distribution Tree – ProvideRoutingInfo
• Multicast IPv6 Address Format Defined by RFC 3513 – FF00::/8 address prefix format
Practical Applications of IP Multicast • Typical Applications:
– VideoConferencing
– DigitalSignage/CorporateCommunications – StockQuoteDistribution
– Distance Learning
• Common Implementation Examples: – AoIP
Courtesy: AXIA – A Telos Company
AoIP Implementation
AXIA “Livewire” System Heart
Adequate Hardware Platform is a Given. Non-Blocking Backplane.
Adequate Frame Forwarding Rate
The Key Is the Software!
Multilayer Software Image (SMI) – Layer 2/3 Priority Queuing
Multicast Feature Support
IGMP Support
IPTV Implementation
Hotel Room TV System
Acronym Glossary
References
http://www.cisco.com/en/US/docs/ios/solutions_docs/ip_multicast/White_papers/mcst_ovr.html
• RFC 1112
• RFC 1918
• RFC 2362
• RFC 2365
• RFC 2770
• RFC 2283
Host Extension for IP Multicasting
Additional IETF References
Internet Engineering Task Force
Address Allocation for Private Internets
Administratively Scoped IP Multicast GLOP Addressing
Multiprotocol Extensions for BGP‐4
www.ietf.org
Takeaway Summary
• IP Multicast Focused on “One to Many” Communications • IETF RFC’s Define IP Multicast Implementation
• Class D IP Address Space is “Reserved” for IP Multicast
• IP Multicast Limited to “UDP” Packet Delivery
• Multicast “Reverse Path” Routing is the Key to Implementation
• IPv6 Natively Incorporates IP Multicast
• The “Internet” Does Not Support IP Multicast!
Thank You for Attending!
Texas A&M University
979.845.5662
? Questions ?
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