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Multicast Address
Discovery Protocol
IETF Vancouver – Oct 2005
MulticastAddressLocationProtocol
1
Problem
• Enterprise Networks wish to deploy Scoped Zones.
– Allows them to limit the scope of applications.
• Examples: Norton Ghost, Altiris
– Many applications use “fixed” addresses.
• Often due to need for (near) zero-configuration operation.
• Some haven’t even bothered to register with IANA!!
– Address Assignment by “Atmospheric Extraction”.
– Scope range maintenance becomes complex
• Must make exceptions for these “rogue” applications.
• More and more such applications popping up.
– Need a way to achieve (near) zero-configuration and yet
give network admin control of addresses used by apps.
MulticastAddressLocationProtocol
2
RFC 2365 – Administratively Scoped Zones
239.0.0.0
• Defines only 2 Well-Known Scopes
RFC 2365
Org.-Local
Expansion
239.192.0.0
RFC 2365
Org-Local
Scope
239.196.0.0
239.255.253.0
239.255.0.0
239.255.255.255
Unassigned
– Organization-Local Scope (239.192/14)
• Largest scope within the Enterprise
network.
– Local Scope (239.255/16)
• Smallest possible scope within the
Enterprise network.
– Other scopes may be equal to but not
smaller in scope.
– Both scopes have expansion space below
their range.
RFC 2365
Local Scope
Expansion
RFC 2365
Local
Scope
(Not to scale.)
MulticastAddressLocationProtocol
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Scope Relative Addresses – RFC 2365
Top 256 Addresses of every Admin. Scope Range.
Last
Octet
Offset
Description
.255
0
SAP Session Announcement Protocol (SDR)
.254
1
MADCAP Protocol
.253
2
SLPv2 Protocol
.252
3
MZAP Protocol
.251
4
Multicast Discovery of DNS Services
.250
5
SSDP
.249
6
DHCPv4
.248
7
AAP
.247
8
MBUS
9 - 255
MulticastAddressLocationProtocol
Unassigned
4
Scope Relative – Local Scope
239.0.0.0
Address
239.255.0.0
Local Scope
239.254.255.255
239.255.255.0
239.255.255.255
Description
239.255.255.255
SAP Session Announcement Protocol (SDR)
239.255.255.254
MADCAP Protocol
239.255.255.253
SLPv2 Protocol
239.255.255.252
MZAP Protocol
239.255.255.251
Multicast Discovery of DNS Services
239.255.255.250
SSDP
239.255.255.249
DHCPv4
239.255.255.248
AAP
239.255.255.247
MBUS
Local Scope
Scope Relative
(Not to scale.)
MulticastAddressLocationProtocol
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Scope Relative – Org-Local Scope
239.0.0.0
Address
239.192.0.0
Org-Local Scope
239.195.254.255
239.195.255.0
239.195.255.255
Description
239.195.255.255
SAP Session Announcement Protocol (SDR)
239.195.255.254
MADCAP Protocol
239.195.255.253
SLPv2 Protocol
239.195.255.252
MZAP Protocol
239.195.255.251
Multicast Discovery of DNS Services
239.195.255.250
SSDP
239.195.255.249
DHCPv4
239.195.255.248
AAP
239.195.255.247
MBUS
Org-Local
Scope Relative
(Not to scale.)
MulticastAddressLocationProtocol
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Administratively-Scoped Zone Example
• ACME Enterprises:
– Three levels of internal scopes
• Campus Scope
• Region Scope
• Org-Local Scope
– aka Enterprise-Wide Scope
– One external scope
• Global scope
• i.e. everything else (Internet)
MulticastAddressLocationProtocol
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ACME’s Scoped Zones
Australia
North
America
ASIAPAC
China
Canada
India
East Coast
US
Japan
West Coast
US
Core
North
Region
EMEA
Eastern
Region
Internet
South Region
MulticastAddressLocationProtocol
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ACME’s Scoped Zones
Campus Scope
Australia
North
America
ASIAPAC
China
Canada
India
East Coast
US
Japan
West Coast
US
Core
North
Region
EMEA
Eastern
Region
Internet
South Region
• Campus Scope: 239.190.x.x/16
MulticastAddressLocationProtocol
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ACME’s Scoped Zones
Regional Scope
Australia
North
America
ASIAPAC
China
Canada
India
East Coast
US
Japan
West Coast
US
RP
RP
Core
North
Region
EMEA
Eastern
Region
Internet
South Region
RP
•
Regional Scope : 239.191.x.x/16
MulticastAddressLocationProtocol
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ACME’s Scoped Zones
Enterprise Scope
Australia
North
America
ASIAPAC
China
Canada
India
East Coast
US
Japan
West Coast
US
Core
North
Region
EMEA
Eastern
Region
Internet
South Region
• Enterprise Scope: 239.192.x.x/14
– i.e. Org-Local Scope
MulticastAddressLocationProtocol
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ACME’s Scoped Zones
Global (Internet) Scope
Australia
North
America
ASIAPAC
China
Canada
India
East Coast
US
Japan
West Coast
US
Core
North
Region
EMEA
Eastern
Region
Internet
South Region
• Global Scope: 224.0.1.x – 238.255.255.255
MulticastAddressLocationProtocol
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ACME’s Address Assignments
239.0.0.0
239.190.0.0
239.191.0.0
Campus
Scope (/16)
Region
Scope (/16)
239.192.0.0
Enterprise
Scope (/14)
• Enterprise scope = RFC 2365 Org-Local
• Keep Local scope separate.
– Avoids moving applications when smaller
scopes are added later.
• Lots of other ways to assign this space.
RFC 2365
Organization-Local Scope
239.196.0.0
239.255.0.0
239.255.255.255
MulticastAddressLocationProtocol
RFC 2365
Local
Scope
13
Solution
• Multicast Address Discovery Protocol
– Very light-weight
– Assumes no support infrastructure other than:
• IP Multicast
• RFC 2365 Administratively Scoped Zones
– Well-Known Scopes (Local & Org. Local Scopes)
– Scope Relative Addresses
– Runs entirely in Application Clients and Servers
MulticastAddressLocationProtocol
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MADP Basics
• Uses a single Scope Relative Address
• Clients send Queries on this address
– Request info on what multicast address(es)
application “X” is using.
– Initial Queries sent in the Local Scope.
– If no response, then queries the Org-Local Scope.
• Servers listen on these addresses.
– When a Request is received, they check to see if they are
the Server for application “X”.
– If so, they send a Response containing multicast address
information.
• Address information was preconfigured by network admin.
MulticastAddressLocationProtocol
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