Multicast%20Address%20Discovery%20Protocol

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Multicast AddressDiscovery Protocol

• IETF Vancouver Oct 2005

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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 havent 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.

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RFC 2365 Administratively Scoped Zones
239.0.0.0
RFC 2365 Org.-LocalExpansion

• Defines only 2 Well-Known Scopes
• 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.

239.192.0.0
RFC 2365 Org-Local Scope
239.196.0.0
Unassigned
239.255.253.0
RFC 2365 Local ScopeExpansion
RFC 2365 Local Scope
239.255.0.0
239.255.255.255
(Not to scale.)
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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 Unassigned
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Scope Relative Local Scope
239.0.0.0
Address 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
239.255.0.0
Local Scope
239.254.255.255
239.255.255.0
Local Scope Scope Relative
239.255.255.255
(Not to scale.)
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Scope Relative Org-Local Scope
239.0.0.0
Address 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
239.192.0.0
Org-Local Scope
239.195.254.255
239.195.255.0
Org-Local Scope Relative
239.195.255.255
(Not to scale.)
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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)

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ACMEs Scoped Zones
9
ACMEs Scoped Zones
Campus Scope

• Campus Scope 239.190.x.x/16

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ACMEs Scoped Zones
Regional Scope
Australia
North America
ASIAPAC
China
Canada
East Coast US
India
Japan
West Coast US
Core
North Region
EMEA
Eastern Region
Internet
South Region

• Regional Scope 239.191.x.x/16

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ACMEs Scoped Zones
Enterprise Scope
Australia
North America
ASIAPAC
China
Canada
East Coast US
India
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

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ACMEs Scoped Zones
Global (Internet) Scope
Australia
North America
ASIAPAC
China
Canada
East Coast US
India
Japan
West Coast US
Core
North Region
EMEA
Eastern Region
Internet
South Region

• Global Scope 224.0.1.x 238.255.255.255

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ACMEs Address Assignments
239.0.0.0

• 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.

239.190.0.0
Campus Scope (/16)
239.191.0.0
Region Scope (/16)
239.192.0.0
Enterprise Scope (/14)
RFC 2365Organization-Local Scope
239.196.0.0
RFC 2365 Local Scope
239.255.0.0
239.255.255.255
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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

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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)applica
  tion 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.