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Link-Layer Hints for
Detecting Network Attachments
Alper Yegin, Eric Njedjou,
Siva Veerepalli, Nicolas Montavont,
Thomas Noel
Objective
• draft-yegin-dna-l2-hints-00.txt
• Identify how link-layer can assist DNA algorithms
– Catalogue existing link-layers and their capabilities
•
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GPRS
cdma2000
IEEE 802.11
…
– Define an abstraction
GPRS
ACTIVATE PDP CONTEXT REQUEST
MN
ACTIVATE PDP CONTEXT ACCEPT
(allocated IP address, QoS parameters)
SGSN
GGSN
IP connectivity
MN Mobile Node
SGSN GPRS Access Point
GGSN
GPRS Access Router
cdma2000
MS
BS_1x
BS_2x
BS_1y
PCF_1x
PCF_2x
PCF_1y
PDSN_x
PDSN_y
MS hands off
to BS_2x
No change in nw layer configuration
MS hands off
to BS_1y
New PPP - NW layer configuration change
Radio Link Protocol (RLP)
A8 GRE Tunnel
A10 GRE Tunnel
Point to Point Protocol (PPP)
MS: Mobile Station
BS: Base Station
PCF: Packet Control Function
PDSN: Packet Data Serving Node
IEEE 802.11
New Access Router
New Access Point
Active scanning
Mobile
Probe Request
Probe Response
Passive scanning
Beacon
Authentication
Authentication
Assoc. Request
Assoc. Response
Router Solicitation
Router Advertisement
Triggers and Hints…
• Event notifications from the link-layer will
trigger the DNA algorithm:
– Link up:
• PDP context activated on GPRS
• PPP established on cdma2000
• (re)association or secure association on IEEE 802.11
Triggers and Hints…
• Hints may be optionally provided along the
triggers, which may help optimize the DNA
process
– The IP address is provided during PDP context
activation on GPRS
– Same with the PPP on cdma2000
– IEEE 802.11… not straight forward
Hints in IEEE 802.11
• No L3 configuration in L2
• Need for an identifier to associate links with
networks (configurations)
– BSSID (L2 address of AP)?
• No one-to-one mapping to a network
– SSID (service set identifier)?
• Same SSID might be used across a routed network.
• SSID does not mean much when the network is selected during
the authentication phase (dynamic VLAN assignment)
• Any useful hints for DNA without modifying
IEEE 802.11?