Comet Labs IPTEL-S Bedienungsanleitung PDF herunterladen (Seite 44)

NAT Transversal

8/31/2005 Copyright - Ahlgren 2005 44

AhlTek

 SIP end points behind Firewalls/NAT do not have public IP

address

 There are at lease 4 types of NATs – Network Address

Translation

 Full Cone – port is open

 Restricted Cone – port is open to destination IPs

 Port Restricted Cone – open to destination IP – Port pairs

 Symmetric - only the destination computer can respond

 NAT Transversal Gateways use NAT discovery techniques.

 UPnP – Universal Plug n Play, Microsoft,

 External Query – Client asks an external server

 STUN – Simple Transversal of UDP through NAT

 gets IP/port map + NAT type, Needs 4 tests

 Symmetric NAT require RTP media stream to go thru gateway

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Comet Labs IPTEL-S Bedienungsanleitung Seite 44