We recently implemented VOIP on one of our sites, the main callmanager is in the head office and all traffic goes through a PIX 515. The VOIP phone would get the correct IP address from DHCP but simply didnt work properly. After removing the fixup h232 command it started working fine, can someone pls explain exactly what fixup does and how removing it fixed the prob? Thanks in advance.
"Application Inspection" is also known as "Fixup".The fixup protocol h323 command provides support for H.323-compliant endpoints. PIX Firewall Version 5.3 through Version 6.2 supports H.323 Version 2. PIX Firewall Version 6.3 supports H.323 Version 3 and Version 4.
H.323 is a suite of protocols defined by the International Telecommunication Union (ITU) for multimedia conferences over LANs. H.323 supports VoIP gateways and VoIP gatekeepers. H.323 Version 2 adds the following functionality:
"Fast Connect or Fast Start Procedure for faster call setup
"H.245 tunneling for resource conservation, call synchronization, and reduced set up time
Table of ContentsIntroductionVersion HistoryPossible Future
UpdatesDocuments PurposeNAT Operation in ASA 8.3+ SectionsRule Types
Network Object NATTwice NAT / Manual NATRule Types used per SectionNAT
Types used with Twice NAT / Manual NAT and Network Obje...
Table of Contents Introduction:This document describes details on how
NAT-T works. Background: ESP encrypts all critical information,
encapsulating the entire inner TCP/UDP datagram within an ESP header.
ESP is an IP protocol in the same sense that TCP an...