11.2 NAT Operation
11.2.2 Traffic types supported in Cisco IOS NAT

The following traffic types are supported by Cisco IOS NAT:

  • Any TCP/UDP traffic that does not carry source or destination IP addresses in the application data stream

  • Hypertext Transfer Protocol (HTTP)

  • Trivial File Transfer Protocol (TFTP)

  • Telnet

  • Archie

  • finger

  • Network Timing Protocol (NTP)

  • Network File System (NFS)

  • rlogin, rsh, rcp

Although the following traffic types carry IP addresses in the application data stream, they are supported by Cisco IOS NAT:

  • ICMP

  • File Transfer Protocol (FTP) (including PORT and PASV commands)

  • NetBIOS over TCP/IP (datagram, name, and session services)

  • Progressive Networks' RealAudio

  • White Pines' CuSeeMe

  • Xing Technologies' Streamworks

  • DNS "A" and "PTR" queries

  • H.323/NetMeeting [12.0(1)/12.0(1)T and later]

  • VDOLive [11.3(4)11.3(4)T and later]

  • Vxtreme [11.3(4)11.3(4)T and later]

  • IP multicast [12.0(1)T] (source address translation only)

The following traffic types are not supported by Cisco IOS NAT:

  • Routing table updates

  • Domain Name System (DNS) zone transfers

  • BOOTP

  • talk, ntalk

  • Simple Network Management Protocol (SNMP)

  • NetShow

The source for the Cisco NAT support information is the Cisco IOS Network Address Translation (NAT) Packaging Update, found at the following web link:

Web Links
Cisco Connections