ZyXEL Communications P-660HWP-D1, User Manual

Page: 138 / 374

Chapter 9 Network Address Translation (NAT)
P-660HWP-D1 User’s Guide
138
The following table summarizes these types.
9.2 SUA (Single User Account) Versus NAT
SUA (Single User Account) is a ZyNOS implementation of a subset of NAT that supports two
types of mapping,
Many-to-One
and
Server
. The P-660HWP-D1 also supports
Full
Feature NAT to map multiple global IP addresses to multiple private LAN IP addresses of
clients or servers using mapping types as outlined in Table 48 on page 138 .
• Choose SUA Only if you have just one public WAN IP address for your P-660HWP-D1.
• Choose Full Feature if you have multiple public WAN IP addresses for your P-660HWP-
D1.
9.3 SIP ALG
Some applications, such as SIP, cannot operate through NAT (are NAT un-friendly) because
they embed IP addresses and port numbers in their packets’ data payload.
Some NAT routers may include a SIP Application Layer Gateway (ALG). An Application
Layer Gateway (ALG) manages a specific protocol (such as SIP, H.323 or FTP) at the
application layer.
A SIP ALG allows SIP calls to pass through NAT by examining and translating IP addresses
embedded in the data stream.
When the P-660HWP-D1 registers with the SIP register server, the SIP ALG translates the P-
660HWP-D1’s private IP address inside the SIP data stream to a public IP address. You do not
need to use STUN or an outbound proxy if your P-660HWP-D1 is behind a SIP ALG.
Table 48 NAT Mapping Types
TYPE IP MAPPING
One-to-One ILA1 ÅÆ IGA1
Many-to-One (SUA/PAT) ILA1 ÅÆ IGA1
ILA2 ÅÆ IGA1
…
Many-to-Many Overload ILA1 ÅÆ IGA1
ILA2 ÅÆ IGA2
ILA3 ÅÆ IGA1
ILA4 ÅÆ IGA2
…
Many-to-Many No Overload ILA1 ÅÆ IGA1
ILA2 ÅÆ IGA2
ILA3 ÅÆ IGA3
…
Server Server 1 IP ÅÆ IGA1
Server 2 IP ÅÆ IGA1
Server 3 IP ÅÆ IGA1