[SIPForum-discussion] Difference Between NAT and ALG

[Onur Cinar]

Hi Nithya,

As Vilas described, NAT simply does address translation at network layer,
however, ALG is capable of altering SIP messages at application layer as
well. In other words, when a SIP message goes through an ALG, you will
notice that all IP addresses and ports in both SIP headers and SDP are
modified.

If you are developing your proprietary NAT traversal logic, you need to pay
extra attention to detect ALG's.

-onur


On 12/4/07, nithya kumar <nithyakr at huawei.com> wrote:
>
>  Hi All,
>
>        Both NAT and ALG  done the process of mapping Private Address to
> public Address. Then what is the exact difference in behavior.
>
>        Thanks in advance.
>
>
>
>
>
> Regards,
>
> NithyaKumar.R
>
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