NAT & PAT

[samsam_wang]

for PAT,

how many PCs I can connect internet in same time? if 1000 PCs share the ONE ip, the PAT works? or not?

for NAT,

if the pool size is 10 IPs, how many PCs can connect the internet?

thanks

[Georg Pauwen]

Hello,

a pool size of 10 IP addresses is no problem, your hosts will all be able to connect to the Internet (keeping in mind that they have to share bandwidth).

The NAT session limit is actually bound by the amount of available DRAM in the router. Each NAT translation consumes about 160 bytes in DRAM. As a result, 10,000 translations (more than would generally be handled on a single router) can consume about 1.6 MB. Therefore, a typical routing platform has more than enough memory to support thousands of NAT translations.

PAT can make a maximum of 65535 translations , so 1000 PCs sharing one IP will work.

PAT (NAT overloading) divides the available ports per global IP address into three ranges of 0-511, 512-1023, and 1024-65535. PAT (NAT overloading), assigns a unique source port for each User Datagram Protocol (UDP) or Transmission Control Protocol (TCP) sessions. It will attempt to assign the same port value of the original request. However, if the original source port has already been used, it will start scanning from the beginning of the particular port range to find the first available port and assign it to the conversation.

HTH,

Georg

[samsam_wang]

thanks a lot

for discussing, I don't think so.

just imagine, I have a router with 1024M DRAM/1024M flash, so the memory no problem.

do you think 65535 clients will work in same time? 65536 is only a value based theory. I just want to make sure the actual size.