about SNAT and NAT

SNAT and NAT are similar, except SNAT does not accept devices that initiate inbound connections. SNATs are used to change the source IP address, specifically to force the L3 return path for response traffic through the load balancer when routing from the real server back to the client's real address would bypass the load balancer. An example would be that you want to load balance a server where the server's gateway is not the load balancer.

 

 

NAT also IP address translation, in the case of F5 they are mainly used to provide administrative access to backend servers via the load balancer. For example you may have a private non-routable network on the load balancer but you need your administrators to RDP or SSH directly. So you would use a NAT where from the routable address it can be reached.

 

 

I am sure there are examples but this is what is typically used for.

 

 

Hope this helps,

 

CB

 

 

 

 

 

 

 

 

When I enable Address Translation and Choose SNAT Auto Map in Virtual Server, what will BIGIP handle the traffic to this virtual server??

With SNAT automap, LTM will select a floating self IP addresses on the egress VLAN to source traffic from.

 

 

Aaron

I did a testing in my BIGIP. I created a virtual server (outbound_wildcard) and a pool (default_gateway_pool).

 

 

outbound_wildcard:

 

Destination: 0.0.0.0

 

Type: Perfomrance (Layer 4)

 

Protocol: All

 

VLAN Traffic: All VLAN

 

Default Pool: default_gateway_pool

 

Address Translation: Enabled

 

Port Translation: Enabled

 

SNAT Pool: Auto Map

 

 

**NAT List is empty**[\b]

 

 

I have setup a server and it's gateway point to my BIGIP. I tried to access the Internet from this server but not succeeded. When I unchecked Address Translation in the Virtual Server (outbound_wildcards), this server can access the Internet. Why?? In addition, why only "Standard" and "Performance (Layer 4)" have Address Translation and Port Translation option???

What you're seeing is expected. The checkbox for Address translation on the virtual server refers to destination address translation. If you have a network virtual server (destination is not a specific host) you would not want to translate the destination address to the selected pool member's IP address.

 

 

Aaron

So for my case, if I access www.google.com from my server, www.google.com will be translated to default_gateway_pool members IP address. is it correct?

 

 

I have read the configuration guide of BIGIP LTM. This guide told me that NAT is a one-to-one mapping and can do address translation for incoming and outgoing connection.

 

 

I have mixed up "Address Translation" in virtual server and NAT. They are not the same thing.

hi,

 

try this hope this will work for u.

 

 

outbound_wildcard:

 

Destination: 0.0.0.0

 

Type: Perfomrance (Layer 4)

 

Protocol: All

 

VLAN Traffic: All VLAN

 

Default Pool: default_gateway_pool

 

Address Translation: Disabled

 

Port Translation: Enabled

 

SNAT Pool: Auto Map

 

 

Aj