When do we use NAT No Alias

[dradhika]

Hi,

Can someone explain what is the meaning of nat aliasing and when do we use nat no-alias command.

I could not understand the notes given in cisco docs clearly.

So any example would be helpful.

Thanks,

Radhika

[dradhika]

I meant with respect to a router.

Thanks,

Radhika

[dradhika]

when we enable nat with aliasing and the global address is an unused ip from attached subnet then the ip appears in the alias table which is used for replying arp requests.

Still not clear when we use no-alias option.

Any clarification would be appreciated.

Got some notes from the below links.

http://lists.netfilter.org/pipermail/netfilter/2003-January/041616.html

http://www.cisco.com/en/US/customer/tech/tk648/tk361/technologies_white_paper09186a0080091cb9.shtml

Router(config)#ip nat inside source stat 192.168.5.4 192.168.2.5

Router(config)#do sh ip alias

Address Type IP Address Port

Interface 192.168.2.2

Dynamic 192.168.2.4

Interface 192.168.0.6

Dynamic 192.168.2.5

Router(config)#ip nat inside source stat 192.168.5.4 192.168.2.5 no

Router(config)#ip nat inside source stat 192.168.5.4 192.168.2.5 no-alias

Router(config)#do sh ip alias

Address Type IP Address Port

Interface 192.168.2.2

Dynamic 192.168.2.4

Interface 192.168.0.6

[colin.dsouza1]

When you configure NAT with a VRF-enabled interface address that acts as the global address, you must configure the ip nat inside source static no-alias command. If the no-alias keyword is not configured, Telnet to the VRF-enabled interface address fails.