Re: Alias feature in NAT

Hi,
I wasn't enought clear, sorry. By Ending connections, I mean that you will
have a one-way connection like a dynamic NAT. So if you are translating the
ip address 192.168.1.1 to 134.1.1.1, then you are unable to contact the
other device using the 134.1.1.1. For instance, you couldn't telnet it, or
close a bgp peering to 134.1.1.1.

The second question about ip unnumbered. Ip unnumbered feature share a
single ip address with a second interface.
For instance, int fa0/0 use the loopback 0 ip address. But this feature has
some limitations, for the interface using the ip unnumbered feature, like
use dynamic routing protocols, hsrp, static-arp and use the main interface
and this one at diferents vrf.
http://www.cisco.com/en/US/docs/switches/lan/catalyst4500/12.2/31sga/configuration/guide/unnumber.pdf
The Ip address at ip unnumbered, is used just for outgoing connections, and
the incomming connections has restrictions.
It's similar to using static nat with no-alias at the end. Your outgoing
connections will work, but not incomming connections will be allowed.
hth,
Robclav

2011/9/22 Routing Freak <routingfreak_at_gmail.com>

> Hi Roberto,
>
> What do u mean by " ENDING CONNECTIONS" . Wat does IP Unnumbered does . IP
> unnumbered is nothing but utilizing the ip address of another interface .
> How do u compare the IP Unnumbered with Alias feature.
> Can u brief me dude?
>
>
> On Thu, Sep 22, 2011 at 8:12 PM, Roberto Clavero <robclav_at_gmail.com>wrote:
>
>> Hi,
>> the nat command with the no-alias feature at the end, prevents the router
>> to enable the IP for ending connections.
>> BUT, the router is still allowed to reply using proxy-arp for the
>> translated ip. Is something similar to ip unnumbered command.
>> You can check it trying a telnet to the nat with no-alias statement.
>> Hth,
>> Robclav
>>
>> 2011/9/22 Routing Freak <routingfreak_at_gmail.com>
>>
>>> Hi guys,
>>>
>>> I have enable no-alias feature in NAT which prevents creation of
>>> proxy-arp
>>> entries, but still the router is responding to arp requests for global ip
>>> address. Am i getting the concept wrong. Can some help me out in this
>>> issue
>>>
>>> What is the real logic of ALIAS Feature in IOS . and how does it work in
>>> NATTING ?
>>>
>>>
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>>
>>
>> --
>> Robert Clavero
>> CCIE RS/wr, CCNP, CCSP, CCSE NGX, SCSA 9, WLFES, BNP y JNCIA WX
>> blog:http://robclavbcn.blogspot.com
>>
>> web:http://www.kubsolutions.com
>>
>>
>

-- 
Robert Clavero
CCIE RS/wr, CCNP, CCSP, CCSE NGX, SCSA 9, WLFES, BNP y JNCIA WX
blog:http://robclavbcn.blogspot.com
 web:http://www.kubsolutions.com
Blogs and organic groups at http://www.ccie.net