Re: NAT no-alias

Hi,

NAT with no-alias is about the local router not responding to ARP requests
within a NAT range and may have been of use in a redundant situation where
two gateways use HSRP/VRRP and you see log entries about duplicate IDs - I
suspect this is a knob used before stateful NAT was developed.

http://www.cisco.com/en/US/docs/ios-xml/ios/ipaddr_nat/configuration/15-mt/iadnat-ha.html

Cheers,
Adam

On Fri, Nov 29, 2013 at 2:02 AM, Matt Sherman <matt.sherman2_at_gmail.com>wrote:

> Thank you Tony. So this command only applies to MPLS? Seems like it's
> origin is pre-MPLS.
>
> Matt
>
>
> On Wed, Nov 27, 2013 at 5:01 PM, Tony Singh <mothafungla_at_gmail.com> wrote:
>
> >
> >
> >
> > *Note*
> > ------------------------------
> >
> > 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.
> > ------------------------------
> >
> > So use case in your scenario is lost as it's not a vrf enabled interface
> >
> > --
> > BR
> >
> > Tony
> >
> > Sent from my iPad
> >
> > On 27 Nov 2013, at 21:41, Matt Sherman <matt.sherman2_at_gmail.com> wrote:
> >
> > Hello,
> >
> > Can someone clear up for me what "no-alias" is supposed to do with NAT.
> > The scenario I'm testing is this -
> >
> > R7 (f0/0) -- (f0/0) R1 (s1/1) -- (s1/1) R3
> >
> > R7 (f0/0) = 192.168.4.110
> > R1 (f0/0) = 192.168.4.1
> > R1 (s1/1) = 192.168.13.1
> > R3 (s1/1) = 192.168.13.3
> >
> > Translating R3's 192.168.13.3 to 192.168.4.3 on R1 works fine. I can
> ping
> > R7 from R3.
> > _________________________________________________
> > ((R1))
> > ip nat inside source static 192.168.13.1 192.168.4.3
> > !
> > int s1/1
> > ip nat inside
> > !
> > int f0/0
> > ip nat outside
> > _________________________________________________
> >
> > But when I put the no-alias extenstion on the static NAT (ip nat inside
> > source static 192.168.13.1 192.168.4.3 no-alias), R3 can no longer ping
> or
> > connect to R7.
> >
> > I know that adding the "no-alias" makes R1 no longer reply to ARPs for
> the
> > translated address (192.168.4.3) but then what's the point? It breaks
> all
> > communication.
> >
> > Thanks,
> > Matt
> >
> >
> > Blogs and organic groups at http://www.ccie.net
> >
> > _______________________________________________________________________
> > Subscription information may be found at:
> > http://www.groupstudy.com/list/CCIELab.html
>
>
> Blogs and organic groups at http://www.ccie.net
>
> _______________________________________________________________________
> Subscription information may be found at:
> http://www.groupstudy.com/list/CCIELab.html

Blogs and organic groups at http://www.ccie.net
Received on Fri Nov 29 2013 - 06:42:16 ART