From: Brian Dennis (bdennis@internetworkexpert.com)
Date: Wed Aug 03 2005 - 14:38:21 GMT-3
Shanky,
Comments inline:
@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
***********************************
*** InARP Disabled for DLCI 102 ***
***********************************
interface Serial0/0
no ip address
encapsulation frame-relay
!
interface Serial0/0.1 point-to-point
ip address 10.1.1.1 255.255.255.0
frame-relay interface-dlci 102
Why is InArp disabled for the above scenario ? We never disabled it on the Phy. S0/0 and not on the Sub-if either ? Is it because Inverse Arp is disabled by default for P2P I/Fs ?
@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
This is a point-to-point subinterface so no mappings are required. Also it doesn't matter if inverse-ARP was disabled under the physical interface since the subinterfaces will not inherit that command from the physical interface.
@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
***********************************
*** InARP Disabled for DLCI 102 ***
***********************************
interface Serial0/0
no ip address
encapsulation frame-relay
!
interface Serial0/0.1 multipoint
ip address 10.1.1.1 255.255.255.0
frame-relay interface-dlci 102
no frame-relay inverse-arp
In the above scenario, inverse arp has been disabled on the Sub-If, and we are using
frame-relay interface-dlci 102 ... so how does the router map the remote end IP Address to the local DLCI ?
As per my understanding, frame-relay interface-dlci # uses inverse arp for mapping of remote IP address to the local DLCI, but if we disable inverse-arp as shown above and dont use the map commands , how does the mapping happen ?
@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
The example was just showing you the state of inverse-ARP it wasn't showing you how to reach a remote router.
HTH,
Brian Dennis, CCIE #2210 (R&S/ISP-Dial/Security)
bdennis@internetworkexpert.com
Internetwork Expert, Inc.
http://www.InternetworkExpert.com
Toll Free: 877-224-8987
Direct: 775-745-6404 (Outside the US and Canada)
________________________________________
From: Shanky [mailto:shankyz@gmail.com]
Sent: Wednesday, August 03, 2005 3:55 AM
To: Brian Dennis
Cc: Thomwin Chen; Desmond Ong; lab
Subject: Re: frame-relay inverse arp
Hi Brian,
***********************************
*** InARP Disabled for DLCI 102 ***
***********************************
interface Serial0/0
no ip address
encapsulation frame-relay
!
interface Serial0/0.1 point-to-point
ip address 10.1.1.1 255.255.255.0
frame-relay interface-dlci 102
Why is InArp disabled for the above scenario ? We never disabled it on the Phy. S0/0 and not on the Sub-if either ? Is it because Inverse Arp is disabled by default for P2P I/Fs ?
further for
***********************************
*** InARP Disabled for DLCI 102 ***
***********************************
interface Serial0/0
no ip address
encapsulation frame-relay
!
interface Serial0/0.1 multipoint
ip address 10.1.1.1 255.255.255.0
frame-relay interface-dlci 102
no frame-relay inverse-arp
In the above scenario, inverse arp has been disabled on the Sub-If, and we are using
frame-relay interface-dlci 102 ... so how does the router map the remote end IP Address to the local DLCI ?
As per my understanding, frame-relay interface-dlci # uses inverse arp for mapping of remote IP address to the local DLCI, but if we disable inverse-arp as shown above and dont use the map commands , how does the mapping happen ?
TIA
Shanky
On 8/3/05, Brian Dennis <bdennis@internetworkexpert.com> wrote:
Thomwin,
You do not need to disable inverse-ARP on the physical
interfaces if you are using only subinterfaces. This is because the "no
frame-relay inverse-arp" command is not inherited by subinterfaces.
Here are some examples of when inverse-ARP is enabled or disable
based on the configuration itself or based on the use of the "no
frame-relay inverse-arp" command.
**********************************
*** InARP Enabled for DLCI 102 ***
**********************************
interface Serial0/0
no ip address
encapsulation frame-relay
!
interface Serial0/0.1 multipoint
ip address 10.1.1.1 255.255.255.0
frame-relay interface-dlci 102
**********************************
*** InARP Enabled for DLCI 102 ***
**********************************
interface Serial0/0
no ip address
encapsulation frame-relay
no frame-relay inverse-arp
!
interface Serial0/0.1 multipoint
ip address 10.1.1.1 255.255.255.0
frame-relay interface-dlci 102
***********************************
*** InARP Disabled for DLCI 102 ***
***********************************
interface Serial0/0
no ip address
encapsulation frame-relay
!
interface Serial0/0.1 multipoint
ip address 10.1.1.1 255.255.255.0
frame-relay interface-dlci 102
no frame-relay inverse-arp
*****************************************
*** InARP Disabled for IP on DLCI 102 ***
*****************************************
interface Serial0/0
no ip address
encapsulation frame-relay
!
interface Serial0/0.1 multipoint
ip address 10.1.1.1 255.255.255.0
frame-relay interface-dlci 102
no frame-relay inverse-arp IP 102
*****************************************
*** InARP Disabled for IP on DLCI 102 ***
*****************************************
interface Serial0/0
no ip address
encapsulation frame-relay
!
interface Serial0/0.1 multipoint
ip address 10.1.1.1 255.255.255.0
frame-relay map ip 10.1.1.1 102 broadcast
***********************************
*** InARP Disabled for DLCI 102 ***
***********************************
interface Serial0/0
no ip address
encapsulation frame-relay
!
interface Serial0/0.1 point-to-point
ip address 10.1.1.1 255.255.255.0
frame-relay interface-dlci 102
Also it's a myth (aka urban legend ;-) that the "no arp
frame-relay" command stops the replies to inverse-ARP. It doesn't.
HTH,
Brian Dennis, CCIE #2210 (R&S/ISP-Dial/Security)
bdennis@internetworkexpert.com
Internetwork Expert, Inc.
http://www.InternetworkExpert.com
Toll Free: 877-224-8987
Direct: 775-745-6404 (Outside the US and Canada)
-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
Thomwin Chen
Sent: Tuesday, August 02, 2005 8:45 PM
To: Desmond Ong; 'lab'
Subject: Re: frame-relay inverse arp
Hi Desmond,
you can test it by using a simple command :
debug frame-relay packet and see why most workbooks suggest no
frame-relay inverse-arp configured on physical FR interface.
probably, you will also need this to know : no arp frame-relay
Rgds,
Thomwin
Desmond Ong <desmond.gk@netstarnetworks.com> wrote:
hi there,
anyone can enlighten me on the following?
when to use "no frame-relay inverse arp" and when to specifically use
"no
frame-relay inverse arp ip " ???
Thanks!
Regards,
Des
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