RE: Frame-Relay Inverse-Arp

From: Brian Dennis (bdennis@internetworkexpert.com)
Date: Tue Mar 02 2004 - 21:57:56 GMT-3


InARP is not enabled for a DLCI assigned to a P2P subinterface as layer 3 to
layer 2 mapping is automatic for a P2P subinterface. A P2P subinterface
will reply to an InARP request from another router but will not actively
InARP itself.

Here are a few InARP subinterface examples:

**********************************
*** 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

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: Scott Morris [mailto:swm@emanon.com]
Sent: Tuesday, March 02, 2004 4:27 PM
To: 'Kenneth Wygand'; 'Brian Dennis'; 'Ahmed Mustafa';
ccielab@groupstudy.com
Subject: RE: Frame-Relay Inverse-Arp

Inverse ARP is enabled by default for all DLCI's. It's not particular to an
interface type or not.

What he's getting at is two-fold.

1. If you have a sub-interface, you must ASSIGN a DLCI here, nothing gets
stuck their automagically.
2. If you have a static mapping, this overrides a dynamic one when you look
at the "show frame map" output.

Normally we look at having inverse arp off because the exam tells us to. If
we have a full mesh of PVC's, we'd learn about connections that we should
have via our physical interface (leftover/unassigned dlci's).

HTH,

 
Scott Morris, CCIE4 (R&S/ISP-Dial/Security/Service Provider) #4713, CISSP,
JNCIS, et al.
IPExpert CCIE Program Manager
IPExpert Sr. Technical Instructor
swm@emanon.com/smorris@ipexpert.net
http://www.ipexpert.net

-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
Kenneth Wygand
Sent: Tuesday, March 02, 2004 6:59 PM
To: Brian Dennis; Ahmed Mustafa; ccielab@groupstudy.com
Subject: RE: Frame-Relay Inverse-Arp

Brian,
 
If it's not too much bother (I'm sure you know them off the top of your
head), can you tell me for which (sub)interface types inverse-arp is
en/disabled?
 
Thanks!
Ken

        -----Original Message-----
        From: nobody@groupstudy.com on behalf of Brian Dennis
        Sent: Tue 3/2/2004 5:57 PM
        To: 'Ahmed Mustafa'; ccielab@groupstudy.com
        Cc:
        Subject: RE: Frame-Relay Inverse-Arp
        
        

                The rule of thumb is that the command is applied wherever
the IP
        address is assigned.
        
                As a side note, if using multipoint subinterfaces with only
static
        mappings then InARP does not need to be disabled.
        
        Brian Dennis, CCIE #2210 (R&S/ISP-Dial/Security)
        bdennis@internetworkexpert.com
        Internetwork Expert, Inc.
        http://www.InternetworkExpert.com
<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
        Ahmed Mustafa
        Sent: Monday, March 01, 2004 9:49 PM
        To: ccielab@groupstudy.com
        Subject: Frame-Relay Inverse-Arp
        
           Can the command "No Frame-relay Inverse-Arp" be applied on a
        sub-interface
        or has to be a physical interface.
        
        If there is a case where Hub router has a multipoint interface to
spoke 1
        and
        spoke 2, and another multipoint interface to spoke 3. The scenerio
requires
        that dynamic frame-relay must be disabled on first multipoint
interface, and
        not on second one.
        
        



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