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Frame-relay map and inverse-arp

 
 
allangiganson@yahoo.com
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Posts: n/a
 
      02-10-2005
Hi Group,

Under Configuring Static Address Mapping in
http://www.cisco.com/univercd/cc/td/....htm#wp1001012
It says,
"A static map links a specified next-hop protocol address to a
specified DLCI. Static mapping removes the need for Inverse ARP
requests; when you supply a static map, Inverse ARP is automatically
disabled for the specified protocol on the specified DLCI."

However, I lab this up and it does not seem to be the case.
Can anyone clarify why? I thought it's the IOS version but I am using
12.2.

Thanks in advance.

Al

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

I used a hub and spoke topology. Here's my relevant configurations.

Hub

interface Serial0
ip address 192.168.1.1 255.255.255.0
encapsulation frame-relay
no fair-queue

Spoke1
interface Serial0
ip address 192.168.1.2 255.255.255.0
encapsulation frame-relay
no fair-queue
frame-relay map ip 192.168.1.3 201

Spoke2
interface Serial0
ip address 192.168.1.3 255.255.255.0
encapsulation frame-relay
no fair-queue
frame-relay map ip 192.168.1.2 301

I rebooted Spoke1. Inverse arp to the Hub should be disabled but it
isn't as seen below.

spoke1#show frame-relay map
Serial0 (up): ip 192.168.1.1 dlci 201(0xC9,0x3090), dynamic,
broadcast,, status defined, active
Serial0 (up): ip 192.168.1.3 dlci 201(0xC9,0x3090), static,
CISCO, status defined, active

I cleared the table and inverse arp disappeared as can be seen below.
r1#clear frame-relay inarp
r1#show fram
r25031#show frame-relay map
Serial0 (up): ip 192.168.1.3 dlci 201(0xC9,0x3090), static,
CISCO, status defined, active

However, after I rebooted dynamic connection to the hub came back.
spoke1#show frame-relay map
Serial0 (up): ip 192.168.1.1 dlci 201(0xC9,0x3090), dynamic,
broadcast,, status defined, active
Serial0 (up): ip 192.168.1.3 dlci 201(0xC9,0x3090), static,
CISCO, status defined, active

The same holds to spoke2.

 
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JNCIP#0136
Guest
Posts: n/a
 
      02-11-2005
Your FR switch probably has Spoke1-Spoke2 PVC defined and active. Try to
delete it and Your dynamic mapping should be gone.
HTH,
Cheers
Alex
<(E-Mail Removed)> wrote in message
news:(E-Mail Removed) oups.com...
> Hi Group,
>
> Under Configuring Static Address Mapping in
>

http://www.cisco.com/univercd/cc/td/....htm#wp1001012
> It says,
> "A static map links a specified next-hop protocol address to a
> specified DLCI. Static mapping removes the need for Inverse ARP
> requests; when you supply a static map, Inverse ARP is automatically
> disabled for the specified protocol on the specified DLCI."
>
> However, I lab this up and it does not seem to be the case.
> Can anyone clarify why? I thought it's the IOS version but I am using
> 12.2.
>
> Thanks in advance.
>
> Al
>
> ************************************************** ******************
>
> I used a hub and spoke topology. Here's my relevant configurations.
>
> Hub
>
> interface Serial0
> ip address 192.168.1.1 255.255.255.0
> encapsulation frame-relay
> no fair-queue
>
> Spoke1
> interface Serial0
> ip address 192.168.1.2 255.255.255.0
> encapsulation frame-relay
> no fair-queue
> frame-relay map ip 192.168.1.3 201
>
> Spoke2
> interface Serial0
> ip address 192.168.1.3 255.255.255.0
> encapsulation frame-relay
> no fair-queue
> frame-relay map ip 192.168.1.2 301
>
> I rebooted Spoke1. Inverse arp to the Hub should be disabled but it
> isn't as seen below.
>
> spoke1#show frame-relay map
> Serial0 (up): ip 192.168.1.1 dlci 201(0xC9,0x3090), dynamic,
> broadcast,, status defined, active
> Serial0 (up): ip 192.168.1.3 dlci 201(0xC9,0x3090), static,
> CISCO, status defined, active
>
> I cleared the table and inverse arp disappeared as can be seen below.
> r1#clear frame-relay inarp
> r1#show fram
> r25031#show frame-relay map
> Serial0 (up): ip 192.168.1.3 dlci 201(0xC9,0x3090), static,
> CISCO, status defined, active
>
> However, after I rebooted dynamic connection to the hub came back.
> spoke1#show frame-relay map
> Serial0 (up): ip 192.168.1.1 dlci 201(0xC9,0x3090), dynamic,
> broadcast,, status defined, active
> Serial0 (up): ip 192.168.1.3 dlci 201(0xC9,0x3090), static,
> CISCO, status defined, active
>
> The same holds to spoke2.
>



 
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JNCIP#0136
Guest
Posts: n/a
 
      02-11-2005
On a second thought Spoke1-Spoke2 PVC seems not to be the case What
seems to be the case is that after reboot FR INARP
first gets dynamic mapping and then later on gets disabled as it should be.
Would You be able to "clear fame-relay inarp" and then wait sufficiently
long (~1 hour) for dynamic mapping to reappear?
If it doesn't reappear then it is definitely disabled
HTH,
Cheers
Alex

<(E-Mail Removed)> wrote in message
news:(E-Mail Removed) oups.com...
> Hi Group,
>
> Under Configuring Static Address Mapping in
>

http://www.cisco.com/univercd/cc/td/....htm#wp1001012
> It says,
> "A static map links a specified next-hop protocol address to a
> specified DLCI. Static mapping removes the need for Inverse ARP
> requests; when you supply a static map, Inverse ARP is automatically
> disabled for the specified protocol on the specified DLCI."
>
> However, I lab this up and it does not seem to be the case.
> Can anyone clarify why? I thought it's the IOS version but I am using
> 12.2.
>
> Thanks in advance.
>
> Al
>
> ************************************************** ******************
>
> I used a hub and spoke topology. Here's my relevant configurations.
>
> Hub
>
> interface Serial0
> ip address 192.168.1.1 255.255.255.0
> encapsulation frame-relay
> no fair-queue
>
> Spoke1
> interface Serial0
> ip address 192.168.1.2 255.255.255.0
> encapsulation frame-relay
> no fair-queue
> frame-relay map ip 192.168.1.3 201
>
> Spoke2
> interface Serial0
> ip address 192.168.1.3 255.255.255.0
> encapsulation frame-relay
> no fair-queue
> frame-relay map ip 192.168.1.2 301
>
> I rebooted Spoke1. Inverse arp to the Hub should be disabled but it
> isn't as seen below.
>
> spoke1#show frame-relay map
> Serial0 (up): ip 192.168.1.1 dlci 201(0xC9,0x3090), dynamic,
> broadcast,, status defined, active
> Serial0 (up): ip 192.168.1.3 dlci 201(0xC9,0x3090), static,
> CISCO, status defined, active
>
> I cleared the table and inverse arp disappeared as can be seen below.
> r1#clear frame-relay inarp
> r1#show fram
> r25031#show frame-relay map
> Serial0 (up): ip 192.168.1.3 dlci 201(0xC9,0x3090), static,
> CISCO, status defined, active
>
> However, after I rebooted dynamic connection to the hub came back.
> spoke1#show frame-relay map
> Serial0 (up): ip 192.168.1.1 dlci 201(0xC9,0x3090), dynamic,
> broadcast,, status defined, active
> Serial0 (up): ip 192.168.1.3 dlci 201(0xC9,0x3090), static,
> CISCO, status defined, active
>
> The same holds to spoke2.
>



 
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Brad
Guest
Posts: n/a
 
      02-11-2005
You need to tell each interface what its dlci is with the
frame-relay interface-dlci command.

 
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Al
Guest
Posts: n/a
 
      02-11-2005
Alex, thanks for your reply. Ok I'd had some time to kill and crazy
enough to wait for 2 hours . After clearing inarp, the dynamic
mapping to the hub never came back, so inverse-arp is disabled.
However, after reboot, it came back again which goes against the
documentation statement that frame-relay map disables inverse-arp after
reboot. I tried to dig deeper and went to the bookstore and found out
that Caslow's Cisco Certification:Bridges, routers and switches for
ccie, page 118, supported the documentation. I am still banging my head
on this one. What did I miss?

JNCIP#0136 wrote:
> On a second thought Spoke1-Spoke2 PVC seems not to be the case

What
> seems to be the case is that after reboot FR INARP
> first gets dynamic mapping and then later on gets disabled as it

should be.
> Would You be able to "clear fame-relay inarp" and then wait

sufficiently
> long (~1 hour) for dynamic mapping to reappear?
> If it doesn't reappear then it is definitely disabled
> HTH,
> Cheers
> Alex
>
> <(E-Mail Removed)> wrote in message
> news:(E-Mail Removed) oups.com...
> > Hi Group,
> >
> > Under Configuring Static Address Mapping in
> >

>

http://www.cisco.com/univercd/cc/td/....htm#wp1001012
> > It says,
> > "A static map links a specified next-hop protocol address to a
> > specified DLCI. Static mapping removes the need for Inverse ARP
> > requests; when you supply a static map, Inverse ARP is

automatically
> > disabled for the specified protocol on the specified DLCI."
> >
> > However, I lab this up and it does not seem to be the case.
> > Can anyone clarify why? I thought it's the IOS version but I am

using
> > 12.2.
> >
> > Thanks in advance.
> >
> > Al
> >
> >

************************************************** ******************
> >
> > I used a hub and spoke topology. Here's my relevant configurations.
> >
> > Hub
> >
> > interface Serial0
> > ip address 192.168.1.1 255.255.255.0
> > encapsulation frame-relay
> > no fair-queue
> >
> > Spoke1
> > interface Serial0
> > ip address 192.168.1.2 255.255.255.0
> > encapsulation frame-relay
> > no fair-queue
> > frame-relay map ip 192.168.1.3 201
> >
> > Spoke2
> > interface Serial0
> > ip address 192.168.1.3 255.255.255.0
> > encapsulation frame-relay
> > no fair-queue
> > frame-relay map ip 192.168.1.2 301
> >
> > I rebooted Spoke1. Inverse arp to the Hub should be disabled but it
> > isn't as seen below.
> >
> > spoke1#show frame-relay map
> > Serial0 (up): ip 192.168.1.1 dlci 201(0xC9,0x3090), dynamic,
> > broadcast,, status defined, active
> > Serial0 (up): ip 192.168.1.3 dlci 201(0xC9,0x3090), static,
> > CISCO, status defined, active
> >
> > I cleared the table and inverse arp disappeared as can be seen

below.
> > r1#clear frame-relay inarp
> > r1#show fram
> > r25031#show frame-relay map
> > Serial0 (up): ip 192.168.1.3 dlci 201(0xC9,0x3090), static,
> > CISCO, status defined, active
> >
> > However, after I rebooted dynamic connection to the hub came back.
> > spoke1#show frame-relay map
> > Serial0 (up): ip 192.168.1.1 dlci 201(0xC9,0x3090), dynamic,
> > broadcast,, status defined, active
> > Serial0 (up): ip 192.168.1.3 dlci 201(0xC9,0x3090), static,
> > CISCO, status defined, active
> >
> > The same holds to spoke2.
> >


 
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Al
Guest
Posts: n/a
 
      02-11-2005
I am using physical interfaces. I thought interface-dlci can only be
used with subinterfaces. However, I stand corrected.

 
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JNCIP#0136
Guest
Posts: n/a
 
      02-14-2005
Hello again,
"frame-relay interface-dlci" command can be used on physical/multipoint
interface, but it doesn't change the interface type.
The main purpose for this command on phy/mpoint interface is to assign
different FR traffic-shaping/class parameters to different DLCIs if there is
more than one DLCI.
FR switch normally advertises active DLCIs to routers via FR LMI "Status"
messages so there should be normally no need to manually configure DLCIs
with "frame-relay interface-dlci" command
HTH,
Cheers
Aelx


"Al" <(E-Mail Removed)> wrote in message
news:(E-Mail Removed) oups.com...
> I am using physical interfaces. I thought interface-dlci can only be
> used with subinterfaces. However, I stand corrected.
>



 
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vatsalp24 vatsalp24 is offline
Junior Member
Join Date: Apr 2009
Posts: 1
 
      04-03-2009
"Static mapping disables Inverse ARP on an interface"
- This interface will never initiate outgoing InARP requests once the Static map is configured.
- But if an InARP request is coming in from another interface, then our subject interface will indeed reply to it. i.e. InARP replies are NOT disabled.

The Dynamic Map you see above in the Spokes is because the Hub is sending InARP requests to Spoke1 and Spoke2 which is allowing the Spokes to learn of the mapping of near-end DLCI to far-end Hub IP address.

Solution:
1) Explicitly Disable InvARP on the Hub interfaces( no frame-relay inverse arp)
OR
2) Create Static Map Statements on Hub as well ( like you did on the Spokes)

Hub and spoke will work just fine with the Physical Multipoint topology that you have in place so no need to create logical interfaces or anything.

Hope this helps !
 
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