Re: FR iARP - how to force iARP request

From: Scott M Vermillion (scott_ccie_list@it-ag.com)
Date: Fri Mar 27 2009 - 18:11:46 ART

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In response to the first part of your question, in the lab and often
times elsewhere, debug will be your only friend:

Rack1R1#debug frame packet
Frame Relay packet debugging is on
Rack1R1#conf t
Enter configuration commands, one per line. End with CNTL/Z.
Rack1R1(config)#int s2/0
Rack1R1(config-if)#shut
Rack1R1(config-if)#no shut
11:55:44: %LINK-5-CHANGED: Interface Serial2/0, changed state to
administratively down
Rack1R1(config-if)#no shut
11:55:44: %ENTITY_ALARM-6-INFO: ASSERT INFO Se2/0 Physical Port
Administrative State Down
11:55:45: %LINEPROTO-5-UPDOWN: Line protocol on Interface Serial2/0,
changed state to down
Rack1R1(config-if)#no shut
Rack1R1(config-if)#
<misc output omitted>
11:55:50: Serial2/0(o): dlci 102(0x1861), pkt encaps 0x0300 0x8000
0x0000 0x806 (ARP), datagramsize 34
11:55:50: FR: Sending INARP Request on interface Serial2/0 dlci 102
for link 7(IP)
11:55:50: Serial2/0(o): dlci 103(0x1871), pkt encaps 0x0300 0x8000
0x0000 0x806 (ARP), datagramsize 34
11:55:50: FR: Sending INARP Request on interface Serial2/0 dlci 103
for link 7(IP)
11:55:50: Serial2/0(o): dlci 104(0x1881), pkt encaps 0x0300 0x8000
0x0000 0x806 (ARP), datagramsize 34
11:55:50: FR: Sending INARP Request on interface Serial2/0 dlci 104
for link 7(IP)
11:55:50: Serial2/0(o): dlci 105(0x1891), pkt encaps 0x0300 0x8000
0x0000 0x806 (ARP), datagramsize 34
11:55:50: FR: Sending INARP Request on interface Serial2/0 dlci 105
for link 7(IP)
11:55:50: Serial2/0(o): dlci 113(0x1C11), pkt encaps 0x0300 0x8000
0x0000 0x806 (ARP), datagramsize 34
11:55:50: FR: Sending INARP Request on interface Serial2/0 dlci 113
for link 7(IP)
11:55:50: broadcast dequeue
11:55:50: Serial2/0(o):Pkt sent on dlci 102(0x1861), pkt encaps 0x300
0x8000 0x0 0x806 (ARP), datagramsize 34
11:55:50: broadcast dequeue
11:55:50: Serial2/0(o):Pkt sent on dlci 103(0x1871), pkt encaps 0x300
0x8000 0x0 0x806 (ARP), datagramsize 34
11:55:50: broadcast dequeue
11:55:50: Serial2/0(o):Pkt sent on dlci 104(0x1881), pkt encaps 0x300
0x8000 0x0 0x806 (ARP), datagramsize 34
11:55:50: broadcast dequeue
11:55:50: Serial2/0(o):Pkt sent on dlci 105(0x1891), pkt encaps 0x300
0x8000 0x0 0x806 (ARP), datagramsize 34
11:55:50: broadcast dequeue
11:55:50: Serial2/0(o):Pkt sent on dlci 113(0x1C11), pkt encaps 0x300
0x8000 0x0 0x806 (ARP), datagramsize 34
Rack1R1(config-if)#
11:55:51: %LINEPROTO-5-UPDOWN: Line protocol on Interface Serial2/0,
changed state to up

In your home lab, you can (and should) do some actual packet capture.
Captured from above shut/no shut:

No. Time Source Destination
Protocol Info
8
0.240899
                                                                   
Inverse ARP Who is 1891? Tell 0000

Frame 8 (34 bytes on wire, 34 bytes captured)
Frame Relay
     First address octet: 0x18
     Second address octet: 0x91
     DLCI: 105
     Control field: U, func=UI (0x03)
     Padding
     NLPID: SNAP (0x80)
     Organization Code: Encapsulated Ethernet (0x000000)
     Type: ARP (0x0806)
Address Resolution Protocol (inverse request)
     Hardware type: Frame Relay DLCI (0x000f)
     Protocol type: IP (0x0800)
     Hardware size: 2
     Protocol size: 4
     Opcode: inverse request (0x0008)
     Sender hardware address: 0000
     Sender IP address: 10.1.1.1 (10.1.1.1)
     Target hardware address: 1891
     Target IP address: 0.0.0.0 (0.0.0.0)

As far as the second part of your question, none of which I'm aware.
Stuff like 'clear frame inarp' doesn't seem to have any impact. But
as long as FR inarp is enabled on the interface, an inarp will go out
for all known DLCIs every minute:

Rack1R1#
12:20:02: Serial2/0(o): dlci 102(0x1861), pkt encaps 0x0300 0x8000
0x0000 0x806 (ARP), datagramsize 34
12:20:02: FR: Sending INARP Request on interface Serial2/0 dlci 102
for link 7(IP)
12:20:02: Serial2/0(o): dlci 103(0x1871), pkt encaps 0x0300 0x8000
0x0000 0x806 (ARP), datagramsize 34
12:20:02: FR: Sending INARP Request on interface Serial2/0 dlci 103
for link 7(IP)
12:20:02: Serial2/0(o): dlci 104(0x1881), pkt encaps 0x0300 0x8000
0x0000 0x806 (ARP), datagramsize 34
12:20:02: FR: Sending INARP Request on interface Serial2/0 dlci 104
for link 7(IP)
12:20:02: Serial2/0(o): dlci 105(0x1891), pkt encaps 0x0300 0x8000
0x0000 0x806 (ARP), datagramsize 34
12:20:02: FR: Sending INARP Request on interface Serial2/0 dlci 105
for link 7(IP)
12:20:02: Serial2/0(o): dlci 113(0x1C11), pkt encaps 0x0300 0x8000
0x0000 0x806 (ARP), datagramsize 34
12:20:02: FR: Sending INARP Request on interface Serial2/0 dlci 113
for link 7(IP)
12:20:02: broadcast dequeue
12:20:02: Serial2/0(o):Pkt sent on dlci 102(0x1861), pkt encaps 0x300
0x8000 0x0 0x806 (ARP), datagramsize 34
12:20:02: broadcast dequeue
12:20:02: Serial2/0(o):Pkt sent on dlci 103(0x1871), pkt encaps 0x300
0x8000 0x0 0x806 (ARP), datagramsize 34
12:20:02: broadcast dequeue
12:20:02: Serial2/0(o):Pkt sent on dlci 104(0x1881), pkt encaps 0x300
0x8000 0x0 0x806 (ARP), datagramsize 34
12:20:02: broadcast dequeue
12:20:02: Serial2/0(o):Pkt sent on dlci 105(0x1891), pkt encaps 0x300
0x8000 0x0 0x806 (ARP), datagramsize 34
12:20:02: broadcast dequeue
12:20:02: Serial2/0(o):Pkt sent on dlci 113(0x1C11), pkt encaps 0x300
0x8000 0x0 0x806 (ARP), datagramsize 34
Rack1R1#
Rack1R1#
12:21:02: Serial2/0(o): dlci 102(0x1861), pkt encaps 0x0300 0x8000
0x0000 0x806 (ARP), datagramsize 34
12:21:02: FR: Sending INARP Request on interface Serial2/0 dlci 102
for link 7(IP)
12:21:02: Serial2/0(o): dlci 103(0x1871), pkt encaps 0x0300 0x8000
0x0000 0x806 (ARP), datagramsize 34
12:21:02: FR: Sending INARP Request on interface Serial2/0 dlci 103
for link 7(IP)
12:21:02: Serial2/0(o): dlci 104(0x1881), pkt encaps 0x0300 0x8000
0x0000 0x806 (ARP), datagramsize 34
12:21:02: FR: Sending INARP Request on interface Serial2/0 dlci 104
for link 7(IP)
12:21:02: Serial2/0(o): dlci 105(0x1891), pkt encaps 0x0300 0x8000
0x0000 0x806 (ARP), datagramsize 34
12:21:02: FR: Sending INARP Request on interface Serial2/0 dlci 105
for link 7(IP)
12:21:02: Serial2/0(o): dlci 113(0x1C11), pkt encaps 0x0300 0x8000
0x0000 0x806 (ARP), datagramsize 34
12:21:02: FR: Sending INARP Request on interface Serial2/0 dlci 113
for link 7(IP)
12:21:02: broadcast dequeue
12:21:02: Serial2/0(o):Pkt sent on dlci 102(0x1861), pkt encaps 0x300
0x8000 0x0 0x806 (ARP), datagramsize 34
12:21:02: broadcast dequeue
12:21:02: Serial2/0(o):Pkt sent on dlci 103(0x1871), pkt encaps 0x300
0x8000 0x0 0x806 (ARP), datagramsize 34
12:21:02: broadcast dequeue
12:21:02: Serial2/0(o):Pkt sent on dlci 104(0x1881), pkt encaps 0x300
0x8000 0x0 0x806 (ARP), datagramsize 34
12:21:02: broadcast dequeue
12:21:02: Serial2/0(o):Pkt sent on dlci 105(0x1891), pkt encaps 0x300
0x8000 0x0 0x806 (ARP), datagramsize 34
12:21:02: broadcast dequeue
12:21:02: Serial2/0(o):Pkt sent on dlci 113(0x1C11), pkt encaps 0x300
0x8000 0x0 0x806 (ARP), datagramsize 34
Rack1R1#
Rack1R1#
12:22:02: Serial2/0(o): dlci 102(0x1861), pkt encaps 0x0300 0x8000
0x0000 0x806 (ARP), datagramsize 34
12:22:02: FR: Sending INARP Request on interface Serial2/0 dlci 102
for link 7(IP)
12:22:02: Serial2/0(o): dlci 103(0x1871), pkt encaps 0x0300 0x8000
0x0000 0x806 (ARP), datagramsize 34
12:22:02: FR: Sending INARP Request on interface Serial2/0 dlci 103
for link 7(IP)
12:22:02: Serial2/0(o): dlci 104(0x1881), pkt encaps 0x0300 0x8000
0x0000 0x806 (ARP), datagramsize 34
12:22:02: FR: Sending INARP Request on interface Serial2/0 dlci 104
for link 7(IP)
12:22:02: Serial2/0(o): dlci 105(0x1891), pkt encaps 0x0300 0x8000
0x0000 0x806 (ARP), datagramsize 34
12:22:02: FR: Sending INARP Request on interface Serial2/0 dlci 105
for link 7(IP)
12:22:02: Serial2/0(o): dlci 113(0x1C11), pkt encaps 0x0300 0x8000
0x0000 0x806 (ARP), datagramsize 34
12:22:02: FR: Sending INARP Request on interface Serial2/0 dlci 113
for link 7(IP)
12:22:02: broadcast dequeue
12:22:02: Serial2/0(o):Pkt sent on dlci 102(0x1861), pkt encaps 0x300
0x8000 0x0 0x806 (ARP), datagramsize 34
12:22:02: broadcast dequeue
12:22:02: Serial2/0(o):Pkt sent on dlci 103(0x1871), pkt encaps 0x300
0x8000 0x0 0x806 (ARP), datagramsize 34
12:22:02: broadcast dequeue
12:22:02: Serial2/0(o):Pkt sent on dlci 104(0x1881), pkt encaps 0x300
0x8000 0x0 0x806 (ARP), datagramsize 34
12:22:02: broadcast dequeue
12:22:02: Serial2/0(o):Pkt sent on dlci 105(0x1891), pkt encaps 0x300
0x8000 0x0 0x806 (ARP), datagramsize 34
12:22:02: broadcast dequeue
12:22:02: Serial2/0(o):Pkt sent on dlci 113(0x1C11), pkt encaps 0x300
0x8000 0x0 0x806 (ARP), datagramsize 34
Rack1R1#

On Mar 25, 2009, at 1:35 , nowy1981 wrote:

> Hi All,
>
> Like in topic. Does shutdown and not shut force router to send iARP
> request, I think yes. Is there any command to do it?
>
> Thanks
>
>
> 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

• Next message: Bryan Bartik: "Re: Tunnel interface not able to ping"
• Previous message: Cisco Fanatic: "Tunnel interface not able to ping"
• Maybe in reply to: nowy1981: "FR iARP - how to force iARP request"
• Messages sorted by: [ date ] [ thread ] [ subject ] [ author ] [ attachment ]

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