From: Brian Dennis (brian@labforge.com)
Date: Sat May 24 2003 - 16:44:02 GMT-3
R5 is a point-to-point subinterface so this means that it doesn't need
inverse-arp. R5 assumes every address of the 10.100.0.0/16 subnet is at
the other end of the DLCI.
Brian Dennis, CCIE #2210 (R&S/ISP-Dial/Security)
-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
Jonathan V Hays
Sent: Saturday, May 24, 2003 10:38 AM
To: ccielab@groupstudy.com
Subject: is frame-relay inverse-arp really disabled?
I thoroughly understand how to manipulate frame-relay for the CCIE Lab.
This is just something I'm curious about.
I have noticed some frame-relay inverse-arp behavior that I would not
expect. In this scenario R3 and R5 are connected via frame-relay. Both
are running Version 12.1(5)T14Version 12.1(5)T14. Normally I would
configure frame-relay map types the same on both ends of a PVC. However,
in this case I configured a dynamic PVC on R5's S1.1 (point-to-point)
and a static PVC on R3. I also manually disabled inverse-arp sending and
receiving on R3, though I am aware that the IOS is supposed to turn it
off when a static PVC is configured.
You would think that R5 would NOT be able to get a frame-relay map to R3
with inverse-arp disabled circumstances. But even after rebooting both
routers I can ping okay.
Why?
R3:
interface Serial1
ip address 10.100.1.6 255.255.0.0
encapsulation frame-relay
ip ospf network point-to-point
clockrate 64000
no arp frame-relay
frame-relay map ip 10.100.1.3 305 broadcast
no frame-relay inverse-arp
!
r3#show frame-relay map
Serial1 (up): ip 10.100.1.3 dlci 305(0x131,0x4C10), static,
broadcast,
CISCO, status defined, active
r3#
R5:
interface Serial1
no ip address
encapsulation frame-relay
!
interface Serial1.1 point-to-point
description PVC to R3
ip address 10.100.1.3 255.255.0.0
frame-relay de-group 1 503
frame-relay interface-dlci 503
!
r5#show frame-relay map
Serial1.1 (up): point-to-point dlci, dlci 503(0x1F7,0x7C70), broadcast
status defined, active
r5#ping 10.100.1.6
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 10.100.1.6, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 60/61/64 ms
r5#
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