RE: Frame-relay mystery

From: OhioHondo (ohiohondo@columbus.rr.com)
Date: Sun Feb 16 2003 - 13:31:08 GMT-3


Hunt

Since you are using p[oint to multipoint you have /32 entries in the routing
tables. Look in the routing table of a spoke. You should have a /32 entry
for the other spoke that has a next-hop address of the hub.

Note: Even though the serial interfaces of the spokes are on the same
subnet, a ping (or any other packet) from one spoke router to the serial
interface of the other spoke router "hops" through the hub. Try a trace
route to confirm this.

-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com]On Behalf Of
Hunt Lee
Sent: Sunday, February 16, 2003 7:54 AM
To: ccielab@groupstudy.com
Subject: Frame-relay mystery

Hi friends,

I have a little confusion in a very simple FR setup (hub & spoke
topology)... all 3
are in OSPF (not that I think it would have any affect on this ;)

R3 R5
  \ /
   R1

IP Addressing:

R1 - 137.20.101.1/24
R3 - 137.20.101.3/24
R5 - 137.20.101.5/24

I don't understand that even if each of my spoke ONLY has a frame-relay map
ip
statement pointing to the hub (R1), that they somehow can still managed to
ping each
other!!!

On R1 (hub)

R1#sh run
Building configuration...

Current configuration : 1868 bytes
!
interface Serial0/0
 no ip address
 encapsulation frame-relay
 no ip mroute-cache
 no fair-queue
!
interface Serial0/0.1 multipoint
 ip address 137.20.101.1 255.255.255.0
 ip access-group blockR6 in
 ip ospf network point-to-multipoint
 frame-relay map ip 137.20.101.3 103 broadcast
 frame-relay map ip 137.20.101.5 105 broadcast
 no frame-relay inverse-arp
!
end

On R3 (spoke)

interface Serial0
 ip address 137.20.101.3 255.255.255.0
 encapsulation frame-relay
 ip ospf network point-to-multipoint
 no ip mroute-cache
 frame-relay map ip 137.20.101.1 301 broadcast
 no frame-relay inverse-arp
 bridge-group 1
end

On R5 (other spoke)

R5#sh run
Building configuration...

!
interface Serial0
 ip address 137.20.101.5 255.255.255.0
 encapsulation frame-relay
 ip ospf network point-to-multipoint
 no fair-queue
 clockrate 64000
 frame-relay map ip 137.20.101.1 501 broadcast
 no frame-relay inverse-arp
!
end

R3#ping 137.20.101.5

Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 137.20.101.5, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 116/118/128 ms
R3#

R5#ping 137.20.101.3

Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 137.20.101.3, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 116/138/220 ms
R5#

Yet, I was expecting that the spoke, without the additional frame-relay map
ip
statement pointing with each other, should not be able to ping each other...
(apart
from able to ping the hub).

Anyone has any clue on this?

Regards,
L.

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