From: Arun Arumuganainar (aarumuga@hotmail.com)
Date: Tue Aug 23 2005 - 08:37:15 GMT-3
Cool ... Pretty interesting problem though ... But I would need some more
information to confirm my suspicion .
Pls. provide me with show ip route <tunnel destination > ... taken at two
different times .
a)When ping packets are going through fine
b) when ping are not going through .
If my suspicion is right then your tunnel protocol state in the "show
interface tunnel 0" command should toggle between UP and DOWN state !!! at
regular intervals.
Only work around for this problem add a following static route in tunnel end
points .
R2 .
ip route 172.16.35.0 255.255.255.252 serial 1/1
R3
ip route 172.16.25.0 255.255.255.252 serial 1/1
This kind of problems are bound to happen especially when you enable routing
protocols on a tunnel interface . Some times routers could have learned a
better route for tunnel destination via tunnel interface themselves . This
creates a loop . i.e Tunnel recurses over Tunnel destination and tunnel
destination reclurse over tunnel !!! Under this scenario there will be
flapping of tunnel interface at regular intervals !!!
Best way to address it , is to have static route for tunnel destination
alone via an interface other than Tunnel .
Pls. Note : Static route is always preferred . Hence accidental loops will
not be introduced through Dynamic Routing protocols .
Pls. do let me know if this solves the problem .
Thanks and Regards
Arun
----- Original Message -----
From: "Thomwin Chen" <thomwin_chen@yahoo.com>
To: "Loi, Choon Ho" <ChoonHo.Loi@getronics.com>; <ccielab@groupstudy.com>
Sent: Tuesday, August 23, 2005 3:30 PM
Subject: Re: OSPF Virtual-Link & GRE
> Choon,
>
> Have you try to put the tunnel0 interface in R2 and R3 into area 0 ?
> I saw your config, the tunnel is in area 3.
>
> Rgds,
> Thomwin
>
>
> "Loi, Choon Ho" <ChoonHo.Loi@getronics.com> wrote:
> Hi,
>
> I lab-up the following Scenario for OSPF:
>
> Area 0 | R2 -----Area 1------- R5 ------Area 2--------R3--------| Area 3
>
> Everything works fine... but, my ping drop intermittently when I try to
> ping from Area3 to Area0.
> Anything wrong with my configuration?
>
> Thanks.
>
>
> Following is my configuration:
>
> hostname r2
> !
>
> !
> interface Loopback0
> ip address 192.2.2.2 255.255.255.0
> !
> interface Tunnel0
> ip address 23.23.23.2 255.255.255.248
> tunnel source Serial1/1
> tunnel destination 172.16.35.1
> !
> interface Serial1/1
> ip address 172.16.25.1 255.255.255.252
> encapsulation ppp
>
> router ospf 1
> router-id 2.0.0.2
> log-adjacency-changes
> area 1 virtual-link 5.0.0.5
> network 23.23.23.0 0.0.0.7 area 3
> network 172.16.25.0 0.0.0.3 area 1
> network 192.2.2.0 0.0.0.255 area 0
> ------------------------------------------------------------------------
> ---
> !
> hostname r5
>
> interface Loopback0
> ip address 100.100.100.100 255.255.255.0
> !
> interface Loopback1
> ip address 5.0.0.5 255.255.255.255
>
> interface Serial0/0
> ip address 172.16.25.2 255.255.255.252
> encapsulation ppp
> no fair-queue
> !
> interface Serial0/1
> ip address 172.16.35.2 255.255.255.252
> encapsulation ppp
> !
> router ospf 1
> router-id 5.0.0.5
> log-adjacency-changes
> area 1 virtual-link 2.0.0.2
> network 172.16.25.0 0.0.0.3 area 1
> network 172.16.35.0 0.0.0.3 area 2
> neighbor 5.5.5.2
> !
>
>
> ------------------------------------------------------------------------
> ------
> !
> hostname r3
>
> interface Loopback0
> ip address 10.10.10.3 255.255.255.255
> !
> interface Tunnel0
> ip address 23.23.23.3 255.255.255.248
> tunnel source Serial1/1
> tunnel destination 172.16.25.1
>
> interface Serial1/1
> ip address 172.16.35.1 255.255.255.252
> encapsulation ppp
> serial restart_delay 0
> clockrate 64000
>
> router ospf 1
> router-id 3.0.0.3
> log-adjacency-changes
> network 10.10.10.0 0.0.0.255 area 3
> network 23.23.23.0 0.0.0.7 area 3
> network 172.16.35.0 0.0.0.3 area 2
> ------------------------------------------------------------------------
> -------------------------------------
>
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