From: Shawn Zandi (szmetal@gmail.com)
Date: Wed May 28 2008 - 03:41:37 ART
Ash,
You know that most of switches, cannot act as a *GRE* tunnel endpoint? Whats
your switch. if you disable keepalive it doesn't mean that your tunnel is
up, cause you have no info from the other side.
Shawn Zandi,
www.shafagh.com
On Wed, May 28, 2008 at 9:57 AM, ccietester55 ccietester55 <
ccietester55@gmail.com> wrote:
> I need some help with establishing a GRE tunnel between a router and a
> switch. The topology is SW1 ----trunk---- SW2 ---- R6. SW1 and SW2
> have a working trunk between them. SW1 and R6 are communicating over
> vlan 120. There's an SVI for this vlan on SW1.
>
> On SW1
> interface Vlan120
> ip address 10.1.1.1 255.255.255.0
>
> On R6
> interface Ethernet0/0
> ip address 10.1.1.6 255.255.255.0
>
> SW1 can ping R6 and vice versa. All looks good. Now I create a GRE
> tunnel between SW1 and R6:
>
> On SW1
> interface Tunnel0
> ip address 192.168.0.1 255.255.255.0
> keep 10 3
> tunnel source Vlan120
> tunnel destination 10.1.1.6
>
> On R6
> interface Tunnel0
> ip address 192.168.0.6 255.255.255.0
> keep 10 3
> tunnel source Ethernet0/0
> tunnel destination 10.1.1.1
>
>
> ...and here's where I hit the problem. The tunnel does not come up.
> When I do a "debug tunnel keep" on both devices I see SW1 sending and
> receiving keepalives but R6 only sends them. It appears that SW1 is
> dropping the keepalives from R6. When I turn off keepalives at both
> ends the tunnel comes up and I can ping 192.168.0.6 from SW1 and
> 192.168.0.1 from R6.
>
> I'm completely at a loss to explain this behavior. Vlan 120 on SW1 and
> e0/0 on R6 can ping each other and yet they can't exchange keepalives?
> And yet once keepalives are turned off the two devices can happily
> exchange packets over the tunnel? Please help with this. I've been
> looking at it for 5 hours and can't work it out!
>
> Thanks,
> Ash
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