Configure more than one Tunnel with the same tunnel source.

[davidyangyi]

When I configure the second GRE Tunnel with the same tunnel source as the first, I get this warning:

%Warning: Using same source IP for more than one IP/GRE tunnels may cause software
switching packets for tunnels using this address. If possible, use an unique
tunnel source for Interface Tunnel2

how much bandwidth can they support? and what problem it would cause when it is over the limit?

configuration as follow:

interface Tunnel1
ip address 10.157.102.2 255.255.255.248
tunnel source 10.157.100.220
tunnel destination 10.161.0.2

interface Tunnel2
ip address 10.157.102.30 255.255.255.252
tunnel source 10.157.100.220
tunnel destination 10.159.0.2

[Reza Sharifi]

It is usually recommended to have a different source for different GRE tunnels. If not, you can not take advantage of hardware routing/switching.

So you may see performance degradation, because of software switching

HTH

Reza

[Leo Laohoo]

We had cases when we sites where it was too small to put two routers.  So what we did was do similar to your setup:  One WAN link but two GRE tunnels going back to the different data centre.

Using OSPF, we put a lower cost on the preferred link to force all traffic down Tunnel 1 and use Tunnel 2 as a redundancy.  We never use both Tunnel 1 and Tunnel 2 as a "load balance" because some applications simply hated it.

[davidyangyi]

Thank you all.

I wonder that if I use different tunnel source, must I use different physical port ?