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New Member

DMVPN spoke router load balancing over multiple T1's

Will the DMVPN tunnel at the spoke end use and load balance encrypted traffic if I have multiple T1's starting on the same router and teminating both circuits on the same router at the other end?

Thanks,

4 REPLIES

Re: DMVPN spoke router load balancing over multiple T1's

Hello,

you could use Multilink PPP to bundle the different T1 into one logical interface. Both routers would have a similar configuration like:

interface Multilink1

ip address 10.1.1.1 255.255.255.252

ppp multilink

multilink-group 1

!

interface Serial0/0

no ip address

encapsulation ppp

ppp multilink

multilink-group 1

!

interface Serial0/1

no ip address

encapsulation ppp

ppp multilink

multilink-group 1

Replace the IP addresses and interface numbering to match your environment. This way Layer2 (MLPPP) would take care about load sharing and you would not need to care about CEF IP routing and other things like that.

Hope this helps! Please rate all posts.

Regards, Martin

New Member

Re: DMVPN spoke router load balancing over multiple T1's

Thank you Martin, that is a great suggestion. However, I'm wondering what the outcome is if the circuits are left the way they are currently. Basically in a L3 routing situation using CEF per-packet. Do you know if the DMVPN tunnel will use both circuits and load balance? Is there additional configuration that needs to happen? Is the tunnel from the spoke created using both T1's?

Thank You,

New Member

Re: DMVPN spoke router load balancing over multiple T1's

This has multiple problems, the first of which is IPSec, not NHRP. I haven't attempted this for some time, but having two IPSec sessions between two routers via two different IP Addresses is a problem in and of itself.

The solution that we use is two smaller routers. This works fine.

New Member

Re: DMVPN spoke router load balancing over multiple T1's

Typically, if you want try load balancing it makes more sense to do it at L2 not L3. In reality L3 really will not do a true load-balancing. You may want to talk to your ISP about utilizing some form of L2 device, similar to the TASMAN series of equipment. In most cases the TASMAN 1400 can handle up to 8T1's and has the capabilities of using BGP if you have more than one ISP for diversity. Other than that, any L3 path, will not really give you a true load-balancing scenario. Thanks - Chip

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