Inter-Site WAN MLPPP Use

mikem · ‎11-05-2008

I have multiple WAN sites with dual P2P T-1 links between them. Right now, we are doing load balancing on them which isn't using bandwidth efficiently due to most of the traffic only going to a handful of destination IP addresses. I would like to use MLPPP to span the links instead, but I didn't know if:

1. That would adversly impact VOIP traffic.

2. If there is any magic to provisioning the lines.

The T-1 circuits are conventionally provisioned data lines from AT&T, and the routers are 2851's with two VWIC-1MFT-T1 cards in them. Any insight or configuration tips would be appriciated. Mike Morgan - Network Engineer.

merryllem · ‎11-05-2008

Hello Mike,

I have clarification question. Is this circuit MPLS or P2P? The reason I asked is if it is MPLS that would mean that ATT PE would need to also support MLPPP. This might be a bit off topic to your question but I wanted to bring that up.

The link below might help

http://www.cisco.com/en/US/tech/tk652/tk698/technologies_tech_note09186a0080094660.shtml#link_frag

mikem · ‎11-05-2008

The circuits are P2P conventional T-1s. We haven't moved to MPLS as our needs have only been about 2Mb average. Thanks for the reply! Mike

Richard Burts · ‎11-06-2008

Mike

I would not think that configuring the links for PPP multilink would have any impact on VOIP. The configuration is fairly simple. You configure the multilink interface which is a virtual interface and where the IP address is configured. It would look something like this:

interface Multilink1

ip address x.x.x.x 255.255.255.252

ip virtual-reassembly

no keepalive

no cdp enable

ppp multilink

ppp multilink group 1

and on the physical interfaces you make sure the encapsulation is ppp, remove the IP address and assign them to the multilink:

interface Serial0/0

description multilink connection to xxx

no ip address

encapsulation ppp

no fair-queue

no cdp enable

ppp multilink

ppp multilink group 1

interface Serial0/1

description multilink connection to xxx

no ip address

encapsulation ppp

no fair-queue

no cdp enable

ppp multilink

ppp multilink group 1

HTH

Rick

HTH

Rick

bbaillie · ‎11-07-2008

Maybe MLPPP isn't your best choice here, alternate solutions are always worth a look.

An example is a new Cisco Express Forwarding feature that balances traffic across multiple links with the twist that it includes source and destination ports in the path selection decision. Its a "12.4" "T" train feature that is easy to implement and works great. Upgrade the IOS and add one command, its that simple.

http://www.cisco.com/en/US/docs/ios/ipswitch/configuration/guide/cef_load_balancng.html

ip cef load-sharing algorithm {original | tunnel [id] | universal [id] include-ports {source [id] | [destination] [id] | source [id] destination [id]}}

Example:

Router(config)# ip cef load-sharing algorithm include-ports source destination

The reasoning is different conversations use different source/destination pairs, simple actually and brilliant at the same time.

Cheers,

Brian