Multilink PPP per packet balancing

MICHAEL WAISBROT · ‎06-06-2007

Need help getting per packet loadbalancing working over two t1s, two cisco 1700 routers on each end...

I have cef enabled with the following interface configs.

It works, but is only doing per destination balancing

interface Multilink20

description MLP to TLC Multilink20

ip address 10.97.23.2 255.255.255.252

no ip redirects

no ip proxy-arp

ip load-sharing per-packet

ip pim sparse-dense-mode

fair-queue

ppp multilink

ppp multilink links minimum 1

ppp multilink group 20

!

interface FastEthernet0/0

ip address 10.20.254.235 255.255.0.0

speed 100

full-duplex

!

interface Serial0/0

description T1 to TLC Se0/0 T1 ID 11-DHXS-000650

bandwidth 1544

no ip address

ip load-sharing per-packet

ip pim sparse-dense-mode

encapsulation ppp

no fair-queue

service-module t1 timeslots 1-24

service-module t1 fdl att

ppp multilink

ppp multilink group 20

!

interface Serial1/0

description T1 to TLC Se0/1 T1 ID 11-DHXS-000650

bandwidth 1544

no ip address

ip load-sharing per-packet

ip pim sparse-dense-mode

encapsulation ppp

no fair-queue

service-module t1 timeslots 1-24

service-module t1 fdl att

ppp multilink

ppp multilink group 20

Richard Burts · ‎06-06-2007

MICHAEL

I am very curious to know how you have determined how you distinguish on the multilink whether it is doing per packet or per destination load balancing.

With multilink there is only 1 logical path between the routers and per packet or per destination result in the same behavior: all traffic is sent over the 1 logical link between the routers.

HTH

Rick

HTH

Rick

devang_etcom · ‎06-07-2007

Yes Rick,

what ever i know is if you have 4 link and you creat the logical Mulitlink interface for all that 4 link then arrived packet is fragmented in 4 subpacket and those packets will travel through those 4 links...

regards

Devang

bvsnarayana03 · ‎06-07-2007

with cef enabled, it should be per packet load balancing.

MICHAEL WAISBROT · ‎06-07-2007

The reason I believe it is doing per destination load balancing is because I have two t1's, and when I start up an ftp over the MLPPP I am only getting a max throughput of 1.5MB, never anymore. Lead me to believe the it is doing per destination and send all traffic over one link.

I have CEF enable, and routes point to the MLPPP interface on both sides.

Any thoughts...should I be doing fragmentation?

thanks,

Richard Burts · ‎06-07-2007

MICHAEL

I am surprised that you would not get more than T1 throughput. I do not believe that it is a matter of load balancing. Since there is 1 logical path between the routers there is no balancing to be done.

I wonder if there might be an issue on one of the links that is impacting throughput. Could you post the output of show interface for all the serials interfaces involved, the output of show service-module, and the output of show ppp multilink. It would be best if we could see these outputs from both routers.

Without knowing a bit more about your environment and the mix of traffic going over the multilink we can not say whether fragmentation would be beneficial. My guess is that it will not matter. Of course you could configure it and see if any behavior changes.

HTH

Rick

HTH

Rick

MICHAEL WAISBROT · ‎06-07-2007

Here is some of the output information

Richard Burts · ‎06-07-2007

MICHAEL

Thanks for posting the additional output. It does not show anything abnormal. I notice that the interface output and the service module output were cleared and show the last 5 or 6 minutes only. Would I assume that you cleared them and ran the test again?

The output shows that both T1s are approximately equally balanced and both are carrying load. So it looks like the multilink is working correctly (and there is no load balancing issue). I am wondering if there could be some other factor that is constraining the throughput of your FTP transfer.

HTH

Rick

HTH

Rick