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New Member

Multilink PPP

Hi folks -

I am planning to bundle 6 T1's together using Multilink PPP on a Cisco 2821 router. For that, I plan to order 3 dual

WIC's for terminating the 6T1's.

That being said, how is the traffic load balanced over the 6T1's? If the load balancing happens, is it per packet or per destination. The router will have CEF enabled.

All the 6T1's are from the same provider.

Thanks!

1 ACCEPTED SOLUTION

Accepted Solutions
Hall of Fame Super Silver

Re: Multilink PPP

Hello Kunal,

>> So if a router has to transmit a 100 MB file across a WAN using the 6T1's bundle, and assuming there is no traffic on the bundle, will the 100MB file fragments be sent over the first T1 alone or will the packets be evenly distributed over the 6 T1's?

evenly distributed over member links using a round robin algorithm eventually fragmented with each fragment sent on a different member link.

This is one of the reasons for using multilink ppp

Hope to help

Giuseppe

5 REPLIES
New Member

Re: Multilink PPP

Hi,

On a Multilink bundled it is only per packet by default and by RFC also.

http://www.faqs.org/rfcs/rfc1717.html

Thanks,

GK

New Member

Re: Multilink PPP

Hi,

you can check the below link also, how packets are handled on the multilink interfaces

http://www.cisco.com/en/US/tech/tk713/tk507/technologies_tech_note09186a008009408f.shtml

hope this helps you,

Thanks,

GK

Super Bronze

Re: Multilink PPP

"That being said, how is the traffic load balanced over the 6T1's? If the load balancing happens, is it per packet or per destination. The router will have CEF enabled. "

If you place all the links into a MLPPP bundle, the router will only "see" one link. I.e. L3 load balancing isn't an issue.

MLPPP as it receives packets, should (ideally) send a packet on the first physically available link. Optionally, MLPPP can fragment a packet and send fragments across all physical links.

Packets can arrive out of sequence on the receiving side, and/or MLPPP fragmented, but MLPPP receiver will reconstruct flow before forwarding.

New Member

Re: Multilink PPP

So if a router has to transmit a 100 MB file across a WAN using the 6T1's bundle, and assuming there is no traffic on the bundle, will the 100MB file fragments be sent over the first T1 alone or will the packets be evenly distributed over the 6 T1's?

What configuration do I need for this?

"Optionally, MLPPP can fragment a packet and send fragments across all physical links".

Hall of Fame Super Silver

Re: Multilink PPP

Hello Kunal,

>> So if a router has to transmit a 100 MB file across a WAN using the 6T1's bundle, and assuming there is no traffic on the bundle, will the 100MB file fragments be sent over the first T1 alone or will the packets be evenly distributed over the 6 T1's?

evenly distributed over member links using a round robin algorithm eventually fragmented with each fragment sent on a different member link.

This is one of the reasons for using multilink ppp

Hope to help

Giuseppe

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