Multilink PPP in Ethernet

Answered Question
Mar 9th, 2010
Dear experts,
If I am given to configure Multilink PPP between two Leased Line link. The challenge here is
LINK 1 is on SERIAL
LINK 2 is on ETHERNET
In this case How I will configure Multilink PPP between the two links(Since in Ethernet I wil not be able to configure PPP). The whole idea is to bundle both the links and make it as a single channel
Thanks in advance
regards,
sairam
I have this problem too.
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Correct Answer by Giuseppe Larosa about 6 years 9 months ago

Hello Sairam,

>>

Serial Interface Link speed is 2 Mbps

Ethernet interface link sepeed is 4 Mbps

The idea is to bundle the two links using Multilink PPP thus make a virtual thick pipe.

how could multilink PPP realize that second link is faster?

How to deal with different MTU if PPPoE were used on ethernet?

multilink PPP works on ISDN B channels (all at 64 or 56 kbps depending on how it used)

or it works on multiple serial interfaces of same speed.

Use EIGRP if it is a Cisco only environment with variance or do the following if possible:

divide and conquer approach:

if Vlan subinterfaces can be used on ethernet define two vlan subinterfaces that you use as two routed links assign a bandwidth of 2000 kbps and you can use OSPF or RIP or ISIS on the three links with no MTU problems

At the end some solutions may appear interesting but this is too troublesome it does not pay off.

consider that modern CEF supports per packet load balancing that would be similar to ML PPP load balancing.

per packet load balancing is not recommended and you should be happy with flow based CEF.

Hope to help

Giuseppe

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Giuseppe Larosa Tue, 03/09/2010 - 22:48

Hello Sairam,

only some considerations here.

you can run PPPoE over an ethernet interface with one device acting as PPPoE client and one device acting as NAS side.

In any case a PPPoE frame is still an ethernet frame.

If I understand you correctly you would like to create a PPP multilink bundle using one serial interface and one ethernet interface.

The practical interest for a similar setup is small.

Because the two links have probably different characteristics like speed and latency.

And unfortunately PPPoE MTU is 1492 smaller then MTU on serial interface.

If you are able to invoke the same virtual-template on both links  you could do this trick.

also authentication should match.

I would see more reasonable to try to use multilink PPP over two PPPoE links then using mixed media links.

But I've never heard of multilink PPP over ethernet.

I've seen examples of ML PPP over PPP

over FR or ATM.

Hope to help

Giuseppe

snarayanaraju Wed, 03/10/2010 - 01:04

Hi Guiseppe,

Hope you are doing well. Thanks for your interest and suggestion.

The scenario is, I have 2 links connecting  the Head office and branch office. One link is on Ethernet Interface and other is on Serial Interface.

Serial Interface Link speed is 2 Mbps

Ethernet interface link sepeed is 4 Mbps

The idea is to bundle the two links using Multilink PPP thus make a virtual thick pipe.

It is only a conceptual test and thought process. (However I am aware that the 2 links can be effectively used using EIGRP between them or using PBR ).

Yes, as you also suggested I am having pppoe on my mind.  I initially had a thought to use half bridging concept here. But realised it is not relevant to this scenario.

Your opinion is highly valuable to me. I appreciate your response

sairam

Correct Answer
Giuseppe Larosa Wed, 03/10/2010 - 01:49

Hello Sairam,

>>

Serial Interface Link speed is 2 Mbps

Ethernet interface link sepeed is 4 Mbps

The idea is to bundle the two links using Multilink PPP thus make a virtual thick pipe.

how could multilink PPP realize that second link is faster?

How to deal with different MTU if PPPoE were used on ethernet?

multilink PPP works on ISDN B channels (all at 64 or 56 kbps depending on how it used)

or it works on multiple serial interfaces of same speed.

Use EIGRP if it is a Cisco only environment with variance or do the following if possible:

divide and conquer approach:

if Vlan subinterfaces can be used on ethernet define two vlan subinterfaces that you use as two routed links assign a bandwidth of 2000 kbps and you can use OSPF or RIP or ISIS on the three links with no MTU problems

At the end some solutions may appear interesting but this is too troublesome it does not pay off.

consider that modern CEF supports per packet load balancing that would be similar to ML PPP load balancing.

per packet load balancing is not recommended and you should be happy with flow based CEF.

Hope to help

Giuseppe

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