PPPOE solution ?

Unanswered Question
Jan 30th, 2009

Hi All,

We have a requirement on which working on and would really appreciate any help on the same.

We have a scenario, where 2 routers are connected over ethernet but passing through as bridge circuit over ML cards.Like as below

R1 - ML Card 1 -RPR ring -- ML Card 2 --- R2.

The one thing which we are trying to acheive is,whithout using dynamic routing protocol and using static route to route between subnets on R1 and R2. We were assuming that,while using static route and if the link between ML Card2 and R2 fails,R1 static route would be still active,as the link from R1 to ML Card 1 stays live.

Do we have a method to overcome it,also assume that we can't use SAA feature to track routes.

We were randomly thinking,will PPPOE will use in this scenario but couldn't understand how it would be.

Any help would be really appreciated.


Anantha Subramanian Natarajan

I have this problem too.
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Overall Rating: 3.4 (5 ratings)
anasubra_2 Fri, 01/30/2009 - 09:43


ML card is an Layer2/Layer3 blade on Cisco ONS 15454.RPR is a resilient packet ring build over those cards to carry bridged/routed traffic among the ML cards.

Is that make sense ?

Kindly let me know


Anantha Subramanian Natarajan

Paolo Bevilacqua Fri, 01/30/2009 - 09:54


I do not see why PPPoE should enter the scenario. The job of the ONS system is that you are guaranteed ethernet traffic between endpoints. So when there are only two routers attached, there is no additional measure you can take for having them communicate in a more robust manner.

anasubra_2 Fri, 01/30/2009 - 10:11


Thanks for the response. So,do you think,when the one side of the link from ML Card to R1 goes down,the R2 should know about it ? ..If that the case,we didn't see that ...


Anantha Subramanian Natarajan

Paolo Bevilacqua Fri, 01/30/2009 - 10:40


The other side will not know, however with routing or SLA config, it will stop sending traffic to it. Another simple mechanism for the router to know would with GRE and keepalives.

Note you may want to review how the rating systems work as low rating are not to be given to correct answers like mine above.

anasubra_2 Fri, 01/30/2009 - 14:59

Hi beviliacqua,

Thanks for the response. Actually we may not be able to use any dynamic routing or SLA config. We would like to acheive with static route.

Kindly let me know,if you see some solution on the same.



Anantha Subramanian Natarajan

anasubra_2 Fri, 01/30/2009 - 15:03

Hi Bevilacqua,

Thanks and would like to avoid GRE for possible MTU issues . The main idea is to have simpler configuration in our customer router and lower processing power required on our customer router to support most models of the router.

Do you have any ideas and still you think GRE solution is a better idea to go about .

Also will like to know,how PPPOE works ,any links mentioning configuring of PPPOE between two cisco routers would be helpful.



Anantha Subramanian Natarajan

Paolo Bevilacqua Fri, 01/30/2009 - 15:06

Seems to me GRE is the only way to do what you want. The best would be routing or SLA, not sure why you can't do that.

PPPoE is more complicated and also reduces MTU.

anasubra_2 Fri, 01/30/2009 - 15:10

Hi Beviliacqua,

Thanks for the response. Actually there are certain customers of us ,who may not be so comfortable on dynamic routing protocols and also SLA feature is not supported on the current IOS we are running on R2(MPLS Node with 12.2(18)SXF4). These are the reasons to avoid the solution of dynamic routing protocol and SLA routing.

Thanks for your suggestion on GRE and do you know how PPPOE works between 2 routers and the configuration sample if any .

Thank you


Anantha Subramanian Natarajan

Paolo Bevilacqua Fri, 01/30/2009 - 15:15

Hi, I don't think the sup 720 supports PPPoE.

You wants the benefits of routing without enabling routing. That is not possible and you should educate your customers how to use routing that is nothing bad.


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