Solved: A request to Rburts, Rick Sir !!

illusion_rox · ‎05-26-2009

Dear Rick, first my apologies that i have to write a post like this but i couldnt resist my urge to make this request. I am quite sure it will be helpful to all ppl like me who want to gain expertise like you and other experts here.

My question is simple, we all can see you are proficient in almost all areas of routing and switching. How do you do this ? i know you are in this field for a long time but one can be judged by his wordings and explanations that you dont only know how to make something work but also have a sound background information on how something is actually working. How do you approach to understand something ?

Take for example, i have seen your answers on AAA. Lets talk about it. What path will you take to understand AAA so that you are sure you have understand each and everything and are able to implement it with complete knowledge. There are simply lots of things right ? so how do you approach them to make sure you understand them fully !!!

I am not afraid of hardworking but no matter how much i read i still think i havent even reach the intermediate level of that technology.

No one shares his secret but over here i am making a request if you could share how to understand technology like you.

Kindly just dont skip this post, provide something that could really help me, after all its just a request Sir.

I admire all the experts here, pls no one be offended as to i just addressed Rick but i simply admire him and have learnt a lot from his answers here.

Waiting for your answer Sir....

Richard Burts · ‎05-28-2009

Ovais

I have looked at your post about using ppp over Frame Relay with virtual-access and I believe that the explanation given by Giuseppe is pretty good. It is a fairly well known fact that to ping your own IP address on a serial interface the router must actually send the ping request over the interface which will be received by the peer at the other end of the link. And the peer must forward the ping request back to you. (and then you must send the response over the link and the peer must receive the response and send it back to you).

When the encapsulation on the link is ppp or HDLC the situation is straightforward and you can ping your own address since the router will forward everything for the subnet out the interface. But when the encapsulation is Frame Relay the situation introduces the necessity of mapping addresses to DLCIs. It is a reasonably well known fact that in multipoint Frame Relay that you can not ping your own IP address until you provide a mapping of the address to a DLCI since Frame Relay will not automatically produce that mapping.

The situation becomes more complex when you mix PPP and Frame Relay. When you run PPP over Frame Relay there is not a good way to map your own address to a DLCI.

HTH

Rick

HTH

Rick

View solution in original post

Richard Burts · ‎05-26-2009

Ovais

Thank you for the very nice things that you say about me. I will certainly not skip this post and will answer as best I can.

As you say, I have been working with Cisco equipment for a long time (and other types of networking before I started with Cisco equipment). My nature is to want to figure out how things work, and having figured out how things work I enjoy sharing that knowledge with other people. That desire to share knowledge with people is what led me to be a teacher in 2 parts of my career. I was a certified Cisco Instructor and actively taught a variety of Cisco classes for 7 years. The training that I received to teach those classes and the experience of teaching the classes and answering student questions has contributed a great deal to what I have learned and what I share.

My approach to learning something (like AAA) is to start by reading about it. There are lots of good resources on the Cisco site for getting familiar with what we need to know (config guides, command references, and new feature guides, and tech notes are usually especially helpful). After I have read some I usually then try to get some equipment and configure it to see how it really works. I frequently learn more as I configure it then I did when I read about it. I find that I learn the most when I configure something and it does not work. :( and I have to troubleshoot it.

I also learn a lot about technologies like AAA by participating in things like the NetPro forum. I read items in a variety of forums. When I see questions about a technology that I know I like to answer, and when I see questions about an aspect of the technology that I am not as familiar with I sometimes take that as a challenge that I should learn that aspect of the technology.

So my approach to acquiring knowledge about networking includes a lot of reading, learning a lot from hands on exposure to the technologies, and participation in NetPro forum.

Best wishes as you strive to acquire understanding of the networking technologies.

HTH

Rick

HTH

Rick

illusion_rox · ‎05-26-2009

Sir, sometime some details are not given anywhere. If you had looked at my query of ppp over fr using virtual access is an example of it. When do you know that you cant find an answer to something ? or you should stop looking now, its been a week i have searched everywhere but couldnt find answer to this behaviour :-(. How do you tackle this when you think you are looking for is not present on cisco site, do you just accept that particular behaviour as a piece of fact or what you do ?

This is my last question, kindly answer it generously like you did before. I wont be asking more question to bother you.

Thanks in advance Sir.

Richard Burts · ‎05-27-2009

Ovais

The answers to many issues are found on the Cisco site. Sometimes the answers are easy to find but sometimes they are not. And sometimes the answer may not be on the Cisco site.

If I am looking for an answer and am having problems finding the answer I will sometimes post the question in the forum, as you have done. Sometimes I will seek out colleagues and discuss the issue with them and find inspiration about the answer from them. And sometimes I find that a Google search will point to resources other than the Cisco site which may help with the answer.

HTH

Rick

HTH

Rick

illusion_rox · ‎05-27-2009

Dear Sir Rick, thanks a lot for this positive feedback. I really owe you :-)

Sir if possible kindly take out some time and look at my query of ppp over Fr using virtual-access interface...

Thanks again

Richard Burts · ‎05-28-2009

Ovais

I have looked at your post about using ppp over Frame Relay with virtual-access and I believe that the explanation given by Giuseppe is pretty good. It is a fairly well known fact that to ping your own IP address on a serial interface the router must actually send the ping request over the interface which will be received by the peer at the other end of the link. And the peer must forward the ping request back to you. (and then you must send the response over the link and the peer must receive the response and send it back to you).

When the encapsulation on the link is ppp or HDLC the situation is straightforward and you can ping your own address since the router will forward everything for the subnet out the interface. But when the encapsulation is Frame Relay the situation introduces the necessity of mapping addresses to DLCIs. It is a reasonably well known fact that in multipoint Frame Relay that you can not ping your own IP address until you provide a mapping of the address to a DLCI since Frame Relay will not automatically produce that mapping.

The situation becomes more complex when you mix PPP and Frame Relay. When you run PPP over Frame Relay there is not a good way to map your own address to a DLCI.

HTH

Rick

HTH

Rick

rakesh.hegde · ‎05-28-2009

Hi Rick,

I just want to bounce this off you.

Mapping ip to a dlci doesn't make sense since we are carrying PPP frames over frame relay right ? I remember it was not possible to ping locally configured virtual template IP even with a point to point frame relay interface. I think it's because of double encapsulation.

Please let me know if I am missing some thing.

-Rakesh

Richard Burts · ‎05-28-2009

Rakesh

I would agree that the fundamental problem is that the router in this situation does not know how to send the ping for its own address to a peer through the interface. Double encapsulation is another way to explain why there is not a mapping that works for your own address.

I do not think that you missed anything.

HTH

Rick

HTH

Rick