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Beginner

overwhelming number of routers

My new job with major ISP,  I am looking to console and see 500+ OSPF network links, 500+ ABR, many OSPF process, many Areas, some are purposely isolated from backbone.. all these tricks ! BGP, MPLS..

My theory vaporized.

How you expert would see this network? Would you start drawing diagrams just link first thing came to my mind?

Could somebody tell me how to "quickly watch" this network?

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Beginner

Re: overwhelming number of routers

Best thing to do is , yeah maybe draw out how it all connects just so you can see the "scale" of it.

Then i would look at their IGP ( Probably OSPF yea? ) I would spend some time figuring out what they are doing with it..

Its the most important part of the network.

See how their areas connect. Why they might have separate areas and why and why they dont connect in certain places.

Get a nice mental picture of that layer.

Once done, Look at their next protocols.. Maybe start with BGP.. How are they using it? WHy ar ethey using it in certain places.. What connects to what. What routes are shared by it? What are shared in BGP and not in OSPF..

Get a good picture of how that layer sits onton of their IGP.

Now look at the MPLS network.. Understand how they have it configured. How is it configured on their P's ? How is it configured on their PE's? What are they doing about route reflection? how are MPLS routes being shared between PE's?

ISP's have big networks, Sometimes with very nasty hacks in place to get things working certain ways.

No one would expect you to understand it all straight away but I would suspect they would expect you to understand how they have achieved certain things.

So Spend time on the phsical topology. How are their DC's / Sites setup in general. Then start looking at their configurations layer by layer. Its pointless trying to understand their BGP , MPLS, Multicast etc ect unless you have understood how and why they have done things in OSPF first.

-Graham
Please note: My comments are simply suggestions. I cannot be held liable for any loss of data, life or marbles due to following my instructions.

Live chat software for websites. Increase sales.

-Graham
Please note: My comments are simply suggestions. I cannot be held liable for any loss of data, life or marbles due to following my instructions.

Got a website? Need some live chat software?

9 REPLIES 9
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Beginner

overwhelming number of routers

hi

try to see it with the help of NMS.

regards

shivlu jain    

Advisor

overwhelming number of routers

I would actually be shocked if they didn't have diagrams for this already. Otherwise, it sounds like it's going to be a very, very long process....

HTH,
John

*** Please rate all useful posts ***

HTH, John *** Please rate all useful posts ***
Hall of Fame Master

Re: overwhelming number of routers

That is normal in big networks.

Sure you can start drawing diagrams, but do not assume that

  • they will actually help (at least in the way ISP currently do things)
  • you be thanked for
  • you will ever be done drawing.
Beginner

Re: overwhelming number of routers

Actually I can draw diagrams,

I just wondering how those who has deep knowledge in networking do this kind of things.

Is it practical to analyze this kind of network by show commands without depending on diagrams?

Hall of Fame Master

Re: overwhelming number of routers

If you know what you're doing, yes. The diagram forms itself in your mind.

Beginner

Re: overwhelming number of routers

Best thing to do is , yeah maybe draw out how it all connects just so you can see the "scale" of it.

Then i would look at their IGP ( Probably OSPF yea? ) I would spend some time figuring out what they are doing with it..

Its the most important part of the network.

See how their areas connect. Why they might have separate areas and why and why they dont connect in certain places.

Get a nice mental picture of that layer.

Once done, Look at their next protocols.. Maybe start with BGP.. How are they using it? WHy ar ethey using it in certain places.. What connects to what. What routes are shared by it? What are shared in BGP and not in OSPF..

Get a good picture of how that layer sits onton of their IGP.

Now look at the MPLS network.. Understand how they have it configured. How is it configured on their P's ? How is it configured on their PE's? What are they doing about route reflection? how are MPLS routes being shared between PE's?

ISP's have big networks, Sometimes with very nasty hacks in place to get things working certain ways.

No one would expect you to understand it all straight away but I would suspect they would expect you to understand how they have achieved certain things.

So Spend time on the phsical topology. How are their DC's / Sites setup in general. Then start looking at their configurations layer by layer. Its pointless trying to understand their BGP , MPLS, Multicast etc ect unless you have understood how and why they have done things in OSPF first.

-Graham
Please note: My comments are simply suggestions. I cannot be held liable for any loss of data, life or marbles due to following my instructions.

Live chat software for websites. Increase sales.

-Graham
Please note: My comments are simply suggestions. I cannot be held liable for any loss of data, life or marbles due to following my instructions.

Got a website? Need some live chat software?

Beginner

Re: overwhelming number of routers

Thanks, it gave me beautiful insight in to the job in my hand.

Engager

Re: overwhelming number of routers

If they're an already existing ISP, I bet a network architect or someone from engineering already have produced or have an existing network diagram at hand.

A good start would be asking around if such document exists.

Sent from Cisco Technical Support iPhone App

Beginner

Re: overwhelming number of routers

                   Hello ,

To save time doing that , you can automate tasks by using tcl scripts , for example for each routers you can list all ospf process running with areas number for each process with simply tcl script.

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