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Bronze

Can 0.0.0.0/0 be influenced with communities?

I need to influence the default-network (0.0.0.0/0) being sent to my remote sites.

:

Network:

:

  HQ1-----HQ2

   |       |

provider CLOUD

      |

Remote-sites (~200+ remote sites)

:

HQ1 and HQ2 sends the default-network to the provider cloud

HQ1, HQ2 and ALL remote-sites use different AS numbers

Provider cloud uses the same AS number throughout the cloud

:

Can BGP communities be used to influence the default-network throughout the provider cloud?

I need the provider cloud to forward the default-network from HQ1 to some remote-sites and the other remote-sites the default-network from HQ2.

Thanks again!

Frank

1 ACCEPTED SOLUTION

Accepted Solutions

Re: Can 0.0.0.0/0 be influenced with communities?

Frank,

Not sure if you still got the solution to this. But the only thing that comes to my mind is that maybe by using GRE Tunnels or something between the Remote sites and the HQ1's pointing the default route to the tunnel end point

For eg:

you have sites A,B,C that need to get default route from HQ1. Then you can create GRE tunnels and put static routes for the default to HQ at each site. The remote sites will receive the default route from the ISP but will ignore it. Hope I am making sense here.

This is lot of admin work though if you have like ~200 sites. but does work.

Not sure if someone else has come up with any better solution. If you already have a solution then do share it with us here

HTH

Kishore

7 REPLIES

Can 0.0.0.0/0 be influenced with communities?

Hi Frank

I believe this is the same question as in the WAN section posted 1 day back where me and couple of other people have tried to give you a valid explaination for your requirement.I would request you that if you have still some doubts please continue on the old post itself so that the persons taking out time and trying to help you with do not merely be loosing their time on it.

https://supportforums.cisco.com/message/3477641#3477641

Now coming back to this question as everyone has tried to explain you over there its only within the control of SP Network to do the manipulation and send the resepctive HQ's Default-Route to Selected Sites and the other HQ's Default-Route to other sites..

Regarding Communities as I have explained before in the other post yes its totally possible and way too complex to be feasible from my understanding as SP has to do lot of work in their cloud

"As an alternative SP can match on some normal BGP communites tagged uniquely onto the default routes adverised from Each HQ and set the LP to be high per the Coast the MPLS-PE falls in to prefer that default-route from the required coast and advertise same to CEs but I don't know how feasible this will be for the ISP to do as this has to be done on a lot of MPLS-PEs inside the SP-CLoud with a list in hand on where to do what. May be we can put this requirement to ISP and ask them if its feasible from their side to be done or not.

Hope this helps to answer your question. If you have still more questions please put them forward and would again request you not to open muliple threads for same issue.

Regards

Varma

Bronze

Re: Can 0.0.0.0/0 be influenced with communities?

: I moved my question to this group to get away from your incomprehensible ramble.  It you intend to be helpful, trying using complete and correct grammar.  Stop wasting everyone’s time by pasting the same gibberish over and over again.  If you don't have a real answer, stop replying. You are not being helpful.

Re: Can 0.0.0.0/0 be influenced with communities?

Hi Frank

Sure I will not waste your time and wish you get the required help from the experts.

Regards

Varma

Cisco Employee

Re: Can 0.0.0.0/0 be influenced with communities?

Hi Frank,

communities alone are not enough without SP collaboration. In MP-BGP (within the SP cloud) only 1 prefix (of the 2 default routes) is advertised and it is the one with the shorter AS path. Remotes sites will only get that one (unless SP advertises multiple paths). To influence it via communities you need the SP to configure some kind of policy to react to your communities in order to differentiate the behavior. Therefore you need to get in touch with SP and discuss about that as the final word on what to actually configure (multiple options exist) is only theirs.

Having said that let me please ask you to use a tone more appropriate for a support forum where people with different backgrounds try their best to help others just for the sake of sharing experience and knowledge.

If you don't like the type of answers you might get here or you can't stand people not able to communicate by using complete and correct grammar , quite possible as just a lucky minority (which likely you belong to) can use their own mother tongue in this forum, I am afraid to tell you that you are in the wrong place.

regards,

Riccardo

Bronze

Re: Can 0.0.0.0/0 be influenced with communities?

Hey Varma,

Thanks for your understanding and no ill will, and thanks for pointing out the service provider position. Someone cannot just assume the servie provider will follow the customers directions.

Have a great day!!

Frank

Re: Can 0.0.0.0/0 be influenced with communities?

Frank,

Not sure if you still got the solution to this. But the only thing that comes to my mind is that maybe by using GRE Tunnels or something between the Remote sites and the HQ1's pointing the default route to the tunnel end point

For eg:

you have sites A,B,C that need to get default route from HQ1. Then you can create GRE tunnels and put static routes for the default to HQ at each site. The remote sites will receive the default route from the ISP but will ignore it. Hope I am making sense here.

This is lot of admin work though if you have like ~200 sites. but does work.

Not sure if someone else has come up with any better solution. If you already have a solution then do share it with us here

HTH

Kishore

Bronze

Re: Can 0.0.0.0/0 be influenced with communities?

Hi Kishore,

Yes, tunnels along with bgp multi-hop solves this problem completly. There are other workable options also, but sticking to the KISS method.

:

In this setup, each remote-site receives two 0.0.0.0/0 routes via bgp. Since I have the default from both HQ1 and HQ2, I control (via remote-site config) which path the remote-site takes for unknown destinations. Since I have 2 defaults, the failover is dynamic (as long as the single T1 is up/up and active).

:

Also, If I want asymmetric or symmetric routing, I can control this too.

:

I do not have to involve the service provider at all as this is completely transparent to them.

:

BTW, communities will not work in this setup.

Thank U's for your help!!

Frank

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