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Firass81

Anyone from YOU has used (backdoor, not-advertise) in exactly H2+???

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Hi,

 

in H2+ thier is a Requst to use NOT-advertise in a single command and this is done and easy.

 

On the other hand thier a REQUEST not to use aggregate command on CEs HQ's Jacobs (R55,R56) and hier is the main point?

 

When you did everything and finished, you think this is the perfect way and nothing more. Nooooooooooooo

 

the prifix 172.18.1.0 is arleady the DC's Jameson could reach the Backdoor route (R18,R57). But what about the CE's routers (R15,16) they got the same prefix from WAN (mpls backbone hier) throuhg ebgp.

and they prefer this route because of AD = 20 and exteranl ospf 110 from R18!!!

 

Hier we have the problem and we break the rules of Request not all routers in Jameson's DC go the R18!!!!!

 

I have to make this exactly route as a backdoor under BGP proccess router and this is work.

 

anyone have the better idea, " especially when we have in a real network more prefixes" to change the EBGP routes more than AD of interior routing protocol. the access-lists not scalable on this way.

 

I have searched to change AD through route-map but i didn't finde a thing.

 

Any idea???

 

Thanks.

Edited by Firass81

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You are supposed to redistribute from BGP to OSPF on 15/16 with higher metric than the one on r18 / or with E2 vs E1 in DC OSPF and all will be fine.

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172.18.1.0/24 can only be on Jamesons as exact /24 vía unsupress map or not supressing the adv vía summary only in R57.

 

You must have it as /24 to properly select where to go to either R18 or L3VPN. You can not "not have it" because it the exam outputs require a different path between 17.18.1.0 and 172.x.x.0/24.

 

Depending on the variation, if you have the /24 only vía R18, no metric type change is needed.

 

If you know the /24 on both 15,16 and 18, just redistr E1 im 18 or increase the cost metric on 15/16 redistribution to higher than 20

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Yes, you have right,

 

But my problem not with redistribution and then how to treat the external prefix in the prospective domain, actually the problem is on the bordres routers itself befor even the redistribution.

 

Like for example:

 

Try to do on R16, show ip route command. you will see the exactly prefix 172.18.1.0 is as external bpg on it, therefor the R16 will prefer it than the other same prefix external ospf E1 AD 110???

 

This is my problem here, what i want to do is, make borders router to prefer the prefix throuhg R18 directly.

 

I have done this. with command: network 172.16.18.0 255.255.255.0 backdoor. under BGP proccess on both router R15,16, so ther two routers will take the route through R18.

 

thanks.

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If you want all routers to go throug R18, just advertise a default local preference on R18. Route will be received by RR, advertised to R15 and R16. Based on tiebreakers, Local Preference will win over eBGP, even if AD is 20 vs 200, Local Preference will win nonetheless.

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If you want all routers to go throug R18, just advertise a default local preference on R18. Route will be received by RR, advertised to R15 and R16. Based on tiebreakers, Local Preference will win over eBGP, even if AD is 20 vs 200, Local Preference will win nonetheless.

 

There is no RR in DC and yet R15 and R16 cannot learn a Local Preference from R18.

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