MPLS two vrf inter-communication

Answered Question
Apr 7th, 2009
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Hi all,


Customer requirement


1- Location near to PE1 should use PE1 to access internet

2- Location near to PE2 (i.e CE3) use PE2 to access internet

3- CE1,CE2 and CE3 should communicate to each other

4- Incase PE2-CE2 link goes down CE3 should access internet from PE1


What we offered


1- We have created two vrf one is for PE1 (MESH-1) and One is for PE1 (MESH-2) (First Two requirement fulfilled)

2- Done intervrf communication between PE1 and PE2 (3rd requirement meet)

3- Now customer is announcing default from CE1 with AS path contain one AS

default from CE2 with AS path contain three AS (It is not path prepend)


In above situation default from PE1 became best and CE2 uses PE1 to access internet which customer do not want


We have tried to insert default route from PE1 by decreasing local preference to 50 towards PE2

with extcommunity RT but in this scenario CE4 starts accessing internet via PE2


Is here any wayout for this ?

Let me know if any more iput is required


Thanks in advance


Mahesh




Correct Answer by Laurent Aubert about 8 years 2 weeks ago

Hi,


To be sure PE2 always prefer the default route received from CE2, you should increase the weight. As this attribute will never be transmitted it will not influence PE1 route selection and it will choose the one with the shortest AS PATH.


If CE3 and CE4 are directly connected to PE2 and PE1 then you should be fine. If not, I would configure PE1 and PE2 to export those default routes with different community. Remote PEs will set different LP based on the community during the import process.


HTH


Laurent.






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Correct Answer
Laurent Aubert Tue, 04/07/2009 - 17:47
User Badges:
  • Cisco Employee,

Hi,


To be sure PE2 always prefer the default route received from CE2, you should increase the weight. As this attribute will never be transmitted it will not influence PE1 route selection and it will choose the one with the shortest AS PATH.


If CE3 and CE4 are directly connected to PE2 and PE1 then you should be fine. If not, I would configure PE1 and PE2 to export those default routes with different community. Remote PEs will set different LP based on the community during the import process.


HTH


Laurent.






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