I asked something similarly weird earlier, then gave up on it, but now I have been testing it and am just confused
Here's situation 1: R1------AREA0-----R2----------AREA111---------R3----------MPLS--------------R4---------------AREA 222------------R5 Now, without a virtual link through area 111, area 0 and area 111 are isolated, and only know OSPF information from each other. This makes sense. Now if I extend a virtual link through area 111 to the PE, I have reachability to the Area 222. To break this down, and all sham link configurations set aside*, if I have area 0 at any site in my MPLS VPN topology (as the customer), I must extend it to the MPLS with a virtual link? Is that right? * Now, on to situation 2: *R1*------AREA0-----R2----------AREA111---------R3----------MPLS--------------R4---------------AREA 222------------R5----------AREA 222-----*----R1* Note this is a circle with R1 being an ABR for areas 0 and 222. Loopbacks are all R.R.R.R R1s loopback is in area 222 R2 L0 in area 0 R5 L0 in Area 222 So you can probably see where this is going, R5 - R1 would be my good ol "Backdoor link" Right now with no manipulation, R2 gets to R5's L0 via R1 and the backdoor link. In fact regardless of manipulation this is the case. Now, I want all traffic from R2 to area 222 to go over MPLS. So I configured the virtual link through 111 as described in the previous example, then I configured an area 0 sham link over MPLS. Then magically, I can route however I want over MPLS by playing with cost. Specifically, if I want R2 to get to R5's loopback via MPLS, I just cost up the link between R1 and R2 on R2. None of this works without the sham link, but I thought we needed area 0 on both sides of the sham link for this to work? Is there an exception? The sham link is acting kinda like a virtual link but not really. HELP So my situation is this: R1--AREA0---R2-----AREA 69----(vrf)R3------MPLS------R4(vrf)--------AREA 5-----------R5 Lets say I have that mess. In order to communicate from area 69 to area 5, I need area 0 to be extended. I can use a virtual link through area 69, but then what? If I configure an area 0 sham link through the cloud
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