Refer to the exhibit. An architect is designing a hierarchical ISIS solution for a customer with these requirements:
• Routers will double in all areas within the next 24 months.
• Link flaps within areas 20 and 30 must not impact the backbone area.
• Traffic originating from A201 and A302 routers must connect to application servers in the backbone.
Which design must the architect select?
In order to design a hierarchical ISIS solution that meets the given requirements, it is essential to understand the roles of Level 1 (L1) and Level 2 (L2) routers. L1 routers exchange routing information within the same area, while L2 routers handle routing information across different areas. This setup helps contain routing issues, such as link flaps, within their respective areas without impacting other areas, including the backbone. Given the design needs: 1) to avoid the impact of link flaps within areas 20 and 30 on the backbone, and 2) to ensure connectivity from A201 and A302 to the application servers in the backbone, the correct configuration is to have C101 as both an L1 and L2 router, A201 as an L1 router, and A101 as an L2 router. This configuration ensures that A201 can communicate within its area (20) while also reaching the backbone via C101's L2 routes. Similarly, A302 in Area 30 can use L2 routes through the backbone without causing issues between different areas.
OCG Book says: An L2 router is similar to an OSPF backbone router. A router that has both Level 1 and 2 routes is similar to an OSPF area border router (ABR). IS-IS does not define a backbone area like OSPF’s area 0, but you can consider the IS-IS backbone a continuous path of adjacencies among Level 2 ISs. Answer A
The most stupid question of all time
Can someone explain A more, I understand the principle behind level 1 and 2 but I have 0 clue why A is the answer
B seems correct to me
C. is correct
sorry I meant B, when creating a Backbone, there should never be a L1 router between L2-only or L1/L2 routers.
no A. is the only sensible answare!!!
Or maybe is D...
Or maybe is D...
no A. is the only sensible answare!!!
Or maybe is D...
Or maybe is D...
How can A be the answer when C201 is L1 in A20 it will never talk to C101 in A0 because L1 routers cant form adjacencies with L1/L2 routers in a different area. This question is stupid B is the only answer that makes sense
To met requirement for flaps in area 20/30 we need to ensure that A2xx/A3xx routers are L1 only. Backbone ideally should consist only L2 rotuers but L2/L1 is also acceptable - seems to most accurate A.