[Lsr] Question about OSPF (transit area routing loop)

[Sergey SHpenkov <[e-mail]>]

Hi,

In section 16.3 of the OSPF RFC 2328 standard, it is stated that all ABR
routers
connected to a transit area are required to check the sumLSA contained
within
this area in order to possibly improve the intra-area and inter-area
backbone routes
for themselves.

See the picture:
[image: VL_Loop.PNG]
The RT_1 and ABR_3 routers will use different paths to the ASBR router:

ABR_3 -> RT_1 -> ABR_1 -> ASBR = cost 3
RT_1 -> ABR_3 -> ABR_2 -> ASBR = cost 21

route loop between RT_1 and ABR_3

Please explain this situation

Thanks,
Sergey