scenario 1:


RA (L2) ----SERIAL LINK ----- RB (L2) ------ETHERNET ----- RC (L2) ---- WORKING FINE NO PROBLEM.

scnario 2:


RA (L1) ----SERIAL LINK ----- RB (L1L2) ------ETHERNET ----- RC (L2) ----


RB is forming l2 isis neighbor relationship wiht RC but

RA is not forrming L1 isis neighbor relationship with RB

configured both global and interface command.



  • cciesp


    2 neighbors cannot form a L1 ISIS relationship if they are in different areas.  Did you make sure that RA and RB are in the same area.


    From your scenario you described probably you have RA configured for L1 only.  RB is configured for L1L2, However, if RA and RB are in different areas, this would require RA to be capable of establishing L2  relationships, which it cannot if it is configured for L1 only.



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