The whole point in fabric is to configure service on the edge ONLY. BCB is just a transport and you typically do not configure anything on it - except SPBM
If you can't pass traffic between devices than most probably you:
a. did not configure SPBM on the nodes properly, and/or
b. did not enable Gi ports (in older voss versions all ports are disabled by default!!), and/or
c. did not configure Gi0/1 edge ports properly (encapsulation dot1q, flex-uni enable etc), and/or
d. did not configure end-system device properly (it does not do vlan tagging for example), and/or
To configure SPBM on nodes use this on each switch:
enable
config terminal
run spbm
And go through wizard.
Afterwards you need to see neigbors when you do:
show isis adjacencies
In your case when ran on BCB, you should see two neighbors BEB1 and BEB2 (similar to example below):
==================================================================================================================================
ISIS Adjacencies
==================================================================================================================================
INTERFACE L STATE UPTIME PRI HOLDTIME SYSID HOST-NAME STATUS AREA AREA-NAME
----------------------------------------------------------------------------------------------------------------------------------
Port1/1 1 UP 8d 23:00:15 127 18 020d.0211.0010 L2-D1-1 ACTIVE HOME
Port1/2 1 UP 8d 22:59:55 127 20 020d.0211.0020 L2-D1-2 ACTIVE HOME