Description: This object specifies the base of bridge domain. The bridge domain range is 1~16k, cevcSIForwardBdNumberBase is to track what is the base of each 4k bitmap. In this way we can specify all the 16k bridge domains using four 1k bitmaps and having the base which describes that is the base of each 4k bitmap. The four 1k bitmaps, cevcSIForwardBdNumber1kBitmap represents 0~1023, cevcSIForwardBdNumber2kBitmap represents 1024~2047, cevcSIForwardBdNumber3kBitmap represents 2048~3071, cevcSIForwardBdNumber4kBitmap represents 3072~4095 And cevcSIForwardBdNumberBase is one of 0, 4096, 8192, 12288, 16384. SNMP Administrator can use cevcSIForwardBdNumberBase + (position of the set bit in four 1k bitmaps) to get BD number of a service instance.