Guang Cheng, Ok, so maybe you need to go back to my original suggested solution,...
rewrote getslnodes in python
Merge branch 'master' of ssh://git.code.sf.net/...
modifygrub doesn't support different IP range from MN
Fixed in the latest xCAT-SoftLayer rpm
Configure dns to respond to other networks in the networks table
I tested this in 2.8.5 and it works. Thx!