routing question about CHI protocol in ruby sytem

[gxflying]

Hi sir, as far as I know the supported system with CHI protovol uses SimplePt2Pt topology,
and all the controllers are connected to the interconnect node in the SimplePt2Pt::connectControllers
the question here is:
in chi protocol, the HN is the POC, and all the requests should be routed to HN first, and then be routed to mem controller(ddr) if the line was not cached ever, or be routed to other node (cache controller) to get the cached copy.
but I can not find the code which recording which node in the interconnect is HN,
then how could a request be routed to HN when it does know which node is HN ?