channel bonding for myrinet

hello,

In www.myri.com/scs/faq/faq-gm.html#gmq13,the main interest of channel
bonding for myrinet is in high availability,as the performance of two IP
over Myrinet devices aggregated will be less than one device.But why?while
in general ethernet bonging can increase the bandwidth.
In addition,channel bonding is only support by IP over myrinet.If I want to
implement bonding on GM over myrinet to achive 300MB bandwidth,how do I do
it? Can I imitate bonding for IP over myrinet?

Thank you very much!

Jason