In it's simplest form, a two node cluster can have two separate LLT links and use just a crossover cable to connect node to node:

NODEA                                  NODEB
-------                                  -------
Link0 -------- Link0
Link1 -------- Link1

From the example above, "link0" cannot see "link1".   Each switch must be separate and all of the "Link0" connections must be connected together and all of the "Link1" connections must be connected together on separate and isolated switches.  

In 5.0 MP3, VCS supports "crossed links" now that LLT uses point-to-point and not broadcast heartbeats.   In 5.0mp3, LLT will issue the "LLT WARNINGV-14-1-10498 recvarpack cross links?" messages.

Common reasons why this message may occur are LLT links on the same VLAN, the same layer 2 ethernet broadcast network, or duplicate ethernet MAC addresses.

The whole point of having at least two links without common parts is to eliminate a single point of failure.  The result of a complete failure of communications between nodes can potentially result in data corruption.