Here is how I believe a Knossos works:
A jump point is a collection of [some sort of molecules, energy...?]. This collection is higher than normal space, which is why vessels can travel much farther with jump nodes than in normal space. Each node is linked in some way (perhaps the polarity of the energy, type of molecules?). However, as ships move through these collections of [energy/molecules] they distort them, causing them to dissipate. While the collections dissipate on their own, these disturbances accelerate the process further, meaning that if a large enough disturbance was created, i.e. a destroyer exploding, the pressure would further dissipate the particles, thus making the [molecules/energy] degrade close to the normal levels of [molecules energy;subspace particles?]. This means that the jump node is no longer a jump node, though still linked to its counterpart, which will also be disspated (since they are linked). Any ships that enter these "collapsed" jump nodes will also dissipate, resulting in the loss of all hands, meaning that these nodes are generally avoided. Shivan vessels may be able to travel through these nodes because there subspace drives are more powerful or can temporarily coalesce the nodes enough to stabilize them for transit. A Knossos usues a more advanced technique to coalesce these more permanently. It does this by emitting some sort of energy and using its rotation to draw the subspace particles together in the center, while still emitting the special energy. While emitting this energy, a subspace portal's color may be redshifted due to the larger wavelength from the higher energy in the portal. A side effect of a Knossos is that the higher energy normally results in a more stable tunnel; therefore lower-power subspace drives can be used, and explosions are not as damaging to the portal, though they may cause a feedback surge to the Knossos itself. Also, only one Knossos is needed, since the Subspace particles mirror each other.
I did that a while back on the VBB, but I just registered here a few days ago