How secure is secure?

The TV is full of talk about "securing the border" before doing an immigration bill.  Sounds good, but what do we mean by "secure".  No matter what we do, the occasional lucky alien will get across now and then.  And, those that do, won't tell anyone that they made it.  So there is no way to actually measure the security of the border, in terms of how many aliens got thru or didn't get thru.
   More reasonable is to talk about a level of effort.  How much effort should be expended on border security?  For me, I'd settle for a good chain link fence running all the way from the Pacific to the Gulf of Mexico, paralleled with a road to permit jeep borne patrols all along the border.  And enough Border Patrolmen to run a patrol about once an hour.  Do this much, and I'd call the border secure even if a few illegal aliens did slip across from time to time. 
   Others might call for more or less security.
   If  "a secure border" is necessary to more forward on an immigration bill, then we need to agree on just how secure is secure enough.  That is, if we honestly want to negotiate an immigration bill.
   We have plenty of dishonest politicians who talk the talk but actually won't walk the walk.