I don't believe it's right for each state to have different rules regarding whether or not a felon is eligible to vote, I believe that after someone has servered their debt to society then they should be free to vote in elections, these people still pay taxes and deserve to vote on what representation they get, I believe it should be a federal law allowing them to vote.
I definitely think that felony voting laws should be addressed on the federal level instead. I think that the concept of allowing felons to vote is a ridiculous one. And I think that the issue is something that needs to be addressed on the federal level before it cause problems.
No, I do not think that felony voting laws by state should be address on the federal level, because there is likely to be more enforcement at the state level. At the federal level, prosecutors will be busier working with violent crime, or high-cost white collar crimes, and felony voting won't be prosecuted much.
The states are given the right to handle voting in the constitution. Much like education, there may be some federal funding and guidelines that are necessary for continuity. If a state wants to be more restrictive with felony voting laws, that is their right. The federal level should not interfere.