MACsec is layer-2 and is done hop-by-hop. Also, not every device can support it.
2.1 Benefits and Limitations
MACsec offers the following benefits on wired networks:
• Confidentiality: MACsec helps ensure data confidentiality by providing strong encryption at Layer 2.
• Integrity: MACsec provides integrity checking to help ensure that data cannot be modified in transit.
• Flexibility: You can selectively enable MACsec using a centralized policy, thereby helping ensure that MACsec is enforced where required while allowing non-MACsec-capable components to access the network.
• Network intelligence: Unlike end-to-end, Layer 3 encryption techniques that hide the contents of packets from the network devices they cross, MACsec encrypts packets on a hop-by-hop basis at Layer 2, allowing the network to inspect, monitor, mark, and forward traffic according to your existing policies.
Here is the doc for more info:
http://www.cisco.com/en/US/prod/collateral/iosswrel/ps6537/ps6586/ps6638/deploy_guide_c17-663760.html
HTH