I have Cisco 2811 with 2 serial interfaces (2xT1).Originally there was only 1 serial card installed with ip flow v5 enabled on it. Then 2nd serial card was added, and bundled into multilink int. Here's the question: how should I configure netflow? Should I enable it on the 2nd serial interface or perhaps just on multilink interface?
Here's a document that discusses the testing result of NetFlow config on a Multilink interface and its underlying serial interfaces, on pgs 10-12. It reads to me that the member serial interfaces won't produce NetFlow, so just enable NetFlow on the logical Multilink interface, similar to the scenario of layer-3 EthterChannel and its member physical ports.