IOS 15.1SY Product Bulletin and New BFD Features

As a continuation to my previous post about IOS 15.1SY and 12.2SX, here is the product bulletin for IOS 15.1SY (for Sup720 and Sup2T):

It presents the highlights in a different way to the Release Notes. The most interesting new features for me personally are the following:

  • BFD (Bidirectional Forwarding Detection): Static Route Support
  • BFD: VRF Support
  • BFD over SVI

At least the last one is definitely something I want to try in the lab at some point. I have no real-life experience on BFD previously as most of the systems I’m involved are mixed L2/L3 systems with SVIs. I must say though that all the new service provider connections have long been L3 interfaces now but BFD has not been used anyway.

You can read more about BFD for example here:

The IP Routing BFD Configuration Guide (Cisco IOS Release 15SY) ( is somewhat irritating to read: even though the guide is specifically titled to be for 15.xSY train it still talks a lot about other platforms than Catalyst 6500 (or even Cisco 7600), even though 15.xSY is for Catalyst 6500 only. Apparently they just want to re-use the material as much as possible, while still changing the document titles to give the readers a bit better confidence that the document is the correct one for their platform. (Yeah, there is the disclaimer in the title page of the guide.) Anyway, the BFD configuration guide does not give any hints about SVI (VLAN interface) configurations regardless of the announcement in the bulletin. For Cisco 7600 15.0S the documentation is available in Configuring Bidirectional Forwarding and Detection over Switched Virtual Interface ( Let’s see.

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