Configuring BFD Offload
Bidirectional Forwarding Detection (BFD) offload support provides the functionality to offload a BFD session to the field-programmable gate array (FPGA). BFD is a forwarding path failure detection protocol and reduces the overall network convergence time by sending rapid failure detection packets (messages) to the routing protocols for recalculating the routing table. Previously the performance of BFD was restricted to the capabilities of CPU and IOS on the RP of the switch. Effective failure detection requires BFD to run at high frequencies (using aggressive timers as low as 50ms), which was not possible because of CPU and IOS restrictions.
For information on configuring BFD see Configuring BFD section of ME 3800x and ME 3600x Switches Software Configuration Guide.
Note On the Cisco ME 3600X-24CX, BFD session will be supported only on the FPGA, BFD sessions on the RP are not supported.
Restrictions for BFD Offload Support
- Only BFD version 1 is supported.
- Only FPGA offloaded BFD sessions are supported, BFD sessions on RP are not supported on ME 3600X-24CX-M.
- The switch supports BFD only in Asynchronous mode or no echo mode.
- The switch supports 511 asynchronous BFD sessions.
- BFD hardware offload is supported for IPv4 sessions with non-echo mode only.
- BFD offload is supported on port-channel interfaces.
- BFD offload is supported only for the ethernet interface.
- BFD offload is not supported for IPv6 BFD sessions.
- BFD offload is not supported for BFD with TE/FRR
Configuring BFD Offload Support
The BFD offload functionality is enabled by default. You can configure BFD hardware offload on the route processor.
Verifying BFD Offload Support
You must ensure that the Session host is showing as Hardware. Use the show bfd neighbors detail to verify the configuration of BFD Offload. Hardware BFD sessions have a LD of 1-511.
Note Sometimes if BFD session is brought up after the registered protocol is up the session may come up in Software. Shutdown the interface and apply the BFD config to ensure that session comes back up in Hardware.
Switch# show bfd neighbours details
NeighAddr LD/RD RH/RS State Int
126.96.36.199 1/11 Up Up Vl3336
Session state is UP and not using echo function.
Local Diag: 0, Demand mode: 0, Poll bit: 0
MinTxInt: 50000, MinRxInt: 50000, Multiplier: 3
Received MinRxInt: 100000, Received Multiplier: 3
Holddown (hits): 0(0), Hello (hits): 100(0)
Elapsed time watermarks: 0 0 (last: 0)
Registered protocols: ISIS CEF OSPF
Last packet: Version: 1 - Diagnostic: 0
State bit: Up - Demand bit: 0
Poll bit: 0 - Final bit: 0
Multiplier: 3 - Length: 24
My Discr.: 11 - Your Discr.: 294
Min tx interval: 100000 - Min rx interval: 100000
Min Echo interval: 0 ould