Generally applicable proactive OAM parameters are configured using templates.
7210 SAS-R6, 7210 SAS-R12, and 7210 SAS-T only support BFD-based CC mode. BFD-based CC-CV mode is not supported in the current release.
Proactive CC and CV uses BFD parameters such as Tx/Rx timer intervals, multiplier and other session/fault management parameters which are specific to BFD. These are configured using a BFD Template. The BFD Template may be used for non-MPLS-TP applications of BFD, and therefore contains the full set of possible configuration parameters for BFD. Only a sub-set of these may be used for any specific application.
Generic MPLS-TP OAM and fault management parameters are configured in the OAM Template.
Named templates are referenced from the MPLS-TP Path MEP configuration, so different parameter values are possible for the working and protect paths of a tunnel.
The BFD Template is configured as follows.
config
router
bfd
[no] bfd-template <name>
[no] transmit-interval <transmit-interval>
[no] receive-interval <receive-interval>
[no] echo-receive <echo-interval>
[no] multiplier <multiplier>
[no] type <cpm-np>
exit
The parameters are as follows:
transmit-interval transmit-interval and the rx receive-interval: These are the transmit and receive timers for BFD packets. If the template is used for MPLS-TP, then these are the timers used by CC packets. Values are in milliseconds: 10ms to 100,000ms, with 1ms granularity. Default 10ms for CPM3 or better, 1 sec for other hardware.
For MPLS-TP CV packets, a transmit interval of 1 sec is always used.
multiplier multiplier: Integer 3 – 20. Default: 3. This parameter is ignored for MPLS-TP combined cc-v BFD sessions, and the default of 3 used, as per RFC6428.
echo-receive echo-interval: Sets the minimum echo receive interval, in milliseconds, for a session. Values: 100ms – 100,000ms. Default: 100. This parameter is not used by a BFD session for MPLS-TP.
type iom-hw type: This parameter controls the system to use the IOM based hardware BFD session for the local termination point. Hardware based BFD session is enabled by default, when BFD is configured for use with MPLS-TP LSPs.
If the above BFD timer values are changed in a template, any BFD sessions on MEPs to which that template is bound will try to renegotiate their timers to the new values. BFD implementations in some MPLS-TP peer nodes may not be able handle this renegotiation, as allowed by Section 3.7.1 of RFC6428, and may take down the BFD session. This could result in unwanted behavior, for example an unexpected protection switching event. It is therefore recommended that in these circumstances, the user of 7210 SAS exercises care in modifying the BFD timer values after a BFD session is UP.
Commands within the BFD-template use a begin-commit model. To edit any value within the BFD template, a <begin> needs to be executed after the template context has been entered. However, a value will still be stored temporarily until the commit is issued. After the commit is issued, values will actually be used by other modules like the mpls-tp module and bfd module.
A BFD template is referenced from the OAM template. The OAM Template is configured as follows.
config
router
mpls
mpls-tp
oam-template "state-machine-oam-template-prot"
bfd-template "state-machine-bfd-template-prot"
hold-time-down 0
hold-time-up 20
exit
hold-time-down interval: 0-5000 deciseconds, 10ms steps, default 0. This is equivalent to the standardized hold-off timer.
hold-time-up interval: 0-500 centiseconds in 100ms steps, default 2 seconds This is an additional timer that can be used to reduce BFD bouncing.
bfd-template name: This is the named BFD template to use for any BFD sessions enabled under a MEP for which the OAM template is configured.
An OAM template is then applied to a MEP as described above.