Hi Sami, would C have BFD sessions to A and B respectively or it use anycast address? The more I look at the use case, the more I think of VRRP ;)
Regards, Greg On Tue, Nov 28, 2017 at 2:15 PM, Sami Boutros <sbout...@vmware.com> wrote: > > Hi Ashesh, > > The topology is more like the following: > > A <—\ > | \ > BFD C > | / > B<—/ > > A and B are nodes providing L2 and L3 services for C, with A/S redundancy. > > A can be active and B standby, if A goes down then B start providing the > services. > > Thanks, > > Sami > From: Ashesh Mishra <mishra.ash...@outlook.com> > Date: Tuesday, November 28, 2017 at 1:45 PM > > To: Sami Boutros <sbout...@vmware.com>, Ankur Dubey <adu...@vmware.com>, " > rtg-bfd@ietf.org" <rtg-bfd@ietf.org> > Cc: Reshad Rahman <rrah...@cisco.com> > Subject: Re: Service Redundancy using BFD > > Okay. That makes sense now. > > > > So in a scenario where you have a primary overlay service between A and B, > and a backup overlay service between C and D, the BFD sessions in question > will be between A and C, and B and D (so that the backup can send diag code > to primary)? > > > > A <------- primary service --------->B > > | | > > BFD BFD > > | | > > C<-------- backup service ---------->D > > > > -- > > Ashesh > > > > > > *From: *Sami Boutros <sbout...@vmware.com> > *Date: *Tuesday, November 28, 2017 at 4:21 PM > *To: *Ashesh Mishra <mishra.ash...@outlook.com>, Ankur Dubey < > adu...@vmware.com>, "rtg-bfd@ietf.org" <rtg-bfd@ietf.org> > *Cc: *Reshad Rahman <rrah...@cisco.com> > *Subject: *Re: Service Redundancy using BFD > > > > Hi Ashesh, > > > > A service is an overlay service running on a routing node, this could be a > L2 or L3 VPN service running on set of links connected to 2 or more nodes, > where one node is active for a service at a given point in time, and one > node is standby. > > > > Now, BFD is running on underlay links between the 2 nodes active and > standby, once BFD goes down, the standby assumes that the active went down > and activates the services that it shares with the active. On the BFD > session the standby would signal to the old active when it came back up > that it activated the non-preemptive services via this diag code saying > that it didn’t fail, so the old active node doesn’t activate those > non-preemptive services. > > > > Thanks, > > > > Sami > > *From: *Ashesh Mishra <mishra.ash...@outlook.com> > *Date: *Tuesday, November 28, 2017 at 1:14 PM > *To: *Sami Boutros <sbout...@vmware.com>, Ankur Dubey <adu...@vmware.com>, > "rtg-bfd@ietf.org" <rtg-bfd@ietf.org> > *Cc: *Reshad Rahman <rrah...@cisco.com> > *Subject: *Re: Service Redundancy using BFD > > > > Thanks for the response, Sami. I think our disconnect lies in the > definition of a service. From a BFD perspective, I expect the service to be > established across two nodes, at the very least, so that BFD can monitor > its liveness. Can you elaborate on > > > > - What, in the context of this draft, a service is? > > - How does BFD signal for a service that it is not monitoring > the liveness for? > > > > Thanks, > > Ashesh > > > > *From: *Sami Boutros <sbout...@vmware.com> > *Date: *Tuesday, November 28, 2017 at 1:23 PM > *To: *Ashesh Mishra <mishra.ash...@outlook.com>, Ankur Dubey < > adu...@vmware.com>, "rtg-bfd@ietf.org" <rtg-bfd@ietf.org> > *Cc: *Reshad Rahman <rrah...@cisco.com> > *Subject: *Re: Service Redundancy using BFD > > > > Hi Ashesh, > > > > Thanks for your comments. > > > > For your first comment the draft applies to both single hop or what you > call interface BFD and multi hop BFD too. And yes the per service could be > per interface too if this is a single hop BFD, we can clarify that in the > draft. > > > > For your second comment, I am not sure I understand. The service will be > active only on one node, if the service is associated with the whole node, > then the BFD session is monitoring the node liveness. And when the service > is associated with an interface the BFD session will monitor the interface > connectivity as well. So, a primary service can’t be active at the 2 node > endpoints hosting the BFD session. > > > > Thanks, > > > > Sami > > >
