Drake, John E wrote:
-----Original Message----- From: Ong, Lyndon [mailto:Lyong@Ciena.com] Sent: Friday, October 28, 2005 1:28 PM To: ibryskin@movaz.com; dpapadimitriou@psg.com; dimitri.papadimitriou@alcatel.be Cc: Drake@movaz.com; Drake, John E; dimitri.papadimitriou@alcatel.be;IgorBryskin; Zafar Ali; Kim Young Hwa; ccamp@ops.ietf.org Subject: RE: Two Drafts for Resilience of Control Plane Hi Igor, Are you referring to controlling the LSP while one of the controllersisstill down? That would mean that no restart has yet taken place. The draft seems to be focused on providing standby control channels,[JD]What is the utility of having standby control channels, as opposed to just having multiple *active* control channels?
none - (except if the hardware is limited and does not allow load spreading among multiple channels but this is not a "feature")
what you're suggesting sounds more like a standby signaling controller.[JD]A standby signaling controller is an implementation option that shouldn't affect the existing GMPLS protocols
it would surprise that hot swappable control plane instance would require any external coordination (i would say the objective is quite the opposite i.e. to disturb as less as possible neighbors)
Cheers, Lyndon -----Original Message----- From: owner-ccamp@ops.ietf.org [mailto:owner-ccamp@ops.ietf.org] On Behalf Of ibryskin@movaz.com Sent: Friday, October 28, 2005 1:08 PM To: dpapadimitriou@psg.com; dimitri.papadimitriou@alcatel.be Cc: ibryskin@movaz.com; Drake@movaz.com; John E; dimitri.papadimitriou@alcatel.be; Igor Bryskin; Zafar Ali; Kim Young Hwa; ccamp@ops.ietf.org Subject: Re: Two Drafts for Resilience of Control Plane Dimitri, See in-line.igor - you are already going beyond the specific discussion context 1. what is a control plane partitioned LSP ?LSPs with one or more controllers down, so there is/are partitions in hop-by-hop signaling2. when you state "Suppose one or more signaling controllersmanagingsome LSP went out of service leaving the LSP's data planeintact."what does it mean "one or more controllers" ? what if yousupportRSVP GR ? why are you not able to recover the states ? etc.See my response to John. There are no restarts in my examplehence, i still miss the exact problem wrt to the control plane protocol resilience but i think there is another issue (which is even more important) - the resilience mechanisms of the control plane that we have todayhavebeen provided based on experience from the common use of the control plane and for being resilient wrt common failures - but not for ALL use of the control plane in ANY condition and for ALL possible failures - indeed what you are asking here is like what shall i do when the CP is completely down and the DP still up; it wouldsurpriseme that the CP would be of any help in this specific conditionBelieve me, CP could be still of a great help in such conditions. You need some signaling extensions - which is why I think CP resilience is an important topic within CCAMP - and then you can manage LSPs with control plane gaps at least to the extend I described. Igorthanks, - dimitri. ibryskin@movaz.com wrote:Hi, Here is one of the problems that I've been thinking for a while - control plane partitioned LSPs. Suppose one or more signaling controllers managing some LSP went out of service leaving the LSP's data plane intact. As far as the user is concerned such LSP is perfectly healthy and operational. Such situation could last for a considerable period of time. Do we need to manage such LSP via control plane? Sure, we must be capable to tear down such LSP, perform mb4b rerouting, distribute alarms between operational controllers, signal data plane faults andperformrecovery switchover, modify LSP status, etc. Can we do this today? No, but with some (signaling) extensions the problem I believe is solvable. Is this some artificial, "fabricated" problem? No, I think it is real. Does it fall under the control plane resilience problem space? I believeit does.IgorI agree with Zafar and Dimitri. If someone wanted to document the GMPLS control plane resiliency features, as was done for GMPLS addressing, that might be a useful activity.-----Original Message----- From: dimitri papadimitriou [mailto:dpapadimitriou@psg.com] Sent: Friday, October 28, 2005 9:56 AM To: Igor Bryskin Cc: Zafar Ali (zali); Kim Young Hwa; ccamp@ops.ietf.org Subject: Re: Two Drafts for Resilience of Control Plane igor - over time CCAMP came with a set of mechanims to improve control plane resilience (RSVP and LMP GR upon channel/node failure) other WGprotocolwork are also usable used here OSPF GR, etc. ... on the otherside,mechanism such as link bundling have built-in resilience capabilities and most GMPLS control plane capabilities have been designed such astobe independent of the control plane realisation (in-band, out-of-band, etc.) so indeed i share the concern of Zafar what could we do more here than document these tools and provide our experience in usingthem;now, before stating there are (potential) problems(s) arising - would you please be more specific on what are these potential issue(s)and/orproblems ? (not related to policy/config. - note: all the issuesyouhave pointed here below are simply policy/config specific but none of them highlights a missing IP control plane resiliency feature) thanks, - dimitri. Igor Bryskin wrote:Zafar, The problem arises when the control plane is decoupled from the data plane. The question is do we need such decoupling in IP networks? Consider, for example, the situation when several parallel PSC data links bundled together and controlled by asinglecontrol channel. Does it mean in this case that when the control channel fails all associated data links also fail? Do we need to reroute in thiscaseLSPs that use the data links? Can we rely in this case on control plane indications to decide whether an associated data link is healthy or not (in other words, can we rely on RSVP Hellos or should we use, for example, BTD)? Should we be capable to recover control channels without disturbing data plane? I think control plane resilience is important for all layers. You are right, Internet does work, however, we do need for some reason TE and (fast) recovery in IP as much as in other layers,don't we? Cheers, Igor --- "Zafar Ali (zali)" <zali@cisco.com> wrote:Hi All, I am unable to understand the problem we are trying to solve or fabricate. My control network is IP based and IP has proven resiliency (Internet *does* work), why would I like to take control plan resiliency problem at a layer *above-IP* and complicate my life. Did I miss something? Thanks Regards... Zafar ________________________________ From: owner-ccamp@ops.ietf.org [mailto:owner-ccamp@ops.ietf.org] On Behalf Of Kim Young Hwa Sent: Friday, October 28, 2005 6:04 AM To: ccamp@ops.ietf.org Subject: Two Drafts for Resilience of Control Plane Dear all, I posted two drafts for the resilience of control plane. One is for requirements of the resilience of controlplane,theother is for a protocol specification as a solution of that . These are now available at:http://www.ietf.org/internet-drafts/draft-kim-ccamp-cpr-reqts-01.txthttp://www.ietf.org/internet-drafts/draft-kim-ccamp-accp-protocol-00.txtI want your comments. Regards Young. ===================================> >> Young-Hwa Kim Principal Member / Ph.D BcN Research Division, ETRI Tel: +82-42-860-5819 Fax: +82-42-860-5440 e-mail: yhwkim@etri.re.kr ===================================> >><http://umail.etri.re.kr/External_ReadCheck.aspx?email=ccamp@ops.ietf.org&name=ccamp%40ops.ietf.org&fromemail=yhwkim@etri.re.kr&messageid=%3C8630a6db-0c31-49ab-a798-13b0dda04553@etri.re.kr%3E>__________________________________ Yahoo! Mail - PC Magazine Editors' Choice 2005 http://mail.yahoo.com ...