[c-nsp] Fw: Re: Difference between ISIS NSR and ISIS NSF Cisco-Style

[Dhamija Amit]

--- On Thu, 1/10/13, Dhamija Amit <amiitdhamija at yahoo.com> wrote:

> From: Dhamija Amit <amiitdhamija at yahoo.com>
> Subject: Re: [c-nsp] Difference between ISIS NSR and ISIS NSF Cisco-Style
> To: "Oliver Boehmer (oboehmer)" <oboehmer at cisco.com>
> Date: Thursday, January 10, 2013, 12:32 PM
> Hi Oli,
> 
> Many Thanks for your prompt response.
> 
> We have one interop issue where my peer is Juniper ERX
> which doesn't support NSF IETF implementation , So we are
> testing NSF cisco style where cisco router sends special LSP
> a CSNP packet (purpose of sending special LSP is to get all
> the valid LSP's from neigh.)and juniper ERX is not
> understanding and is not sending PSNP is response to
> CSNP and since delivery of ISIS is unreliable cisco needs
> PSNP which he didnt get and after few number of tries it
> reset the adj. 
>  
> My concern is there is no seperate NSR for ISIS in cisco ,
> only nsf cisco is NSR .NSR is a local mechanism  but still
> some-how in this scenario we have to depend upon neighbour.
> So that's why i would like to understand in NSR do we really
> need some refresh mechanism from neighbour or is it purely
> independent.
> 
> Also you mentioned in nsf cisco-style only adjacency table
> is synced with standby RP , However in actuall NSR both adj
> table & LSDB will be synced.
> 
> So if we have NSR implementation ( with both LSDB & Adj)
> syncing to standby , then still do we need to depend on
> neighs.
> 
> Thanks.
>   
> --- On Thu, 1/10/13, Oliver Boehmer (oboehmer) <oboehmer at cisco.com>
> wrote:
> 
> 
> From: Oliver Boehmer (oboehmer) <oboehmer at cisco.com>
> Subject: Re: [c-nsp] Difference between ISIS NSR and ISIS
> NSF Cisco-Style
> To: "Dhamija Amit" <amiitdhamija at yahoo.com>,
> "cisco-nsp at puck.nether.net"
> <cisco-nsp at puck.nether.net>
> Date: Thursday, January 10, 2013, 11:54 AM
> 
> 
> 
> 
> >I would like to know the difference between actuall ISIS
> NSR and ISIS NSF
> >cisco style.
> > 
> >Most documentation says they are same , however thereare
> some differences
> >also and it's not real  NSR. Also i have seen in some
> packet sniffer in
> >cisco style cisco router sends a dummy special CSNP
> packet to neighbour
> >to get all the valid LSP's in database.
> > 
> >Will NSR also depends upon some refresh information from
> Neighbours ??
> 
> Which ISIS NSR implementation are you referring to?
> 
> I am asking as folks actually call "isis nsf cisco"
> "Non-Stop Routing".
> There is a point as this NSF/GR implementation indeed does
> not require any
> special help of the neighbours (the special CSNP packet
> triggering the
> neighbours to send all their LSPs is just regular ISIS
> protocol
> mechanism), unlike BGP GR or OSPF GR which requires protocol
> extensions.
> So it is likely an academic discussion if "nsf cisco" is a
> creative GR or
> an NSR implementation. From a design standpoint, "nsf cisco"
> does not
> require any new function/config on the neighbors, so there
> is no
> difference. That's at least how I look at it.
> 
> a "real" ISIS NSR implementation would require to sync the
> complete LSP
> database between active and standby RP, not only the
> adjacency table which
> is synced with "nsf cisco". But what would be the benefit to
> your
> network/services/design over "nsf cisco"?
> 
>     oli
> 
> 
>