[j-nsp] NSR+GRES vs Graceful restart

[Richard A Steenbergen]

On Wed, Feb 23, 2011 at 10:19:14AM -0800, Doug Hanks wrote:
> GRES+NSR+ISSU works just fine with DPCs.  The ISSU for Trio is still 
> roadmap.

For some definition work "works just fine", where "works" equals 
"doesn't work" perhaps. :) I haven't been able to successfully ISSU an 
MX/DPC for over 2 years, and Juniper has all but given up trying to fix 
it.

But GRES+NSR is typically going to be a much better idea than GRES+GR. 
GR is actually pretty darn flawed in its design, as it assumes that all 
failures are graceful, even the non-graceful ones. If you don't want to 
blackhole a lot of traffic, NSR is a MUCH better alternative. Of course 
I have yet to encounter an RE failure in the wild where GRES+anything 
actually saves the day, but doing a hitless NSR switchover has been 
surprisingly helpful as a way to kick the box in response to a large 
number of random/obnoxious bugs, without actually having to disrupt 
forwarding.

-- 
Richard A Steenbergen <ras at e-gerbil.net>       http://www.e-gerbil.net/ras
GPG Key ID: 0xF8B12CBC (7535 7F59 8204 ED1F CC1C 53AF 4C41 5ECA F8B1 2CBC)