[j-nsp] Question about Routing Engine Redundancy on MX

[Gabriel Blanchard]

Yes, just bought the book, for anyone that has MXes deployed...highly
recommend.

And Doug, just noticed, didn't you write this book? :-P

On 13-01-09 06:10 PM, Doug Hanks wrote:
> Harry wrote a great chapter on RE redundancy in the new MX book.
> 
> http://tinyurl.com/junipermx
> 
> 
> On 1/9/13 11:39 AM, "Harry Reynolds" <harry at juniper.net> wrote:
> 
>> My .02.
>>
>> I too cannot find documentation that mandates the same RE hardware or
>> Junos SW for all HA features. The 12.2 HA guide does mandate the same
>> version for NSR, and my extension ISSU. (page 80):
>>
>> http://www.juniper.net/techpubs/en_US/junos12.2/information-products/topic
>> -collections/config-guide-high-availability/config-guide-high-availability
>> .pdf
>>
>> IMO, GRES/NSR/ISSU is complex enough. Generally speaking you are only
>> adding potential for "less than desirable" outcomes if you attempt to
>> deploy such features with mismatched RE hardware or Junos versions. It
>> would be safe to say that testing HA features with all possible
>> mismatches of RE HW and SW is not done routinely; it may work, or may
>> not, and you may well be the first to know, being the first to ever try
>> some specific test with some specific set of mismatched HW or SW.
>>
>> As with all things in life, to some degree success or failure is a matter
>> of how significant the mismatch is. Junos 7.0 on master and 12.2 on BU as
>> opposed to 12.1R1 vs. 12.1R2; here the later will likely do OK... Same
>> with RE hardware. If the master RE is significantly faster or has
>> significantly more memory than the BU, you may hit timing issues with
>> kernel or NSR synchronization, or, may find that post NSR things go
>> poorly as the new master RE struggles to keep up now that it has to run
>> the show. If you expect the BU RE to take over with no hit, it's quite
>> reasonable to mandate that it at least have the same capabilities as the
>> master.... 
>>
>> In the end it's a complex interaction of how significant the mismatch is,
>> whether it effects some key feature that is in use, and the degree to
>> which the test box is scaled; in the end its intractable to try and
>> predict all the possible permutations.
>>
>> As a final anecdote, I would never open a PR for a HA feature where the
>> DUT had any such mismatch (unless it was a specific feature that mandated
>> the disparity), as the first thing the engineer will ask is for me to try
>> and repro with matched settings....
>>
>> HTHs
>>
>> Regards
>>
>>
>>
>>
>>
>>
>>
>> -----Original Message-----
>> From: juniper-nsp-bounces at puck.nether.net
>> [mailto:juniper-nsp-bounces at puck.nether.net] On Behalf Of Paul Stewart
>> Sent: Wednesday, January 09, 2013 10:52 AM
>> To: 'Jose Sanchez'
>> Cc: 'juniper-nsp'
>> Subject: Re: [j-nsp] Question about Routing Engine Redundancy on MX
>>
>> Nothing that I have handy - sorry. we asked this question a few times to
>> our Juniper SE and were told that (so presumed it to be factual)
>>
>>
>>
>> J
>>
>>
>>
>> From: Jose Sanchez [mailto:jasjuniper at gmail.com]
>> Sent: January-09-13 1:49 PM
>> To: Paul Stewart
>> Cc: juniper-nsp
>> Subject: Re: [j-nsp] Question about Routing Engine Redundancy on MX
>>
>>
>>
>> Thank you,
>>
>>
>>
>> Any link to the documentation that require this?
>>
>>
>>
>> Thanks again
>>
>>
>>
>> Jose
>>
>>
>>
>>
>>
>> On Wed, Jan 9, 2013 at 12:43 PM, Paul Stewart <paul at paulstewart.org>
>> wrote:
>>
>> Both same hardware....
>>
>>
>> -----Original Message-----
>> From: juniper-nsp-bounces at puck.nether.net
>> [mailto:juniper-nsp-bounces at puck.nether.net] On Behalf Of Jose Sanchez
>> Sent: January-09-13 1:39 PM
>> To: juniper-nsp
>> Subject: [j-nsp] Question about Routing Engine Redundancy on MX
>>
>> Hello,
>>
>> Does anybody know if the RE Redundancy in Juniper MX Routers requires
>> that both RE are the same hardware or it is enough that the REs has the
>> same JUNOS Version?
>>
>> Thanks
>>
>> Jose
>>
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