Re: [netmod] Comment on draft-clacla-netmod-yang-model-update-02

Randy Presuhn <randy_presuhn@alumni.stanford.edu> writes:

> Hi -
>
> On 11/15/2017 2:02 AM, Balazs Lengyel wrote:
>> While a server may correctly support multiple versions, the human 
>> operator on the CLI has a 99% chance of mixing up which version he is 
>> using. Humans will not check every type and leaf  to check that they 
>> remember the little differences between model versions. It is a recipe 
>> for human mistakes. According to some statistics 50% of downtime is 
>> caused by human errors, so we should not provide the operator with a gun 
>> to shoot himself. Ericsson has a rule never to have multiple versions of 
>> the same module on a network node.
>
> Does this mean that they require all line cards in a chassis to have
> exactly the same firmware revision level?  If so, when a card with a
> newer firmware revision level is swapped in, does that require all other
> cards of the same type in that chassis to also be replaced concurrently?
> Sounds like even a fairly routine/minor update/repair would effectively
> result in a system outage.

To be fair, there is no good solution to this in the current state of
affairs either. The limiting factor is the document-oriented nature of
YANG. It is a good use case for schema mount though.

Lada

>
> Randy
>
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-- 
Ladislav Lhotka
Head, CZ.NIC Labs
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