Thank you for clarifying this. Therefore it has no sense to make it more
complicated in this way.

Anyway, I'd like to have there at least a note saying that if the prefix
limit is too tight, you may get an unwanted bgp session drop simply due
to temporary conditions. Is this reasonable?

Thanks
Maria

On 4/1/19 7:54 PM, Robert Raszuk wrote:
> Well you still need to indicate to prefix limit check when it should
> start x2 multiplication and when the specific upgrade which requires it
> is over.
> 
> Note that vast majority of customers use prefix limit as a safety fuse
> normally allowing x2 or even x5 under normal operation.
> 
> Best,
> R.
> 
> On Mon, Apr 1, 2019, 19:50 Maria Matějka <[email protected]
> <mailto:[email protected]>> wrote:
> 
>     Oops, I forgot to write there that during the grace period the limit
>     should be only temporarily raised by a factor of 2 to allow complete
>     route exchange, not lifted at all.
> 
>     I think this would be much simpler for the users than fiddling with
>     the limit more times.
> 
>     Thx
>     Mariais 
> 
>     On April 1, 2019 6:30:45 PM GMT+02:00, Robert Raszuk
>     <[email protected] <mailto:[email protected]>> wrote:
> 
>         Hi Maria,
> 
>         So your suggestion is not to apply this limit at all (ie. have
>         unlimited transient) - don't you think that in such a case your
>         weakest network elements may just crash if say they expect 10
>         and will get 700K prefixes ? 
> 
>         I think what you are asking for can be easily achieved today
>         during described migration if you adjust the prefix limit to
>         some controlled higher value before your planned policy change
>         then simply revert it back. Seems like very safe and problem
>         free operation. 
> 
>         Many thx,
>         R.
> 
>         On Mon, Apr 1, 2019 at 5:29 PM Maria Matějka <[email protected]
>         <mailto:[email protected]>> wrote:
> 
>             Hello!
> 
>             I'd like to suggest adding a grace time to the Prefix Limit
>             ORF-Type.
>             Its purpose is to allow temporary overrun of the limit while
>             reloading
>             the routes after a policy is changed.
> 
>             Why: If the peer exports e.g. 2001:db8:0/48 through
>             2001:db8:7/48 and
>             it wants to substitute them for 2001:db8:0/45, it first has
>             to add the
>             less specific prefix and then drop the more specific
>             prefixes. Doing this
>             on large scale may override the limits temporarily which
>             would lead to
>             unneeded BGP session drop.
> 
>             Here are the changes to be done to the RFC text:
> 
>             * append to section 3:
>                     The "Grace-Time" is a two-byte unsigned integer. It
>             indicates
>                     the number of seconds for which the Prefix-Limit can
>             be exceeded.
> 
>             * append to section 4 the Grace-Time directly after the
>             Prefix-Limit
> 
>             * insert to section 6.1.1 after 2nd paragraph:
>                     The sending speaker MUST wait for the Grace-Time
>             period before
>                     taking corrective action. If the peer gets from the
>             Prefix-Limit
>                     violation during the Grace-Time period, no
>             corrective action is taken.
>                     The Grace-Time period is reset every time the
>             violation is gone.
> 
>             Thank you for cnnsidering my suggestion
>             Maria
> 
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> 
> 
>     -- 
>     Sent from my Android device with K-9 Mail. Please excuse my brevity.
> 

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