[j-nsp] mpls auto bandwidth - minimum bw

[Adam Vitkovsky]

Hi Tim,

> tim tiriche
> Sent: Tuesday, February 09, 2016 6:41 AM
>
> Hi,
>
> In my network, i have mostly 10G links and i have mpls auto bw with min-bw
> of 10m configured.
> which means when i create an lsp, 10m is always reserved.
>
> however, there are remote sites where i have 10m/100m and with 10m min-
> bw reservation the lsp fails to come up.
>
> how do folks address this?  is there any harm in keeping the min-bw 10bps
> uniformly everywhere?  will that cause any side effect?
>
My experience is to have it at 1kbps.
But now that I think about it depends.
I guess you can think of it as a preliminary check to see if the link is absolutely fully booked (resulting in immediate recalculation of the LSP after new BW is signalled -if it was signalled with 0 BW reservations initially) or whether there is a space to squeeze at least x-Kbps reservation - then change the x-kbps for a value you consider to be a valid link availability check.
It also depends on the re-optimization timers.
Consider this corner case:
If the path is successfully signalled with only 1kbps reservation but there's only 3Mbps worth of BW available on that link, then the 5Mbps of traffic using the path might experience congestion for the duration of the re-optimization period.
But this would happen only when the head-end reboots or is severed from the core or the LSP is bounced for some reason.


adam





        Adam Vitkovsky
        IP Engineer

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