[c-nsp] ISR detects interface status with delay

[Martin T]

Lukasz,

thanks for the reply! Just to make sure, there isn't a way to decrease
this polling interval on ISR platform, is there?


Martin

On Sat, Feb 7, 2015 at 11:42 AM, Łukasz Bromirski <lukasz at bromirski.net> wrote:
>
>> On 06 Feb 2015, at 10:36, Martin T <m4rtntns at gmail.com> wrote:
>>
>> In order to illustrate this behavior I made a short video where IOS
>> detects that interface Fa0/0 went down with almost 13 seconds delay.
>> Usually this delay is around 5 to 8 seconds, but sometimes up to 15
>> seconds. Video can be seen here:
>> https://www.dropbox.com/s/yb9o379935s3hou/20150206_110347.mp4 PHY chip
>> should detect this within micro- or milliseconds and as seen from the
>> video, LED's indicating the link status went off immediately when I
>> removed the cable, but why does it take so long for IOS to detect
>> this?
>
> First of all, carrier-delay on ISRs is not supported. The command is for
> that hardware platforms, that have more extensive instrumentation
> on the edge between hardware and software.
>
> Second, ISR polls interface controllers for up/down, so your
> better bet would be to use BFD, despite it being CPU-intensive,
> to detect link up/down event.
>
> --
> "There's no sense in being precise when |               Łukasz Bromirski
>  you don't know what you're talking     |      jid:lbromirski at jabber.org
>  about."               John von Neumann |    http://lukasz.bromirski.net
>