Serial link flaps when congested

[Volodymyr Khrystenko]

I tried to congest serial link. When the link was congested - I get flapping:

%LINEPROTO-5-UPDOWN: Line protocol on Interface Serial0/0, changed state to down

%LINEPROTO-5-UPDOWN: Line protocol on Interface Serial0/0, changed state to up

Can somebody explain why? Are there any keepalives on serial links?

[paolo bevilacqua]

Yes there are keepalives, but that should not happen.

Update IOS on both sides of the link, and check again.

[Subeh Sharma]

Hi,

Line protocol should not be going done even when the load increases as the keepalives carries a higher priority than the rest of the packets. can you paste the output of the 'show interface serial 0/0' taken 2-3 times at the time of the issue? Also let me know if you see the issue at the time when the serial link is not oversaturated?

please paste the configuration of show run int s0/0 as well.

Regards,

Subeh

[Volodymyr Khrystenko]

Hi.

I repeated the situation. No flaps are observed. Probably physical issue)))