I believe newer SPD implementations support prioritizing of frame-relay LMI
packets. Not sure when it was/will be available though..
-danny
> Alex:
> There is a known (at least to networks with large Cascade deployments)
> problem with Ciscos and Cascades in that high link utilization will cause
> LMI drops and thus interface drops. The problem as was explained to me is
> that LMI is not prioritized over other traffic, so when discards have to
> occur, LMI can also go. This has been known to occur as low as 60-70% line
> utilization.
> So far the only resolution to this is "no keepalives". You now have to
> rely on the routing protocol to determine when the far end is unreachable
> (i.e. link is down).
> I haven't seen this occur on HDLC links, except when there were sufficient
> BGP bounces/instability to max out the CPU and cause further BGP bouncing.
> ...karl
>
> At 06:59 PM 3/28/98 -0500, you wrote:
> >I posted about this before in the context of FR over HSSI and Greg Ketell
> >posted some useful stuff back, but the problem is wider and repeatable.
> >I don't know if anyone else has seen this.
> >
> >7513 & 7507, running 11.1.12CA1, 11.1.15CA1 and 11.1.17CA1 with CX-HIP,
> >both under point to point HDLC through Digilinks, and running FR
> >into a Cascade FR switch, appear to drop line protocol when the router
> >hits high CPU load (for instance through oscillating lines or BGP
> >recalculation). As this causes oscillating lines and BGP recalculation,
> >this is a bad thing.
> >
> >Has anyone else seen this? (Bug Navigator hasn't). Does anyone have a fix?
> >I have increased the broadcast queues and played with various LMI timers
> >for the FR stuff which mitigated the problem a little on the FR side.
> >It appears to be perfectly repeatable (unfortunately today gave me the
> >chance to test this...)
> >
> >--
> >Alex Bligh
> >GX Networks (formerly Xara Networks)
> >
> >
> >
This archive was generated by hypermail 2b29 : Sun Aug 04 2002 - 04:13:16 EDT