[c-nsp] PPPOE intermittently fails to respond to PPP keepalives on 7204xvr with 12.4(24)T5

[Blake Dunlap]

What is the cpu usage level showing in your graphs for said BRAS 7200?

-Blake


On Wed, Aug 21, 2013 at 12:49 PM, Richard Haakma <richard at kci.net.nz> wrote:

> Hi.
>
> I have a 7204VXR (yes I know it is old) which is serving broadband
> customers over ethernet. Another party supplies the last mile and we get
> a Gigabit ethernet connection with QinQ where end users get a VLAN each.
>
> e.g.
>
> interface GigabitEthernet0/3.2
>  encapsulation dot1Q 2 second-dot1q any
>  pppoe enable group mypppoe
>
> etc.
>
> and using this
>
> interface Virtual-Template2
>  mtu 1492
>  ip unnumbered Loopback0
>  ip tcp adjust-mss 1452
>  peer default ip address pool dsl-pool
>  ppp authentication pap dsl-auth
>  ppp authorization dsl-authorize
>  ppp accounting dsl-account
>  ppp ipcp address required
>
> AAA is by radius.
>
> The problem is that intermittently IOS on the 7204VXR will not respond
> to PPP keepalive packets. Some CPEs send keepalives and when they don't
> get a reply they disconnect the PPP session and reconnect. Some
> customers notice the short outage and it can be repeated several times
> over a few minutes. This has been verified by observing packets at the
> CPE.
>
> I think that PPP keepalives are handled by a CPU process and something
> may be stopping the process from running in time. The 7204 is not
> heavily loaded and we first saw this behaviour with only a handful of
> connections. I attempted to recreate it in a lab setup with one PPPOE
> client on a test BRAS but that runs cleanly.
>
> Also possible is that the last mile provider is dropping keepalive or
> keepalive replies. They may drop when the QOS bits are set incorrectly
> but this is unlikely as the pattern is intermittent.
>
> Please help, has anyone seen this kind of problem and fixed it up? Has
> this been changed in 12.4(24)T8 ?
>
>
> Regards,
> Richard Haakma.
>
>
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