Hierarchical Modular QoS - adapt the DSL trained BW with EEM to the "policy-map shaper"

[Christian Steger]

hi EEM guys,

probably a few of you have a lot more experience like me on the EEM side :) - hier my brief question|requirement:

dsl lines are more unstable the longer a line could be or the more crostalk is on the line etc.. - means line could be for some reason

disconected. (of course ISP´s try to avoid that while increasing the SNR etc....) - however the bandwith "could" change..

also for an standard HQoS it would be great if there is an method of setting "automatically the shape bandwith)

so i am wondering of someone of you had already implemented such requirement or an similar one via EEM:

here my scenario:

policy-map PM_AT_3Q
 class P1_CLASSIFY
  priority level 1
  set cos 5
  set ip precedence 5
 class P2_CLASSIFY
  set cos 6
  set ip precedence 6
  priority level 2
 class class-default
  set cos 2
  set ip precedence 2
  random-detect
policy-map QOS-POLICY
 class class-default
  shape average <EEM-Script-Output>
   service-policy PM_AT_3Q

requirement to the EEM:

show interfaces ethernet 0 | i BW
  MTU 1940 bytes, BW 5120 Kbit/sec, DLY 1900 usec,

calculate 97% from the BW and put the output in bit/s in the <EEM-Script-Output>

this should be only done if the interface resets (down|up)

any idea how to solve that?

thank you!

christian

[Christian Steger]

hey joseph,

everything is working fine for me now.. great job doing that with the EEM.

there is still one other question:

DSLAMS support SRA (seamles-rate-adaption) without disconnecting the DSL line. - means the interface is always up by continiously changing the bandwith.

(of course not so much often - but it could change)

the question is:

is there an way recognicing the BW change and run again through the EEM-script and adapt the shape average BW accordingly?

(the interface ATM0|Ethernet0 knows it)

thanks!

chris

[Joe Clarke]

You could add a watchdog timer event to your policy to periodically check the output of the show interface command to get the new bandwidth.  The rest of the applet would remain the same.  This, of course, would cause the applet to reconfigure the QoS policy even if the bandwidth didn't change.  You could add logic to prevent that, but it would add a lot more complexity.