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COS on an Unknown Pipe Size

‎03-03-2014 12:03 PM

Hi all,

 

I need to come up with a solution to allocate a high priority forwarding-class a percentage of a pipe size whose size is unknown. 

 

Eg. I need forwarding-class PRIORITY to be allocated 80%, on a link that we don't know how much bandwidth it has (think of an ISP giving you an ethernet 100Mb physical connection, on a X Mb Cable Internet circuit - but not knowing the value of X).

 

Do any of your have any suggestions on how to accomplish this? 

--
Chris Jones
JNCIE-ENT #272
Former JNCIP-SP
Former CCIE #25655
Former Juniper Ambassador
7 REPLIES 7
Routing

Re: COS on an Unknown Pipe Size

‎03-03-2014 11:56 PM

Sounds like you would need to use a policer where you can specify a % instead of absolute bit rate and set the forwarding classa nd loss priority. But that would be on ingress interface, you would also need to ensure that the schedulers for would be configured to enure timely processing and in that case you could use a specific percentage fro transmit rate and buffer size which would be quite low for other quesues and then remainder for your top priority queue.

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Routing

Re: COS on an Unknown Pipe Size

[ Edited ]
‎03-04-2014 01:40 PM

But even as a %, you'd still need to know the total size you're allocating a % from.

 

That's the problem, I need to know the total size. I'm really thinking this simply isn't possible. 

 

The only "good" way I can imagine ensuring a certain forwarding class always has preference would be to give it strict-high priority, but I understand that can/will starve other queues in times of congestion. In this case, I think my customer can accept that. 

--
Chris Jones
JNCIE-ENT #272
Former JNCIP-SP
Former CCIE #25655
Former Juniper Ambassador
Routing

Re: COS on an Unknown Pipe Size

‎03-04-2014 02:22 PM

set firewall policer Hi-Speed if-exceeding bandwidth-percent 80
set firewall policer Hi-Speed if-exceeding burst-size-limit 128k

set firewall policer HI_Speed then loss-priority low
set firewall policer HI_Speed then forwarding-class assured-forwarding

 

You can apply it using a firewall filter.

When you configure the transmit rate (it is a factor of 100 (percent) they must just add up to 100.

There is another document but it is about the WCX policers, I am betting that would help you better than I can.

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Routing

Re: COS on an Unknown Pipe Size

‎03-04-2014 02:29 PM

Yea, that unfortunately doesn't help me. You've configured a policer at 80%. But... 80% of what? Same problem with transmit-rate. 

 

If you're on Ethernet (100Mb) but you only have a $x Mb upstream cable Internet subscription, then you need to know what $x is in order to police to 80% of it. 

 

To me, it's a simple math issue. If I said to you "tell me what 80% of x is", you would say you need to know the value of x in order to give an answer. Same issue here. Again, I'm guessing it's not possible.

--
Chris Jones
JNCIE-ENT #272
Former JNCIP-SP
Former CCIE #25655
Former Juniper Ambassador
Highlighted
Routing

Re: COS on an Unknown Pipe Size

‎03-04-2014 03:27 PM

I thought that was question?

I need to come up with a solution to allocate a high priority forwarding-class a percentage of a pipe size whose size is unknown. 

 

Eg. I need forwarding-class PRIORITY to be allocated 80%, on a link that we don't know how much bandwidth it has (think of an ISP giving you an ethernet 100Mb physical connection, on a X Mb Cable Internet circuit - but not knowing the value of X)""

 

Yes it is simple math. You did not ask for a specific bandwidth which you would guessing if the pipe is unknown.  If your available bandwidth was 100M then you want to guarantee 80M for your high priority traffic. If it was 10M then want to to allocate 8M to you interesting traffic. So what ever the bandwidth the system would allow your interesting traffic to to 80/100 x Value. Since you are not specifying the absolute value, you are expressing it as a percentage of the unknow Value. Percent assumes an unknown variable X. But I understand if this cannot work, then there may not be way other than using a Wan Accelerator.

Same thing with the scheduler. In this example the transmit rate is configured as a percnetage value instead of an absolute value:

[edit class-of-service]schedulers {be-DATA-scheduler {transmit-rate percent 40;buffer-size percent 40;priority low;}ef-FIN-scheduler {transmit-rate percent 10;buffer-size percent 10;priority high;}af-AV-scheduler {transmit-rate percent 45;buffer-size percent 45;priority high;drop-profile-map loss-priority low protocol any drop-profile af-AV-normal;drop-profile-map loss-priority high protocol any drop-profile af-AV-with-PLP;}nc-CONTROL-scheduler {transmit-rate percent 5;buffer-size percent 5;priority low;

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If this solution worked for you please flag my post as an "Accepted Solution" so others can benefit..]
Routing

Re: COS on an Unknown Pipe Size

‎03-04-2014 03:31 PM

Yeah. Won't work. Thanks for trying, though. 

 

" If your available bandwidth was 100M then you want to guarantee 80M for your high priority traffic."

 

Exactly. I have no idea what the available bandwidth is.

--
Chris Jones
JNCIE-ENT #272
Former JNCIP-SP
Former CCIE #25655
Former Juniper Ambassador
Routing

Re: COS on an Unknown Pipe Size

‎03-07-2014 08:58 PM
Can you set up a pair of laptops on either end and run iperf to see what the max bandwidth is?