PFC MLS QOS minimum bandwidth guarantee

[paul amaral]

I need to configure Qos for about 4 customers, I'm classifying each customer by their ips on the class-map.I have a 100Mb wan link on the interface terminating this link i went ahead and configured QOS policies using the bandwidth percent command which will normally give me a minimum bandwidth allowing the use of further bandwidth should it be available. However this will not on a 6504 with a PFC which does QOS in hardware and it does not accept the bandwidth command. what is the alternative on the 6500 to set a minimum bandwidth.

My question is on MLS Qos how can i guarantee a minimum bandwidth and allow it to use more bandwidth if its available. I want each customer to get their CIR but use whatever current bandwidth is not by other customers. 

I know i can use shape or police but this sets only the max bandwidth that is allowed, i cant figure out how to burst using the remaining bandwidth if available.

I know i can use police cir and pir but will this guarantee the min bandwitdh with i also set the PIR?

I would appreciate any advise on this,

Paul

[Joseph W. Doherty]

Many 6500 (LAN) line cards support 4 hardware egress queues that you can allocate bandwidth ratios to.  Allocating it, sets a minimum guarantee.

[paul amaral]

Joseph thanks for responding.

The issue is i have a multi tenant configuration and i need to give each tenant a different minimum bandwidth based on their ip address. I know you can adjust the hardware queue the problem is that its either all or nothing meaning i can't specify which customer traffic gets what queue and for how long, at least i dont think you can do that. 

Im just mainly interested in controlling how much bandwidth each customer gets, so customer 1 can get 45Mb customer 2 gets 10Mb minimum but i would like them to burst to 100Mb is the bandwidth is available. Right now im testing with police cir and pir dual bucket but im not sure if doing this will cause one customer to use up all the bandwidth before the other has a chance to use it.

paul

[Joseph W. Doherty]

If your number of customers is not greater than the number of hardware queues, you can dedicate a hardware queue to each customer.  Each hardware queue's bandwidth guarantee can be independently set.  I.e. what you're requesting, might be possible (again if you don't have more customers than hardware queues).

[paul amaral]

If anyone is looking here is how i sort of achieved this. After reading through the 6500 qos documents I came to the conclusion that the 6500 can't set the minimum bandwidth with the bandwidth command under the MQC configuration. This uses the PFC to do hardware qos once you enable mls qos on the config i just never realized that you can only use a policer and shaper with no minimum guarantees you just simply cannot use the bandwidth command under MQC.

What i ended up doing was just set up and CIR and BE to be able to burst up the logical line's max throughput. For example for the 10Mb customer i setup a policer like this.

police cir 10000000 bc 625000 be 5625000    conform-action transmit     exceed-action transmit     violate-action drop

this will give you 10Mb of bandwidth by refilling the token bucket committed rate Bc every Tc and any spillover goes in the Be bucket. I'm using a Tc of .0625 which is about 16 time slices every 1sec.  so if a customer is  constantly using bandwidth the most they will avg around is 10Mb from the Bc bucket since there wont be much spillover to the Bc bucket however if they stop and have enough tokens in the Be bucket they can burst up to around 100Mb for a brief period of time, Be 10Mb + Bc 90Mb = 100 Mb.

While you can't directly set a minimum bandwidth on the 6500 PFC hardware QOS you can at least give brief bursts of bandwidth if that customer has accumulated enough tokens to do so. Since this is a brief burst it should not starve out the rest of the customers or are sharing the max 100Mb logical limit.

thanks P

[Joseph W. Doherty]

After reading through the 6500 qos documents I came to the conclusion that the 6500 can't set the minimum bandwidth with the bandwidth command under the MQC configuration.

Yes, that's correct, although as I tried to explain in my earlier post, you can guarantee a minimum amount of bandwidth to each hardware egress queue, as the 6500 line cards generally have 4 or 8 egress queues, you can direct traffic to those queues and provide each a minimal bandwidth guarantee.

Also, I didn't mention, 6500 FlexWAN line cards support much router QoS.  I think, though, they are EoL.

The 6500 is considered a L3 LAN switch, so it's LAN line card QoS support is weak compared to many routers.  Also BTW, some "WAN" line cards on the the 7600 support some additional QoS features, but they too are often still weak compared to many other Cisco ISRs.  The only line card, that I'm aware that supports most ISR QoS features, is the already mentioned FlexWAN cards.

[paul amaral]

Joseph, the particular card im using has 3 regular queues and 1 pri queue how would i go about guaranteeing a minimum bandwidth per queue for the 4 customers i have? i am classifying them by ip address  FYI. I just couldnt find a way with the WRR commands to set this up.

 Port is untrusted
 Extend trust state: not trusted [COS = 0]
 Default COS is 0
   Queueing Mode In Tx direction: mode-cos
   Transmit queues [type = 1p3q8t]:
   Queue Id    Scheduling  Num of thresholds
   -----------------------------------------
      01         WRR                 08
      02         WRR                 08
      03         WRR                 08
      04         Priority            01

   WRR bandwidth ratios:  100[queue 1] 150[queue 2] 200[queue 3]
   queue-limit ratios:     50[queue 1]  20[queue 2]  15[queue 3]  15[Pri Queue]

[Joseph W. Doherty]

My bad.  I forgot the PQ is not a option on the 6500 line cards, like it is on other smaller Catalyst switches (e.g. 3750).

If you only had 3 customers, you would okay with a 1p3q card.  However, for 4 customers, you would need a 1p7q card.

If you had 3 customers, you would map each customer to each of the non-PQ queues, and set its bandwidth ratio to guarantee its ratio to the other customers.  For example, if you wanted all you customers to get an equal share of bandwidth, you would set their bandwidth ratios the same (unlike your current 100:150:200).

For four customers, you least expensive option would be to add another router or small Catalyst that supports 4 or 8 queues.  (Yes, can police, but that sets a maximum allowance, not a minimum.)