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Levels of QoS in ASR9K


I work for a ADSL service provider. We offer service over PPPoE solution. We are going to change our current BRAS to Some other platform. During my research I encountered ASR9K router. There are some key items for selecting the device as BRAS for us:

1) Maximum Number of supported PPPoE session on the device and also the Line Card on that device.

2) Type of QoS which device can provide.

For the first question, I found in this forum, ASR9K-BNG supports upto 128K PPPoE subscribers as for now. I need a confirmation on this.

For the second question we have this scenario, I am trying to explain it in a very simple manner:

1) A group of subscribers reside in an exchange and their PPPoE traffic is tagged with dot1q. This dot1q is identical for each exchange. Each subscriber is assigned two qos policies upon session initiation: one Shaping policy for download traffic(Outbound) and one Policing policy for upload traffic(Inbound).(This is the first level of QoS)Traffic of subscribers are marked by some routers before the BRAS so for example, HTTP Browsing has DSCP mark AF41 and Bittorrent has DSCP Mark AF11.

2) The overall topology on BRAS side is based on Ethernet, BRAS has no sense of congestion, while the remote exchange is connected to BRAS cloud via some slower links, for example TDM-based links.

3) We have different packages to offer but we need a method for differentiating the offered rate to different susbcribers in the time of congestion in TDM-Based link. so for example, subscriber with 4Mbps package has better service in comparison with subscriber with 2Mbps package in the time of congestion. We must note the physical interface which PPPoE VLAN is reside on the BRAS has at least 1Gbps speed.

4) For simulating this congestion, we put another QoS policy on the PPPoE sub-interface and offered a rate via Shape command.(This is the second level of QoS).

4) We have several PPPoE sub-interface which belong to the Exchanges in a residential area for example a City.  We want to aggregate the traffic of several cities over a physcial GE port. In this case, we use QinQ feature. This means, each exchange has its on inner-tag and a set of exchanges with different inner-tags has one outer-tag.

5) For differentiation between set of exchanges we also assign, the third qos policy with shape feature on QinQ sub-interface.(This is the third level of QoS).

6) In some cases, there are several QinQ sub-interfaces on a physcial port, then we also assign fourth QoS policy with Shape feature on that port.(This is the fourth level of QoS)

Another thing which is importatnt to us is differentiation between traffic types based on DSCP values, this is a sample scenario:

In Exchange#1, we have two subscribers, and Exchange link is congested via second policy-map. Subscriber#1 starts Bittorrent and fully utilizes the link. Meanwhile, subscriber#2 starts browsing Web. Since Web has better DSCP marking(AF41), the traffic rate of Bittorrent will be dropped and Web has higher priority.

Also we need to have this feature between exchanges and cities(If it is applicable).

Can we have this type of QoS implementaion on ASR9K?

Thank you for your help.

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