Bandwidth distribution per ip

James Bensley jwbensley at
Thu Dec 21 12:27:03 CST 2017

On 20 December 2017 at 15:52, Saku Ytti <saku at> wrote:
> On 20 December 2017 at 16:55, Denys Fedoryshchenko <denys at> wrote:
>> And for me, it sounds like faulty aggregation + shaping setup, for example,
>> i heard once if i do policing on some models of Cisco switch, on an
>> aggregated interface, if it has 4 interfaces it will install 25% policer on
>> each interface and if hashing is done by dst ip only, i will face such
>> issue, but that is old and cheap model, as i recall.
> One such old and cheap model is ASR9k trident, typhoon and tomahawk.
> It's actually pretty demanding problem, as technically two linecards
> or even just ports sitting on two different NPU might as well be
> different routers, they don't have good way to communicate to each
> other on BW use. So N policer being installed as N/member_count per
> link is very typical.


In the case of ASR9K IOS-XR 6.0.1 added the following command:
"hw-module all qos-mode bundle-qos-aggregate-mode"

This splits the bandwidth over the links and takes into account the
link bandwidth; with bundle bandwidth 50G (with 10G+40G members) the
ratios become 5/1 and 5/4 respectively (it is supporting unbalanced
member link speeds).

Also the NPUs don't need to talk to each other on the ASR9K; the
central fabric arbiter has a view of bandwidth per VoQ and can control
the bandwidth across the LAG member interfaces when they are spread
over multiple lines cards and NPUs.


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