[c-nsp] vss and mlq qos 10g-only command

[Tóth András]

Hi Arne,

When you enter the mls qos 10g-only command, a supervisor engine with
both 1-Gigabit and 10-Gigabit Ethernet uplink ports reallocates the
interface queue capacity to improve the performance of its 10-Gigabit
Ethernet ports. The reallocation is possible only in 10g-only mode, in
which the supervisor engine's 1-Gigabit Ethernet ports are not used.
In the normal mode, when all supervisor engine ports are active, the
queue structure is 2q4t on receive and 1p3q4t on transmit. In 10g-only
mode, the queue structure is 8q4t on receive and 1p7q4t on transmit.

http://www.cisco.com/en/US/docs/ios/qos/command/reference/qos_m2.html#wp1041041

Andras


On Sat, Nov 26, 2011 at 5:30 PM, Arne Larsen  / Region Nordjylland
<arla at rn.dk> wrote:
> Hi all
>
>
> Can someone explain exactly what the vss command mls qos 10g-only does.
> I know it changes queuing and buffer mechanism, but I'm a bit astonished by the impact.
> We had a problem on a datacenter where we uses a VSS144 setup.
> We have both vss links on the supervisior modules.
> The problem was between Xen provisionings servers and Xen client hosts. The Xen client OS that is streamed to the client, had retransmissions.
> After enabling the command all works fine.
> We are talking max 3Gb certain rate. Can this really overrun the vss-links ??
>
> /Arne
>
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