search

brownsys / pane

Participatory Networking
http://pane.cs.brown.edu
Other
5 stars 4 forks source link

Units for bandwidth #29

Open adferguson opened 12 years ago

adferguson commented 12 years ago

Add units for bandwidth so we can reserve "10Mb" or "25kb" etc.

adferguson commented 12 years ago

Also for time.

adferguson commented 12 years ago

bandwidth units came into play today when we switched from the software reference switch to Open vSwitch.

OvS expects guaranteed minimum bandwidth requirements in bits per second. the reference switch is doing something else. also, the queue configuration proposal (the OpenFlow 1.0 extension used by the reference switch) only allocates 16 bits for the rate size. therefore, if you do the naive thing and accept the reservation as in bits/second for OvS, then you can only reserve up to 65,535 bits per second (8 MB/sec) when using the reference switch.

adferguson commented 12 years ago

whatever we decide to do here, it will be relevant for the new Java API

adferguson commented 12 years ago

we should use Mbps for bandwidth reservations. @chen-liang determined that the reference switch (with the OF 1.0 extensions) treats the 16 bit field for the rate as tenths of a percentage of the link speed.

in other words, for a 1 Gbps link, the minimum reservation is 0.1%, or 1 Mbps.

we'll need to put proper unit handling in the front-end (and Java library, I think?) ... and then we also need to convert this Mbps amount (which will be the unit of PANE's internal representation) into a correct value for the link inside PANE's controller. in other words, if it's a 100 Mbps link, then it should be multiplied by 10.