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PollDevice Element Documentation


PollDevice -- Click element; polls packets from network device (kernel)


PollDevice(DEVNAME [, keywords PROMISC, BURST, TIMESTAMP...])

Ports: no inputs, 1 output
Processing: push
Drivers: linuxmodule
Package: linuxmodule (core)


Poll packets received by the Linux network interface named DEVNAME. Packets will be pushed to output 0. The packets include the link-level header. DEVNAME may also be an Ethernet address, in which case PollDevice searches for a device with that address. Each time PollDevice is scheduled, it emits at most BURST packets. By default, BURST is 8. This element is only available in the Linux kernel module. Keyword arguments are:

Boolean. If true, the device is put into promiscuous mode while FromDevice is active. Default is false.
Unsigned integer. Sets the BURST parameter.
Boolean. If true, then ensure that received packets have correctly-set timestamp annotations. Default is true.
Boolean. If true, then suppress device up/down messages. Default is false.
Unsigned. Amount of extra headroom to request on each packet. Default is 64.
Unsigned integer. Sets the minimum size requested for packet buffers. Should be at least as large as your interface's MTU; some cards require even more data than that. Defaults to a number derived from the driver, which is usually the right answer.
Allow nonexistent devices. If true, and no device named DEVNAME exists when the router is initialized, then PollDevice will report a warning (rather than an error). Later, while the router is running, if a device named DEVNAME appears, PollDevice will seamlessly begin emitting its packets. Default is false.
Write handler. If supplied, this handler is called when the device or link comes up.
Write handler. If supplied, this handler is called when the device or link goes down.


Linux won't see any packets from the device. If you want Linux to process packets, you should hand them to ToHost. Also, if you would like to send packets while using PollDevice, you should also define a ToDevice on the same device. This element can only be used with devices that support the Click polling extension. We have written polling patches for the Tulip Ethernet driver. Linux device drivers, and thus FromDevice, should set packets' timestamp, packet-type, and device annotations.


count (read-only)
Returns the number of packets PollDevice has received from the input card.
reset_counts (write-only)
Resets count counter to zero when written.


FromDevice, ToDevice, FromHost, ToHost

Generated by 'click-elem2man' from '../elements/linuxmodule/polldevice.hh' on 28/Feb/2010.


elements/polldevice.txt · Last modified: 2010/02/28 13:58 (external edit)
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