SKBPRIO(8)			     Linux			    SKBPRIO(8)

NAME
       skbprio - SKB Priority Queue


SYNOPSIS
       tc qdisc ... add skbprio [ limit packets ]


DESCRIPTION
       SKB Priority Queue is a queueing discipline intended to prioritize the
       most important packets during a denial-of-service ( DoS ) attack. The
       priority of a packet is given by skb->priority , where a higher value
       places the packet closer to the exit of the queue. When the queue is
       full, the lowest priority packet in the queue is dropped to make room
       for the packet to be added if it has higher priority. If the packet to
       be added has lower priority than all packets in the queue, it is
       dropped.

       Without SKB priority queue, queue length limits must be imposed on
       individual sub-queues, and there is no straightforward way to enforce a
       global queue length limit across all priorities. SKBprio queue enforces
       a global queue length limit while not restricting the lengths of
       individual sub-queues.

       While SKB Priority Queue is agnostic to how skb->priority is assigned.
       A typical use case is to copy the 6-bit DS field of IPv4 and IPv6
       packets using tc-skbedit(8).  If skb->priority is greater or equal to
       64, the priority is assumed to be 63.  Priorities less than 64 are
       taken at face value.

       SKB Priority Queue enables routers to locally decide which packets to
       drop under a DoS attack.	 Priorities should be assigned to packets such
       that the higher the priority, the more expected behavior a source
       shows.  So sources have an incentive to play by the rules.


ALGORITHM
       Skbprio maintains 64 lists (priorities go from 0 to 63).	 When a packet
       is enqueued, it gets inserted at the tail of its priority list. When a
       packet needs to be sent out to the network, it is taken from the head
       of the highest priority list. When the queue is full, the packet at the
       tail of the lowest priority list is dropped to serve the ingress packet
       - if it is of higher priority, otherwise the ingress packet is dropped.
       This algorithm allocates as much bandwidth as possible to high priority
       packets, while only servicing low priority packets when there is enough
       bandwidth.


PARAMETERS
       limit  Maximum queue size specified in packets. It defaults to 64.  The
	      range for this parameter is [0, UINT32_MAX].


SEE ALSO
       tc-prio(8), tc-skbedit(8)


AUTHORS
       Nishanth Devarajan <devarajn@uci.edu>, Michel Machado
       <michel@digirati.com.br>

       This manpage maintained by Bert Hubert <ahu@ds9a.nl>

iproute2			13 August 2018			    SKBPRIO(8)