Manual: tc-skbprio

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-ser‐
       vice  (	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  straight‐
       forward	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 as‐
       sumed 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 prior‐
       ity 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 band‐
       width 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 , Michel Machado 

       This manpage maintained by Bert Hubert 

iproute2					       13 August 2018						  SKBPRIO(8)