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-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 pri‐
       ority. 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.	Pri‐
       orities 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 , Michel Machado 

       This manpage maintained by Bert Hubert 

iproute2				       13 August 2018					  SKBPRIO(8)