{"id":571,"date":"2018-10-26T22:15:15","date_gmt":"2018-10-26T22:15:15","guid":{"rendered":"http:\/\/feralpacket.org\/?p=571"},"modified":"2018-10-26T22:15:15","modified_gmt":"2018-10-26T22:15:15","slug":"qos-weighted-fair-queueing-wfq-notes","status":"publish","type":"post","link":"https:\/\/feralpacket.org\/?p=571","title":{"rendered":"QoS Weighted Fair Queueing (WFQ) Notes"},"content":{"rendered":"

QoS Weighted Fair Queueing (WFQ)<\/span><\/p>\n

\u00a0– Does not use MQC<\/p>\n

\u00a0– Uses packet flows<\/p>\n

\u00a0 \u00a0 \u00a0-> The collection of packets with the same header information<\/p>\n

\u00a0 \u00a0 \u00a0-> Source \/ destination IP addresses<\/p>\n

\u00a0 \u00a0 \u00a0-> Source \/ destination port numbers<\/p>\n

\u00a0 \u00a0 \u00a0-> Protocol<\/p>\n

\u00a0 \u00a0 \u00a0-> Precedence value<\/p>\n

\u00a0– Every flow creates a software queue<\/p>\n

\u00a0– Maximum number of queues is 4096<\/p>\n

\u00a0– Flows are treated according to two things<\/p>\n

\u00a0 \u00a0 \u00a0-> Precedence<\/p>\n

\u00a0 \u00a0 \u00a0-> Packet length<\/p>\n

\u00a0– Higher precedence and smaller packets are preferred over lower precedence and bigger packets<\/p>\n

e.g. –<\/p>\n

\u00a0– Flow1<\/p>\n

\u00a0 \u00a0 \u00a0-> src IP – 10.0.0.1<\/p>\n

\u00a0 \u00a0 \u00a0-> dst IP – 15.0.0.1<\/p>\n

\u00a0 \u00a0 \u00a0-> src port – 4001<\/p>\n

\u00a0 \u00a0 \u00a0-> dst port – 80<\/p>\n

\u00a0 \u00a0 \u00a0-> precedence – 5<\/p>\n

\u00a0– Flow2<\/p>\n

\u00a0 \u00a0 \u00a0-> src IP – 10.0.0.1<\/p>\n

\u00a0 \u00a0 \u00a0-> dst IP – 15.0.0.1<\/p>\n

\u00a0 \u00a0 \u00a0-> src port – 5000<\/p>\n

\u00a0 \u00a0 \u00a0-> dst port – 80<\/p>\n

\u00a0 \u00a0 \u00a0-> precendence – 6<\/p>\n

<\/p>\n

WFQ Schedular Mechanism<\/span><\/p>\n

<\/p>\n

Sequence Number (SN) (Finish time) = old sequence number + ( packet length * weight )<\/p>\n

\u00a0– Lower is better<\/p>\n

Weight = 32384 \/ IPP + 1<\/p>\n

Scheduler\u00a0selects the packet with the lowest sequence number among flows<\/p>\n

\u00a0– Within a flow, packets are FIFO<\/p>\n

\u00a0– Between flows, the scheduler selects the next packet based on sequence numbers<\/p>\n

Congestive Discard Threshold (CDT)<\/span><\/p>\n

\u00a0– Drop mechanism for WFQ<\/p>\n

\u00a0– If the queue is full and a new packet arrives for the queuethe the sequence number is calculated for the packet and the following happens<\/p>\n

\u00a0 \u00a0 \u00a0-> If the SN of the packet is the highest, then the packet is dropped<\/p>\n

\u00a0 \u00a0 \u00a0-> If there is another in any queue having a higher SN, then the packet with the higher SN is dropped<\/p>\n

CDT value = queue length = 64 by default<\/p>\n

Dynamic queues = 256 by default<\/p>\n

RSVP queues = 0 by default<\/p>\n

\u00a0 \u00a0 \u00a0-> Can be created to provide very low weight reserved queues for RSVP traffic<\/p>\n

WFQ Packet Limit = 4096 packets<\/p>\n

WFQ is the default for serial interfaces with clock rates lower than 2000kbps<\/p>\n

\u00a0– For other interfaces, FIFO is the default<\/p>\n

int fa0\/0<\/span><\/p>\n

\u00a0fair-queue [congestive-discard threshold [dynamic-queues [reservable-queues]]]<\/span><\/p>\n

hold-queue <number> out<\/span><\/p>\n

\u00a0 \u00a0 \u00a0-> Max number of packets that can be held in memory<\/p>\n

sh queueing fair<\/span><\/p>\n

sh int fa0\/0<\/span><\/p>\n","protected":false},"excerpt":{"rendered":"

QoS Weighted Fair Queueing (WFQ)<\/p>\n","protected":false},"author":1,"featured_media":569,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[6],"tags":[31,45],"class_list":["post-571","post","type-post","status-publish","format-standard","hentry","category-ccie","tag-published","tag-qos"],"_links":{"self":[{"href":"https:\/\/feralpacket.org\/index.php?rest_route=\/wp\/v2\/posts\/571","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/feralpacket.org\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/feralpacket.org\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/feralpacket.org\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/feralpacket.org\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=571"}],"version-history":[{"count":1,"href":"https:\/\/feralpacket.org\/index.php?rest_route=\/wp\/v2\/posts\/571\/revisions"}],"predecessor-version":[{"id":610,"href":"https:\/\/feralpacket.org\/index.php?rest_route=\/wp\/v2\/posts\/571\/revisions\/610"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/feralpacket.org\/index.php?rest_route=\/wp\/v2\/media\/569"}],"wp:attachment":[{"href":"https:\/\/feralpacket.org\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=571"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/feralpacket.org\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=571"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/feralpacket.org\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=571"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}