networking - What's the difference between Flow Control and Congestion Control in TCP? -


what's difference between flow control , congestion control in tcp? can broken down 2 parts: 1) overall purpose of flow vs congestion control, , 2) how task accomplished?

according wikipedia, tcp flow control relies on window size reported in ack message. congestion control relies on acknowledgement messages. know difference between 2 goals, , how work.

as part 1, super general overview:

flow control controlled receiving side. ensures sender sends receiver can handle. think of situation fast fiber connection might sending on dialup or similar. sender have ability send packets quickly, useless receiver on dialup, need way throttle sending side can send. flow control deals mechanisms available ensure communication goes smoothly.

congestion control method of ensuring across network has "fair" amount of access network resources, @ given time. in mixed-network environment, needs able assume same general level of performance. common scenario understand office lan. have number of lan segments in office doing thing within lan, may need go out on wan link slower constituent lan segments. picture having 100mb connections within lan go out through 5mb wan link. kind of congestion control need in place there ensure there no issues across greater network.

as part 2:

if interview-prep question, said above, consider taking time read on tcp/ip in general. don't use wikipedia. rtfm! worth time. argue important protocol holding of modern internet.

things read flow control: stop , wait, sliding window, pause frames.

things read congestion control: qos (quality-of-service), retransmission policies, windowing policies.

beyond that, can search particular vendor implementations (cisco, etc..)


Comments

Post a Comment

Popular posts from this blog

linux - xterm copying to CLIPBOARD using copy-selection causes automatic updating of CLIPBOARD upon mouse selection -

i've tried various ways coerce xterm (versions 285 , 292) copy selection clipboard clipboard whenever press ctrl-shift-c. promising way far has been, in ~/.xresources, put this: xterm*vt100.translations: #override \ ctrl shift <keypress> c: copy-selection(clipboard) \n\ ctrl shift <keypress> v: insert-selection(clipboard) ctrl-shift-v works perfectly, copying has nuance... if restart xterm, highlighting text puts things in primary clipboard; expected, proper, default behavior. if hit ctrl-shift-c, copies current selection clipboard clipboard. the bug, however, if highlight text after first time pressed ctrl-shift-c, you'll see highlighting copies both primary and clipboard. cannot figure out how stop xterm updating clipboard upon selection... , doesn't make sense me in first place. i said, @ specific point in time, copy selection clipboard... yet starts updating automatically upon selection after doing once... anyone have workaround...
Read more

c++ - qgraphicsview horizontal scrolling always has a vertical delta -

Image
i've subclassed qgraphicsview custom canvas used in cad application. i've reimplemented qgraphicsview::wheelevent check keyboard modifiers control key and, if control key pressed, zoom. i'm trying implement horizontal scroll when user holds shift , uses wheel. the problem i'm having horizontal scrolling always scrolls 0.279. not huge problem, hugely annoying , points else being wrong. so, here questions: is right way implement horizontal scrolling? if not, is? how eliminate delta of 0.279? thanks in advance. code , sample output below void myview::zoom(int delta) { double factor = pow(1.2, delta/abs(delta)); this->scale(factor, factor); } void myview::scrollhorizontal(int level) { qpointf center = maptoscene(viewport()->rect().center()); qdebug() << "center: " << center.x() << ", " << center.y(); centeron(qpointf(center.x() - level, center.y())); } void myview::wheelevent(qwheeleve...
Read more