Message-ID: <20240111184451.48227-4-stephen@networkplumber.org>
Date: Thu, 11 Jan 2024 10:44:10 -0800
From: Stephen Hemminger <stephen@...workplumber.org>
To: netdev@...r.kernel.org
Cc: Stephen Hemminger <stephen@...workplumber.org>
Subject: [PATCH iproute2-next 3/4] doc: remove ifb README

Most of this document goes back to when IFB was first integrated
and covers the motivation. Only of historical interest.

Signed-off-by: Stephen Hemminger <stephen@...workplumber.org>
---
 doc/actions/ifb-README | 125 -----------------------------------------
 1 file changed, 125 deletions(-)
 delete mode 100644 doc/actions/ifb-README

diff --git a/doc/actions/ifb-README b/doc/actions/ifb-README
deleted file mode 100644
index 5fe91714671b..000000000000
--- a/doc/actions/ifb-README
+++ /dev/null
@@ -1,125 +0,0 @@
-
-IFB is intended to replace IMQ.
-Advantage over current IMQ; cleaner in particular in in SMP;
-with a _lot_ less code.
-
-Known IMQ/IFB USES
-------------------
-
-As far as i know the reasons listed below is why people use IMQ.
-It would be nice to know of anything else that i missed.
-
-1) qdiscs/policies that are per device as opposed to system wide.
-IFB allows for sharing.
-
-2) Allows for queueing incoming traffic for shaping instead of
-dropping. I am not aware of any study that shows policing is
-worse than shaping in achieving the end goal of rate control.
-I would be interested if anyone is experimenting.
-
-3) Very interesting use: if you are serving p2p you may want to give
-preference to your own locally originated traffic (when responses come back)
-vs someone using your system to do bittorent. So QoSing based on state
-comes in as the solution. What people did to achieve this was stick
-the IMQ somewhere prelocal hook.
-I think this is a pretty neat feature to have in Linux in general.
-(i.e not just for IMQ).
-But i won't go back to putting netfilter hooks in the device to satisfy
-this.  I also don't think its worth it hacking ifb some more to be
-aware of say L3 info and play ip rule tricks to achieve this.
---> Instead the plan is to have a conntrack related action. This action will
-selectively either query/create conntrack state on incoming packets.
-Packets could then be redirected to ifb based on what happens -> eg
-on incoming packets; if we find they are of known state we could send to
-a different queue than one which didn't have existing state. This
-all however is dependent on whatever rules the admin enters.
-
-At the moment this 3rd function does not exist yet. I have decided that
-instead of sitting on the patch for another year, to release it and then
-if there is pressure i will add this feature.
-
-An example, to provide functionality that most people use IMQ for below:
-
---------
-export TC="/sbin/tc"
-
-$TC qdisc add dev ifb0 root handle 1: prio
-$TC qdisc add dev ifb0 parent 1:1 handle 10: sfq
-$TC qdisc add dev ifb0 parent 1:2 handle 20: tbf rate 20kbit buffer 1600 limit 3000
-$TC qdisc add dev ifb0 parent 1:3 handle 30: sfq
-$TC filter add dev ifb0 protocol ip pref 1 parent 1: handle 1 fw classid 1:1
-$TC filter add dev ifb0 protocol ip pref 2 parent 1: handle 2 fw classid 1:2
-
-ifconfig ifb0 up
-
-$TC qdisc add dev eth0 ingress
-
-# redirect all IP packets arriving in eth0 to ifb0
-# use mark 1 --> puts them onto class 1:1
-$TC filter add dev eth0 parent ffff: protocol ip prio 10 u32 \
-match u32 0 0 flowid 1:1 \
-action ipt -j MARK --set-mark 1 \
-action mirred egress redirect dev ifb0
-
---------
-
-
-Run A Little test:
-
-from another machine ping so that you have packets going into the box:
------
-[root@...y action-tests]# ping 10.22
-PING 10.22 (10.0.0.22): 56 data bytes
-64 bytes from 10.0.0.22: icmp_seq=0 ttl=64 time=2.8 ms
-64 bytes from 10.0.0.22: icmp_seq=1 ttl=64 time=0.6 ms
-64 bytes from 10.0.0.22: icmp_seq=2 ttl=64 time=0.6 ms
-
---- 10.22 ping statistics ---
-3 packets transmitted, 3 packets received, 0% packet loss
-round-trip min/avg/max = 0.6/1.3/2.8 ms
-[root@...y action-tests]#
------
-Now look at some stats:
-
----
-[root@...ndrake]:~# $TC -s filter show parent ffff: dev eth0
-filter protocol ip pref 10 u32
-filter protocol ip pref 10 u32 fh 800: ht divisor 1
-filter protocol ip pref 10 u32 fh 800::800 order 2048 key ht 800 bkt 0 flowid 1:1
-  match 00000000/00000000 at 0
-        action order 1: tablename: mangle  hook: NF_IP_PRE_ROUTING
-        target MARK set 0x1
-        index 1 ref 1 bind 1 installed 4195sec  used 27sec
-         Sent 252 bytes 3 pkts (dropped 0, overlimits 0)
-
-        action order 2: mirred (Egress Redirect to device ifb0) stolen
-        index 1 ref 1 bind 1 installed 165 sec used 27 sec
-         Sent 252 bytes 3 pkts (dropped 0, overlimits 0)
-
-[root@...ndrake]:~# $TC -s qdisc
-qdisc sfq 30: dev ifb0 limit 128p quantum 1514b
- Sent 0 bytes 0 pkts (dropped 0, overlimits 0)
-qdisc tbf 20: dev ifb0 rate 20Kbit burst 1575b lat 2147.5s
- Sent 210 bytes 3 pkts (dropped 0, overlimits 0)
-qdisc sfq 10: dev ifb0 limit 128p quantum 1514b
- Sent 294 bytes 3 pkts (dropped 0, overlimits 0)
-qdisc prio 1: dev ifb0 bands 3 priomap  1 2 2 2 1 2 0 0 1 1 1 1 1 1 1 1
- Sent 504 bytes 6 pkts (dropped 0, overlimits 0)
-qdisc ingress ffff: dev eth0 ----------------
- Sent 308 bytes 5 pkts (dropped 0, overlimits 0)
-
-[root@...ndrake]:~# ifconfig ifb0
-ifb0    Link encap:Ethernet  HWaddr 00:00:00:00:00:00
-          inet6 addr: fe80::200:ff:fe00:0/64 Scope:Link
-          UP BROADCAST RUNNING NOARP  MTU:1500  Metric:1
-          RX packets:6 errors:0 dropped:3 overruns:0 frame:0
-          TX packets:3 errors:0 dropped:0 overruns:0 carrier:0
-          collisions:0 txqueuelen:32
-          RX bytes:504 (504.0 b)  TX bytes:252 (252.0 b)
------
-
-You send it any packet not originating from the actions it will drop them.
-[In this case the three dropped packets were ipv6 ndisc].
-
-cheers,
-jamal
-- 
2.43.0

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