218 lines
11 KiB
Plaintext
218 lines
11 KiB
Plaintext
COLO-proxy
|
|
----------
|
|
Copyright (c) 2016 Intel Corporation
|
|
Copyright (c) 2016 HUAWEI TECHNOLOGIES CO., LTD.
|
|
Copyright (c) 2016 Fujitsu, Corp.
|
|
|
|
This work is licensed under the terms of the GNU GPL, version 2 or later.
|
|
See the COPYING file in the top-level directory.
|
|
|
|
This document gives an overview of COLO proxy's design.
|
|
|
|
== Background ==
|
|
COLO-proxy is a part of COLO project. It is used
|
|
to compare the network package to help COLO decide
|
|
whether to do checkpoint. With COLO-proxy's help,
|
|
COLO greatly improves the performance.
|
|
|
|
The filter-redirector, filter-mirror, colo-compare
|
|
and filter-rewriter compose the COLO-proxy.
|
|
|
|
== Architecture ==
|
|
|
|
COLO-Proxy is based on qemu netfilter and it's a plugin for qemu netfilter
|
|
(except colo-compare). It keep Secondary VM connect normally to
|
|
client and compare packets sent by PVM with sent by SVM.
|
|
If the packet difference, notify COLO-frame to do checkpoint and send
|
|
all primary packet has queued. Otherwise just send the queued primary
|
|
packet and drop the queued secondary packet.
|
|
|
|
Below is a COLO proxy ascii figure:
|
|
|
|
Primary qemu Secondary qemu
|
|
+--------------------------------------------------------------+ +----------------------------------------------------------------+
|
|
| +----------------------------------------------------------+ | | +-----------------------------------------------------------+ |
|
|
| | | | | | | |
|
|
| | guest | | | | guest | |
|
|
| | | | | | | |
|
|
| +-------^--------------------------+-----------------------+ | | +---------------------+--------+----------------------------+ |
|
|
| | | | | ^ | |
|
|
| | | | | | | |
|
|
| | +------------------------------------------------------+ | | | |
|
|
|netfilter| | | | | | netfilter | | |
|
|
| +----------+ +----------------------------+ | | | +-----------------------------------------------------------+ |
|
|
| | | | | | out | | | | | | filter excute order | |
|
|
| | | | +-----------------------------+ | | | | | | +-------------------> | |
|
|
| | | | | | | | | | | | | | TCP | |
|
|
| | +-----+--+-+ +-----v----+ +-----v----+ |pri +----+----+sec| | | | +------------+ +---+----+---v+rewriter++ +------------+ | |
|
|
| | | | | | | | |in | |in | | | | | | | | | | | | |
|
|
| | | filter | | filter | | filter +------> colo <------+ +--------> filter +--> adjust | adjust +--> filter | | |
|
|
| | | mirror | |redirector| |redirector| | | compare | | | | | | redirector | | ack | seq | | redirector | | |
|
|
| | | | | | | | | | | | | | | | | | | | | | | |
|
|
| | +----^-----+ +----+-----+ +----------+ | +---------+ | | | | +------------+ +--------+--------------+ +---+--------+ | |
|
|
| | | tx | rx rx | | | | | tx all | rx | |
|
|
| | | | | | | | +-----------------------------------------------------------+ |
|
|
| | | +--------------+ | | | | | |
|
|
| | | filter excute order | | | | | | |
|
|
| | | +----------------> | | | +--------------------------------------------------------+ |
|
|
| +-----------------------------------------+ | | |
|
|
| | | | | |
|
|
+--------------------------------------------------------------+ +----------------------------------------------------------------+
|
|
|guest receive | guest send
|
|
| |
|
|
+--------+----------------------------v------------------------+
|
|
| | NOTE: filter direction is rx/tx/all
|
|
| tap | rx:receive packets sent to the netdev
|
|
| | tx:receive packets sent by the netdev
|
|
+--------------------------------------------------------------+
|
|
|
|
1.Guest receive packet route:
|
|
|
|
Primary:
|
|
|
|
Tap --> Mirror Client Filter
|
|
Mirror client will send packet to guest,at the
|
|
same time, copy and forward packet to secondary
|
|
mirror server.
|
|
|
|
Secondary:
|
|
|
|
Mirror Server Filter --> TCP Rewriter
|
|
If receive packet is TCP packet,we will adjust ack
|
|
and update TCP checksum, then send to secondary
|
|
guest. Otherwise directly send to guest.
|
|
|
|
2.Guest send packet route:
|
|
|
|
Primary:
|
|
|
|
Guest --> Redirect Server Filter
|
|
Redirect server filter receive primary guest packet
|
|
but do nothing, just pass to next filter.
|
|
|
|
Redirect Server Filter --> COLO-Compare
|
|
COLO-compare receive primary guest packet then
|
|
waiting scondary redirect packet to compare it.
|
|
If packet same,send queued primary packet and clear
|
|
queued secondary packet, Otherwise send primary packet
|
|
and do checkpoint.
|
|
|
|
COLO-Compare --> Another Redirector Filter
|
|
The redirector get packet from colo-compare by use
|
|
chardev socket.
|
|
|
|
Redirector Filter --> Tap
|
|
Send the packet.
|
|
|
|
Secondary:
|
|
|
|
Guest --> TCP Rewriter Filter
|
|
If the packet is TCP packet,we will adjust seq
|
|
and update TCP checksum. Then send it to
|
|
redirect client filter. Otherwise directly send to
|
|
redirect client filter.
|
|
|
|
Redirect Client Filter --> Redirect Server Filter
|
|
Forward packet to primary.
|
|
|
|
== Components introduction ==
|
|
|
|
Filter-mirror is a netfilter plugin.
|
|
It gives qemu the ability to mirror
|
|
packets to a chardev.
|
|
|
|
Filter-redirector is a netfilter plugin.
|
|
It gives qemu the ability to redirect net packet.
|
|
Redirector can redirect filter's net packet to outdev,
|
|
and redirect indev's packet to filter.
|
|
|
|
filter
|
|
+
|
|
redirector |
|
|
+--------------+
|
|
| | |
|
|
| | |
|
|
| | |
|
|
indev +---------+ +----------> outdev
|
|
| | |
|
|
| | |
|
|
| | |
|
|
+--------------+
|
|
|
|
|
v
|
|
filter
|
|
|
|
COLO-compare, we do packet comparing job.
|
|
Packets coming from the primary char indev will be sent to outdev.
|
|
Packets coming from the secondary char dev will be dropped after comparing.
|
|
COLO-compare needs two input chardevs and one output chardev:
|
|
primary_in=chardev1-id (source: primary send packet)
|
|
secondary_in=chardev2-id (source: secondary send packet)
|
|
outdev=chardev3-id
|
|
|
|
Filter-rewriter will rewrite some of secondary packet to make
|
|
secondary guest's tcp connection established successfully.
|
|
In this module we will rewrite tcp packet's ack to the secondary
|
|
from primary,and rewrite tcp packet's seq to the primary from
|
|
secondary.
|
|
|
|
== Usage ==
|
|
|
|
Here is an example using demonstration IP and port addresses to more
|
|
clearly describe the usage.
|
|
|
|
Primary(ip:3.3.3.3):
|
|
-netdev tap,id=hn0,vhost=off,script=/etc/qemu-ifup,downscript=/etc/qemu-ifdown
|
|
-device e1000,id=e0,netdev=hn0,mac=52:a4:00:12:78:66
|
|
-chardev socket,id=mirror0,host=3.3.3.3,port=9003,server,nowait
|
|
-chardev socket,id=compare1,host=3.3.3.3,port=9004,server,nowait
|
|
-chardev socket,id=compare0,host=3.3.3.3,port=9001,server,nowait
|
|
-chardev socket,id=compare0-0,host=3.3.3.3,port=9001
|
|
-chardev socket,id=compare_out,host=3.3.3.3,port=9005,server,nowait
|
|
-chardev socket,id=compare_out0,host=3.3.3.3,port=9005
|
|
-object iothread,id=iothread1
|
|
-object filter-mirror,id=m0,netdev=hn0,queue=tx,outdev=mirror0
|
|
-object filter-redirector,netdev=hn0,id=redire0,queue=rx,indev=compare_out
|
|
-object filter-redirector,netdev=hn0,id=redire1,queue=rx,outdev=compare0
|
|
-object colo-compare,id=comp0,primary_in=compare0-0,secondary_in=compare1,outdev=compare_out0,iothread=iothread1
|
|
|
|
Secondary(ip:3.3.3.8):
|
|
-netdev tap,id=hn0,vhost=off,script=/etc/qemu-ifup,down script=/etc/qemu-ifdown
|
|
-device e1000,netdev=hn0,mac=52:a4:00:12:78:66
|
|
-chardev socket,id=red0,host=3.3.3.3,port=9003
|
|
-chardev socket,id=red1,host=3.3.3.3,port=9004
|
|
-object filter-redirector,id=f1,netdev=hn0,queue=tx,indev=red0
|
|
-object filter-redirector,id=f2,netdev=hn0,queue=rx,outdev=red1
|
|
-object filter-rewriter,id=f3,netdev=hn0,queue=all
|
|
|
|
If you want to use virtio-net-pci or other driver with vnet_header:
|
|
|
|
Primary(ip:3.3.3.3):
|
|
-netdev tap,id=hn0,vhost=off,script=/etc/qemu-ifup,downscript=/etc/qemu-ifdown
|
|
-device e1000,id=e0,netdev=hn0,mac=52:a4:00:12:78:66
|
|
-chardev socket,id=mirror0,host=3.3.3.3,port=9003,server,nowait
|
|
-chardev socket,id=compare1,host=3.3.3.3,port=9004,server,nowait
|
|
-chardev socket,id=compare0,host=3.3.3.3,port=9001,server,nowait
|
|
-chardev socket,id=compare0-0,host=3.3.3.3,port=9001
|
|
-chardev socket,id=compare_out,host=3.3.3.3,port=9005,server,nowait
|
|
-chardev socket,id=compare_out0,host=3.3.3.3,port=9005
|
|
-object filter-mirror,id=m0,netdev=hn0,queue=tx,outdev=mirror0,vnet_hdr_support
|
|
-object filter-redirector,netdev=hn0,id=redire0,queue=rx,indev=compare_out,vnet_hdr_support
|
|
-object filter-redirector,netdev=hn0,id=redire1,queue=rx,outdev=compare0,vnet_hdr_support
|
|
-object colo-compare,id=comp0,primary_in=compare0-0,secondary_in=compare1,outdev=compare_out0,vnet_hdr_support
|
|
|
|
Secondary(ip:3.3.3.8):
|
|
-netdev tap,id=hn0,vhost=off,script=/etc/qemu-ifup,down script=/etc/qemu-ifdown
|
|
-device e1000,netdev=hn0,mac=52:a4:00:12:78:66
|
|
-chardev socket,id=red0,host=3.3.3.3,port=9003
|
|
-chardev socket,id=red1,host=3.3.3.3,port=9004
|
|
-object filter-redirector,id=f1,netdev=hn0,queue=tx,indev=red0,vnet_hdr_support
|
|
-object filter-redirector,id=f2,netdev=hn0,queue=rx,outdev=red1,vnet_hdr_support
|
|
-object filter-rewriter,id=f3,netdev=hn0,queue=all,vnet_hdr_support
|
|
|
|
Note:
|
|
a.COLO-proxy must work with COLO-frame and Block-replication.
|
|
b.Primary COLO must be started firstly, because COLO-proxy needs
|
|
chardev socket server running before secondary started.
|
|
c.Filter-rewriter only rewrite tcp packet.
|