Mininet on OpenBSD. Using rdomains for Interactive SDN Testing and Development. Ayaka Koshibe. AsiaBSDCon

Transcription

1 Mininet on OpenBSD Using rdomains for Interactive SDN Testing and Development Ayaka Koshibe AsiaBSDCon 2018

2 SDN? Network split into programmable nodes that handle traffic and entities that program them applications northbound API control plane controller(s) control channel datapath(s) data plane

3 OpenFlow A control channel protocol standardized by the ONF datapath follows flow rules installed on one or more flow tables flow/match: traffic class defined by packet header pattern action: output to port/group, rewrite field, search another table... controller discovers datapath features from initial handshake, state from requests

4 OpenBSD and SDN OpenBSD has its own OpenFlow 1.3 SDN stack since 6.1 switch(4): datapath switchn has /dev/switchn as its control channel switchd(8): controller implements flow forwarding logic can forward control messages to other controllers switchctl(8): control application for switchd(8)

5 Scenario You are an SDN developer. How do you test your work? hardware testbeds? personal dev environment?

6 Mininet An Emulator for rapid prototyping of Software Defined Networks mn command to launch networks and run tests a set of APIs for scripting topologies and test scenarios CLI for topologies topology creation GUI (MiniEdit)

7 Basic Usage: mn command Quick testing with built-in tests (ping, iperf) ping among hosts across a chain of three switches: # mn topo=l i n e a r, 3 t e s t=p i n g a l l C r e a t i n g network Adding c o n t r o l l e r (... s t a r t u p o u tput ) Ping : t e s t i n g p i n g r e a c h a b i l i t y h1 > h2 h3 h2 > h1 h3 h3 > h1 h2 R e s u l t s : 0% dropped (6/6 r e c e i v e d ) (... teardown o u t p ut ) completed i n seconds

8 Basic Usage: CLI Launch a CLI to manipulate topology break links, run commands in nodes... # mn topo=l i n e a r, 3 v e r b o s i t y=o u tput m i n i n e t > l i n k s1 s2 down m i n i n e t > p i n g a l l Ping : t e s t i n g p i n g r e a c h a b i l i t y h1 > X X h2 > X h3 h3 > X h2 R e s u l t s : 66% dropped (2/6 r e c e i v e d ) m i n i n e t > l i n k s1 s2 up m i n i n e t > m i n i n e t > h1 p i n g c 1 h2 PING ( ) 56(84) b y t e s o f data. 64 b y t e s from : i c m p s e q=1 t t l =64 time =3.97 ms p i n g s t a t i s t i c s 1 p a c k e t s t r a n s m i t t e d, 1 r e c e i v e d, 0% p a c k e t l o s s, time 0ms r t t min/ avg /max/mdev = / / / ms m i n i n e t >

9 Basic Usage: Python API Create a custom topology: $ c a t t e s t. py #!/ u s r / b i n / env python # example u s i n g high l e v e l API from m i n i n e t. topo i m p o r t Topo from m i n i n e t. n e t i m p o r t M i n i n e t from m i n i n e t. c l i i m p o r t CLI c l a s s MinimalTopo ( Topo ) : d e f b u i l d ( s e l f ) : h1 = s e l f. addhost ( h1 ) h2 = s e l f. addhost ( h2 ) s1 = s e l f. addswitch ( s1 ) #. / t e s t. py m i n i n e t > nodes a v a i l a b l e nodes a r e : c0 h1 h2 s1 m i n i n e t > l i n k s h1 eth0< >s1 eth1 (OK OK) h2 eth0< >s1 eth2 (OK OK) m i n i n e t > s e l f. addlink ( h1, s1 ) s e l f. addlink ( h2, s1 ) net = Mininet ( topo=minimaltopo ( ) ) n e t. s t a r t ( ) CLI ( n e t ) n e t. s t o p ( )

10 Basic Usage: Python API Run commands for experiments: cmd(): run commands on a node quietrun(): run commands against the network # b u i l d network o f two h o s t s : h1 h2 ( mid l e v e l API example ) net = Mininet ( ) h1 = n e t. addhost ( h1 ) h2 = n e t. addhost ( h2 ) n e t. addlink ( h1, h2 ) n e t. s t a r t ( ) # s t a r t s i m p l e s e r v e r i n h2 and f e t c h page from h1 h2. cmd ( python m SimpleHTTPServer 80 & ) s l e e p ( 2 ) p r i n t ( h1. cmd ( c u r l, h2. IP ( ) ) ) # p r i n t i n t e r f a c e s on t h e h o s t and e x i t p r i n t ( quietrun ( i p l i n k ) ) n e t. s t o p ( )

11 Development Workflow I have a... controller/application: use a topology pointed at a running instance mn --controller=remote,ip=x.x.x.x,port=y net.addcontroller(controller=remotecontroller) add a custom controller node (--controller=myctl) switch: add a custom vswitch node (--switch=myswitch) use a topology with a physical port wired to a switch

12 Internals: Mininet objects Mininet : coordinates the emulation process Topo : graph of nodes, ports(intfs), and links Node : bash running interactively in network namespace Intf : virtual ethernet (veth) interfaces Link : pairs of Intfs created/configured with iproute2 Switch : nodes running vswitches OpenvSwitch(default), ofsoftswitch13, Linux bridge... Controller : nodes running controller applications Stanford reference controller(default), Ryu, Nox...

13 Internals: Topology creation C r e a t i n g network Adding c o n t r o l l e r Adding h o s t s : Adding s w i t c h e s : mnexec bash n o r c i s m i n i n e t : c0 ( r e p e a t f o r h1, h2, s1 ) Adding l i n k s : i p l i n k add name s1 eth1 type veth peer name h1 eth0 i p l i n k s e t s1 eth1 n e t n s <s1> i p l i n k s e t h1 eth0 n e t n s <h1> i f c o n f i g s1 eth1 up i f c o n f i g h1 eth0 up ( r e p e a t f o r s1 eth2 < > h2 eth0 ) C o n f i g u r i n g h o s t s i f c o n f i g h1 eth / 8 up ( r e p e a t f o r h2 eth0 a t ) S t a r t i n g c o n t r o l l e r ( i n c0 ) c o n t r o l l e r v ptcp : >/tmp/ c0. l o g 2>/tmp/ c0. l o g & S t a r t i n g 1 s w i t c h e s ( i n s1 ) ovs v s c t l c r e a t e C o n t r o l l e r t a r g e t = t c p : : S t a r t i n g CLI : m i n i n e t >

14 Initial goals recreate core features ( base Mininet) topology emulation, CLI, remote controller switchd(8) and switch(4) incorporated as nodes aim to eventually get it upstreamed preserve Linux support (for github fork)

15 Minimum requirements network virtualization (separate address space), L2 and up vswitches and controllers for nodes applications for baseline tests

16 rdomain(4) and pair(4) a routing domain provides separate network address spaces recieves traffic via interfaces attached to them can restrict a process and descendants to its address space a pair(4) interface pairs with another to form endpoints of a virtual Ethernet link can be attached to an rdomain

17 Implementation: Mininet objects Node: ksh running in a routing domain Switch: node dedicated to a switch(4) instance switchd in forwarding mode for RemoteController case Controller: node running switchd(8) uses Mininet-specific switchd.conf(5) Link: two patched pair(4)s

18 Implementation: A comparison Linux OpenBSD Hosts bash ksh setns(mnexec) route Links veth pair iproute2(ip link) ifconfig Switches OVS switch ovs-vsctl/ovs-ofctl switchctl, ifconfig Controllers controller switchd + switchctl Bridges Linux bridge bridge brctl ifconfig

19 Topology creation revisited C r e a t i n g network Adding c o n t r o l l e r Adding h o s t s : Adding s w i t c h e s : r o u t e T <rdomain> e x e c / b i n / ksh i s m i n i n e t : c0 ( r e p e a t f o r h1, h2, s1 ) Adding l i n k s : i f c o n f i g p a i r 1 c r e a t e rdomain <s1> up i f c o n f i g p a i r 2 c r e a t e rdomain <h1> patch p a i r 1 up i f c o n f i g p a i r 1 d e s c r i p t i o n s1 eth1 i f c o n f i g p a i r 2 d e s c r i p t i o n h1 eth0 ( r e p e a t f o r p a i r 3 / s1 eth2 < > p a i r 4 /h2 eth0 ) C o n f i g u r i n g h o s t s i f c o n f i g p a i r / 8 up ( r e p e a t f o r p a i r 4 a t ) S t a r t i n g c o n t r o l l e r s w i t c h d f / e t c / s w i t c h d. m i n i n e t. c o n f D c t l i p = D p o r t =6653 S t a r t i n g 1 s w i t c h e s i f c o n f i g s w i t c h 0 c r e a t e d e s c r i p t i o n s1 up i f c o n f i g s w i t c h 0 add p a i r 1 add p a i r 3 s w i t c h c t l c o n n e c t / dev / s w i t c h 0 S t a r t i n g CLI : m i n i n e t >

20 Implementation: Multiple platform support Nodes and Intfs per OS - API for OS-specific commands BaseNode getshell : start host shell for a node popen : run commands tied to a node BaseIntf makeintfpair : create virtual link endpoints moveintfpair : attach endpoints to nodes rename : rename interfaces for book-keeping in topology

21 Implementation: Multiple platform support Mid/high-level APIs largely untouched CLI, topology construction (Topo, Mininet) kept as-is mn untouched other than addition of new node types $ doas. / t e s t. py m i n i n e t > nodes a v a i l a b l e nodes a r e : c0 h1 h2 s1 m i n i n e t > l i n k s h1 eth0< >s1 eth1 (OK OK) h2 eth0< >s1 eth2 (OK OK) m i n i n e t > m i n i n e t > dump <Host h1 : h1 eth0 : p i d =79277> <Host h2 : h2 eth0 : p i d =58592> <I f S w i t c h s1 : l o 0 : , s1 eth1 : None, s1 eth2 : None p i d =56473> <Switchd c0 : : p i d =92044> m i n i n e t >

22 Implementation: Some weirdness the ksh prompt for root and cmd() visibility assumptions of a namespace renaming interfaces topology startup order

23 Current status Core features are done (barring bugs) A longer list of to-dos... untested/unported: MiniEdit resource-limited links and nodes (cgroups, tc, iptables) tons of example scripts other controllers/vswitches? don t always run as root upstreaming...

24 Availability net/mininet, available since Aug 2017 github fork (also with FreeBSD, Linux support):

25 Acknowlegements Special thanks to: Bob Lantz, Mininet developer for insight into Mininet and interest in having it ported, Reyk Flöter for introductions to switch and switchd and pointers to rdomains, Kazuya Goda for insight into switchd s forwarding features, Peter Hessler (phessler@) for the crash course on port creation, mentorship, and suggesting this paper topic.

26 Questions?