|Revision 1.0||2004-04-23||Revised by: EJH|
|Final review complete. Document published to the LDP collection.|
|Revision 0.6||2004-04-19||Revised by: LKS|
|Thanks to Thomas Zimmerman <thomas (at) zimres net> for a language review! Updated to latest version number and added a section on plugin-support in OLSRd. Changed lisence back to GFDL|
|Revision 0.5||2004-03-08||Revised by: LKS|
|An almost complete rewrite. Adding OLSRd (old uOLSR), updated to RFC3626. Removed NROLSR and CRCOLSR. Converted to XML Docbook. Changed the license from GFDL to OPL due to some GFDL problems.|
|Revision 0.3||2003-08-05||Revised by: LKS|
This document describes the software and procedures to set up and use Optimized Link State Routing Protocol (OLSR) with IPv6 for Linux.
An English translation of ad-hoc is "For a particular purpose (improvised, made up in an instant)" (source: Wikipedia). An Ad-hoc network, or "spontaneous network", is especially useful when dealing with wireless devices in which some of the devices are part of the network only for the duration of a communications session and the need for a dynamic network topology is eminent. A "Mobile Ad hoc Network" is usually called a MANET.
" A MANET consists of mobile platforms (e.g., a router with multiple hosts and wireless communications devices)--herein simply referred to as 'nodes'--which are free to move about arbitrarily. The nodes may be located in or on airplanes, ships, trucks, cars, perhaps even on people or very small devices, and there may be multiple hosts per router. A MANET is an autonomous system of mobile nodes. The system may operate in isolation, or may have gateways to and interface with a fixed network." --- RFC2501: Mobile Ad hoc Networking (MANET), section 3 (page 3).
"OLSR is a proactive routing protocol for mobile ad hoc networks. The protocol inherits the stability of a link state algorithm and has the advantage of having routes immediately available when needed due to its proactive nature. OLSR is an optimization over the classical link state protocol, tailored for mobile ad hoc networks."
"OLSR is designed to work in a completely distributed manner and does not depend on any central entity. The protocol does NOT REQUIRE reliable transmission of control messages: each node sends control messages periodically, and can therefore sustain a reasonable loss of some such messages. Such losses occur frequently in radio networks due to collisions or other transmission problems." --- RFC3626: OLSR, section 1.3 (page 8)
"The Optimized Link State Routing Protocol (OLSR) is developed for mobile ad hoc networks. It operates as a table driven, proactive protocol, i.e., exchanges topology information with other nodes of the network regularly. Each node selects a set of its neighbor nodes as 'multi-point relays' (MPR). In OLSR, only nodes, selected as such MPRs, are responsible for forwarding control traffic, intended for diffusion into the entire network. MPRs provide an efficient mechanism for flooding control traffic by reducing the number of transmissions required." --- RFC3626: OLSR, section 1 (page 4)
The IEEE 802.11 standard defines two modes:
Infrastructure mode: The wireless network consist of at least one access point (AP) connected to the wired network and a set of wireless nodes (WN). This configuration is called a Basic Service Set (BSS). Extended Service Set (ESS) is a set of two or more BSSs (multiple cells).
Ad hoc mode: Also called "IEEE ad-hoc mode" or "peer-to-peer mode". This configuration is called Independent Basic Service Set (IBSS) and is useful for establishing a network where wireless infrastructure does not exist or where services are not required.
So why use OLSR when we can use "IEEE ad-hoc mode"? IEEE ad-hoc mode does NOT support multi-hop. See figure below
IP version 6 (IPv6) is a new version of the Internet Protocol, designed as the successor to IP version 4 (IPv4) [RFC-791]. The changes from IPv4 to IPv6 fall primarily into the following categories:
Expanded addressing capabilities
Header format simplification
Improved support for extensions and options
Flow labeling capability
Authentication and privacy capabilities
For more information on IPv6 in general, visit the IETF's IPv6 Working Group.
There are several OLSR implementation for Linux, but not all of them support IPv6. You should know how to enable and use IPv6 on Linux. Peter Bieringer has written an excellent Linux IPv6 HOWTO.
There is one OLSR implementation that is becoming the "standard" and most widely used. It goes by the descriptive name "OLSRd" (old Unik-OLSR).
OLSRd is an implementation based on the INRA C code, but has been almost completely rewritten, so there is not much left of the original INRA code (that mean it almost GPL). OLSRd also is under very rapid development, and if you report in a bug, it is usually fixed in a matter of hours.
OLSRd fully comply to the OLSR RFC, support for plugins, and it has an optional GUI interface (to see what's going on). The implementation also has a informative "up-to-date" web-page with links to mailing lists and papers.
There are up-to multiple new releases of OLSRd each month, so check the OLSRd web-site for the newest release.
The latest release as of this writing is 0.4.3, but by the time you read this there is almost certain a new release. Fetch the latest release from http://www.olsr.org/index.cgi?action=download.
Unpack, compile and install the source code:
# tar jxvf uolsrd-x.y.z # cd unik-olsrd-x.y.z # make # make install
The olsrd gets installed to /usr/bin/ and a default config file, olsrd.conf can be found under /etc
Check out the /etc/olsrd.conf config file, and change values to fit your system. All values in this file can be overridden with command line options to olsrd. The main options to change are:
# Debug level(0-9) # If set to 0 the daemon runs in the background DEBUG 1 # IP version to use (4 or 6) IPVERSION 6 # A list of whitespace separated interface names INTERFACES eth1
Later on, when you know OLSRd is configured correctly, you may set "DEBUG" to 0 to make it run in the background. You may then also add it to your init scripts. But to test that everything first, set this to at least 1 (setting this higher will produce a lot more info messages on APM, forwarding, parsing of the config file etc.)
When OLSRd is installed and configured, it can be started as root with:
All the settings in /etc/olsrd.conf can be overridden by command line options:
# olsrd -i eth1 -ipv6 -d 1
Would start olsrd listening on interface eth1 using IPv6 and with debug messages.
We start olsrd:
# olsrd -i eth1 -d 1 -ipv6 *** UniK olsrd-0.4.3 *** hello interval = 2.00 hello int nonwireless: = 4.00 tc interval = 5.00 polling interval = 0.10 neighbor_hold_time = 6.00 neighbor_hold_time_nw = 12.00 topology_hold_time = 15.00 tos setting = 16 hna_interval = 15.00 mid_interval = 5.00 Willingness set to 3 - next update in 20.000000 secs Using IP version 6 Using multicast address ff05::15 ---- Interface configuration ---- eth1: Address: fec0:106:2700::10 Multicast: ff05::15 Interface eth1 set up for use with index 0 Main address: fec0:106:2700::10 NEIGHBORS: l=linkstate, m=MPR, w=willingness Thread created - polling every 0.10 seconds neighbor list: 11:43:17.214807 neighbor list: 11:43:19.194967 neighbor list: 11:43:21.395046 neighbor list: 11:43:23.604800 neighbor list: 11:43:25.694875
Another thing worth noticing, is that an entry is added to our routing table:
# route -A inet6 Destination: Next Hop Flags Metric Ref Use Iface ... ff05::15/128 ff05::15 UAC 0 1 1 eth1 ...
This is the IPv6 multicast address OLSR is using to talk to other nodes running OLSR.
There is no point in using OLSRd on only one node, so we add some nodes. You will then see the "neighbor list" gets updated:
neighbor list: 12:55:14.733586 neighbor list: 12:55:18.803585 Willingness for fec0:106:2700::11 changed from 0 to 3 - UPDATING neighbor list: 12:55:22.763585 fec0:106:2700::11:l=0:m=0:w=3[2hlist:] neighbor list: 12:55:26.833589 fec0:106:2700::11:l=1:m=0:w=3[2hlist:] Willingness for fec0:106:2700::12 changed from 0 to 2 - UPDATING neighbor list: 12:55:30.903585 fec0:106:2700::12:l=0:m=0:w=2[2hlist:] fec0:106:2700::11:l=1:m=0:w=3[2hlist:] neighbor list: 12:55:34.863585 fec0:106:2700::12:l=0:m=0:w=2[2hlist:] fec0:106:2700::11:l=1:m=0:w=3[2hlist:] neighbor list: 12:55:39.153586 fec0:106:2700::12:l=1:m=0:w=2[2hlist:fec0:106:2700::11:] fec0:106:2700::11:l=1:m=0:w=3[2hlist:fec0:106:2700::12:] neighbor list: 12:55:43.443605 fec0:106:2700::12:l=1:m=0:w=2[2hlist:fec0:106:2700::11:] fec0:106:2700::11:l=1:m=0:w=3[2hlist:fec0:106:2700::12:]
You will also see the routing table is updated with the new hosts:
# route -A inet6 Destination: Next Hop Flags Metric Ref Use Iface ... fec0:106:2700::11/128 :: UH 1 0 0 eth1 fec0:106:2700::12/128 :: UH 1 0 0 eth1 ...
The real beauty of OLSR is when you add a bunch of nodes and move them around. You can still reach each one of them either directly (if they are close), or through other nodes.
When every node can reach every other node, it's no fun. Let's start moving the nodes, so that node "A" and "B" are out of (radio) range of each other. So when we move node "A" far enough away so that it can't hear node "C", all traffic must go through node "B":
Tip: Instead of physically moving the nodes around, you can use ip6tables. You can drop all packet using the MAC-address. You just need to block on one node:
# ip6tables -A INPUT -m mac --mac-source XX:XX:XX:XX:XX:XX -j DROP
The output from OLSRd on host A is then:
neighbor list: 13:22:35.693587 fec0:106:2700::11:l=1:m=1:w=3[2hlist:fec0:106:2700::12:] neighbor list: 13:22:40.093588 fec0:106:2700::11:l=1:m=1:w=3[2hlist:fec0:106:2700::12:] neighbor list: 13:22:44.053594 fec0:106:2700::11:l=1:m=1:w=3[2hlist:fec0:106:2700::12:] neighbor list: 13:22:48.233594 fec0:106:2700::11:l=1:m=1:w=3[2hlist:fec0:106:2700::12:] neighbor list: 13:22:52.193605 fec0:106:2700::11:l=1:m=1:w=3[2hlist:fec0:106:2700::12:]
The routing table also gets updated. For node A to reach node C it must go through node B:
# route -A inet6 Destination: Next Hop Flags Metric Ref Use Iface ... fec0:106:2700::11/128 :: UH 1 1 0 eth1 fec0:106:2700::12/128 fec0:106:2700::11 UGH 2 0 0 eth1 ...
" In order to provide this capability of injecting external routing information into an OLSR MANET, a node with such non-MANET interfaces periodically issues a Host and Network Association (HNA) message, containing sufficient information for the recipients to construct an appropriate routing table."
" An example of such a situation could be where a node is equipped with a fixed network (e.g., an Ethernet) connecting to a larger network as well as a wireless network interface running OLSR." --- RFC3626: OLSR, section 12 (page 51).
To have one node, act as a gateway and send out HNA messages, you must change the HNA6 in /etc/olsrd.conf:
# HNA IPv6 routes # syntax: netaddr prefix # Example Internet gateway HNA6 :: 0
When you start OLSRd, you will see the node is sending out HNA messages periodically:
... Sending HNA (48 bytes)... ...
When the other nodes receives a HNA message, they update their routing table:
# route -A inet6 Destination: Next Hop Flags Metric Ref Use Iface ... ::/0 fec0:106:2700::1 UG 1 0 0 eth1 ...
You may also have multiple nodes in a MANET to act as gateways (sending out HNA messages). Each mobile node then use the nearest gateway.
As of version 0.4.3 OLSRd also support plugins. Plugins may be used to add extended functionality in a MANET. If only a subset of the nodes knows how to interpret the messagetype, it will be forwarded by all the nodes by the "default forwarding algorithm" (see section 3.4.1 in the OLSR RFC). This way certain nodes may add special functionlity into OLSR.
As of this writing, two example plugins is included in the OLSRd release. One of these plugins add routing based on powerstatus. If one node has low battery, it can set its willingness lower and traffic may be routed through other nodes.
OLSRd also has an optional GUI, which can show a list of available nodes and grab packets. To compile the GUI front end, you must have GTK2. In unik-olsrd-x.y.z directory do:
# cd front-end # make # make install
Remember to start OLSRd with the -ipc switch or set IPC-CONNECT yes in /etc/olsrd.conf to enable the GUI to chat with OLSRd.
To see some examples of the use of GUI, check out http://www.olsr.org/index.cgi?action=gui
There is also other OLSR implementations, none have gained as much popularity as OLSRd, and none of them (except QOLSR?) are fully RFC compliant.
INRIA was one of the first(?) implementation of OLSR http://hipercom.inria.fr/olsr/#code. Their web-site has not been updated for quite a while, and the OLSR code you can download only complies to draft-ietf-manet-olsr-03.txt (it's now an RFC). There is suppose to be another more up-to-date version of INRIA olsr, but I have not found it. INRIA OLSR does not support IPv6.
The "US Naval Research Laboratory" (NRL) also has an OLSR implementation. It is written in C++, and has IPv6 support. http://pf.itd.nrl.navy.mil/projects/olsr/
CRCOLSR is a implementation based on the French INRIA code. It is is supposed to be maintained by "Communication Research Center" (CRC) in Canada. But as of this writing, there have been no new releases since April 3, 2003. http://pf.itd.nrl.navy.mil/projects/olsr/
Some of these question/answers are from the OLSRd site.
Yes. It even has implemented some of the extra functionality mentioned in the RFC. See the RFC Compliance section for complete list.
Yes. But keep in mind that they intentionally were not designed to be used at the same time. The network topology can be quite "messy" if you start using these two.
You probably don't have the GTK2.0 development libraries installed.
When a new gateway is detected, the Mobile Node checks the distance (number of hops) to this newly discovered gateway compared to the current gateway. If there is a shorter distance, this new gateway becomes the current (default) gateway. See section 12.6.2 in the OLSR RFC (RFC3626)
Most of the time this is a configuration error: Check the following:
If using WLAN interfaces make sure the ESSID/key match.
Make sure the cards are set in "ad-hoc" mode and not "managed".
Make sure you are not blocking UDP/698. If using netfilter run ip6tables -L as root to see what rules are set. ip6tables -F flushes all rules.
OLSRd (old uOLSR) http://www.olsr.org
Optimized Link State Routing Protocol (OLSR) RFC3626 http://www.ietf.org/rfc/rfc3626.txt
Mobile Ad hoc Networking (MANET) RFC2501 http://www.ietf.org/rfc/rfc3626.txt
Mobile Ad-hoc Networks (manet) Working Group (IETF) http://www.ietf.org/html.charters/manet-charter.html
Open Shortest Path First IGP (ospf) http://www.ietf.org/html.charters/ospf-charter.html
Protean Forge - OLSR software (CRC and NRL) http://pf.itd.nrl.navy.mil/projects/olsr/
INRIA OLSR http://hipercom.inria.fr/olsr/
IPv6 Working Group (IETF) http://www.ietf.org/html.charters/ipv6-charter.html
RFC2460 Internet Protocol, Version 6 (IPv6) Specification http://www.ietf.org/rfc/rfc2460.txt
Peter Bieringer's Linux IPv6 HOWTO (en) http://ldp.linux.no/HOWTO/Linux+IPv6-HOWTO/
Current Status of IPv6 Support for Networking Applications http://www.deepspace6.net/docs/ipv6_status_page_apps.html
Copyright (c) 2003, 2004 Lars Strand.
Permission is granted to copy, distribute and/or modify this document under the terms of the GNU Free Documentation License, Version 1.2 or any later version published by the Free Software Foundation; with no Invariant Sections, no Front-Cover Texts, and no Back-Cover Texts. A copy of the license is included in the section entitled "GNU Free Documentation License".
This document was originally written in LaTeX using Emacs. HTML version created with latex2html. Later it was converted to DocBook XML.
An up-to-date version of this document can be found at:
Suggestions, corrections, additions wanted. Contributors wanted and acknowledged. Flames not wanted.
I can always be reached at <lars at unik no>
This document was produced as a part of Interoperable Networks for Secure Communications (INSC task 6)
Thanks to Andreas Hafslund (andreha [at] unik no) for initial support. Also thanks to UniK (University Graduate Center) http://www.unik.no and FFI (Norwegian Defence Research Establishment) http://www.ffi.mil.no for hardware support.
Also thanks to Andreas Tønnesen (andreto [at] unik no) for technical help updating this howto
Thanks also to the other HOWTO authors whose works I have referenced:
Linux IPv6 HOWTO (en) by Peter Bieringer
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