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This page has been created to document experimentations with the OLSR
[1] routing protocol on the Melbourne Wireless network.
GATEWAYING BETWEEN OSPF AND OLSR
As of 27th July 2006, OLSR is running on NodeGHO [2]. It is running
in parallel with Quagga/OSPF. The OLSRd and Quagga daemons cannot
currenly exchange routes satisfactorily, but it is possible to set up
routes to make a node "gateway" between OLSR and OSPF domains. The
specific configurations can be seen below in the example config files.
A node running both Quagga/OSPF and OLSR can send out supernet routes
that represent the whole network. By doing this, the node is saying to
other nodes on the network "if you don't have a route for an ip
address you are trying to reach, send your traffic to me". If a node
running only OSPF is trying to reach a node running only OLSR, it can
do so via the OLSR/OSPF gateway node. The reverse is also true.
The entire Melbourne Wireless network is represented by this address
range:
10.10.0.0/16
Another way of writing this is:
10.10.0.0 netmask 255.255.0.0
Both these ranges represent all ip addresses from 10.10.0.0 to
10.10.255.255.
A node running both OSPF and OLSR should send out a static route that
says "I have a route to the rest of the network". Routers always
prefer narrow-range routes to wide-range routes, so if a router has a
specific route to a node, it will ignore the gateway routes sent from
the OSPF/OLSR nodes.
Normally, to send a gateway route you'd choose the simplest route -
10.10.0.0/16. However, doing this would interfere with one of the more
interesting features of OLSR. On an OLSR node, one can set up a
network interface that has a netmask the same size as the entire
network. This allows direct communication between neighboring nodes
that have not previously arranged to link to each other. This is
called an Adhoc network. In a metropolitain community network, this is
a handy feature indeed.
In our current OSPF, fictional Node YYY has an IP address of
10.10.243.1 and Node ZZZ has an address of 10.10.255.250. In the
Melbourne Wireless netowork, nodes are given an allocation block
consisting of 14 usable IP addresses. This is a netmask of /28 or
255.255.255.240.
The allowed ip ranges for both nodes are as follows:
Node YYY
10.10.243.1
to
10.10.243.14
Node ZZZ
10.10.255.241
to
10.10.255.254
Nodes need to keep within their own IP allocations and not use IP
addresses outside these ranges unless they have made prior arrangement
with another node or are using automatic-address-assignment protocols
such as DHCP. In our current practice of using narrow nemasks, for
Nodes YYY and ZZZ to talk to each other they need to arrange to use
another IP address from either Node YYY or ZZZ's address pool. This is
the problem with using OSPF - it needs to be reconfigured each time a
node makes a new local link. And Quagga does not send routes for nodes
with overlapping netmasks - it consideres them to be on the local
link.
But in a wireless adhoc network, nodes with overlapping netmasks may
not be local to each other - it may take multiple hops for them to
reach each other. 802.11 IBSS (Adhoc) wireless ethernet nodes do not
relay packets at the ethernet layer, so two nodes that are out of
radio range cannot be considered "link local", even if there is a node
between the both of them. To communicate, the two nodes must route
their traffic via the intermediate node(s) at the IP layer. Management
of this process is done by routing protocol.
IP routing can still be used between nodes with overlapping netmasks.
OLSR sends out host routes - /32 (or 255.255.255.255) by default. /32
routes have priority over all other routes in a routing table because
they are the most narrow and specific route possible. So a wireless
interface can have a very wide /16 netmask and not interfere with
routing. But if a /16 static route is being propogated across the
network by OSPF or OLSR, it _will_ cause trouble on a node with a /16
interface netmask. To avoid this problem, we split the static /16
route into two /17 (or netmask 255.255.128.0) routes. They achieve the
same result as a /16, but both /17 routes will always have priority
over any /16 route.
NODE GHO CONFIGS
OLSR CONFIG
The vitals:
olsrd version
0.4.10
ETX Link Quality Metric
enabled - level 2
httpinfo plugin
enabled, all interfaces, port 1978
nameservice plugin
enabled
If you want to run OLSR and connect it to GHO, you need to make sure
you're compatible! You must have the LinkQualityLevel [3] set to 2,
and you should be running olsrd version 0.4.10. The other settings
aren't so important for compatibility, but you should copy them as
they have been optimised for a community wireless network like ours.
Don't forget to change the Interface paramater to the interfaces on
your box that you want to run OLSR on, and you should edit the
Nameservice plugin parameters to match the setup on your node.
For more info, please read the documentation:
OLSRd [4]
Nameservice plugin [5]
httpinfo plugin [6]
example olsrd.conf file [7]
For those using Freifunk Firmware [8], under the OLSR settings
everything should be Enabled except for Hysteresis and DynGW [9].
OLSR Config file, with extra comments by DanFlett [10]
/ETC/OLSRD.CONF
#0 = run in background (daemon) #1 or above = output messages with
increasing verbosity DebugLevel [11] 0 IpVersion [12] 4 ClearScreen
[13] yes # Host Network Announcement # - static routes to be
distributed by OLSR # - until a more elegant solution is developed, #
nodes that are running OSPF and OLSR together # should inject static
network gateway routes into both # OLSR and OSPF - this allows
OSPF-only and OLSR-only # nodes to reach each other # - the whole of
the melbourne wireless network # is 10.10.0.0/16. Here, and in OSPF it
has # been split into two /17 routes # this has been done to ensure
that these routes # have priority over the /16 interface route that #
an adhoc/omni OLSR interface would use Hna4 { 10.10.0.0 255.255.128.0
10.10.128.0 255.255.128.0 } AllowNoInt [14] yes UseHysteresis [15] no
#Everyone MUST set their LinkQualityLevel [16] to 2! LinkQualityLevel
[17] 2 LinkQualityWinSize [18] 100 Pollrate 0.05 TcRedundancy [19] 2
MprCoverage [20] 7 LinkQualityFishEye [21] 1 LinkQualityDijkstraLimit
[22] 0 5.0 #The Network Interface(s) that OLSRd talks on Interface
"vlan0" "vlan1" "vlan2" "vlan3" "vlan4" { HelloInterval [23] 5.0
HelloValidityTime [24] 200.0 TcInterval [25] 0.5 TcValidityTime [26]
260.0 MidValidityTime [27] 100.0 HnaValidityTime [28] 100.0 } #Runs a
tiny webserver on port 1978 with OLSR route info LoadPlugin [29]
"olsrd_httpinfo.so.0.1" { PlParam [30] "port" "1978" PlParam [31]
"Net" "0.0.0.0 0.0.0.0" } #Announces this node's name and address via
OLSR messages #it writes any upstream (i.e. Internet-connected) #DNS
servers to /tmp/resolv.conf #it reads any static entries from
/etc/hosts.static #and it writes any hosts entries to /tmp/hosts.olsr
#/tmp/hosts.olsr is symlinked from /etc/hosts #Other nodes must be
runnning OLSRd with the nameservice plugin #to be able to receive
these messages LoadPlugin [32] "olsrd_nameservice.so.0.2" { PlParam
[33] "name" "nodegho" PlParam [34] "add-hosts" "/etc/hosts.static"
PlParam [35] "hosts-file" "/tmp/hosts.olsr" PlParam [36] "resolv-file"
"/tmp/resolv.conf" }
QUAGGA CONFIG
- edited to add static routes
_null0_ is a blackhole route - if a route can't be found, it goes
into the blackhole and the source node gets the message "destination
unreachable"
/ETC/QUAGGA/ZEBRA.CONF
hostname nodegho password ****** enable password ****** log syslog !
ip route 10.10.0.0 255.255.128.0 null0 ip route 10.10.128.0
255.255.128.0 null0 !
Note that ospfd.conf does not need to be edited - all we need to do
is add static routes to the OSPF domain and that is done in zebra.conf
with the ip route command.
Links:
------
[1] http:///www.olsr.org
[2] http://melbournewireless.org.au/?NodeGHO
[3] http://melbournewireless.org.au/?LinkQualityLevel
[4]
http://olsrd.cvs.sourceforge.net/*checkout*/olsrd/olsrd-current/README
[5]
http://olsrd.cvs.sourceforge.net/*checkout*/olsrd/olsrd-current/lib/nameservice/README
[6]
http://olsrd.cvs.sourceforge.net/*checkout*/olsrd/olsrd-current/lib/httpinfo/README_HTTPINFO
[7]
http://olsrd.cvs.sourceforge.net/*checkout*/olsrd/olsrd-current/files/olsrd.conf.default.lq-fisheye
[8] http://freifunk.net/wiki/FreifunkFirmwareEnglish
[9] http://melbournewireless.org.au/?DynGW
[10] http://melbournewireless.org.au/?DanFlett
[11] http://melbournewireless.org.au/?DebugLevel
[12] http://melbournewireless.org.au/?IpVersion
[13] http://melbournewireless.org.au/?ClearScreen
[14] http://melbournewireless.org.au/?AllowNoInt
[15] http://melbournewireless.org.au/?UseHysteresis
[16] http://melbournewireless.org.au/?LinkQualityLevel
[17] http://melbournewireless.org.au/?LinkQualityLevel
[18] http://melbournewireless.org.au/?LinkQualityWinSize
[19] http://melbournewireless.org.au/?TcRedundancy
[20] http://melbournewireless.org.au/?MprCoverage
[21] http://melbournewireless.org.au/?LinkQualityFishEye
[22] http://melbournewireless.org.au/?LinkQualityDijkstraLimit
[23] http://melbournewireless.org.au/?HelloInterval
[24] http://melbournewireless.org.au/?HelloValidityTime
[25] http://melbournewireless.org.au/?TcInterval
[26] http://melbournewireless.org.au/?TcValidityTime
[27] http://melbournewireless.org.au/?MidValidityTime
[28] http://melbournewireless.org.au/?HnaValidityTime
[29] http://melbournewireless.org.au/?LoadPlugin
[30] http://melbournewireless.org.au/?PlParam
[31] http://melbournewireless.org.au/?PlParam
[32] http://melbournewireless.org.au/?LoadPlugin
[33] http://melbournewireless.org.au/?PlParam
[34] http://melbournewireless.org.au/?PlParam
[35] http://melbournewireless.org.au/?PlParam
[36] http://melbournewireless.org.au/?PlParam
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