bmx6

!bmx6.png!

Bmx6 is a routing protocol for Linux based operating systems.

The following intro provides kind of tutorial to get started.

{{>toc}}

h2. Installation

h3. Requirements

The following tools are needed to obtain, compile, and install bmx6

* git (debian package: git-core)

* gcc

* make

h3. Downloading

Latest development sources are available from bmx6 git repository

<pre>

git clone git://qmp.cat/bmx6.git

cd bmx6

</pre>

h3. Compile and Install

To only compile the main bmx6 daemon (no bmx6 plugins)

<pre>

make

sudo make install

</pre>

h2. Installing in OpenWRT 

Bmx6 is currently in the official routing feed of OpenWRT, so to install it from a existing system you can use opkg

    opkg install bmx6 bmx6-uci-config

h3. Compile it by adding a feed

If you are compiling your own OpenWRT, you can add the routing feed (already enabled by default) which can be found here

     https://github.com/openwrt-routing/packages

Then run "make menuconfig" and select the bmx6 package in _Networking -> Routing and redirection_

It is recommended to select also, at least, the uci plugin (bmx6-uci-config)

You can select "luci-app-bmx6" to have a nice web interface for manage and monitorize the routing daemon.

Finally type "make" to build the image.

h2. Usage (hello mesh)

h3. Starting

In its most simple configuration, the only required parameter are the interfaces names that should be used for meshing.

The following example starts bmx6 on interface wlan0:

<pre>

root@mlc1001:~# bmx6 dev=eth1

</pre>

However, to let this simple command work as expected also check the following basic requirements:

* bmx6 must be executed in root context (with super user permissions). If you are not already root, prepend all commands with sudo (eg: @ sudo bmx6 dev=eth1 @ ).

* NO IP address needs to be configured. By default bmx6 assumes IPv6 and autoconfigures an ULA based IPv6 address for each interface based on the MAC address of the device. Just, the interfaces must be UP. The linux ip command can do this for you (eg: @ ip link set wlan0 up @). Also, if you are using a wireless interface, the wireless interface settings must be set correctly so that link-layer connectivity is given with bmx6 daemons running on other nodes (computers). The good old iwconfig command may help to achieve that. For example @ iwconfig wlan0 mode ad-hoc ap 02:ca:ff:ee:ba:be channel 11 essid my-mesh-network @ is a typical configuration for a wireless mesh setup.

* Bmx6 (by default) works in daemon mode, thus sends itself to background and gives back a prompt. To let it run in foreground specify a debug level with the startup command like: @ bmx6 debug=0 dev=eth1 @ . Of course you may need to kill a previously started bmx6 daemon beforehand (@ killall bmx6 @)

If everything went fine bmx6 is running now, searching for neighboring bmx6 daemons via the configured interface (link), and coordinates with them to learn about existence-of and routes-to all other bmx6 nodes in the network.

h3. Accessing Protocol Events, Status, and Network Information

To access debug and status information of the bmx6 daemon which has just been started, a second bmx6 process can be launched in client mode (with the --connect or -c parameter) to connect to the main bmx6 daemon and retrieve the desired information.

In the following, a few example will be discussed

Continuous debug levels with different verbosity and scope are accessible with the --debug or -d parameter.

* Debug level 0 only reports critical events

* Debug level 3 reports relevant changes and 

* Debug level 4 reports everything.

* Debug level 12 dump in and outgoing protocol traffic

Eg.: @ bmx6 -cd3 @ connects a bmx6 client process to debug-level 3 of the main daemon and logs the output stdout until terminated with ctrl-c

Status, network, and statistic information are accessible with dedicated parameters:

* status

* interfaces

* links

* originators

* descriptions, plus optional sub-parameters for filtering

* tunnels

* traffic=DEV where DEV:= all or eth1, ....

<pre>

root@mlc1001:~# bmx6 -c status

version        compatibility codeVersion globalId                     primaryIp                       myLocalId uptime     cpu nodes 

BMX6-0.1-alpha 16            9           mlc1001.7A7422752001EC4AC4C8 fd66:66:66:0:a2cd:efff:fe10:101 24100101  0:00:40:37 0.1 4

</pre>

So apart from version, compatibility number, and code, the status reveals the daemon's global (see: [[Wiki#Global-ID]] ) and local ID, its primary (self-configured) IPv6 address, the time since when it is running (40 minutes), its current cpu consumption (0.1%) and the total number of 4 learned nodes in the network (including itself).

These desired types can be combined. Also the above given example shows kind of shortcut. The long argument would be

@ bmx6 connect show=status @. A more informative case using the long form would be:

<pre>

root@mlc1001:~# bmx6 connect show=status show=interfaces show=links show=originators show=tunnels

status:

version        compatibility codeVersion globalId                     primaryIp                       myLocalId uptime     cpu nodes

BMX6-0.1-alpha 16            9           mlc1001.7A7422752001EC4AC4C8 fd66:66:66:0:a2cd:efff:fe10:101 06100101  0:00:53:19 0.3 4

interfaces:

devName state type     rateMin rateMax llocalIp                    globalIp                           multicastIp primary

eth1    UP    ethernet 1000M   1000M   fe80::a2cd:efff:fe10:101/64 fd66:66:66:0:a2cd:efff:fe10:101/64 ff02::2     1

links:

globalId                     llocalIp                 viaDev rxRate txRate bestTxLink routes wantsOgms nbLocalId

mlc1000.0AE58311046412F248CD fe80::a2cd:efff:fe10:1   eth1   100    100    1          1      1         9B100001

mlc1002.91DCF042934B5913BB00 fe80::a2cd:efff:fe10:201 eth1   100    100    1          2      1         BB100201

originators:

globalId                     blocked primaryIp                       routes viaIp                    viaDev metric lastDesc lastRef

mlc1000.0AE58311046412F248CD 0       fd66:66:66:0:a2cd:efff:fe10:1   1      fe80::a2cd:efff:fe10:1   eth1   999M   3193     3 

mlc1001.7A7422752001EC4AC4C8 0       fd66:66:66:0:a2cd:efff:fe10:101 0      ::                       ---    128G   3197     0

mlc1002.91DCF042934B5913BB00 0       fd66:66:66:0:a2cd:efff:fe10:201 1      fe80::a2cd:efff:fe10:201 eth1   999M   3196     3 

mlc1003.09E796BC491D386248C3 0       fd66:66:66:0:a2cd:efff:fe10:301 1      fe80::a2cd:efff:fe10:201 eth1   576M   22       3 

</pre>

Only if relevant information for a requested type is available it will be shown.

In this example no tunnels are configured nor offered by other nodes and therefore no tunnel information is shown.

The loop argument can be prepended to the connect argument to continuously show the requested information.

Many of the long arguments are usable via a short notation, like l for loop, c for connect, s for show, d for debug.

And there is another shortcut summarizing my current favorite information types via debug level 8

The following commands do the same as above: @ bmx6 -lc status interfaces links originators tunnels @ or just @ bmx6 -lcd8 @.

Description of the provided info:

* interfaces: Followed by one line per configured interface

** dev: Interface name

** state and type: Whether the interface is UP or DOWN and its assumed link-layer type.

** rateMin and rateMax: Min- and maximum transmit rates assumed for this interface.

** llocalIp: IPv6 link-local address (used as source address for all outgoing protocol data).

** globalIp: Autoconfigured address used for sending network traffic via this interface and which is propagated to other nodes.

** multicastIp: Multicast IP (used as destination address for all bmx6 protocol traffic send via this interface).

** primary: Indicates whether the global ip of this interface is used as primary ip for this daemon.

* links: Followed by one line per detected neighboring bmx6 node.

** globalId: GlobalId of that neighbor (see: [[Wiki#Global-ID]] ).

** llocalIp: Link-local IP of the neighbor's interface building the other side of the link.

** viaDev: Interface of this node for the link.

** rxRate: Measured receive rate in percent for the link.

** txRate: Measured transmit rate in percent for the link.

** bestTxLink: Indicates whether this link is the best link to a neighboring nodes.

** routes: Indicates for how much routes to other nodes this link is used.

** wantsOgms: Indicates whether the neighboring node has requested (this node) to propagate originator messsages (OGMs) via this link.

** nbLocalId: Neighbors local ID.

* originators: Followed by one line per aware originator in the network (including itself).

** globalId: Global Id of that node (see: [[Wiki#Global-ID]] ).

** blocked: Indicates whether this node is currently blocked (see: [[Wiki#Blocked-Nodes]] ).

** primaryIp: The primary IP of that node. 

** routes: Number of potential routes towards this node.

** viaIp: Next hops link-local IP of the best route towards this node.

** viaDev: Outgoing interface of the best route towards this node.

** metric: The end to end path metric to this node

** lastDesc: Seconds since the last description update was received (see: [[Widi#Description]] )

** lastRef: Seconds since this node was referenced by any neighboring node (like last sign of life)

Quick summary of provided info:

* Node mlc1001 uses one wired interface (eth1) which is up and actively used for meshing.

* Node mlc1001 got aware of 2 neighbors and 4 nodes (originators) including itself.

* The link qualities (rx and tx rate) to its neighbors are perfect (100%) and actively used (bestTxLink)

* Routes to nodes mlc1000 and mlc1002 are via interface eth1 and directly to the neighbor's link-local address with a metric of 999M (nearly maximum tx/rx rate of the configured interface)

* Route to node mlc1003 is setup via interface eth1 and via the link-local address of neighbor mlc1002 (at least two hops to the destination node).

The following links of the total network topology can be guessed from this information (further links may exist):

@ mlc1000 --- mlc1001 --- mlc1002 - - - mlc1003 @

h3. Simple Ping Test

This could be verified using traceroute6 towards the primary IP of the other nodes.

To mlc1000's primary IP fd66:66:66:0:a2cd:efff:fe10:1 shows one hop:

<pre>

root@mlc1001:~# traceroute6 -n -q 1 fd66:66:66:0:a2cd:efff:fe10:1

traceroute to fd66:66:66:0:a2cd:efff:fe10:1 (fd66:66:66:0:a2cd:efff:fe10:1), 30 hops max, 80 byte packets

 1  fd66:66:66:0:a2cd:efff:fe10:1  0.324 ms

</pre>

To mlc1002's primary IP fd66:66:66:0:a2cd:efff:fe10:201 shows one hop:

<pre>

root@mlc1001:~# traceroute6 -n -q 1 fd66:66:66:0:a2cd:efff:fe10:201

traceroute to fd66:66:66:0:a2cd:efff:fe10:201 (fd66:66:66:0:a2cd:efff:fe10:201), 30 hops max, 80 byte packets

 1  fd66:66:66:0:a2cd:efff:fe10:201  0.302 ms

</pre>

To mlc1003's primary IP fd66:66:66:0:a2cd:efff:fe10:301 shows two hops:

<pre>

root@mlc1001:~# traceroute6 -n -q 1 fd66:66:66:0:a2cd:efff:fe10:301

traceroute to fd66:66:66:0:a2cd:efff:fe10:301 (fd66:66:66:0:a2cd:efff:fe10:301), 30 hops max, 80 byte packets

 1  fd66:66:66:0:a2cd:efff:fe10:201  0.313 ms

 2  fd66:66:66:0:a2cd:efff:fe10:301  0.429 ms

</pre>

h3. Dynamic Reconfiguration

Most bmx6 parameters can be applied not only at startup, but also dynamically to an already running main daemon, using the --connect command.

For example interfaces can be added, removed, or specified with more details:

The following example removes interface eth1 and adds eth2 with a max rate of 100 Mbits (overwriting the default assumption of 1000Mbits for ethernet interfaces).

<pre>

bmx6 -c dev=-eth1 dev=eth2 /rateMax=100000

bmx6 -cd8

</pre>

Checking new status of interfaces, links, and originator:

<pre>

root@mlc1001:~# bmx6 -cd8

status:

version        compatibility codeVersion globalId                     primaryIp                       myLocalId uptime     cpu nodes 

BMX6-0.1-alpha 16            9           mlc1001.7A7422752001EC4AC4C8 fd66:66:66:0:a2cd:efff:fe10:102 06100101  0:02:26:00 0.1 4 

interfaces:

devName state type     rateMin rateMax llocalIp                    globalIp                           multicastIp primary 

eth2    UP    ethernet 100M    100M    fe80::a2cd:efff:fe10:102/64 fd66:66:66:0:a2cd:efff:fe10:102/64 ff02::2     1       

links:

globalId                     llocalIp               viaDev rxRate txRate bestTxLink routes wantsOgms nbLocalId 

mlc1000.0AE58311046412F248CD fe80::a2cd:efff:fe10:2 eth2   89     88     1          3      1         9B100001  

originators:

globalId                     blocked primaryIp                       routes viaIp                  viaDev metric lastDesc lastRef 

mlc1000.0AE58311046412F248CD 0       fd66:66:66:0:a2cd:efff:fe10:1   1      fe80::a2cd:efff:fe10:2 eth2   81757K 18       0      

mlc1001.7A7422752001EC4AC4C8 0       fd66:66:66:0:a2cd:efff:fe10:102 0      ::                     ---    128G   80       0      

mlc1002.91DCF042934B5913BB00 0       fd66:66:66:0:a2cd:efff:fe10:201 1      fe80::a2cd:efff:fe10:2 eth2   83620K 14       4      

mlc1003.09E796BC491D386248C3 0       fd66:66:66:0:a2cd:efff:fe10:301 1      fe80::a2cd:efff:fe10:2 eth2   81488K 9        0

</pre>

It can be seen that:

* Interface eth1 has been replaced by eth2 with a lower rate.

* The primary IP of the node has changed (using the autoconfigured IP from eth2.

* The old links (via eth1) are removed and a single new link via eth2 to mlc1000 has been detected

* All routes are now going via eth2 and mlc1000's link-local IP fe80::a2cd:efff:fe10:2

h2. Concepts

h3. Global ID

Each bmx6 node creates during its initialization (booting) a global ID for itself. 

This ID is created as a concatenation of the node's hostname and a random value.

In the above given example with node hostname: "mlc1001" the globalID is: mlc1001.7A7422752001EC4AC4C8

When the bmx6 daemon restarts the hostname will remain. But the rand part will change.

As a consequence, the restarted node will appear as a new node to other nodes in the mesh while the old Global ID is still present in their node table.

Since both node IDs are announcing the same resources (eg the same primary IP), the ID that appears later will be blocked until the state maintained for the first ID expires.

h3. Descriptions

Instead of propagating individual routing updates for each announced network and interface address, each bmx6 daemon summarizes this and other node specific attributes into a single node-specific description. A specific description is propagated only once to all other nodes. Subsequent routing updates are referencing to the corresponding description with it's hash.

If a node is reconfigured, for example because its interfaces change or a new network shall be announced, than also the node's description changes.

Other nodes are becoming aware of the changed attributes of a reconfigured node by receiving a corresponding description update.

Subsequent references to this node will use the hash of the new description.

Because the description is designed very generic it can be easily used to piggyback other non-routing specific data. For example the bmx6-sms plugin is taking advantage of this option by adding arbitrary short messages data to the node's description.

Currently there is a limit for the total size of a description of 1400 bytes. While this is more than sufficient for quite a number of interfaces and announced networks per node, it is critical few when considering a gateway node with BGP route exchange that is announcing 100eds of networks.

h3. Blocked Nodes

Nodes may be blocked by other nodes.

When a node is blocked no routing updates (OGMs) of the blocked node are propagated by the blocking node.

The decision for blocking another node is done locally based on the detection of more than one node announcing the same unique resource.

This happens if two nodes are declaring themselves as the owner of a unique resource. Then one of those two nodes (usually the latter) is blocked to avoid the propagation of conflicting allocations (and ambiguous forwarding state). Duplicate address usage is the most common reason for such events which happens if two nodes are using (and announcing) the same primary IPs. Another typical scenario causing such case temporary is the rebooting of a node. Once a bmx6 daemon restarts it appears as a new node (with a new random part of it's global ID) to the network but (due to a typically persistant configuration) announcing the same address as the previous process. Since the resources allocated by the previous resources are still in the database of other nodes in the mesh they will block the new process until this information expires (by default after 100 seconds).

h2. Unicast Host Network Announcements (UHNA)

A Host Network Announcements (HNA) describes the advertisement of IP addresses and networks by a node to other nodes in the mesh.

Typically (but not with BMX6), several nodes can announce the same or overlapping HNAs at the same time.

Announced networks do overlap if they are equal or one being a subset of another (eg. 10.1.1.0/24 is a subset and overlapped by 10.1.0.0/16).

Packets with a destination address matching an announced networks will be routed toward any node that originated a corresponding HNA.

Therefore these HNA types may also be called anycast HNA.

In bmx6, HNAs have an unicast nature (UHNAs) because each network can only be announced once and announced networks MUST NOT overlap (See also [[Wiki#Blocked-Nodes]]).

This way it can be ensured that the destination of an UHNA routed packet is exactly known.

In a sense the origination and propagation (by intermediate nodes) of UHNA announcements can be thought of a promise that guarantees:

1. All packets with a destination address matching an announced UHNA network will be routed exactly to the node (with the global ID) that originated the UHNA and

2. each node on the forwarding path towards the originator of the UHNA is supporting this promise.

By default, Bmx6 only announces primary and non-primary interface addresses via UHNAs.

The auto address configuration ensures that interface addresses are unique.

Using UHNAs for the announcements of networks requires a strict coordination to ensure that no network is announced twice.

Technically, multiple UHNAs, each wrapped into a single message, are aggregated into a UHNA frame and attached to the description of a node.

If Bmx6 is configured in IPv6 mode only IPv6 UHNAs can be announced and in IPv4 mode only IPv4 UHNAs

h3. UHNA Configuration

The announcement of UHNAs can be configured with the --unicastHna or -u parameter followed by a network specification in ip/prefixlen notation.

By default all interface addresses are announced via UHNAs. However, this can be disabled by setting the --dev subparameter /announce or /a to 0.

The following example reconfigures an already running bmx6 daemon (in IPv6 mode) to UHNA announce the network fd00:ffff:ffff:ffff::/64 and fd01:ffff:ffff::/48.

By omitting the --connect / -c parameter, the same could be configured as startup parameter for bmx6.

<pre>

bmx6 -c u=fd00:ffff:ffff:ffff::/64 u=fd01:ffff:ffff::/48

</pre>

An already active announcement can be removed by preceeding the network with the '-' char:

<pre>

bmx6 -c u=-fd00:ffff:ffff:ffff::/64

</pre>

Before bmx6 accepts a dynamically configured UHNA announcement it checks if this UHNA is not overlapping with an already existing UHNA announcement form another node.

If this is the case the configuration will fail.

To check if a chain of dynamic commands would be accepted by a bmx6 daemon without actually applying it, the --test command may follow the --connect /-c command.

h2. Tunnel Announcements

Tunnel announcements offer an alternative mechanism to propagate routes. 

Tunnel announcements are currently only implemented for Bmx6-IPv6 mode. 

However, in IPv6 mode IPv6 and IPv4 networks can be announced.

In contrast to UHNAs, using tunnel announcements, the same or overlapping networks can be announced from different nodes. Tunnel announcements are an offer from the originating node to other nodes. Other nodes can take the offer or not. For example several nodes in a network may offer to share their DSL connection by doing a default-route (0.0.0.0/0 or ::/0) tunnel announcement.

Other nodes looking for a route to the internet (a default route) can choose between the multiple offers by establishing a tunnel to one specific of the offering nodes.

Therefore an unidirectional (onw-way) tunnel is established from the searching to the offering node.

At the searching node, the remote (outer) tunnel address is configured with an UHNA address (usually the primary address) of the offering node.

The networks advertised with the tunnel announcements are configured at the client side as routes via (into) the unidirectional tunnel.

This way, each node can make an individual choice between networks offered via tunnel announcements.

The automatic selection can be specified via a policy description that considers parameters such as advertised bandwidth, path metric, trust in specific GW nodes, hysteresis, ... .

Since an UHNA address is used as the outer (remote) tunnel address, the client end of the tunnel can be sure that all packets routed into the tunnel will indeed end up at the intended GW node (see [[Wiki#Unicast-Host-Network-Announcements-UHNA]]).

Technically, multiple tunnel announcements, each wrapped into a single tun4/6in6-net message, are aggregated into a tun4/6in6-net frame and attached to the description of a node.

Tunnel announcements are also used for redistributing routes from other routing protocols (see [[Wiki#Quagga-Plugin]]) into a bmx6 zone. 

Therefore, each announcements message is decorated with a route-type field indicating the routing protocol that exported the route for being redistributed.

h3. Tunnel Configuration and Debugging

In general, a specific tunnel configuration is described from two perspectives:

* Gateway (GW) nodes or just GWs are offering GW services to networks via the advertizement of tunnel announcements and the provisioning of tunnel-end-points.

* GW-client nodes (or just GW-clients) that are searching for GWs with tunnel endpoints and routing services to networks.

A node can (and usually is) operating in both modes (as GW and as GW-client). 

But regarding a specific network each node is operating either in GW mode (thus, offering GW-services to that network) or in GW-client mode (thus, searching and using GW-services to that network)!

Remark: Since master commit f2fd75072f7dc4738069be6c69625419b9cc7767 the syntax for configuring tunnels has changed.

In the following the new syntax is explained. 

For the old syntax please use the build-in --help and --verboseHelp of the binary you are using

h4. Tunnel Device Configuration

Operation in GW and/or GW-client mode implies the configuration of a bmx6 tunnel device and the IPv4 and/or IPv6 addresses that shall be used for tunnel traffic.

The following command dynamically configures:

* A linux ip4/6in6 tunnel device called bmx6Default (check it with <pre>ip link</pre> command)

* Assignes the address 10.10.0.1 and 2012:0:0:1000::1 to the tunnel interface and uses them for outgoing tunnel traffic

* Makes a tunnel announcement for these networks so that other nodes can select it for tunneling packets to this node.

<pre>

bmx6 -c tunDev=Default /tun4Address=10.10.0.1/24 /tun6Address=2012:0:0:1000::1/64

</pre>

h4. Gateway Nodes

The advertisement of a tunnel endpoint to a network can be configured with the --tunIn=<arbitrary name>  and /network=<network> argument and an optional bandwidth specification (given as bits per second) using the /bandwidth or /b sub parameter.

Announcement can be removed by preceeding the name argument with a '-' char. 

The configuration can be done during daemon startup or dynamically (using --connect / -c parameter). 

The following command dynamically configures the advertisement of the following routes:

* An IPv4 default route 0.0.0.0/0 with a bandwidth of 32 Mbps.

* A more specific route to 10.10.0.0/16 with a bandwidth of 10 Mbps (could be a local v4 Network).

* An IPv6 route to the [RFC 4291] designated 2000::/3 global unicast address space with a bandwidth of 16 Mbps.

* A more specific route to the 2012:1234::/32 IPv6 space at 10 Mbps (could be a local v6 Network).

<pre>

bmx6 -c tunIn=def4Offer /n=0.0.0.0/0 /b=32000000  tunIn=local4 /n=10.10.0.0/16 /b=10000000  tunIn=def6Offer /n=2000::/3 /b=16000000  tunIn=local6 /n=2012:1234::/32 /b=10000000

</pre>

One aspect that must be considered when configuring GW nodes is that tunnels are unidirectional from the GW client to the GW.

But clients usually also need a route back from the GW to the client to allow a bidirectional communication.

One (however not recommended) option would be that GW clients are using their primary address as source address for all packets routed into the GW tunnel because a route from the GW to the GW-client via the client's primary address already exist. However, by default, the client's primary address is an autoconfigured ULA address which is not routable outside the bmx6 network. Also the primary address is either an IPv4 or an IPv6 address and can only be used to route to a corresponding destination network.

The recommended procedure to let clients use addresses that are routable outside of the bmx6 cloud is that also GW client nodes advertize a host-address via UHNA or tunnel announcements. In the latter (recommended) case, the client node also appears as a GW node to its private address space used for communication with other remote networks. To support this recommended case, the GW node must also be configured as a GW client searching for tunnel announcements from it's potential GW-client nodes to their (rather small) private (but outside routable) address space. The details for such configuration are described in the following section. 

However, for completeness a simple configuration for the GW-node to search for back routes to clients is given here. The following commands essentially configures a GW node to:

* use the IP addresses 10.254.10.1 and 2012:1234:5678:90ab::1 for tunnel traffic

* search and automatically configure back-wards tunnel to nodes that advertise an IPv4 prefix with a minimum length of 24 and are within the range of 10.254.0.0/16

* search and automatically configure back-wards tunnel to nodes that advertise an IPv6 prefix with a minimum length of 64 and are within the range of 2012:1234:5678::/48

<pre>

bmx6 -c tun4Address=10.254.10.1/32 tun6Address=2012:1234:5678:1::1/64 

bmx6 -c tunOut=v4Nodes /network=10.254.0.0/16 /minPrefixLen=24

bmx6 -c tunOut=v6Nodes /network=2012:1234:5678::/48 /minPrefixLen=64

</pre>

For more information please see [[Wiki#Gateway-Client-Nodes]].

h4. Gateway-Client Nodes

The configuration of GW clients can be simple but also, depending on the preferences of a desired GW-selection policy, very complex.

A general requirement for GW clients is the configuration of source addresses for all outgoing tunnels.

At least one network address must be configured for IPv6 and/or IPv4 tunnels using the the --tun4Address and/or --tun6Address parameters.

The specified network address will automatically be advertized as tunnel announcements, allowing the GW client to be reachable via the given addresses.

Thereby, each GW client node is also a GW node to its own (usually small) tunnel address space.

The selection of this address should be coordinated with GW administrators since (depending on the GW connection to other networks) only specific addresses are routable and considered to be originated from the bmx6 cloud.

In the following simple example a GW-client node is:

* specifying its own tunnel addresses for IPv4 and IPv6

* searching for any other kind of offered IPv4 and v6 tunnels

<pre>

bmx6 -c tun4Address=10.254.10.123/32 tun6Address=2012:1234:5678:123::1/64 

bmx6 -c tunOut=v4Default /network=0.0.0.0/0 tunOut=v6Default /network=::/0

</pre>

The disadvantage of the above configured tunnel selection policy is that offered tunnels are selected based on the path metric in the bmx6 cloud, ignoring the prefix-length of announced tunnels (routes that are more specific than others).

Imagine the following address assignment policy for the IPv4. The general idea can be straight translated to IPv6.

* Most nodes in the mesh cloud announce their private address ranges with a prefix length equal or larger than 24 and somewhere in the range of 10.254.0.0/16. Announcements of this type should always be preferred, even if any of the following announced types has a better end-to-end metric.

* Some BGP GW nodes are connected to other mesh clouds/areas of the same overall community network. These clouds are operating in a different IPv4 range (than 10.254.0.0/16) but always somewhere in the range of 10.0.0.0/8. Route announcements of this type should be preferred over the announcement of a default route. 

* Some DSL GW nodes are offering to share their DSL line and are announcing a default route (0.0.0.0/0). Only default route announcements from two well known GWs (with hostname pepe and paula) are acceptible. To mitigate the effects of GW switching if both GWs show a similar end-to-end metric a GW switch should only happen if the other GW is at least 30% better.

The following configuration configures a GW client respectively:

<pre>

bmx6 -c tun4Address=10.254.10.123/32

bmx6 -c tunOut=v4Nodes /network=10.254.0.0/16 /minPrefixLen=24 /ipMetric=2001

bmx6 -c tunOut=v4Clouds /network=10.0.0.0/8 /maxPrefixLen=16 bgp=1 /ipMetric=2002

bmx6 -c tunOut=-v4Default # revert the above configured v4 tunnel search

bmx6 -c tunOut=v4DefaultPepe  /network=0.0.0.0/0 /maxPrefixLen=0 /name=pepe  /hysteresis=30 /ipMetric=2003

bmx6 -c tunOut=v4DefaultPaula /network=0.0.0.0/0 /maxPrefixLen=0 /name=paula /hysteresis=30 /ipMetric=2003

</pre>

h4. Tunnel Status Information

Tunnel status information can be accessed with the --tunnels parameters.

h2. Bmx6 Plugins

h3. Compile and Install

To compile and install bmx6 daemon and all bmx6 plugins simply do:

<pre>

make build_all

sudo make install_all

</pre>

However. specific requirements may need to be fulfilled for some plugins in order to compile correctly.

These requirements are described in the corresponding plugin section.

h2. Config Plugin

h3. Requirements

uci libs are needed for the bmx6-config plugin.

To install it do:

<pre>

wget http://downloads.openwrt.org/sources/uci-0.7.5.tar.gz

tar xzvf uci-0.7.5.tar.gz

cd uci-0.7.5

make

sudo make install

</pre>

Depending on your system there happens to be an error during compilation.

Then edit cli.c and change line 465 to: @ char *argv[MAX_ARGS+2]; @

h3. Compile and Install

<pre>

make -C lib/bmx6_uci_config/ 

sudo make -C lib/bmx6_uci_config/ install

</pre>

h3. Usage

h2. Json Plugin

h3. Requirements

* json-c for bmx6_json plugin (debian package: libjson0 libjson0-dev)

json-c developer libs are needed!

For further reading check: http://json.org/ or https://github.com/jehiah/json-c

Note for debian sid:

The debian package libjson0-dev 0.10-1 seems to miss the file /usr/include/json/json_object_iterator.h

Manually copying it from the below mentioned json-c_0.10.orig.tar.gz archive helps.

To install manually (only if NOT installed via debian or other package management system):

<pre>

wget http://ftp.de.debian.org/debian/pool/main/j/json-c/json-c_0.10.orig.tar.gz

tar xzvf json-c_0.10.orig.tar.gz

cd json-c..

./configure ; make ; make install; ldconfig

</pre>

h3. Compile and Install

To compile and install only the  bmx6 json plugins:

<pre>

make -C lib/bmx6_json/ 

sudo make -C lib/bmx6_json/ install

</pre>

h3. Usage

h2. SMS Plugin

This plug-in uses routing packets to transmit any information from one node to the

whole network. The good point is that propagation works even if there is no continuous data-

path. Even though the WiFi network is under bad conditions (because the Wireless noise,

distance between nodes, etc...), the data will be propagated. However in the current implemen-

tation, there exist a maximum size limit of 240 Bytes for each file.

The API of the sms plug-in is very simple. It simply clones the content of one or more files

given by one node to all other nodes. All other nodes can do the same. Once started, each

node will have two directories:/var/run/bmx6/sms/rcvdSms and /var/run/bmx6/sms/sendSms. Files

put into the sendSms folder will be cloned to all other nodes inside rcvdSms folder.

QMP is using this feature for several things. The positioning Map information is transmitted

using it. There is a chat in web interface which uses it too. And in the future we are planning

to use it for more purposes like statistics, captive portal, MAC filter rules, etc...

h2. Quagga Plugin

The bmx6 quagga plugin can be used to exchange routes with a quagga/zebra daemon.

Both, export and redistribution of routes is supported.

h3. Requirements, Compile, and Install

h4. Quagga

Quagga version 0.99.21 must be patched for bmx6 support.

The bmx6 directory lib/bmx6_quagga/patches/ contains patches to enable quagga for bmx6 support.

The following example provides instructions for obtaining, patching, compiling, and installing quagga:

<pre>

wget http://download.savannah.gnu.org/releases/quagga/quagga-0.99.21.tar.gz

tar xzvf quagga-0.99.21.tar.gz

cd quagga-0.99.21

patch -p1 < ../bmx6/lib/bmx6_quagga/patches/quagga-0.99.21.tar.diff

./configure

make

sudo make install

</pre>

For further instructions to obtain, patch, compile, and install quagga please have a look at:

the file lib/bmx6_quagga/patches/README in the bmx6 sources.

h4. Bmx6

To compile and install the bmx6 part of the quagga plugin simply do:

<pre>

make -C lib/bmx6_quagga/ 

sudo make -C lib/bmx6_quagga/ install

</pre>

h3. Usage

To use the bmx6 quagga plugin it must be loaded during bmx6 daemon startup with the @ plugin=bmx6_quagga.so @ argument. 

Alternatively a plugin section can be defined in the bmx6 config file like this:

<pre>

config 'plugin'

        option 'plugin' 'bmx6_quagga.so'

</pre>

Once the plugin is successfully loaded, the bmx6 daemon will try to connect with the zebra process (via the ZAPI socket) 

and new parameters for exchanging routes with quagga/zebra daemon are enabled.

A quick documentation of the quagga-related parameters is available via the --help and --verboseHelp option.

If the quagga-enabled daemon is already running @ bmc6 -c verboseHelp /r=1 @ will print all currently supported parameters.

h3. Redistributing routes (from quagga/zebra to bmx6)

Redistribution of routes is configurable with the --redistribute parameter.

Similar to the --tunOutNet parameter,  --redistribute must be given with an arbitrary name for referencing to a specific redistribution directive and further sub-criterias.

Further mandatory sub-parameters are /bandwidth and at least one (to-be redistributed route type).

The following route types exist:

<pre>

  /system <VAL>                          def: 0       range: [ 0 , 1 ]

  /kernel <VAL>                          def: 0       range: [ 0 , 1 ]

  /connect <VAL>                         def: 0       range: [ 0 , 1 ]

  /rip <VAL>                             def: 0       range: [ 0 , 1 ]

  /ripng <VAL>                           def: 0       range: [ 0 , 1 ]

  /ospf <VAL>                            def: 0       range: [ 0 , 1 ]

  /ospf6 <VAL>                           def: 0       range: [ 0 , 1 ]

  /isis <VAL>                            def: 0       range: [ 0 , 1 ]

  /bgp <VAL>                             def: 0       range: [ 0 , 1 ]

  /babel <VAL>                           def: 0       range: [ 0 , 1 ]

  /hsls <VAL>                            def: 0       range: [ 0 , 1 ]

  /olsr <VAL>                            def: 0       range: [ 0 , 1 ]

  /batman <VAL>                          def: 0       range: [ 0 , 1 ]

</pre>

Only quagga/zebra routes types that are explicitly specified will be redistributed to the bmx6 network.

In addition, one usually wants to filter out networks from being redistributed based on their prefix.

Therefore the sub parameters /network, /minPrefixLen, and /maxPrefixLen can be used in the same way as for the --tunOutNet parameter.

h4. Route Aggregation

By default, maximum aggregation of to-be redistributed routes is enabled.

This means that to-be redistributed neighboring and overlapping networks with the same route type and bandwidth are aggregated if possible.

The extend of aggregation can be controlled with the /aggregatePrefixLen sub-parameter.

The given value limits the aggregation to a minimum prefix length.

The default of 0 defines maximum aggregation whenever possible which may not be wanted.

For example the GW node may be configured to redistribute the following routes:

* 10.254.20.1/32

* 10.254.20.0/24

* 10.254.21.0/24

* 10.254.22.0/24

* 0.0.0.0/0

The following bmx6 configuration would aggregate all 5 routes into a single 0.0.0.0/0 tunnel announcement since 0.0.0.0/0 is overlapping any other more-specific route:

<pre>

redistribute=ipv4 /bandwidth=10000000 /kernel=1 /aggregatePrefixLen=0

</pre>

This aggregation may be too generic since GW-client nodes are usually looking for more specific routes to specific destination.

The following configuration would aggregate only routes with a prefix-len larger than 16:

<pre>

redistribute=ipv4 /bandwidth=10000000 /kernel=1 /aggregatePrefixLen=16

</pre>

Resulting in the following aggregations:

* 10.254.20.1/32: Aggregated (sub-network of 10.254.20.0/24)! NOT announced!

* 10.254.20.0/24: Aggregated with 10.254.21.0/24! Announced as 10.254.20.0/23 

* 10.254.21.0/24: Aggregated with 10.254.20.0/24! Announced as 10.254.20.0/23 

* 10.254.22.0/24: Not aggregatable into larger network! Announced as is!

* 0.0.0.0/0:      Not aggregated (prefix-len smaller than /aggregatePrefixLen=16)! Announced as is!

h3. Exporting routes (from bmx6 to quagga/zebra)

For exporting routes received as bmx6 tunnel announcements, the /exportDistance can be used as a subparameter of the --tunOut parameter.

The default value of /exportDistance is 256 which is considered as infinit or disabled.

Any lower configured value will export the corresponding outgoing tunnel (once it becomes active) with the given distance to quagga/zebra.

A GW node usually only wants to export bmx6 routes that were announced by other (non-GW) bmx6 nodes in the mesh.

In the following example there are 3 other bmx6 nodes, each tunnel announcing a private /32 network.

The given parametrization configures a GW node to search, establish related tunnels, and export all tunnel announcements for other bmx6 daemons that have a prefix-length smaller that /27 and fall into the network range of 10.254.0.0/16:

<pre>

plugin=bmx6_quagga.so tunOut=privV4Nets /network=10.254.0.0/16 /minPrefixLen=27 /exportDistance=0

</pre>

Checking the export from the quagga perspective show the following:

<pre>

root@mlc1001:~# telnet localhost zebra

Trying ::1...

Trying 127.0.0.1...

Connected to localhost.

Escape character is '^]'.

Hello, this is Quagga (version 0.99.21).

Copyright 1996-2005 Kunihiro Ishiguro, et al.

User Access Verification

Password:

Router> show ip route

Codes: K - kernel route, C - connected, S - static, R - RIP,

       O - OSPF, I - IS-IS, B - BGP, H - HSLS, o - OLSR,

       b - BATMAN, x - BMX6, A - Babel,

       > - selected route, * - FIB route

K>* 0.0.0.0/0 via 10.0.0.1, eth0

C>* 10.0.0.0/11 is directly connected, eth0

x>* 10.254.10.0/32 [0/1024] is directly connected, bmx6_out0000, 00:03:24

C * 10.254.10.1/32 is directly connected, bmx6_out0003

C * 10.254.10.1/32 is directly connected, bmx6_out0002

C * 10.254.10.1/32 is directly connected, bmx6_out0001

C * 10.254.10.1/32 is directly connected, bmx6_out0000

C>* 10.254.10.1/32 is directly connected, bmx6_in0000

x>* 10.254.10.2/32 [0/1024] is directly connected, bmx6_out0001, 00:03:24

x>* 10.254.10.3/32 [0/1024] is directly connected, bmx6_out0002, 00:03:24

x>* 10.254.10.4/32 [0/1024] is directly connected, bmx6_out0003, 00:03:24

C>* 127.0.0.0/8 is directly connected, lo

</pre>