[B.A.T.M.A.N.] BATMAN routing (via gate0)

[B.A.T.M.A.N.] BATMAN routing (via gate0)

[Derek C]

Hi [yet] again!

Can someone detail how BATMAN routes?

For example if I have nodes with IPs like:
     5.255.0.1
     5.255.0.2
     5.255.0.3
       etc

I see that BATMAN makes a tunnel to the gateway and then routes traffic
via the 169.254 gate0 subnet

Does this mean that all outgoing from the node should be NATed?  or is it
possible for the upstream node(s) to ping the node via its true IP address
(5.255.XXX.XXX) ?

thanks again,

Derek


-- 
Derek C

Re: [B.A.T.M.A.N.] BATMAN routing (via gate0)

[Marek Lindner]

On Sunday 23 November 2008 00:20:55 Derek C wrote:
> I see that BATMAN makes a tunnel to the gateway and then routes traffic
> via the 169.254 gate0 subnet
>
> Does this mean that all outgoing from the node should be NATed?  or is it
> possible for the upstream node(s) to ping the node via its true IP address
> (5.255.XXX.XXX) ?

The tunnel is used for internet traffic only. Within the mesh you can use the 
mesh ip addresses.

Regards,
Marek

Re: [B.A.T.M.A.N.] BATMAN routing (via gate0)

[Derek C]

Hi Marek,

Does this mean that the mesh nodes cannot ping all the other nodes?   This
is if there is no routing to allow the nodes talk to "far-away" nodes not
within their own AdHoc single-hop network?

thanks,

Derek


On Sat, November 22, 2008 4:35 pm, Marek Lindner wrote:
> On Sunday 23 November 2008 00:20:55 Derek C wrote:
>
>> I see that BATMAN makes a tunnel to the gateway and then routes traffic
>>  via the 169.254 gate0 subnet
>>
>> Does this mean that all outgoing from the node should be NATed?  or is
>> it possible for the upstream node(s) to ping the node via its true IP
>> address (5.255.XXX.XXX) ?
>>
>
> The tunnel is used for internet traffic only. Within the mesh you can use
> the mesh ip addresses.
>
> Regards,
> Marek
>
>
> _______________________________________________
> B.A.T.M.A.N mailing list
> B.A.T.M.A.N@open-mesh.net
> https://list.open-mesh.net/mm/listinfo/b.a.t.m.a.n
>
>


-- 
Derek C

Re: [B.A.T.M.A.N.] BATMAN routing (via gate0)

[Marek Lindner]

On Sunday 23 November 2008 05:05:36 Derek C wrote:
> Does this mean that the mesh nodes cannot ping all the other nodes?   This
> is if there is no routing to allow the nodes talk to "far-away" nodes not
> within their own AdHoc single-hop network?

May be I was not clear enough:
* You can ping every batman node in range.
* Too far away nodes (out of range) obviously can't be pinged. 
* If you have multiple subnetworks which could ping each other but are routed 
differently you just have to make sure the routing is ok. Using HNA is one 
possible solution.

Does this answer you question ? Please give a sample scenario if not.

Regards,
Marek

Re: [B.A.T.M.A.N.] BATMAN routing (via gate0)

[Simon Wunderlich]

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Hey,

On Sun, Nov 23, 2008 at 11:37:10AM +0800, Marek Lindner wrote:
> On Sunday 23 November 2008 05:05:36 Derek C wrote:
> > Does this mean that the mesh nodes cannot ping all the other nodes?   This
> > is if there is no routing to allow the nodes talk to "far-away" nodes not
> > within their own AdHoc single-hop network?
> 
> May be I was not clear enough:
> * You can ping every batman node in range.
> * Too far away nodes (out of range) obviously can't be pinged. 
> * If you have multiple subnetworks which could ping each other but are routed 
> differently you just have to make sure the routing is ok. Using HNA is one 
> possible solution.

just a note so we don't confuse the terms:

Marek means with "range" where the communication can practically succeed, even 
over multiple hops. As you have some probablity to lose packets on each
hop, the communication becomes "practically" unusable over very long
distances, e.g. >10 hops (depending on your network setup and
environment ...).
Note that this range is not the single-hop range.

regards,
	Simon

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Re: [B.A.T.M.A.N.] BATMAN routing (via gate0)

[Derek C]

Hi guys,

How does the routing work for inter-node communications for > 1 hop
neighbors?

If the gate0 tunnel is the default route for Internet communications how
does a node know how to talk to a node two hops (or more) away (that
doesn't go though the gate0 tunnel)?

This is the bit I don't understand - I thought that range mentioned by
Marek did mean radio range for local (one hop) neighbors.

I can understand how it works with OLSRd because each node has a big
routing table but I'm still confused about how BATMAN does it

Derek

On Sun, November 23, 2008 12:16 pm, Simon Wunderlich wrote:
> Hey,
>
>
> On Sun, Nov 23, 2008 at 11:37:10AM +0800, Marek Lindner wrote:
>
>> On Sunday 23 November 2008 05:05:36 Derek C wrote:
>>
>>> Does this mean that the mesh nodes cannot ping all the other nodes?
>>> This
>>> is if there is no routing to allow the nodes talk to "far-away" nodes
>>> not within their own AdHoc single-hop network?
>>
>> May be I was not clear enough:
>> * You can ping every batman node in range.
>> * Too far away nodes (out of range) obviously can't be pinged.
>> * If you have multiple subnetworks which could ping each other but are
>> routed differently you just have to make sure the routing is ok. Using
>> HNA is one
>> possible solution.
>
> just a note so we don't confuse the terms:
>
> Marek means with "range" where the communication can practically succeed,
> even over multiple hops. As you have some probablity to lose packets on
> each hop, the communication becomes "practically" unusable over very long
> distances, e.g. >10 hops (depending on your network setup and environment
> ...).
> Note that this range is not the single-hop range.
>
>
> regards, Simon
> _______________________________________________
> B.A.T.M.A.N mailing list
> B.A.T.M.A.N@open-mesh.net
> https://list.open-mesh.net/mm/listinfo/b.a.t.m.a.n
>
>


-- 
Derek C

Re: [B.A.T.M.A.N.] BATMAN routing (via gate0)

[Marek Lindner]

Hey,

> How does the routing work for inter-node communications for > 1 hop
> neighbors?
>
> If the gate0 tunnel is the default route for Internet communications how
> does a node know how to talk to a node two hops (or more) away (that
> doesn't go though the gate0 tunnel)?
>
> I can understand how it works with OLSRd because each node has a big
> routing table but I'm still confused about how BATMAN does it

Batman also has a "big" routing table - nothing is different to OLSR (in this 
aspect). To get information about the routing tables read here:
https://dev.open-mesh.net/batman/wiki/RoutingVodoo

The major difference to OLSR is that batman does not know every single step 
towards the final node. Consider this example:

source node -> neighbour1 -> neighbour2 -> destination

The source node will have a routing entry for the destination in its routing 
table which says "use neighbour1 as next hop". In that very moment the source 
node does not know how neighbour1 will route the packets. It simply assumes 
that neighbour1 knows the following step. Once the packet arrives at 
neighbour1 it will get forwarded according to the routing table of neighbour1 
until it arrives neighbour2 and then the destination.

Why does it work that way ?
We think its impossible to keep all nodes of the network in sync about all 
routing changes between all the nodes. If some nodes are out of sync you will 
encounter routing loops. Furthermore, it does not make sense to know the whole 
path because every node can send the packets to its neighbours only. Once the 
packet leaves the host it can't be influenced anymore. Your neighbour may have 
a totally different view regarding the routing and will send the packet into 
another direction. Neighbour2 even does not know what neighbour1 considered 
being the best route.


> This is the bit I don't understand - I thought that range mentioned by
> Marek did mean radio range for local (one hop) neighbors.

Ok, thanks Simon for clarifying that.  :-)

Regards,
Marek