[B.A.T.M.A.N.] Recover in case of node fail

[B.A.T.M.A.N.] Recover in case of node fail

[Carlos Meralto]

Hi guys,

I'm trying to make a study of various protocols for WMN and one of
them is BATMAN. One the tests is the time to recovery in case of node
fail.

I have a topology with 4 routers with 2 possible paths:
A-B-C
A-D-C

For the test i'm doing a continuous ping from A to C (level 3 ping)
and shut down the router that forward the message (i.e B or C). In
this test BATMAN can't recover the PING. But when i cancel the ping
and check the Originators table (batctl o) the route is refreshed. And
when i try to ping again it works.

Is any limitation in BATMAN for recovery in a continuous PING?
Has anyone done this type of test and values obtained?

Thanks in advance.

Best Regards

Re: [B.A.T.M.A.N.] Recover in case of node fail

[Sven Eckelmann]

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On Wednesday 22 July 2015 15:26:23 Carlos Meralto wrote:
> Hi guys,
> 
> I'm trying to make a study of various protocols for WMN and one of
> them is BATMAN. One the tests is the time to recovery in case of node
> fail.
> 
> I have a topology with 4 routers with 2 possible paths:
> A-B-C
> A-D-C
> 
> For the test i'm doing a continuous ping from A to C (level 3 ping)
> and shut down the router that forward the message (i.e B or C). In
> this test BATMAN can't recover the PING. But when i cancel the ping
> and check the Originators table (batctl o) the route is refreshed. And
> when i try to ping again it works.
> 
> Is any limitation in BATMAN for recovery in a continuous PING?

No, sounds more like you are not using batman-adv. Because
batman-adv doesn't know about the l3 stuff. It just
transfers ethernet frames from A to C. B and D are
chosen automatically for each frame (and not for a
l3/l4/... connection).

A `batctl o` does not trigger any route re-calculation.

You can use batctl ping with -R to see the hops and the
switch of the route when D fails.

Btw. if you have a setup with many dynamic changes then you
may want to reduce the originator interval on each node.

> Has anyone done this type of test and values obtained?

Yes, there is a long list of papers doing such things with
batman-adv, bmx, olsrd, babel, ...

And the fall-over worked fine in my last tests. There is
always a small time before the disappeared node is detected
by the tq metric but it is nothing breaks normal connections.

Kind regards,
	Sven

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Re: [B.A.T.M.A.N.] Recover in case of node fail

[Sven Eckelmann]

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Don't contact me directly about batman-adv. At least Cc 
b.a.t.m.a.n@lists.open-mesh.org

On Wednesday 22 July 2015 18:56:41 Carlos Meralto wrote:
[...]
> And with this command i can ping at layer 3. It is not possible in
> batman-adv? I want to measure the recovery time and so I'm doing a
> continuous
> ping. With batctl -p it is possible?

This was not what I said. ICMP ping should work perfectly fine. I just 
suggested that you try `batctl -R` for debugging so you can see the hops
batman-adv uses during a batman-adv native ping.

Kind regards,
	Sven

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Re: [B.A.T.M.A.N.] Recover in case of node fail

[Sven Eckelmann]

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On Wednesday 22 July 2015 20:01:51 Sven Eckelmann wrote:
> This was not what I said. ICMP ping should work perfectly fine. I just 
> suggested that you try `batctl -R`

batctl ping -R ...

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Re: [B.A.T.M.A.N.] Recover in case of node fail

[Carlos Meralto]

I tried "batctl ping -R MAC" and the node recover well. But when i try
"ping IP" does not work and the ping blocks...
It is normal that this happens?

Best Regards,
Carlos Meralto

2015-07-23 8:57 GMT+01:00 Sven Eckelmann <sven@narfation.org>:
> On Wednesday 22 July 2015 20:01:51 Sven Eckelmann wrote:
>> This was not what I said. ICMP ping should work perfectly fine. I just
>> suggested that you try `batctl -R`
>
> batctl ping -R ...

Re: [B.A.T.M.A.N.] Recover in case of node fail

[Sven Eckelmann]

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On Sunday 26 July 2015 19:27:28 Carlos Meralto wrote:
> I tried "batctl ping -R MAC" and the node recover well. But when i try
> "ping IP" does not work and the ping blocks...
> It is normal that this happens?

No, sounds right now like something above batman-adv (higher layer) doesn't 
work in your setup. This could be anything. But right now it sounds like 
something which does connection tracking on L3+ like a stateful firewall, 
masquerade/nat, additional IPv4/IPv6 routing software, ...

Kind regards,
	Sven

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Re: [B.A.T.M.A.N.] Recover in case of node fail

[Simon Wunderlich]

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Hi Carlos,

On Sunday 26 July 2015 19:27:28 Carlos Meralto wrote:
> I tried "batctl ping -R MAC" and the node recover well. But when i try
> "ping IP" does not work and the ping blocks...
> It is normal that this happens?
> 
> Best Regards,
> Carlos Meralto
> 
> 2015-07-23 8:57 GMT+01:00 Sven Eckelmann <sven@narfation.org>:
> > On Wednesday 22 July 2015 20:01:51 Sven Eckelmann wrote:
> >> This was not what I said. ICMP ping should work perfectly fine. I just
> >> suggested that you try `batctl -R`
> > 
> > batctl ping -R ...

it seems strange that batctl ping works but normal ICMP ping doesn't. A couple 
of things you could try are:
 * compare tt tables before and after you remove the router (batctl tg, batctl 
tl)
 * check arp tables (arp -an)
 * check using tcpdump (or batctl tcpdump) if the packets are actually sent, 
and if yes, where they get lost

I assume you are using batman-adv in a recent version for your tests? Also, 
are you using ad-hoc mode? If you need more help, you should try to describe 
your setup in more detail.

Cheers,
    Simon

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