Batman configuration and MTU

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I have being doing some testing with several types of configurations with custom openwrt build and batman in oder to try to come with a basic default "plug & play" ready to deploy firmware evolving the least changes possible other than the router's ip and not much more. I have tried several configurations, more than one subnet and have being trying to see a way to make some nice HOW-Tos regarding this matter for several types of configurations.

So far and from what i seen all working and half working examples do not work for everyone or at least no one or very few post complete configurations of all files in /etc/config/ that actually fully work.

Then there is the question if bridging. Some say bridge this, others say do not bridge that. None supply a fully working example that can be replicated. (i am glad i access the routers over serial cable which i recommend to everyone if they are working on builds and configurations.

I have now collected quite a few pdfs regarding all openwrt, batman and mesh netwroks and only a couple worth to use for configurations as they seem to work.

The best one i found so far can be obtained here:
http://wiki.villagetelco.org/images/0/07/SECN_UserGuideV1d4_compressed.pdf

Mesh Potato: Small Enterprise Campus Network (user guide) SECN_UserGuideV1d4_compressed.pdf

It shows basic fast working examples either using Luci and command line.It's not a perfect guide as it needs a few retouches but by far the best i have found until now.

This guide leads me to quite a few questions as for example i was told not to bridge the lan:
https://forum.openwrt.org/viewtopic.php?id=35517

This led me to more complex configurations that included 2 different subnets and more but still not 100% working.

And following the guide i only got it working doing a bridge. It still find this bridge strange and something confuses me but seems to work.

However there is still a problem that remains which is the MTU. I have tried several ways to enable and they all seem to fail.

Bellow are my current configurations that match the described situation:

- -----

# cat firewall

config 'defaults'
option 'syn_flood' '1'
option 'input' 'ACCEPT'
option 'output' 'ACCEPT'
option 'forward' 'REJECT'
option 'disable_ipv6' '1'

config 'zone'
option 'name' 'lan'
option 'network' 'lan'
option 'input' 'ACCEPT'
option 'output' 'ACCEPT'
option 'forward' 'REJECT'

config 'zone'
option 'name' 'wifi'
option 'network' 'wifi'
option 'input' 'ACCEPT'
option 'output' 'ACCEPT'
option 'forward' 'REJECT'

config 'zone'
option 'name' 'wan'
option 'network' 'wan'
option 'input' 'REJECT'
option 'output' 'ACCEPT'
option 'forward' 'REJECT'
option 'masq' '1'

config 'forwarding'
option 'src' 'lan'
option 'dest' 'wan'

config 'rule'
option 'name' 'Allow-DHCP-Renew'
option 'src' 'wan'
option 'proto' 'udp'
option 'dest_port' '68'
option 'target' 'ACCEPT'
option 'family' 'ipv4'

config 'rule'
option 'name' 'Allow-Ping'
option 'src' 'wan'
option 'proto' 'icmp'
option 'icmp_type' 'echo-request'
option 'family' 'ipv4'
option 'target' 'ACCEPT'

config 'include'
option 'path' '/etc/firewall.user'

- -----

# cat dhcp

config 'dnsmasq'
option 'domainneeded' '1'
option 'boguspriv' '1'
option 'filterwin2k' '0'
option 'localise_queries' '1' option 'rebind_protection' '1' option 'rebind_localhost' '1' option 'local' '/lan/'
option 'domain' 'wireless.domain.com' option 'expandhosts' '1'
option 'nonegcache' '0'
option 'authoritative' '1'
option 'readethers' '1'
option 'leasefile' '/tmp/dhcp.leases' option 'resolvfile' '/tmp/resolv.conf.auto'

config 'dhcp' 'lan'
option 'interface' 'lan'
option 'start' '51'
option 'limit' '254'
option 'leasetime' '24h'

config 'dhcp' 'wan'
option 'interface' 'wan'
option 'ignore' '1'
option 'domain' 'wireless.domain.com'

- -----

g# cat network

config 'switch' 'eth0'

        option 'enable' '1'

config 'switch_vlan' 'eth0_0'

        option 'device' 'eth0'
        option 'vlan' '0'
        option 'ports' '1 2 3 4 5'

config 'switch_vlan' 'eth0_1'

        option 'device' 'eth0'
        option 'vlan' '1'
        option 'ports' '0 5'

config 'interface' 'loopback'
option 'ifname' 'lo'
option 'proto' 'static'
option 'ipaddr' '127.0.0.1'
option 'netmask' '255.0.0.0'

config 'interface' 'lan'

        option 'type' 'bridge'
        option 'proto' 'static'
        option 'ipaddr' '192.168.1.1'
        option 'netmask' '255.255.255.0'
        option 'broadcast' '192.168.1.255'
        option 'ifname' 'eth0.0 bat0 wlan0'
        option 'mtu' '1528'

#config 'interface' 'wifi'

#        option 'proto' 'none'
#        option 'ifname' 'wlan0'
#        option 'mtu' '1528'

#config 'interface' 'lan'

#       option 'proto' 'none'
#       option 'ifname' 'lan'
#       option 'mtu' '1528'

config 'interface' 'wan'
option 'ifname' 'eth0.1'
option 'proto' 'dhcp'

- -----

# cat wireless
config 'wifi-device' 'radio0'
        option 'type' 'mac80211'
        option 'channel' '11'
        option 'phy' 'phy0'
        option 'hwmode' '11g'
        option 'country' 'ca'
        option 'txpower' '20'
        option 'diversity' '1'
        option 'disabled' '0'
        option 'txantenna' '1'
        option 'rxantenna' '1'

config 'wifi-iface'
option 'device' 'radio0'
option 'hidden' '0'
option 'mode' 'adhoc'
option 'ssid' 'wireless'
option 'bssid' '02:16:b8:6b:0a:1a'
option 'encryption' 'none'
#option 'network' 'lan' #is optional or must match bridge name option 'mtu' '1528' #mtu seems to be ignored - needs fix

- -----

# cat batman-adv
config 'mesh' 'bat0'
        option 'ap_isolation' '0'
        option 'bonding' '0'
        option 'aggregation' '1'
        option 'fragmentation' '1'
        option 'gw_bandwidth' '3mbit/384kbit'
        option 'gw_mode' 'client'
        option 'gw_sel_class' '5'
        option 'orig_interval' '1000'
        option 'vis_mode' 'client'
        option 'interfaces' 'wlan0 eth0.0'

# batctl if
eth0.0: active
wlan0: active

# batctl o
[B.A.T.M.A.N. adv 2012.0.0, MainIF/MAC: eth0.0/00:12:17:be:f9:46 (bat0)]
  Originator      last-seen (#/255)           Nexthop [outgoingIF]:
Potential nexthops ...

- -----
The mesh potato guide does not show configurations for batman-adv . I also noticed that replacing bat0 interfaces by "lan" seems to be working as the lan interface already bridges everything. Correct me if i am wrong.

The last problem i now face (assuming that this configuration is valid) is the MTU settings which seem to be ignored no matter where i add them; including creating the following for the other interfaces:

config 'interface' 'wifi'
option 'proto' 'none'
option 'ifname' 'wlan0'
option 'mtu' '1528'

I have lost quite a lot of sleep over these problems and it is natural that i might be missing something very simple.

batman_adv: bat0: The MTU of interface eth0.0 is too small (1500) to handle the transport of batman-adv packets. Packets going over this interface will be fragmented on layer2 which could impact the performance. Setting the MTU to 1528 would solve the problem.

batman_adv: bat0: The MTU of interface wlan0 is too small (1500) to handle the transport of batman-adv packets. Packets going over this interface will be fragmented on layer2 which could impact the performance. Setting the MTU to 1528 would solve the problem.

Right now i am just trying the setup with 1 router and testing with a netbook. I am able to connect, obtain ip from the router in either wired or wireless. I am also able to connect to the wan but while doing so wirelessly the performance is lower and slower which i believe to be caused by the lack of proper MTU adjustment.

Extra details:
wrt54g v2.2
backfire 10.03.2
b43 drivers version 508.1084
batman 2012 v14 + batman-adv_load-module-when-needed.patch

Loaded modules:

nf_nat_tftp              432  0
nf_conntrack_tftp       2400  1 nf_nat_tftp
nf_nat_irc               864  0
nf_conntrack_irc        2592  1 nf_nat_irc
nf_nat_ftp              1360  0
nf_conntrack_ftp        4896  1 nf_nat_ftp
ipt_MASQUERADE           992  1
iptable_nat             2304  1
nf_nat                 11824  5
nf_nat_tftp,nf_nat_irc,nf_nat_ftp,ipt_MASQUERADE,iptable_nat
xt_NOTRACK               672  0
iptable_raw              656  1
xt_state                 800  3
nf_conntrack_ipv4       7808  6 iptable_nat,nf_nat
nf_defrag_ipv4           608  1 nf_conntrack_ipv4
nf_conntrack           42560 12
nf_nat_tftp,nf_conntrack_tftp,nf_nat_irc,nf_conntrack_irc,nf_nat_ftp,nf_conntrack_ftp,ipt_MASQUERADE,iptable_nat,nf_nat,xt_NOTRACK,xt_state,nf_conntrack_ipv4
ipt_REJECT              1984  2
xt_TCPMSS               1952  0
ipt_LOG                 4640  0
xt_comment               464  0
xt_multiport            1904  0
xt_mac                   576  0
xt_limit                1152  1
iptable_mangle           992  0
iptable_filter           768  1
ip_tables               8864  4

iptable_nat,iptable_raw,iptable_mangle,iptable_filter
xt_tcpudp 1856 4
x_tables 9840 13
ipt_MASQUERADE,iptable_nat,xt_NOTRACK,xt_state,ipt_REJECT,xt_TCPMSS,ipt_LOG,xt_comment,xt_multiport,xt_mac,xt_limit,ip_tables,xt_tcpudp

b43                   151056  0
mac80211              260560  1 b43
cfg80211              149136  2 b43,mac80211
compat                 13312  3 b43,mac80211,cfg80211
arc4                     816  2
aes_generic            31056  0
deflate                 1328  0
ecb                     1328  0
cbc                     2016  0
batman_adv            105408  0
crc16                    976  1 batman_adv

diag 7504 0
switch_robo 4208 0
swicth_core 5216 1 switch_robo

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I can send you some sample configs if you wish, I copied some snippets in this mail.

AFAIK mtu is set in config/network, not in config/wireless

I believe you have your bridges mixed up.

For a normal situation, you should make your batman interfaces members of bat0 and then add bat0 to your br-lan, like so:

config 'mesh' 'bat0'
option 'interfaces' 'wlan0-1 eth0'

config 'interface' 'lan'

	option 'type' 'bridge'
	option 'proto' 'static'
	option 'netmask' '255.255.248.0'
	option 'gateway' '10.5.0.1'
	option 'dns' '8.8.8.8'
	option 'mtu' '1500'
	option 'ipaddr' '10.5.0.2'
	option 'ifname' 'bat0 wlan0'

config 'interface' 'wlan0_1'

	option 'proto' 'none'
	option 'mtu' '1528'
	option 'ifname' 'wlan0-1'

In this example, wlan0 runs an open AP where clients can connect, while other mesh nodes connect through eth0 and wlan0-1.

and this is the corresponding wireless config:

config 'wifi-device' 'radio0'

	option 'type' 'mac80211'
	option 'macaddr' '00:15:6d:3e:XX:XX'
	option 'hwmode' '11ng'
	option 'channel' '1'
	option 'country' 'US'
	option 'txpower' '27'
	option 'htmode' 'HT20'
    option 'noscan' '1'

config 'wifi-iface'
option 'network' 'lan'
option 'device' 'radio0'
option 'encryption' 'none'
option 'mode' 'ap'
option 'ssid' 'quintanalibre.org.ar'

config 'wifi-iface'
option 'device' 'radio0'
option 'encryption' 'none'
option 'mode' 'adhoc'
option 'ssid' 'mesh.quintanalibre.org.ar'
option 'bssid' '02:12:34:56:78:9A'
option 'mcast_rate' '54000'

side note: experimenting with mcast_rate is an interesting to force bad routes out of the picture.

I believe that the only time when you want a different bridge setup is when you need to have batman and non-batman connections on the same interface (a router's eth switch), then you'd use the setup described in this document:
http://www.open-mesh.org/wiki/batman-adv/Bridge-loop-avoidance

Here we use a similar method to get the MTU properly set (as you can see in the previous config snippet).
This works well for us.

have you tried setting the MTU from command line, like so:

# ifconfig wlan0 mtu 1528

does this succeed?

we have found no solution for setting MTU above 1500 for wired interfaces. If anyone has instructions about this, I'd also be very interested.

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@ Nicolás

Right now i am trying this setup and batman is not complaining about MTU as it can be seen as set. The purpose of this setup is to allow wireless and wired clients to to use the mesh as if a user connects to the router over wired and accesses the gateway one or 2 nodes after.

However i now have dhcp problems for wireless clients as the router fails to assign the wireless client, the ip. The client (netbook) connects but gets no ip. MTU seems to be fixed with this setup.

Would you be able to show some of those working examples ?

~# cat /etc/config/batman-adv
config 'mesh' 'bat0'
option 'ap_isolation' '0'
option 'bonding' '0'
option 'aggregation' '1'
option 'fragmentation' '1'
option 'gw_bandwidth' '3mbit/384kbit'
option 'gw_mode' 'client'
option 'gw_sel_class' '5'
option 'orig_interval' '1000'
option 'vis_mode' 'client'
option 'interfaces' 'wlan0'

# cat /etc/config/wireless
config 'wifi-device' 'radio0'
        option 'type' 'mac80211'
        option 'channel' '11'
        option 'phy' 'phy0'
        option 'hwmode' '11g'
        option 'country' 'UK'
        option 'txpower' '20'
        option 'diversity' '1'
        option 'disabled' '0'
        option 'txantenna' '1'
        option 'rxantenna' '1'

config 'wifi-iface'
option 'device' 'radio0'
option 'hidden' '0'
option 'mode' 'adhoc'
option 'ssid' 'wireless'
option 'bssid' '02:16:b8:6b:0a:1a'
option 'encryption' 'none'
option 'network' 'wifi'

~# cat /etc/config/network
#### VLAN configuration
config switch eth0
option enable 1

config switch_vlan eth0_0

        option device   "eth0"
        option vlan     0
        option ports    "1 2 3 4 5"

config switch_vlan eth0_1

        option device   "eth0"
        option vlan     1
        option ports    "0 5"

#### Loopback configuration
config interface loopback

        option ifname   "lo"
        option proto    static
        option ipaddr   127.0.0.1
        option netmask  255.0.0.0

#### LAN configuration
config interface lan

        option type     bridge
        option ifname   "eth0.0 bat0"
        option proto    static
        option ipaddr   192.168.1.1
        option netmask  255.255.255.0

#### WIFI configuration
config interface wifi
option proto none
option mtu 1528

#### WAN configuration
config interface wan
option ifname "eth0.1"
option proto dhcp

I would appreciate that very much

According to openwrt mcast for broadcom is still in trunk stage, i
tried it with stable release but i am not sure it it actually worked as it should.

Same issue here. Also looking for a possibility. -----BEGIN PGP SIGNATURE-----
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I have been in the same situaion and at the aned left the uci config
alone using scripting for the complete setup.
This made things much easier .

How abt joining a collaboration-team as i proposed in an earlier mail ?

regards
3zl

2012/4/19 HeXiLeD <[email protected]>: