Re: [lwip-users] Virtual machines in the same host (bridge).

[Sylvain Rochet]

Hi,

On Fri, Jan 30, 2015 at 08:28:20AM -0200, Norberto R. de Goes Jr. wrote:
> Hello Sylvain.
> Below the information asked by you. Thanks in advance!
> Norberto
> 
> 
> >>>>>>>>>> VM#1 (with lwip app):
> 
> address@hidden norberto]# brctl show
> bridge name bridge id STP enabled interfaces
> br0 8000.080027c07dab no p2p1
> tap0

Looks good.


> address@hidden norberto]#
> address@hidden norberto]# ip a s
> 1: lo: <LOOPBACK,UP,LOWER_UP> mtu 16436 qdisc noqueue state UNKNOWN
>     link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
>     inet 127.0.0.1/8 scope host lo
>     inet6 ::1/128 scope host
>        valid_lft forever preferred_lft forever
> 2: p2p1: <BROADCAST,MULTICAST,PROMISC,UP,LOWER_UP> mtu 1500 qdisc
> pfifo_fast master br0 state UP qlen 1000
>     link/ether 08:00:27:c0:7d:ab brd ff:ff:ff:ff:ff:ff
>     inet6 fe80::a00:27ff:fec0:7dab/64 scope link
>        valid_lft forever preferred_lft forever

UP ok.


> 4: br0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue state UP
>     link/ether 08:00:27:c0:7d:ab brd ff:ff:ff:ff:ff:ff
>     inet 169.254.8.218/16 brd 169.254.255.255 scope global br0
>     inet6 fe80::7084:1aff:fe21:998f/64 scope link
>        valid_lft forever preferred_lft forever

UP ok.

> 5: tap0: <BROADCAST,MULTICAST,PROMISC,UP,LOWER_UP> mtu 1500 qdisc
> pfifo_fast master br0 state UNKNOWN qlen 500
>     link/ether 8e:f4:c4:a8:9a:c8 brd ff:ff:ff:ff:ff:ff
>     inet6 fe80::8cf4:c4ff:fea8:9ac8/64 scope link
>        valid_lft forever preferred_lft forever

UP ok.

Note you need to use something inside 169.254.0.0/16 in lwIP as well and 
please check the netmask is fine on the lwIP stack. I am not sure it is 
not actually enforced to something like /24.


> address@hidden norberto]#
> address@hidden norberto]# ip r s
> 169.254.0.0/16 dev br0  proto kernel  scope link  src 169.254.8.218
> address@hidden norberto]#
> 
> >>>>>>>>>> VM#2 (ping executor):
> 
> address@hidden norberto]# brctl show
> bridge name bridge id STP enabled interfaces
> address@hidden norberto]#
> address@hidden norberto]# ip a s
> 1: lo: <LOOPBACK,UP,LOWER_UP> mtu 16436 qdisc noqueue state UNKNOWN
>     link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
>     inet 127.0.0.1/8 scope host lo
>     inet6 ::1/128 scope host
>        valid_lft forever preferred_lft forever
> 2: p2p1: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state
> UP qlen 1000
>     link/ether 08:00:27:a8:38:00 brd ff:ff:ff:ff:ff:ff
>     inet 169.254.4.39/16 brd 169.254.255.255 scope global p2p1
>     inet6 fe80::a00:27ff:fea8:3800/64 scope link
>        valid_lft forever preferred_lft forever

UP ok.


> address@hidden norberto]#
> address@hidden norberto]# ip r s
> 169.254.0.0/16 dev p2p1  proto kernel  scope link  src 169.254.4.39
> 224.0.0.0/4 dev p2p1  proto static
> address@hidden norberto]#

It should work if fedora2.p2p1 and fedora.p2p1 are properly bridged on 
host, check the lwIP netmask then tcpdump's your friend :)


Sylvain

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