veth(4) draft manual page

veth(4) draft manual page

[Michael Kerrisk (man-pages)]

Hello all,

Long ago (http://www.spinics.net/lists/linux-man/msg03193.html), Tomáš
started work on a veth.4 page, and Eric through in some comments as
well, but the effort to complete the page petered out. I decided to
take a shot at picking up what was said so far completing it. Are
there any comments on the page below?

Cheers,

Michael

veth(4)                 Linux Programmer's Manual                 veth(4)

NAME
       veth - Virtual Ethernet Device

DESCRIPTION
       The  veth  devices  are virtual Ethernet devices.  They can act as
       tunnels between network namespaces to create a bridge to a  physi‐
       cal  network  device in another namespace, but can also be used as
       standalone network devices.

       veth devices are always created in interconnected pairs.   A  pair
       can be created using the command:

           # ip link add <p1-name> type veth peer name <p2-name>

       In  the  above,  p1-name and p2-name are the names assigned to the
       two connected end points.

       Packets transmitted on one device  in  the  pair  are  immediately
       received  on  the  other  device.  When either devices is down the
       link state of the pair is down.

       veth device pairs are useful for combining the network  facilities
       of the kernel together in interesting ways.  A particularly inter‐
       esting use case is to place one end of a veth pair in one  network
       namespace  and  the  other  end in another network namespace, thus
       allowing communication between network namespaces.

       ethtool(8) can be used to find the peer of a veth  network  inter‐
       face, using commands something like:

           # ip link add ve_A type veth peer name ve_B   # Create veth pair
           # ethtool -S ve_A         # Discover interface index of peer
           NIC statistics:
                peer_ifindex: 16
           # ip link | grep '^16:'   # Look up interface
           16: ve_B@ve_A: <BROADCAST,MULTICAST,M-DOWN> mtu 1500 qdisc ...

SEE ALSO
       clone(2), ip(8), ip-link(8), ip-netns(8)


-- 
Michael Kerrisk
Linux man-pages maintainer; http://www.kernel.org/doc/man-pages/
Linux/UNIX System Programming Training: http://man7.org/training/
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Re: veth(4) draft manual page

[Tomas Pospisek]

Hello all,

On Wed, 18 Oct 2017, Michael Kerrisk (man-pages) wrote:

> Hello all,
>
> Long ago (http://www.spinics.net/lists/linux-man/msg03193.html), Tomáš
> started work on a veth.4 page, and Eric through in some comments as
> well, but the effort to complete the page petered out. I decided to
> take a shot at picking up what was said so far completing it.

Very nice, thanks!

> Are there any comments on the page below?

Based on the principle that I prefer useful to mathematically orthogonal 
man pages, I'd suggest to document how you actually do create a veth in a 
different network namespace:

> Cheers,
>
> Michael
>
> veth(4)                 Linux Programmer's Manual                 veth(4)
>
> NAME
>       veth - Virtual Ethernet Device
>
> DESCRIPTION
>       The  veth  devices  are virtual Ethernet devices.  They can act as
>       tunnels between network namespaces to create a bridge to a  physi‐
>       cal  network  device in another namespace, but can also be used as
>       standalone network devices.
>
>       veth devices are always created in interconnected pairs.   A  pair
>       can be created using the command:
>
>           # ip link add <p1-name> type veth peer name <p2-name>
>
>       In  the  above,  p1-name and p2-name are the names assigned to the
>       two connected end points.
>
>       Packets transmitted on one device  in  the  pair  are  immediately
>       received  on  the  other  device.  When either devices is down the
>       link state of the pair is down.
>
>       veth device pairs are useful for combining the network  facilities
>       of the kernel together in interesting ways.  A particularly inter‐
>       esting use case is to place one end of a veth pair in one  network
>       namespace  and  the  other  end in another network namespace, thus
>       allowing communication between network namespaces:

         First you create the veth as above and then you move one side of
         the pair to the other namespace:

             # ip link set <p2-name> netns <p2-namespace>

>       ethtool(8) can be used to find the peer of a veth  network  inter‐
>       face, using commands something like:
>
>           # ip link add ve_A type veth peer name ve_B   # Create veth pair
>           # ethtool -S ve_A         # Discover interface index of peer
>           NIC statistics:
>                peer_ifindex: 16
>           # ip link | grep '^16:'   # Look up interface
>           16: ve_B@ve_A: <BROADCAST,MULTICAST,M-DOWN> mtu 1500 qdisc ...
>
> SEE ALSO
>       clone(2), ip(8), ip-link(8), ip-netns(8)

Thanks a lot Michael & best greetings!
*t
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Re: veth(4) draft manual page

[Michael Kerrisk (man-pages)]

Hi Tomáš,

On 19 October 2017 at 12:17, Tomas Pospisek <tpo-UQchlGytWBLoPl2ZpcX+cw@public.gmane.org> wrote:
> Hello all,
>
> On Wed, 18 Oct 2017, Michael Kerrisk (man-pages) wrote:
>
>> Hello all,
>>
>> Long ago (http://www.spinics.net/lists/linux-man/msg03193.html), Tomáš
>> started work on a veth.4 page, and Eric through in some comments as
>> well, but the effort to complete the page petered out. I decided to
>> take a shot at picking up what was said so far completing it.
>
> Very nice, thanks!
>
>> Are there any comments on the page below?
>
> Based on the principle that I prefer useful to mathematically orthogonal man
> pages, I'd suggest to document how you actually do create a veth in a
> different network namespace:

Agreed.

>> Cheers,
>>
>> Michael
>>
>> veth(4)                 Linux Programmer's Manual                 veth(4)
>>
>> NAME
>>       veth - Virtual Ethernet Device
>>
>> DESCRIPTION
>>       The  veth  devices  are virtual Ethernet devices.  They can act as
>>       tunnels between network namespaces to create a bridge to a  physi‐
>>       cal  network  device in another namespace, but can also be used as
>>       standalone network devices.
>>
>>       veth devices are always created in interconnected pairs.   A  pair
>>       can be created using the command:
>>
>>           # ip link add <p1-name> type veth peer name <p2-name>
>>
>>       In  the  above,  p1-name and p2-name are the names assigned to the
>>       two connected end points.
>>
>>       Packets transmitted on one device  in  the  pair  are  immediately
>>       received  on  the  other  device.  When either devices is down the
>>       link state of the pair is down.
>>
>>       veth device pairs are useful for combining the network  facilities
>>       of the kernel together in interesting ways.  A particularly inter‐
>>       esting use case is to place one end of a veth pair in one  network
>>       namespace  and  the  other  end in another network namespace, thus
>>       allowing communication between network namespaces:
>
>
>         First you create the veth as above and then you move one side of
>         the pair to the other namespace:
>
>             # ip link set <p2-name> netns <p2-namespace>

Thanks. I added that.

>>       ethtool(8) can be used to find the peer of a veth  network  inter‐
>>       face, using commands something like:
>>
>>           # ip link add ve_A type veth peer name ve_B   # Create veth pair
>>           # ethtool -S ve_A         # Discover interface index of peer
>>           NIC statistics:
>>                peer_ifindex: 16
>>           # ip link | grep '^16:'   # Look up interface
>>           16: ve_B@ve_A: <BROADCAST,MULTICAST,M-DOWN> mtu 1500 qdisc ...
>>
>> SEE ALSO
>>       clone(2), ip(8), ip-link(8), ip-netns(8)
>
>
> Thanks a lot Michael & best greetings!

Cheers,

Michael

PS Maybe catch up with you someday again in Bern? I'm there now and then.





-- 
Michael Kerrisk
Linux man-pages maintainer; http://www.kernel.org/doc/man-pages/
Linux/UNIX System Programming Training: http://man7.org/training/
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