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Re: [RFC] network namespaces [message #6005 is a reply to message #5978]

Wed, 06 September 2006 16:56

Herbert Poetzl
Messages: 239
Registered: February 2006

Senior Member

On Wed, Sep 06, 2006 at 11:10:23AM +0200, Daniel Lezcano wrote:
> Hi Herbert,
>
> >well, the 'ip subset' approach Linux-VServer and
> >other Jail solutions use is very clean, it just does
> >not match your expectations of a virtual interface
> >(as there is none) and it does not cope well with
> >all kinds of per context 'requirements', which IMHO
> >do not really exist on the application layer (only
> >on the whole system layer)
> >
> >IMHO that would be quite simple, have a 'namespace'
> >for limiting port binds to a subset of the available
> >ips and another one which does complete network
> >virtualization with all the whistles and bells, IMHO
> >most of them are orthogonal and can easily be combined
> >
> > - full network virtualization
> > - lightweight ip subset
> > - both
> >
> >IMHO this requirement only arises from the full system
> >virtualization approach, just look at the other jail
> >solutions (solaris, bsd, ...) some of them do not even
> >allow for more than a single ip but they work quite
> >well when used properly ...
>
> As far as I see, vserver use a layer 3 solution but, when needed, the
> veth "component", made by Nestor Pena, is used to provide a layer 2
> virtualization. Right ?

well, no, we do not explicitely use the VETH daemon
for networking, although some folks probably make use
of it, mainly because if you realize that this kind
of isolation is something different and partially
complementary to network virtualization, you can do
live without the layer 2 virtualization in almost
all cases, nevertheless, for certain purposes layer
2/3 virtualization is required and/or makes perfect
sense

> Having the two solutions, you have certainly a lot if information
> about use cases.

> From the point of view of vserver, can you give some
> examples of when a layer 3 solution is better/worst than
> a layer 2 solution ?

my point (until we have an implementation which clearly
shows that performance is equal/better to isolation)
is simply this:

of course, you can 'simulate' or 'construct' all the
isolation scenarios with kernel bridging and routing
and tricky injection/marking of packets, but, this
usually comes with an overhead ...

> Who wants a layer 2/3 virtualization and why ?

there are some reasons for virtualization instead of
pure isolation (as Linux-VServer does it for now)

- context migration/snapshot (probably reason #1)
- creating network devices inside a guest
(can help with vpn and similar)
- allowing non IP protocols (like DHCP, ICMP, etc)

the problem which arises with this kind of network
virtualization is that you need some additional policy
for example to avoid sending 'evil' packets and/or
(D)DoSing one guest from another, which again adds
further overhead, so basically if you 'just' want
to have network isolation, you have to do this:

- create a 'copy' of your hosts networking inside
the guest (with virtual interfaces)
- assign all the same (subset) ips and this to
the virtual guest interfaces
- activate some smart bridging code which 'knows'
what ports can be used and/or mapped
- add policy to block unwanted connections and/or
packets to/from the guest

all this sounds very intrusive and for sure (please
proove me wrong here :) adds a lot of overhead to the
networking itself, while a 'simple' isolation approach
for IP (tcp/udp) is (almost) without any cost, certainly
without overhead once a connection is established.

> These informations will be very useful.

HTH,
Herbert

> Regards
>
> -- Daniel

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[Message index]

		[RFC] network namespaces By: Andrey Savochkin on Tue, 15 August 2006 14:20
		[PATCH 1/9] network namespaces: core and device list By: Andrey Savochkin on Tue, 15 August 2006 14:48
		Re: [PATCH 1/9] network namespaces: core and device list By: Dave Hansen on Wed, 16 August 2006 14:46
		Re: [PATCH 1/9] network namespaces: core and device list By: Stephen Hemminger on Wed, 16 August 2006 16:45
		[PATCH 2/9] network namespaces: IPv4 routing By: Andrey Savochkin on Tue, 15 August 2006 14:48
		[PATCH 6/9] allow proc_dir_entries to have destructor By: Andrey Savochkin on Tue, 15 August 2006 14:48
		[PATCH 5/9] network namespaces: async socket operations By: Andrey Savochkin on Tue, 15 August 2006 14:48
		Re: [PATCH 5/9] network namespaces: async socket operations By: Daniel Lezcano on Fri, 22 September 2006 15:33
		Re: [PATCH 5/9] network namespaces: async socket operations By: Andrey Savochkin on Sat, 23 September 2006 13:16
		[PATCH 7/9] net_device seq_file By: Andrey Savochkin on Tue, 15 August 2006 14:48
		[PATCH 8/9] network namespaces: device to pass packets between namespaces By: Andrey Savochkin on Tue, 15 August 2006 14:48
		[PATCH 4/9] network namespaces: socket hashes By: Andrey Savochkin on Tue, 15 August 2006 14:48
		Re: [PATCH 4/9] network namespaces: socket hashes By: Daniel Lezcano on Mon, 18 September 2006 15:12
		Re: [PATCH 4/9] network namespaces: socket hashes By: Andrey Savochkin on Wed, 20 September 2006 16:32
		Re: [PATCH 4/9] network namespaces: socket hashes By: Daniel Lezcano on Thu, 21 September 2006 12:34
		[PATCH 9/9] network namespaces: playing with pass-through device By: Andrey Savochkin on Tue, 15 August 2006 14:48
		Re: [RFC] network namespaces By: serue on Wed, 16 August 2006 11:53
		Re: [RFC] network namespaces By: Alexey Kuznetsov on Wed, 16 August 2006 15:12
		Re: [RFC] network namespaces By: ebiederm on Wed, 16 August 2006 17:35
		Re: [RFC] network namespaces By: dev on Thu, 17 August 2006 08:28
		Re: [RFC] network namespaces By: Daniel Lezcano on Tue, 05 September 2006 13:34
		Re: [RFC] network namespaces By: ebiederm on Tue, 05 September 2006 14:45
		Re: [RFC] network namespaces By: Herbert Poetzl on Tue, 05 September 2006 16:53
		Re: [RFC] network namespaces By: Daniel Lezcano on Wed, 06 September 2006 09:10
		Re: [RFC] network namespaces By: Herbert Poetzl on Wed, 06 September 2006 16:56
		Re: Re: [RFC] network namespaces By: kir on Wed, 06 September 2006 17:36
		Re: [RFC] network namespaces By: ebiederm on Wed, 06 September 2006 18:34
		Re: [RFC] network namespaces By: kir on Wed, 06 September 2006 18:56
		Re: [RFC] network namespaces By: Cedric Le Goater on Wed, 06 September 2006 20:53
		RE: [RFC] network namespaces By: Caitlin Bestler on Wed, 06 September 2006 23:06
		Re: [RFC] network namespaces By: Daniel Lezcano on Thu, 07 September 2006 08:25
		Re: [RFC] network namespaces By: ebiederm on Thu, 07 September 2006 18:29
		Re: [RFC] network namespaces By: Herbert Poetzl on Fri, 08 September 2006 06:02
		Re: Re: [RFC] network namespaces By: dev on Thu, 07 September 2006 16:20
		Re: Re: [RFC] network namespaces By: Herbert Poetzl on Thu, 07 September 2006 17:27
		Re: Re: [RFC] network namespaces By: Mishin Dmitry on Fri, 08 September 2006 13:10
		Re: Re: [RFC] network namespaces By: Herbert Poetzl on Fri, 08 September 2006 18:11
		Re: Re: [RFC] network namespaces By: Mishin Dmitry on Sat, 09 September 2006 07:57
		Re: Re: [RFC] network namespaces By: Herbert Poetzl on Sun, 10 September 2006 02:47
		Re: Re: [RFC] network namespaces By: Mishin Dmitry on Sun, 10 September 2006 07:45
		Re: Re: [RFC] network namespaces By: Herbert Poetzl on Sun, 10 September 2006 19:22
		Re: [RFC] network namespaces By: ebiederm on Tue, 12 September 2006 03:26
		Re: Re: [RFC] network namespaces By: ebiederm on Sun, 10 September 2006 03:41
		Re: Re: [RFC] network namespaces By: Mishin Dmitry on Sun, 10 September 2006 08:11
		Re: Re: [RFC] network namespaces By: Herbert Poetzl on Sun, 10 September 2006 19:19
		Re: Re: [RFC] network namespaces By: Daniel Lezcano on Mon, 11 September 2006 14:40
		Re: Re: [RFC] network namespaces By: Herbert Poetzl on Mon, 11 September 2006 14:57
		Re: Re: [RFC] network namespaces By: Daniel Lezcano on Mon, 11 September 2006 15:04
		Re: Re: [RFC] network namespaces By: Mishin Dmitry on Mon, 11 September 2006 15:10
		Re: [RFC] network namespaces By: ebiederm on Tue, 12 September 2006 03:28
		Re: [RFC] network namespaces By: Mishin Dmitry on Tue, 12 September 2006 07:38
		Re: Re: [RFC] network namespaces By: ebiederm on Thu, 07 September 2006 19:50
		Re: Re: [RFC] network namespaces By: Daniel Lezcano on Wed, 06 September 2006 21:44
		Re: [RFC] network namespaces By: ebiederm on Wed, 06 September 2006 17:58
		Re: [RFC] network namespaces By: ebiederm on Tue, 05 September 2006 18:27
		Re: [RFC] network namespaces By: dev on Wed, 06 September 2006 14:52
		Re: [RFC] network namespaces By: Daniel Lezcano on Tue, 05 September 2006 15:32
		Re: [RFC] network namespaces By: dev on Tue, 05 September 2006 15:44
		Re: [RFC] network namespaces By: ebiederm on Tue, 05 September 2006 17:09
		Re: [RFC] network namespaces By: Cedric Le Goater on Wed, 06 September 2006 20:25
		Re: Re: [RFC] network namespaces By: kir on Wed, 06 September 2006 15:09
		Re: [RFC] network namespaces By: ebiederm on Wed, 06 September 2006 20:40
		Re: [RFC] network namespaces By: ebiederm on Wed, 06 September 2006 23:25
		Re: [RFC] network namespaces By: Stephen Hemminger on Thu, 07 September 2006 00:53
		Re: [RFC] network namespaces By: ebiederm on Thu, 07 September 2006 05:11
		Re: [RFC] network namespaces By: Daniel Lezcano on Wed, 04 October 2006 09:40
		Re: [RFC] network namespaces By: ebiederm on Sun, 10 September 2006 11:48

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