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[RFC] network namespaces [message #5165]

Tue, 15 August 2006 14:20

Andrey Savochkin
Messages: 47
Registered: December 2005

Member

Hi All,

I'd like to resurrect our discussion about network namespaces.
In our previous discussions it appeared that we have rather polar concepts
which seemed hard to reconcile.
Now I have an idea how to look at all discussed concepts to enable everyone's
usage scenario.

1. The most straightforward concept is complete separation of namespaces,
covering device list, routing tables, netfilter tables, socket hashes, and
everything else.

On input path, each packet is tagged with namespace right from the
place where it appears from a device, and is processed by each layer
in the context of this namespace.
Non-root namespaces communicate with the outside world in two ways: by
owning hardware devices, or receiving packets forwarded them by their parent
namespace via pass-through device.

This complete separation of namespaces is very useful for at least two
purposes:
- allowing users to create and manage by their own various tunnels and
VPNs, and
- enabling easier and more straightforward live migration of groups of
processes with their environment.

2. People expressed concerns that complete separation of namespaces
may introduce an undesired overhead in certain usage scenarios.
The overhead comes from packets traversing input path, then output path,
then input path again in the destination namespace if root namespace
acts as a router.

So, we may introduce short-cuts, when input packet starts to be processes
in one namespace, but changes it at some upper layer.
The places where packet can change namespace are, for example:
routing, post-routing netfilter hook, or even lookup in socket hash.

The cleanest example among them is post-routing netfilter hook.
Tagging of input packets there means that the packets is checked against
root namespace's routing table, found to be local, and go directly to
the socket hash lookup in the destination namespace.
In this scheme the ability to change routing tables or netfilter rules on
a per-namespace basis is traded for lower overhead.

All other optimized schemes where input packets do not travel
input-output-input paths in general case may be viewed as short-cuts in
scheme (1). The remaining question is which exactly short-cuts make most
sense, and how to make them consistent from the interface point of view.

My current idea is to reach some agreement on the basic concept, review
patches, and then move on to implementing feasible short-cuts.

Opinions?

Next in this thread are patches introducing namespaces to device list,
IPv4 routing, and socket hashes, and a pass-through device.
Patches are against 2.6.18-rc4-mm1.

Best regards,

Andrey

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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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