On Tue, Nov 01, 2016 at 01:59:17PM +1300, Brian E Carpenter wrote:
> I will read that carefully, but for me that doesn't need justification,
> because
> we need the ANI to be self-contained, so depending on mDNS seems wrong. (In
> fact, why wouldn't configuring mDNS/DNS-SD/DNS be an autonomic function
> itself?)
Just justification why to use GRASP instead of CDP/LDP/mDNS based on
the rule "ANIMA should reuse first, and invent only when reuse is not
a sufficient solution to meet requirements".
For example: for GRASP inside ACP we didn't need to put in justification because
nobody ever claimed that there are equivalent prior IETF solutions.
> And that's the problem. GRASP discovery and flooding need sockets that
> supports link-local multicast sending and receiving for each physical
> interface.
>
> Currently the GRASP code finds out how many physical interfaces it has
> and for each one creates a multicast sending socket. It also has a socket
> that listens for incoming link-local multicasts on all physical interfaces.
> I don't see how to do that using the ACP interfaces that you describe.
GRASP should have a separate socket for each interface - but use that
socket both for sending and receiving. No shared socket for reception.
GARSP only needs to figure out which interface is physcial and which
is ACP. On router-OSs, each interface would be assigned to a VRF, so
it's easy to enumerate the interfaces of eg: the ACP being one VRF.
In Linux the closest equivalent are network contexts. ACP could be one
network context. Compared to router-OS, linux is more secure/constrained:
Processes only have access to one network context. So you'd have to run
separate GRASP processes. Which may be a good thing.
> > All packets, unicast or multicast that are sent into or
> > received from those interfaces are protected/encrypted by the fact that
> > they are transmitted
> > encrypted by the seleted ACP channel encryption protocol.
>
> Yes, and I'd like the LL multicast traffic to be protected too.
> But as far as I can see that needs explicit support in the ACP
> to emulate LL multicast sockets. The ideal would be that the ACP
> simply emulates LL interfaces, so that GRASP could treat them exactly
> like physical interfaces.
Right. But this is not a new ACP thing. Any existing IETF protocol
implementation that uses link-local addresses and runs on any type of
any form of physical or virtual interface needs some form of interface
representation at the API level to send/receive LL packets. Thats why
i am somewhat hesitant to add explanatory text for this to the ACP
draft. It's supposed to be implied by the IPv6 addressing model and
common practice in IETF documents that its not regurgitated too much.
> If you want, I can point you the exact Python code that handles this
> in the prototype.
Please do. Just not sure when i'll find time.
Cheers
Toerless
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