Re: [Autoconf] Using DHCPv6 without link-local? Support only EUI-64interfaces?
Ulrich Herberg <ulrich@herberg.name> Mon, 02 August 2010 21:46 UTC
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Date: Mon, 02 Aug 2010 23:46:47 +0200
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From: Ulrich Herberg <ulrich@herberg.name>
To: Teco Boot <teco@inf-net.nl>
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Subject: Re: [Autoconf] Using DHCPv6 without link-local? Support only EUI-64interfaces?
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Teco, On Mon, Aug 2, 2010 at 7:56 PM, Teco Boot <teco@inf-net.nl> wrote: [..] >>> >>> I think it could work this way: >>> 1) Node queries with link-local to All_DHCP_Relay_Agents_and_Servers. >>> 2a) Node acts as also relay and queries with ULA (site-local) to All_DHCP_Servers. >> >> Do you mean that a node is DHCP client and relay in the same time? >> That is not possible according to RFC3315, which says (i) in section >> 15.13 "clients MUST discard any received Relay-forward messages" and >> (ii) section 15.3 "servers and relay agents MUST discard any received >> Advertise messages". > > I don't think there is such limitation. > A node that combines client and relay would not send out a packet that does > not conform to the spec. Fred pointed that out. I wonder whether that demultiplexing is clearly pointed out in the DHCPv6 RFC. But well, too late to change it ;-) I assume that major DHCPv6 implementations do not implement that demultiplexing (they'd need to share the UDP port, demultiplex messsages etc.) (-- I know, that's not so much a problem of the standardization process.. just wondering here) >> Also, the relay would need to have a direct unicast connection to the >> central node or use other relaying mechanisms such as SMF (as you >> mentioned below), because multiple relaying is not really feasible in >> DHCPv6 itself: Relaying uses encapsulation, so packets would be >> encapsulated at every hop, quickly increasing overhead. > > Yes, relaying and encap on every hop is a bad idea, I think. > But we don't have a standard track multicast protocol for MANETs. > We also don't have a protocol for service discovery, for learning the > DHCP server address. > This makes our work experimental. Indeed. It would make life easier to have such protocols as RFCs already :-) With SMF, we have at least a protocol which is not so far from being published as RFC. > > >> And I also >> don't think that DHCP relaying allows duplicate packet detection. > > Why not? > SMF hashing should work. Each packet has a random transaction ID. > Or include a SMF-DPD header option. True. But that is defined in SMF, not in DHCPv6 relaying. >>> 2b) If node is provisioned with DHCP server unicast address, it could use that >>> instead of All_DHCP_Servers. >> >> Sure, that is possible if a unicast routing protocol is used. >> >>> I think this is in line with your RFC 5558. >>> >>> Drawback of 1: it can result in high number of relayed DHCP packets, in case >>> of many neighbors. >> >> True. >> >>> Another drawback of 1: there is a timeout delay when there is no relay or server >>> at one hop. >> >> But I guess this timeout can be set dynamically? > > When 1 is used as a first try, looking for a DHCP-server at one hop, the node > should wait some time for a response. If no response arrives, it could go to step 2. > The timeout would be a configured parameter, I think. > Maybe it is better to skip such a mechanism. Needs more thoughts. Yes, I also have to think more about it. >>> For 2a: the network needs multicast support. Could be SMF. >> >> Yes, that could be a possibility. >> >> >>> >>> For both 2a and 2b: a temporally used unicast address must be routable. So this >>> DHCP mechanism can only be used as a second step, moving from the self-generated >>> address to a centrally managed address. >> >> Yes, that seems possible (but I have to re-read the DHCPv6 RFC after >> my vacations ;-) > > Not _during_ your vacation ?? :-)) hehe, well, my boss would like that ;-) Ulrich
- [Autoconf] Using DHCPv6 without link-local? Suppo… Teco Boot
- Re: [Autoconf] Using DHCPv6 without link-local? S… Dearlove, Christopher (UK)
- Re: [Autoconf] Using DHCPv6 without link-local? S… Templin, Fred L
- Re: [Autoconf] Using DHCPv6 without link-local? S… Teco Boot
- Re: [Autoconf] Using DHCPv6 without link-local? S… Teco Boot
- Re: [Autoconf] Using DHCPv6 without link-local? S… Dearlove, Christopher (UK)
- Re: [Autoconf] Using DHCPv6 without link-local? S… Alexandru Petrescu
- Re: [Autoconf] Using DHCPv6 without link-local? S… Alexandru Petrescu
- Re: [Autoconf] Using DHCPv6 without link-local? S… Teco Boot
- Re: [Autoconf] Using DHCPv6 without link-local? S… Teco Boot
- Re: [Autoconf] Using DHCPv6 without link-local? S… Alexandru Petrescu
- Re: [Autoconf] Using DHCPv6 without link-local? S… Dearlove, Christopher (UK)
- Re: [Autoconf] Using DHCPv6 without link-local? S… Dearlove, Christopher (UK)
- Re: [Autoconf] Using DHCPv6 without link-local? S… Templin, Fred L
- Re: [Autoconf] Using DHCPv6 without link-local? S… Ulrich Herberg
- Re: [Autoconf] Using DHCPv6 without link-local? S… Templin, Fred L
- Re: [Autoconf] Using DHCPv6 without link-local? S… Ulrich Herberg
- Re: [Autoconf] Using DHCPv6 without link-local? S… Teco Boot
- Re: [Autoconf] Using DHCPv6 without link-local? S… Alexandru Petrescu
- Re: [Autoconf] Using DHCPv6 without link-local? S… Ulrich Herberg
- Re: [Autoconf] Using DHCPv6 without link-local? S… Henning Rogge
- Re: [Autoconf] Using DHCPv6 without link-local? S… Ulrich Herberg
- Re: [Autoconf] Using DHCPv6 without link-local? S… Rogge Henning
- Re: [Autoconf] Using DHCPv6 without link-local? S… Teco Boot
- Re: [Autoconf] Using DHCPv6 without link-local? S… Teco Boot
- Re: [Autoconf] Using DHCPv6 without link-local? S… Henning Rogge
- Re: [Autoconf] Using DHCPv6 without link-local? S… Teco Boot
- Re: [Autoconf] Using DHCPv6 without link-local? S… Carlos Jesús Bernardos Cano
- Re: [Autoconf] Using DHCPv6 without link-local? S… Alexandru Petrescu
- Re: [Autoconf] Using DHCPv6 without link-local? S… Joe Macker