Subject: RE: [dhcwg] Address selection for Information-request/Reply messa ges

From: "Bernie Volz (EUD)" <[email-masked]>
Date: Thu, 1 May 2003 14:50:51 -0500

The problem comes about if we change All_DHCP_Servers to include relays to
listen for messages on this address.

Because now both the relays and the routers would forward messages, and the
relays may forward messages forwarded by routers, you could (depending on
the number of relays and routers), get a fairly large packet storm.

The DHCPv6 protocol will work fine and doesn't break. Though the load placed
on the servers and network may not be desireable. That is the point.

Bottom line, IMHO, this is a bad idea. We shouldn't have relays listening
for All_DHCP_Servers traffic. And, if we don't do that, allowing Information-Request
sent directly to All_DHCP_Servers would require site multicast to work and if
it doesn't or is disabled, these clients would fail to receive the requested
information if the server isn't local.

- Bernie

-----Original Message-----
From: Robert Elz [mailto:[email-masked]]
Sent: Thursday, May 01, 2003 3:17 PM
To: Ralph Droms
Cc: [email-masked]
Subject: Re: [dhcwg] Address selection for Information-request/Reply
messages 

    Date:        Thu, 01 May 2003 09:52:19 -0400
    From:        Ralph Droms <[email-masked]>
    Message-ID:  <[email-masked]>

  | Infact, it would be important to note that a site MUST NOT both
  | implement multicast and configure relay agents to listen on
  | All_DHCP_Servers, as such a configuration would result in the
  | servers receiving multiple copies of client messages.

Surely that happens with relay agents anyway?   Any site with half a brain,
or more, configures multiple relay agents for redundancy (assuming it also
has multiple routers for redundancy of course).   If the protocol can't
handle multiple copies of messages being delivered to the servers, it badly
needs fixing (but I actually doubt it has that defect).

kre

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From: "Bernie Volz (EUD)" <[email-masked]>
Date: Thu, 1 May 2003 11:01:48 -0500

Personally, I would prefer we leave this as it is. I think there is too great
a danger for problems with allowing this because of the risk of misconfiguration.
Also, if you allow this for Information-Request, why not allow it also in cases
where a client has obtained some addresses from stateless and is using stateful
for others.

- Bernie

-----Original Message-----
From: Ralph Droms [mailto:[email-masked]]
Sent: Thursday, May 01, 2003 9:52 AM
To: [email-masked]
Subject: [dhcwg] Address selection for Information-request/Reply
messages

At 12:10 AM 4/15/2003 +0900, JINMEI Tatuya / =?ISO-2022-JP?B?GyRCP0BMQEMjOkgbKEI=?= wrote:

>1. address selection of Information-request/Reply exchanges
>
>According to the DHCPv6 base spec, the client should send Information
>Request messages to the All_DHCP_Relay_Agents_and_Servers multicast
>address (FF02::1:2).  However, doesn't it make much sense to allow the
>client to send the requests to the All_DHCP_Servers multicast address
>FF05::1:3?  Since the stateless usage assumes the client has obtained
>its IPv6 addresses through some other mechanism, I don't see a reason
>that the client cannot do so.  If we allow this, the client can access
>an off-link server without relying on a relay agent, which would help
>the deployment.

On the other hand, we don't want to require deployment of multicast
to enable stateless DHCPv6.

One possibility would be to allow the use of All_DHCP_Servers, with
an explicit warning that a site that doesn't implement multicast
MUST use relay agents AND the relay agents must listen to
All_DHCP_Servers (which is a change from the current spec).  In
fact, it would be important to note that a site MUST NOT both
implement multicast and configure relay agents to listen on
All_DHCP_Servers, as such a configuration would result in the
servers receiving multiple copies of client messages.

- Ralph