Re: RS sending in draft-ietf-v6ops-ipv6-cpe-router-04

[Ole Troan <ot@cisco.com>]

Woj,

> As a follow-up to the discussion, here's some proposed text for the "WAN
> side requirements" in Section 4.2:
> 
> W-x:    The router MUST orignate RS messages with a source IP address set to
> one of the interface's unicast addresses.


let me see if I understand where you are coming from. this is for an DSL/GPON access network, where you require some isolation between the CPEs. so you don't do address resolution downstream, but you depend on things like DHCP snooping to learn address to L2 address bindings. then to learn the link-local to L2 binding, you obviously need something different than DHCP. so the only reliable protocol you're left with is the RS/RA exchange. correct?

so something like this?

W-x: The IPv6 CE router MUST generate a link-local address and finish Duplicate Address Detection according to RFC4862 prior to sending any Router Solicitations on the interface. The source address used in the subsequent Router Solicitation MUST be the link-local address on the WAN interface.

this is contrary to the section 4 of RFC4862 by the way, which recommends the processes should be done in parallel. BBF's TR-124i2 also has DAD and router solicitation done in serial.

cheers,
Ole



> 
> On 15/04/2010 16:02, "Wojciech Dec" <wdec@cisco.com> wrote:
> 
>> Hi,
>> 
>> Given that RS triggered access appears to be gaining ground (based on the
>> latest  draft-krishnan-rs-mark) it would appear that the CPE router draft
>> specify a bit more tightly the form of RS messages a CPE sends when connecting
>> to a network. 
>> RFC4861 section 6.3.7 states:
>> " A host sends Router Solicitations to the all-routers multicast
>>   address.  The IP source address is set to either one of the
>>   interface's unicast addresses or the unspecified address."
>> 
>> Now, since the source address is very likely to be one of the identifier keys
>> for a CPE used for authorization, I would like to propose that an RS sending
>> rule be added to the CPE spec which would ensure that the IP source address is
>> NEVER the unspecified address, eg:
>> 
>> The IPv6 CE router MUST use one of its WAN interface unicast addresses when
>> sending RS messages.
>> 
>> Comments?
>> 
>> -Woj.
> 
>