回覆: ndisc_send_ns: always use link-local addr of the leaving device

[Moter Du <Moter_Du@xxxxxxxxxxxxxxxxxxx>]

4.3.  Neighbor Solicitation Message Format

   IP Fields:

      Source Address
                     Either an address assigned to the interface from
                     which this message is sent or (if Duplicate Address
                     Detection is in progress [ADDRCONF]) the
                     unspecified address.

7.2.2.  Sending Neighbor Solicitations
(the 2nd para.)
   If the source address of the packet prompting the solicitation is the
   same as one of the addresses assigned to the outgoing interface, that
   address SHOULD be placed in the IP Source Address of the outgoing
   solicitation.  Otherwise, any one of the addresses assigned to the
   interface should be used.  Using the prompting packet's source
   address when possible insures that the recipient of the Neighbor
   Solicitation installs in its Neighbor Cache the IP address that is
   highly likely to be used in subsequent return traffic belonging to
   the prompting packet's "connection".

Specifications are listed above for your reference.  Note, in the illustration using [RUT] eth1 global-unicast address as Source Address of NS always violates the specification, because it's none of the addresses assigned to the outgoing interface (i.e., eth0).

Any scope of addresses of [RUT] eth0 may be used as Source Address of NS.  The patch uses link-local always and I see no improper at all.  Could you show me more hints for "solicitation avoidance"?

>       Sincerely
>       Moter Du
>
>       ============================================================
>       Moter Du                                  D410, Siemens STSL
>       phone   +886 2 25186011
>       Fax     +886 2 25053866
>       mailto:moter_du@xxxxxxxxxxxxxxxxxxx
                ============================================================

-----原始郵件-----
寄件者: kuznet@xxxxxxxxxxxxx [mailto:kuznet@xxxxxxxxxxxxx]
寄件日期: 2001年2月15日 AM 12:34
收件者: Moter_Du@xxxxxxxxxxxxxxxxxxx
副本: netdev@xxxxxxxxxxx
主旨: Re: ndisc_send_ns: always use link-local addr of the leaving
device

Hello!

> Without the patch, the following scenario illustrates how it violates
> RFC2461 :

Please, cite the place which is violated. (I'm sorry, lazy to search myself).

>   NS contains global-unicast address of eth1 of [RUT] as Source Address
> (ERROR!!)

I see no error. If it is global scope, it is on link by definition.

But bug is really present: it could be link local for another link!

> With the patch:
>   NS contains link-local address of eth0 of [RUT] as Source Address

BTW this is surely error, killing all the idea behind solicitation
avoidance.

Alexey