The MPLS WG Archive

[David Charlap <David.Charlap@marconi.com>]

Marshall Ma Shaowen wrote:
> 
> thanks for David Charlap.he give me the solution.

Sorry.  I accidentally sent my reply to Marshall and not to the group. 
It's been sent now.

> I konw the rfc2205 doesn't talk about the LSPs.but if I follow the
> rfc2205, I will choose the RTD's IP address as the packet's
> destination address. and If I send  the packet with the IP address
> of RTB . I can not let the router that don't know RSVP to forward
> the packet as the rfc2205 said.

You do not send the packet with RTB's address.  You send it with RTD's
address.  RTB is the next-hop, not the destination.

> but along the way of LSP. if a router don't know RSVP. I cannot
> setup a LSP.  So I follow the destination address will be set as
> RTB's IP address.  and I can update my IP stack to let socket send
> out a packet based on the nexthop. and I got another question ,
> if I choose RTB's IP address,do we need to implement Router Alert
> option in IP option ?

Yes, you must use router-alert.  Without it, RTB will forward a
properly-formed packet, which is incorrect behavior.  RTB must intercept
the packet and process it.

If you actually send the packet to RTB, the packet will get delivered
there, but your behavior will be incorrect.

-- David


> RTA
>  |
> -+--------------+---------------+----------------
>                 |               |
>                 |               |
>                RTB             RTC
>                 |               |
>                 |               |
> ----------------+---------------+--------------+-
>                                                |
>                                               RTD