The MPLS WG Archive

["Loa Andersson" <loa.andersson@utfors.se>]

All,

why not forward on L3?

/Loa

suchauhan@hss.hns.com wrote:
> 
> hi mohit!
>      yes that is a definite problem and our point regarding the record route
> being filled in my the ingress is also not done bacause ingress can not know the
> IP address of all intermediate LSR's IP addresses. So even that cannot be done.
> Sorry I dont  have the answer to this. My best guess is that these troublesome
> options cannot be supported for MPLS. Easy after all , eh?! ;o)))
> 
> ciao
> sumit
> 
> mgoel@hss.hns.com on 04/26/2001 04:54:42 PM
> 
> To:   Sumit Chauhan/HSS@HSS
> cc:   mpls@UU.NET
> 
> Subject:  Re: IP Source Route Option
> 
> Hi Sumit !
> 
> But how mpls will handle the IP's Record route option which requires that each
> intermediate router should insert its IP address in the datagram. MPLS cannot
> drop that packet simply because record route option is enabled in it. Moreover
> if explicit routing is there then ingress router can insert the complete IP
> addresses of the intermediate LSRs in the datagram, but what will happen in the
> case of hop by hop LSP.
> 
> Thanks
> Mohit Goel
> 
> suchauhan@hss.hns.com on 04/26/2001 04:23:23 PM
> 
> To:   Mohit Goel/HSS@HSS
> cc:   mpls@UU.NET
> 
> Subject:  Re: IP Source Route Option
> 
> hi mohit!
>      Ideally this thing should be handled at the Ingress LER and he should
> translate the IP Source Route to MPLS sourse Route by defining a complete path
> for the packet (means asking the downstream routers for this). The question
> still hold weight as to what should be done if such a path does not exist at the
> time of the packet coming in or the path cannot be setup even when requested. My
> guess is that its best in both cases to discard the packet and send a normal
> ICMP packet back to source as is normally done.  Going a bit deeper we generally
> use IP Source Routing for testing purposes and not as a means of data path
> reservation. Hence it might make sense to try and set up the LSP requested
> starting at the Ingress LER to the Egress LER if possible while holding on to
> the packet. This does complicate things but I guess if we have to do source
> routing we have to do this. ;o(
> regards
> sumit
> 
> mgoel@hss.hns.com on 04/26/2001 04:20:06 PM
> 
> To:   mpls@UU.NET
> cc:    (bcc: Sumit Chauhan/HSS)
> 
> Subject:  IP Source Route Option
> 
> Hi All,
> 
> I have a small doubt. Let an unlabelled IP packet with IP source route option
> enabled comes in MPLS domain. Let the packet is assigned to a LSP (say numbered
> 1). While traversing the MPLS domain, packet will not go to the Network layer,
> thus the LSR in between the ingress LSR and egress LSR cannot insert their IP
> addresses in the datagram. So does MPLS supports IP source route option or it
> does not support it?
> 
> Thanks
> Mohit Goel

-- 
Loa Andersson
Chief Architect,
Utfors Research, Architecture and Future Lab (URAX)
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