RE: [Softwires] BGP TE attr last call by softwires WG (2nd question)

["Drake, John E" <[e-mail]>]

Igor,

Several years ago when OSPF was first proposed as an autodiscovery
mechanism for L1VPNs, you were told that it was a bad idea due to its
scaling properties and impact on the IGP.

You are now tacitly agreeing with those who told you it was a bad idea.

For your suggested approach to work with sufficient redundancy, the
topology of the overlay needs to be configured such that every selected
P router is connected to at least two other selected P routers and every
PE router needs to be connected to at least two selected P routers.

When you are done with this configuration, you are left with a situation
in which *every* PE and selected P router will have *all* L1VPN routes.

Thanks,

John 

>-----Original Message-----
>From: Igor Bryskin [mailto:[e-mail]] 
>Sent: Friday, August 29, 2008 12:10 PM
>To: Drake, John E; Yakov Rekhter; Lou Berger
>Cc: Yakov Rekhter; Adrian Farrel; [e-mail]; 
>[e-mail]
>Subject: Re: [Softwires] BGP TE attr last call by softwires WG 
>(2nd question)
>
>Are you calling me silly? Are you coming to Minneapolis? :=)
>
>Seriously, what is wrong in your opinion with this approach? 
>Many people are talking about multi-instance IGPs. What they 
>have in mind is improving the IGP scalability:
>a) by removing non-IP advertisements from the instance of IGP 
>that manages IP routing/forwarding tables into separate IGP 
>instance(s);
>b) by distributing non-IP information only to and via 
>inerested parties leaving the bulk of Ps out of the process.
>
>In my opinion this is exactly what is needed for the 
>OSPF-based L1VPN application.
>
>Igor
>
>
>
>
>
>
>----- Original Message ----
>From: "Drake, John E" <[e-mail]>
>To: Igor Bryskin <[e-mail]>; Yakov Rekhter 
><[e-mail]>; Lou Berger <[e-mail]>
>Cc: Yakov Rekhter <[e-mail]>; Adrian Farrel 
><[e-mail]>; [e-mail]; [e-mail]
>Sent: Friday, August 29, 2008 2:31:36 PM
>Subject: RE: [Softwires] BGP TE attr last call by softwires WG 
>(2nd question)
>
>So you are proposing an OSPF route reflector?  At what point 
>does the silliness stop? 
>
>>-----Original Message-----
>>From: Igor Bryskin [mailto:[e-mail]]
>>Sent: Friday, August 29, 2008 11:29 AM
>>To: Drake, John E; Yakov Rekhter; Lou Berger
>>Cc: Yakov Rekhter; Adrian Farrel; [e-mail]; 
>>[e-mail]
>>Subject: Re: [Softwires] BGP TE attr last call by softwires WG (2nd 
>>question)
>>
>>Hi John,
>>
>>No, not really. When you add a PE you configure local 
>interfaces, local 
>>VPN port mappings, stuff like that. While doing this you will also 
>>configure an IPinIP tunnel to one of your spoke Ps and enable L1VPN 
>>OSPF instance on the tunnel.
>>Once you did that the local VPN information will be flooded 
>accross the 
>>overlay, likewise, the new PE will get all the necessary information 
>>from other PEs.
>>
>>Cheers,
>>Igor
>>
>>
>>----- Original Message ----
>>From: "Drake, John E" <[e-mail]>
>>To: Igor Bryskin <[e-mail]>; Yakov Rekhter 
>><[e-mail]>; Lou Berger <[e-mail]>
>>Cc: Yakov Rekhter <[e-mail]>; Adrian Farrel 
>><[e-mail]>; [e-mail]; [e-mail]
>>Sent: Friday, August 29, 2008 11:20:16 AM
>>Subject: RE: [Softwires] BGP TE attr last call by softwires WG (2nd 
>>question)
>>
>>Igor,
>>
>>Doesn't this defeat auto-discovery?  I.e., how is a new PE added to a 
>>given L1VPN?
>>
>>Thanks,
>>
>>John
>>
>>>-----Original Message-----
>>>From: Igor Bryskin [mailto:[e-mail]]
>>>Sent: Friday, August 29, 2008 5:51 AM
>>>To: Yakov Rekhter; Lou Berger
>>>Cc: Yakov Rekhter; Adrian Farrel; [e-mail]; 
>>>[e-mail]
>>>Subject: Re: [Softwires] BGP TE attr last call by softwires WG (2nd
>>>question)
>>>
>>>Yakov,
>>>
>>>You said:
>>>
>>>
>>>... And while on the subject of scaling, please keep in mind 
>that BGP 
>>>only stores L1VPN routes on PEs that have sites of that VPN 
>connected 
>>>to them, and on an RR if used, but *not* on any of the P routers. In 
>>>contrast, rfc5252 (OSPF for L1VPN
>>>autodiscovery) results in storing *all VPN TE information for all the
>>>VPNs* on *all* the IGP nodes, both P and PE. So, clearly BGP-based 
>>>approach scales better than OSPF-based approach.
>>>
>>>Yakov.
>>>
>>>This is not true in case of multi-instance OSPF: one can build an 
>>>overlay interconnecting PEs via one or small number of Ps
>>using IPinIP
>>>tunnels and run in this overlay an instance of OSPF specifically 
>>>designated for distribution of L1VPN information. In this
>>case the OSPF
>>>solution won't scale any worse than the BGP approach. Note. 
>>that rfc252
>>>never said that the instance of OSPF used for flooding of the L1VPN 
>>>information must be the same instance that is used for the
>>distribution
>>>of IP-related LSAs.
>>>
>>>Regards,
>>>Igor
>>>
>>>
>>>
>>>
>>
>>
>>
>>
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