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

[Igor Bryskin <[e-mail]>]

And I am not arguing that sufficient redundancy must be provided. However you said:
>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.

If you just simply interconnect all VPN-aware PEs into a single ring via IPinIP tunnels and run an instance of OSPF to distribute VPN-related information between them, it will provide sufficient redundancy and involve exactly *zero* Ps.
So, I want you to drop your lecturing tone for a minute and simply tell in what respect in your opinion this approach is not perfect fo the L1VPN application. Otherwise, I am not interested in this discussion any longer. I do like to hear comments from other people.

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: Wednesday, September 3, 2008 8:10:07 AM
Subject: RE: [Softwires] BGP TE attr last call by softwires WG (2nd question)

Igor,

Actually, I am not sure that you do understand what I wrote, because you
are providing examples of the redundancy that I specified - every PE
router needs to have connectivity to two other routers in the IGP
instance.

Thanks,

John 

>-----Original Message-----
>From: Igor Bryskin [mailto:[e-mail]] 
>Sent: Tuesday, September 02, 2008 3:06 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)
>
>Hi John,
>
>I understand what you are saying and disagree. The overlay I 
>am talking about logically is a separate network and as any 
>network it should be sufficiently redundant to function. There 
>is a number of ways how you can address the redundancy 
>concerns. Look at the examples below:
>
>a) interconnect all VPN-aware PEs into a single ring: 
>PE=======PE
> ||                  ||
>PE               PE 
>||                   ||
>PE               PE 
>||                   ||
>...                ....
>PE=======PE
>
>b) connect each PE to two interconnected Ps 
>
>PE               P                 PE
>                    ||                  
>PE               ||                  PE 
>                    ||                  
>PE               ||                  PE 
>                    ||                  
>...                 ||                   ....
>PE               P                 PE
>
>
>Note that tunnels can traverse any number of VPN-unaware Ps and PEs.
>
>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: Tuesday, September 2, 2008 2:24:26 PM
>Subject: RE: [Softwires] BGP TE attr last call by softwires WG 
>(2nd question)
>
>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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