Re: [Lsr] Regarding OSPF Extended Prefix Range TLV usage for External/NSSA prefixes defined in RFC 8665

[Peter Psenak <[e-mail]>]

Hi Veerendranatha,

On 19/08/2020 11:48, Veerendranatha Reddy V wrote:
> Hi Peter,
> Thanks for the reply.
> As per the discussion, my understanding is Range TLV  defined mainly be used for SRMS entries (to get entries from LDP , for LDP Interoperability).
> The use case mentioned  is different from SRMS (redistribution across IGP protocols) , Range TLV is not applicable to use in that use case?

no. At this point, Range TLV is defined only for SRMS mapping advertisement.

thanks,
Peter

> 
> Thanks & Regards,
> Veerendranath
> 
> 
> -----Original Message-----
> From: Peter Psenak <ppsenak=[e-mail]>
> Sent: Wednesday, August 19, 2020 3:04 PM
> To: Veerendranatha Reddy V <[e-mail]>; [e-mail]
> Subject: Re: [Lsr] Regarding OSPF Extended Prefix Range TLV usage for External/NSSA prefixes defined in RFC 8665
> 
> Veerendranatha,
> 
> On 19/08/2020 11:19, Veerendranatha Reddy V wrote:
>> Hi Peter,
>> Thanks for the reply.
>> For OSPFv2 Extended Prefix TLV  (defined in RFC 7684) has route type and it supports NSSA External Prefixes to carry SID information.
>> In the same way, if Range TLV has Route-Type , we can extend to support for NSSA ASBR to send Range TLVs for redistributed prefixes.
> 
> no. NSSA route type is used for redistribution of prefixes to NSSA areas. There is no such thing as redistribution of SRMS entries. So using NSSA type with SRMS advertisement is not valid.
> 
> Peter
> 
> 
> 
> 
>>
>> Thanks & Regards,
>> Veerendranath
>>
>> -----Original Message-----
>> From: Peter Psenak <ppsenak=[e-mail]>
>> Sent: Wednesday, August 19, 2020 1:39 PM
>> To: Veerendranatha Reddy V <[e-mail]>;
>> [e-mail]
>> Subject: Re: [Lsr] Regarding OSPF Extended Prefix Range TLV usage for
>> External/NSSA prefixes defined in RFC 8665
>>
>> Veerendranath,
>>
>> On 19/08/2020 10:03, Veerendranatha Reddy V wrote:
>>> Hi Peter,
>>> It is not related to SRMS.
>>> If there exist ISIS/OSPF or two instances of OSPF in same device, and all are supporting ST, then I can redistribute SR Prefix information to OSPF from other OSPF instance or from ISIS.
>>
>> yes, you can.
>>
>>> In this case, I may use range TLV to reduce the number of Prefix TLVs, by using  Range TLV, if prefixes and SID are able to convert to Range TLV.
>>
>> you would have to generate one somewhere (on ABR?), but it would not be of NSSA type.
>>
>> Peter
>>
>>
>>>
>>> Thanks & Regards,
>>> Veerendranath
>>>
>>>
>>> -----Original Message-----
>>> From: Peter Psenak <ppsenak=[e-mail]>
>>> Sent: Wednesday, August 19, 2020 1:23 PM
>>> To: Veerendranatha Reddy V <[e-mail]>;
>>> [e-mail]
>>> Subject: Re: [Lsr] Regarding OSPF Extended Prefix Range TLV usage for
>>> External/NSSA prefixes defined in RFC 8665
>>>
>>> Hi Veerendranatha,
>>>
>>> On 19/08/2020 06:23, Veerendranatha Reddy V wrote:
>>>> Hi Peter,
>>>> While redistributing prefix Sid for the prefixes from other protocols (Ex: from ISIS or other OSPF instances), we can consider as range TLV for the prefixes which are advertised in the range TLV in that protocol.
>>>
>>> I don't follow. Are you talking about redistribution of SRMS advertisement between protocols? Such thing has not been defined.
>>>
>>> thanks,
>>> Peter
>>>
>>>
>>>> If it is NSSA, then we need to advertise these redistributed prefixes as area scope, so Range TLV also need to be part of area scope Opaque LSA.
>>>>
>>>> Thanks & Regards,
>>>> Veerendranath
>>>>
>>>> -----Original Message-----
>>>> From: Peter Psenak <ppsenak=[e-mail]>
>>>> Sent: Tuesday, August 18, 2020 11:06 PM
>>>> To: Veerendranatha Reddy V <[e-mail]>;
>>>> [e-mail]
>>>> Subject: Re: [Lsr] Regarding OSPF Extended Prefix Range TLV usage
>>>> for External/NSSA prefixes defined in RFC 8665
>>>>
>>>> Veerendranath,
>>>>
>>>> On 18/08/2020 16:40, Veerendranatha Reddy V wrote:
>>>>> Hi Authors, All,
>>>>>
>>>>> OSPF Extended Prefix Range TLV defined in RFC 8665 has IA flag to
>>>>> distinguish between Intra and Inter Area scope prefixes.
>>>>>
>>>>> Whether any restrictions to not to use Prefix Range TLV for
>>>>> external/NSSA prefixes ?
>>>>
>>>> I don't see how you can use OSPF Extended Prefix Range TLV for NSSA, the usage of OSPF Extended Prefix Range TLV has only been defined in the context of RFC 8665.
>>>>
>>>> thanks,
>>>> Peter
>>>>
>>>>
>>>>>
>>>>> For External Prefixes, we can able to use  Prefix Range TLV  by
>>>>> using LSA type (based on AS scope Opaque Type , so the TLV is for
>>>>> External
>>>>> Prefixes)
>>>>>
>>>>> But If we need to use the Prefix Range TLV for NSSA prefixes
>>>>> (Type-7) , which are in area scope, there is no flag/route-type
>>>>> field in this TLV to distinguish between Intra or NSSA prefixes( as
>>>>> IA flag will not be set anyway).
>>>>>
>>>>> Thanks & Regards,
>>>>>
>>>>> Veerendranath
>>>>>
>>>>
>>>>
>>>>
>>>
>>>
>>>
>>
>>
>>
> 
> 
>