Re: [Idr] [bess] Type 1 RD for Pure IPv6 network -- EVPN

["Acee Lindem (acee)" <[e-mail]>]

Hi Gyan,
Agree with Jakob. There is no reason for the BGP Identifier to be a unique IPv4 address. Consider an IPv6 only AS. However, there is nothing precluding you from using an IPv4 address if you are uncomfortable.

Thanks,
Acee

From: BESS <[e-mail]> on behalf of "Jakob Heitz (jheitz)" <jheitz=[e-mail]>
Date: Thursday, February 4, 2021 at 12:52 AM
To: Gyan Mishra <[e-mail]>
Cc: TULASI RAM REDDY <[e-mail]>, Muthu Arul Mozhi Perumal <[e-mail]>, "[e-mail]" <[e-mail]>, IDR List <[e-mail]>
Subject: Re: [bess] [Idr] Type 1 RD for Pure IPv6 network -- EVPN

RFC 6286 already updates RFC 4271.
Basically, RID is not unique. (ASN,RID) is unique. The only limitation on RID is that RID != 0.

Regards,
Jakob.

From: Gyan Mishra <[e-mail]>
Sent: Wednesday, February 3, 2021 9:42 PM
To: Jakob Heitz (jheitz) <[e-mail]>
Cc: Muthu Arul Mozhi Perumal <[e-mail]>; TULASI RAM REDDY <[e-mail]>; [e-mail]; [e-mail]
Subject: Re: [Idr] [bess] Type 1 RD for Pure IPv6 network -- EVPN



On Wed, Feb 3, 2021 at 11:22 PM Jakob Heitz (jheitz) <[e-mail]<mailto:[e-mail]>> wrote:
<snip RFC4271>
   Syntactic correctness means that the BGP Identifier field represents
   a valid unicast IP host address.
</snip>

     Gyan> I do see that verbiage in section 6.2



   If the BGP Identifier field of the OPEN message is syntactically

   incorrect, then the Error Subcode MUST be set to Bad BGP Identifier.

   Syntactic correctness means that the BGP Identifier field represents

   a valid unicast IP host address.



BGP with IGP call back NH tracker checks the NH but how does BGP code validate the RIB that the router-id is a connected loopback but

and also advertised by IGP.  I have not tried it but if you set a bogus router-id would all the BGP peers go down.

I will try that in the lab.

IOS-XR does not have this check. Nothing breaks by violating this rule. IOS-XR implements RFC 6286.
I think you'll be hard pressed to find a router that checks this.
 Gyan> Agreed.  That is exactly what I thought.  I was going to try on IOS XR but you saved me some time and results as I expected.  I will try test RFC 6286 on XR.  Have you tried doing IPv6 only peers on XR and with BGP identifier set unique to 4 octet IP address and see if that works.  I am guessing it would work as XR does not have the check.

    I  am not crazy about the RFC 6286 AS wide BGP identifier with 4 octet unsigned non zero integer.  Most operators are more comfortable having unique 4 octet IP address as BGP identifier and I think would much rather do that as long as the check does not exist as even with enabling RFC 6286 and having AS wide unique identifier seems odd and scary to me as normally the BGP identifier must always be unique within the domain or breaks BGP.

dual stack edge over v6 core RFC 5565 is becoming more common for operators every day with SRv6 push and thus IPv6 only routers and running into this issue where now you have to enable RFC 6286.

I am thinking it maybe well worthwhile to write a draft that updates RFC 4271 check as vendors don’t follow it anyway and as we all know not checking is not going to break anything and making so that for IPv6 only routers such as in a SRv6 core that the BGP identifier can remain a 4 octet IP and then operators now could keep the same unique BGP identifier IP you had on the router before you ripped it out of the core when transitioned to SRv6.
Regards,
Jakob.

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Gyan Mishra

Network Solutions Architect

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13101 Columbia Pike
Silver Spring, MD