Hi all,
Adding one more item in Q2 of the original email...
Regards,
Sasha
From: Alexander Vainshtein
Sent: Sunday, April 30, 2023 10:52 AM
To: Rabadan, Jorge (Nokia - US/Mountain View) <jorge.raba...@nokia.com>;
wim.henderi...@nokia.com; 'John E Drake' <jdr...@juniper.net>; Wen Lin
<w...@juniper.net>; Ali Sajassi (sajassi) <saja...@cisco.com>
Cc: bess@ietf.org
Subject: Questions about Section 4.4.3 of RFC 9136
Importance: High
Hi all,
I have a couple of question about Section 4.4.3 of RFC
9136<https://datatracker.ietf.org/doc/html/rfc9136#section-4.4.3>.
This section discusses usage of EVPN IP Prefix (Type 5 routes) in the
Interface-ful IP-VRF-to-IP-VRF with Unnumbered SBD IRB scenario.
Q1: Is this scenario relevant for IP-VRFs that carry IPv6 customer traffic? To
the best of my understanding:
1. In this case the IRB that connects IP-VRFs in different NVEs/DGEs to
the SBD are IPv6-capable interfaces
2. As per Section 2.1 of RFC
4291<https://www.rfc-editor.org/rfc/rfc4291.html#section-2.1> "All interfaces
are required to have at least one Link-Local unicast address". Specifically,
each IRB MUST possess at least a unicast link-local IPv6 address
3. Link-local IPv6 addresses of the IRBs that connect IP-VRFs in
different NVEs and DGEs SHOULD be different, otherwise the IPv6 Duplicated
Address Detection check (see Section 5.4 of RFC 4862) would fail. If this
condition is met, the scenario defined in section 4.4.2 of RFC 9136 becomes
applicable.
Q2: Does this scenario implicitly introduce unnumbered LAN interfaces in IPv4?
1. Unnumbered IPv4 interfaces are discussed in multiple IETF standards (RFC
1812, RFC 2328, RFC 5309 and more)
* AFAIK, in all these documents unnumbered IPv4 interfaces are
restricted to be "point-to-point lines" (using the terminology of RFC 1812)
* The IRBs that connect IP-VRFs in different NVEs/DGEs to the SBD are
unnumbered but obviously not point-to-point
2. Consider the network depicted in Figure 10 in the section in question and
suppose that the operator of this network wants to check IP connectivity
between IP-VRF in DGW1 and host IP1.
* Can the operator ping IP1 from IP-VRF in DFW1?
* If yes, then which source IP address would be used in the ping packets?
3. Consider the network depicted in Figure 10 in the section in question and
suppose that a management system that uses the base RIB data model defined in
RFC 8439<https://www.rfc-editor.org/rfc/rfc8349> retrieves the RIB of the
IP-VRF in DGW1 after EVPN IP Prefix routes to host IP1 and to subnets SN1 and
SN2 have been received and installed.
* What will the management receive as the next hops and egress
interfaces of these routes?
* Will these routes be perceived as labeled routes, and if yes, how
would the management system be able to differentiate between these routes and
routes received as VPNv4/VPNv6 routes?
Your feedback would be highly appreciated.
Regards, and lots of thanks in advance,
Sasha
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