Jorge,
Lots of thanks for your response.
Please see more comments inline below.
Regards,
Sasha
From: Jorge Rabadan (Nokia) <jorge.raba...@nokia.com>
Sent: Tuesday, July 11, 2023 6:35 PM
To: Alexander Vainshtein <alexander.vainsht...@rbbn.com>
Cc: bess@ietf.org; draft-sajassi-bess-evpn-ip-aliasing.auth...@ietf.org
Subject: [EXTERNAL] Re: RE: Question and comments on the EVPN IP Aliasing draft
Hi Sasha,
Let me try to reply to your questions:
How can a PE that receives an EVPN Type 1 route decide whether it is a per-EVI
Ethernet A-D route or a per-EVI IP A-D route?
[jorge] The IP A-D per EVI route carries a route target of an IP-VRF.
[[Sasha]] Yes, I have assumed the same. But what is supposed to happen if an
A-D per-EVI route carries RTs that match both some IP-=VRF and some MAC-VRF in
the receiving PE? Should such a route be simply treated as an error (and, if
yes, what would be the action on it), or should one of the two possibilities
given priority? Such a route clearly could not be installed in both places.
2. “The draft defines, without going into details, quite a different
procedure for recursive resolution of such routes that uses per EVI IP A-D
routes introduced in the draft. This procedure inherently assumes that
inter-subnet traffic is carried between the PEs as IP-VPN traffic (i.e.,
without inner L2 encapsulation).
My question is: How can the PE that receives an EVPN IP Prefix routes with a
non-reserved ESI value decide which of these two procedures it should apply to
each specific route?”
[jorge] As discussed, for IP Prefix routes, the draft extends RFC9136 section
4.4.1 (we added some text about it) to support the resolution of IP Prefix
routes to IP A-D routes.
- RFC9136 section 4.4.1 supports both Ethernet NVO tunnels and IP NVO tunnels
(see the terminology section in RFC9136). That is, both inner L2 or L3
encapsulation.
- If an implementation receives an IP Prefix route with a non-reserved ESI
value that is imported in an IP-VRF, the procedures in the draft are followed,
irrespective of whether the PEs use Ethernet NVO or IP NVO tunnels. The route
resolution is described in 5.3.1.
- By the way, the recursive resolution is compatible with RFC9136. See table
1, first two top rows:
+==========+==========+==========+============+===============+
| ESI | GW IP | MAC* | Label | Overlay Index |
+==========+==========+==========+============+===============+
| Non-Zero | Zero | Zero | Don't Care | ESI |
+----------+----------+----------+------------+---------------+
| Non-Zero | Zero | Non-Zero | Don't Care | ESI |
+----------+----------+----------+------------+---------------+
[[Sasha]] Unfortunately, it doesn’t, it seems that my original question has
been presented clearly enough.
My scope of interest is EVPN over an IP/MPLS core, i.e., I am only discussing
only MPLS tunnels.
My understanding of the interface-less IP-VRF-to-IP-VRF model as described in
9136 is that it does not imply recursive resolution and inter-subnet traffic
crosses the core as pure IP over MPLS (i.e., the customer IP header immediately
follows the bottom of the label stack). This is fully aligned with the
mechanism used with Symmetric IRB as defined in Section 5.4 of RFC 9135 that
says: “If the tunnel type is that of an MPLS or IP-only NVO tunnel, then the
TS's IP packet is sent over the tunnel without any Ethernet header.” I assume
that your modified model does not change the way customer inter-subnet traffic
is carried across the IP/NMPLS core (you’ve mentioned that the modified model
still does not use SBD).
At the same time, all the scenarios in RFC 9136 that use recursive resolution
imply insertion of an “inner Ethernet header” between the bottom of the label
stack and the customer IP header, and the difference between these methods is
about the way Destination MAC address of this inner Ethernet header is obtained
(from the suitable RT-2, from the Router MAC Extended Community or by a local
policy). This matches my understanding of Asymmetric IRB as defined in Section
6.3 of RFC 9135: “The ingress PE gets the destination TS's MAC address for that
TS's IP address from its ARP table or NDP cache. It encapsulates the packet
with that destination MAC address and a source MAC address corresponding to
that IRB interface and sends the packet to its destination subnet MAC-VRF/BT.
The destination MAC address lookup in the MAC-VRF/BT results in a BGP next-hop
address of the egress PE along with label1 (L2 VPN MPLS label or VNI).”
With RFC 9136, the PE that receives an IP Prefix Route can decide whether its
handling by the data plane does or does not involve inclusion of the “inner L2
header: recursive resolution always implies inner L2 header, if it is not used,
no inner L2 header is needed.
Your modification breaks this simple rule: data plane handling of a received
and installed an RT-5 with a non-reserved ESI value in its NLRI sometimes
requires usage of inner L2 header (old scenarios from RFC 9136) and sometimes
does not require it (in the new scenario defined in the draft).
My question was: How can the receiving PE differentiate between these two cases?
If the RT attached to the received IP Prefix route with a non-reserved ESI
value matches a MAC-VRF in the receiving PE, inner L2 header is required, and
if it matches an IP-VRF, inner L2 header is not required.
If this is indeed the intention, then handling of the case when one of the RTs
attached to this route matches a MAC-VRF while another matches an IP-VRF should
be explicitly defined.
What, if anything, did I miss?
Let me know if it helps.
Thanks.
Jorge
From: Alexander Vainshtein
<alexander.vainsht...@rbbn.com<mailto:alexander.vainsht...@rbbn.com>>
Date: Sunday, July 9, 2023 at 9:54 AM
To: Jorge Rabadan (Nokia)
<jorge.raba...@nokia.com<mailto:jorge.raba...@nokia.com>>
Cc: bess@ietf.org<mailto:bess@ietf.org> <bess@ietf.org<mailto:bess@ietf.org>>,
draft-sajassi-bess-evpn-ip-aliasing.auth...@ietf.org<mailto:draft-sajassi-bess-evpn-ip-aliasing.auth...@ietf.org>
<draft-sajassi-bess-evpn-ip-aliasing.auth...@ietf.org<mailto:draft-sajassi-bess-evpn-ip-aliasing.auth...@ietf.org>>
Subject: Re: RE: Question and comments on the EVPN IP Aliasing draft
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Jorge and all,
More of the same:
How can a PE that receives an EVPN Type 1 route decide whether it is a per-EVI
Ethernet A-D route or a per-EVI IP A-D route?
My 2c,
Sasha
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________________________________
From: Alexander Vainshtein
<alexander.vainsht...@rbbn.com<mailto:alexander.vainsht...@rbbn.com>>
Sent: Sunday, July 9, 2023 12:57:00 PM
To: Jorge Rabadan (Nokia)
<jorge.raba...@nokia.com<mailto:jorge.raba...@nokia.com>>
Cc: bess@ietf.org<mailto:bess@ietf.org> <bess@ietf.org<mailto:bess@ietf.org>>;
draft-sajassi-bess-evpn-ip-aliasing.auth...@ietf.org<mailto:draft-sajassi-bess-evpn-ip-aliasing.auth...@ietf.org>
<draft-sajassi-bess-evpn-ip-aliasing.auth...@ietf.org<mailto:draft-sajassi-bess-evpn-ip-aliasing.auth...@ietf.org>>
Subject: RE: Question and comments on the EVPN IP Aliasing draft
Jorge,
Lots of thanks for the new revision, it addresses the majority of my comments.
I still have some doubts about co-existence of the “old” (as in RFC 9136
Section 4.4.1) and “new” interface-less IP-VRF-to-IP-VRF models.
Specifically:
1. Section 4.3 of RFC 9136 provides a detailed procedure for recursive
resolution of received EVPN IP Prefix routes with a non-reserved ESI value in
their NLRI. To the best of my understanding, this procedure inherently assumes
that inter-subnet traffic is carried between the PEs as EVPN traffic (i.e.,
with inner L2 encapsulation). This procedure uses the Router MAC Extended
Community, or, in the case of its absence, a local policy for determination of
the Destination MAC address in the inner L2 encapsulation/
2. The draft defines, without going into details, quite a different
procedure for recursive resolution of such routes that uses per EVI IP A-D
routes introduced in the draft. This procedure inherently assumes that
inter-subnet traffic is carried between the PEs as IP-VPN traffic (i.e.,
without inner L2 encapsulation).
My question is: How can the PE that receives an EVPN IP Prefix routes with a
non-reserved ESI value decide which of these two procedures it should apply to
each specific route?
I think that the draft should provide an unambiguous answer to this question.
Regards,
Sasha
From: Jorge Rabadan (Nokia)
<jorge.raba...@nokia.com<mailto:jorge.raba...@nokia.com>>
Sent: Thursday, July 6, 2023 9:23 PM
To: Alexander Vainshtein
<alexander.vainsht...@rbbn.com<mailto:alexander.vainsht...@rbbn.com>>;
draft-sajassi-bess-evpn-ip-aliasing.auth...@ietf.org<mailto:draft-sajassi-bess-evpn-ip-aliasing.auth...@ietf.org>
Cc: bess@ietf.org<mailto:bess@ietf.org>
Subject: [EXTERNAL] Re: Question and comments on the EVPN IP Aliasing draft
Sasha,
We just published version 07 of the EVPN IP Aliasing draft, and tried to
address your comments in this thread. Let us know if you have further comments.
Thank you!
Jorge
From: Jorge Rabadan (Nokia)
<jorge.raba...@nokia.com<mailto:jorge.raba...@nokia.com>>
Date: Tuesday, April 4, 2023 at 5:09 PM
To: Alexander Vainshtein
<alexander.vainsht...@rbbn.com<mailto:alexander.vainsht...@rbbn.com>>,
draft-sajassi-bess-evpn-ip-aliasing.auth...@ietf.org<mailto:draft-sajassi-bess-evpn-ip-aliasing.auth...@ietf.org>
<draft-sajassi-bess-evpn-ip-aliasing.auth...@ietf.org<mailto:draft-sajassi-bess-evpn-ip-aliasing.auth...@ietf.org>>
Cc: bess@ietf.org<mailto:bess@ietf.org> <bess@ietf.org<mailto:bess@ietf.org>>
Subject: Re: Question and comments on the EVPN IP Aliasing draft
Hi Sasha,
I can work on some clarifications in the text based on your feedback.
About whether the draft updates RFC9136, I’m hesitant to add it to the header,
since this spec is obviously optional.
Thanks.
Jorge
From: Alexander Vainshtein
<alexander.vainsht...@rbbn.com<mailto:alexander.vainsht...@rbbn.com>>
Date: Monday, April 3, 2023 at 5:51 AM
To: Jorge Rabadan (Nokia)
<jorge.raba...@nokia.com<mailto:jorge.raba...@nokia.com>>,
draft-sajassi-bess-evpn-ip-aliasing.auth...@ietf.org<mailto:draft-sajassi-bess-evpn-ip-aliasing.auth...@ietf.org>
<draft-sajassi-bess-evpn-ip-aliasing.auth...@ietf.org<mailto:draft-sajassi-bess-evpn-ip-aliasing.auth...@ietf.org>>
Cc: bess@ietf.org<mailto:bess@ietf.org> <bess@ietf.org<mailto:bess@ietf.org>>
Subject: RE: Question and comments on the EVPN IP Aliasing draft
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for additional information.
Hi Jorge,
Lots of thanks for a prompt response.
I have explained my position with regard to IP Aliasing for RT-5 in
Interface-less IP-VRF-to-IP-VRF model in my previous email.
I only can add that the neither the metadata of the IP Aliasing draft nor its
text specify an update to RFC 9136.
Regards,
Sasha
From: Jorge Rabadan (Nokia)
<jorge.raba...@nokia.com<mailto:jorge.raba...@nokia.com>>
Sent: Monday, April 3, 2023 4:17 AM
To: Alexander Vainshtein
<alexander.vainsht...@rbbn.com<mailto:alexander.vainsht...@rbbn.com>>;
draft-sajassi-bess-evpn-ip-aliasing.auth...@ietf.org<mailto:draft-sajassi-bess-evpn-ip-aliasing.auth...@ietf.org>
Cc: bess@ietf.org<mailto:bess@ietf.org>; Dmitry Valdman
<dmitry.vald...@rbbn.com<mailto:dmitry.vald...@rbbn.com>>; Nitsan Dolev
<nitsan.do...@rbbn.com<mailto:nitsan.do...@rbbn.com>>; Michael Gorokhovsky
<michael.gorokhov...@rbbn.com<mailto:michael.gorokhov...@rbbn.com>>; Ron
Sdayoor <ron.sday...@rbbn.com<mailto:ron.sday...@rbbn.com>>; Egon Haparnass
<ehaparn...@rbbn.com<mailto:ehaparn...@rbbn.com>>; Shell Nakash
<shell.nak...@rbbn.com<mailto:shell.nak...@rbbn.com>>; Marina Fizgeer
<marina.fizg...@rbbn.com<mailto:marina.fizg...@rbbn.com>>; Orly Kariv
<orly.ka...@rbbn.com<mailto:orly.ka...@rbbn.com>>; Moti Morgenstern
<moti.morgenst...@rbbn.com<mailto:moti.morgenst...@rbbn.com>>; Rotem Cohen
<rotem.co...@rbbn.com<mailto:rotem.co...@rbbn.com>>
Subject: [EXTERNAL] Re: Question and comments on the EVPN IP Aliasing draft
Hi Sasha,
Please see in-line with [jorge].
Thanks for the good questions/points.
Jorge
From: Alexander Vainshtein
<alexander.vainsht...@rbbn.com<mailto:alexander.vainsht...@rbbn.com>>
Date: Sunday, March 26, 2023 at 11:16 PM
To:
draft-sajassi-bess-evpn-ip-aliasing.auth...@ietf.org<mailto:draft-sajassi-bess-evpn-ip-aliasing.auth...@ietf.org>
<draft-sajassi-bess-evpn-ip-aliasing.auth...@ietf.org<mailto:draft-sajassi-bess-evpn-ip-aliasing.auth...@ietf.org>>
Cc: bess@ietf.org<mailto:bess@ietf.org> <bess@ietf.org<mailto:bess@ietf.org>>,
Dmitry Valdman <dmitry.vald...@rbbn.com<mailto:dmitry.vald...@rbbn.com>>,
Nitsan Dolev <nitsan.do...@rbbn.com<mailto:nitsan.do...@rbbn.com>>, Michael
Gorokhovsky
<michael.gorokhov...@rbbn.com<mailto:michael.gorokhov...@rbbn.com>>, Ron
Sdayoor <ron.sday...@rbbn.com<mailto:ron.sday...@rbbn.com>>, Egon Haparnass
<ehaparn...@rbbn.com<mailto:ehaparn...@rbbn.com>>, Shell Nakash
<shell.nak...@rbbn.com<mailto:shell.nak...@rbbn.com>>, Marina Fizgeer
<marina.fizg...@rbbn.com<mailto:marina.fizg...@rbbn.com>>, Orly Kariv
<orly.ka...@rbbn.com<mailto:orly.ka...@rbbn.com>>, Moti Morgenstern
<moti.morgenst...@rbbn.com<mailto:moti.morgenst...@rbbn.com>>, Rotem Cohen
<rotem.co...@rbbn.com<mailto:rotem.co...@rbbn.com>>
Subject: Question and comments on the EVPN IP Aliasing draft
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for additional information.
Hi all,
A few questions and comments on the EVPN IP Aliasing
draft<https://clicktime.symantec.com/15t5ei6Q21cWwECv3dXHo?h=hLCOzcf5t8oR3LIGwDra1wBHCN4UcxyL3SN_N-D7vPY=&u=https://datatracker.ietf.org/doc/html/draft-sajassi-bess-evpn-ip-aliasing-06>:
Section 3 of the draft states that a PE that is attached to a MH ES shall
advertise a set of IP per ES A-D routes, and Section 4.1 says that these routes
shall be tagged with Export RTs of all IP-VRFs attached to this MH ES. The
following is not mentioned:
Should the ESI Label Extended Community be attached to these routes? My guess
(FWIW) is that this is necessary, since this is the only way to let the remote
PEs to know the MH mode of the MH ES in question.
[jorge] correct
Assuming an affirmative answer to the previous question, what should the ESI
Label Extended Community attached to these routes carry in its Label field? My
guess (FWIW) is that his field is not relevant and should be set to all zeroes.
[jorge] yes. We can add a sentence to that respect. The label field SHOULD be
set to 0 and MUST be ignored on reception.
Section 3 of the draft says that “a remote PE that receives an EVPN MAC/IP
Advertisement route or an IP Prefix route with a non-reserved ESI and the RT of
a particular IP-VRF SHOULD consider it reachable by every PE that has
advertised an IP A-D per ES and IP A-D per EVI route for that ESI and IP-VRF”:
Is the statement above applicable in the case of a MH ES in Single-Active MH
Mode? My guess is that it is only applicable to MH Es in All-Active MH mode
[jorge] same as in rfc7432bis, both modes
If the answer to the previous question is negative, should the PE that receives
an EVPN Type 2 route for an IP→MAC pair treat the IP address in this pair
reachable only via he PE that has advertised this route and treating other PEs
as “backup PEs” (similar to what is defined in Section 14.1.1 of RFC
7432<https://clicktime.symantec.com/15t5pNUxwEyhm7rm8kKb3?h=m9ESlNFEXlL5s4xyn-g6bmr0dWvx9li2FHAjKrC16c0=&u=https://www.rfc-editor.org/rfc/rfc7432.html%23section-14.1.1>)?
[jorge] yes, assuming that PE the has received the AD routes.
The suggestion to attach the Layer 2 Attributes Extended Community to the per
EVI IP A-D route in Section 3.1 of the draft seems to support my guesses above
I also think that if the MH ES in Single-Active mode is attached o more than 2
PEs, the Layer 2 Attributes Extended Community MUST be attached to EVPN per EVI
IP A-D routes.
[jorge] at the moment the addition of the L2 Attr ext community is a SHOULD. I
have no problem in making it a MUST assuming my co-authors are ok.
I have to admit that I do not understand how IP Aliasing should work for EVPN
IP Prefix routes in the Interface-less IP-VRF-to-IP-VRF scenario mentioned in
Section 1.2 of he draft:
Table 1 in RFC
9136<https://clicktime.symantec.com/15t5jYHgUdJ7MB2qbBvSR?h=3pwOHmxhy4P_vmCrfN-Bzd29Fz_PC1o-KGYWe1eTTfY=&u=https://datatracker.ietf.org/doc/html/rfc9136%23fields_overlay_table>
states that a non-zero ESI value in the NLRI of IP Prefix routes is used as an
Overlay index for recursive resolution, while that the Label value in such a
NLRI is “Don’t Care”.
At the same time, section 4.1.1 of this RFC states that the ESI field of the
NLRI f these routes is set to all zeroes in the Interface-less IP-VRF-to-IP-VRF
scenario while the Label field in the NRLI of these routes identifies the IP
VRF in question.
Can you please explain how can, in this scenario, the receiving PE associate
received EVPN IP Prefix routes with a specific MH ES?
[jorge] section 1.2 illustrates an RFC9136 interface-less model since there is
no SBD. However, this draft modifies the interface-less model by using non-zero
ESI on the IP Prefix routes and a recursive resolution to A-D per ES/EVI routes.
Your timely feedback would be highly appreciated.
Regards, and lots of hanks in advance,
Sasha
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