Bruno –
I appreciate why you suggest per-prefix signaling for ELC, but I would
prefer that we not employ that model.
ELC is clearly a node capability – signaling it in per node scope is
therefore most appropriate. And it aligns with the SR model where we do
not need to depend on hop-by-hop signaling as in the LDP case.
As regards the interarea issues you raise:
Both Router Capability TLV (IS-IS) and Router Information LSA (OSPF)
support domain-wide flooding scope. This is not a new capability –
though I do agree with you that the ELC drafts should explicitly mention
the flooding scope requirement.
As regards identifying the source of a prefix advertisement domain-wide,
IS-IS has a complete solution for this as defined in RFC 7794.
OSPF is lacking support for advertising the source Router-ID, but this
can be easily remedied by defining an extension using Extended Prefix
LSA (as has been mentioned by Peter in another thread). And this
functionality is needed for other reasons e.g., to know when PHP
should/should not be done. So it is probably past time when this should
be defined.
So I think it is better if we use the per-node ELC scope proposed in the
ELC drafts.
As an aside, I would prefer that we utilize the existing TE Node
Capability Descriptor registry defined in RFC 5073 rather than invent a
new codepoint/registry (the proposed Non-IGP Functional Capabilities
registry) – but that is a minor point.
Les
*From:*Lsr <[email protected]> *On Behalf Of *[email protected]
*Sent:* Friday, August 03, 2018 12:46 AM
*To:* 徐小虎(义先) <[email protected]>
*Cc:* [email protected]; [email protected]
*Subject:* Re: [Lsr] I-D Action: draft-ietf-isis-mpls-elc-05.txt
Hi Xiaohu,
Thanks for the reply.
You seem to assume/require that (router) capability advertisement be
propagated across IGP areas/domains. If so,
- this is a new requirement for existing multi-area networks that need
to be indicated in the draft
- I find this debatable. This point should be explicitly discussed. I’d
rather advertise the ELC capability on a per Segment basis. This would
also be better aligned with RFC 6790 hence safer if EL extensions are
defined. The (Segment Routing) Prefix-SID sub-TLV has 2 flags remaining.
This may be a good candidate as this information seems SR specific.
Alternatively, RFC7794 may be used.
Thanks
Best regards,
--Bruno
*From:*Lsr [mailto:[email protected]] *On Behalf Of *???(??)
*Sent:* Friday, August 03, 2018 4:13 AM
*To:* Lsr; [email protected]
<mailto:[email protected]>
*Cc:* [email protected] <mailto:[email protected]>
*Subject:* Re: [Lsr] I-D Action: draft-ietf-isis-mpls-elc-05.txt
Hi Bruno,
Thanks for raising this important issue.
In fact, the Routable IP Address TLVs/sub-TLVs as described in
(https://tools.ietf.org/html/draft-ietf-ospf-routable-ip-address-02) and
(https://tools.ietf.org/html/draft-xu-isis-routable-ip-address-01) respectively
were intended to address the problem that you had mentioned (i.e., it is
required for OSPF routers in one area to find correlations between
routable IP addresses and capabilities of OSPF routers in another area).
The following text is quoted from
" There are several situations where it is required for OSPF routers in
one area to find correlations between routable IP addresses and
capabilities of OSPF routers in another area. One example is the
Entropy Label Capability (ELC) advertisement [I-D.xu-ospf-mpls-elc
<https://tools.ietf.org/html/draft-ietf-ospf-routable-ip-address-02#ref-I-D.xu-ospf-mpls-elc>]
across the OSPF domain. In this example, assume the ELC TLV
originated by a router in one area is propagated to another area.
Those routers in the latter area need to find routable IP addresses
of the router originating that ELC TLV before inserting the Entropy
Label (EL) for packets going to the Label Switch Path (LSP) tunnel
towards one of the above routable IP addresses..."
Later, such correlation requirement in the ISIS domain was addressed by
introducing the source IPv4/IPv6 router ID sub-TLVs into the Extended
Reachability TLVs (see https://tools.ietf.org/html/rfc7794). I
forget whether the same extension to OSPF as RFC7794 has been done.
Best regards,
Xiaohu
------------------------------------------------------------------
From:bruno.decraene <[email protected]
<mailto:[email protected]>>
Send Time:2018年8月3日(星期五) 04:50
To:[email protected]
<[email protected]
<mailto:[email protected]>>
Cc:[email protected] <[email protected] <mailto:[email protected]>>
Subject:Re: [Lsr] I-D Action: draft-ietf-isis-mpls-elc-05.txt
Hi authors,
"4. Advertising ELC Using IS-IS
One bit of the Non-IGP Functional Capability Bits (Bit 0 is desired)
is to be assigned by the IANA for the ELC [RFC6790]."
RFC6790 defines ELC capability on a per FEC/LSP egress basis.
Please defines what you mean exactly with this per node capability. If this
is expected to advertise ELC capability in spring networks, it's not crystal
clear to me how it works in multi-area/domain network with IP prefix/SID
redistribution.
Possibly the ELC flag would need to be advertised on a per prefix basis.
Thanks,
Regards,
--Bruno
> -----Original Message-----
> From: Lsr [mailto:[email protected]] On Behalf Of
[email protected] <mailto:[email protected]>
> Sent: Thursday, August 02, 2018 10:24 PM
> To: [email protected]
<mailto:[email protected]>
> Cc: [email protected] <mailto:[email protected]>
> Subject: Re: [Lsr] I-D Action: draft-ietf-isis-mpls-elc-05.txt
>
> Hi authors,
>
> Please find below some minor comments:
>
> 1) Abstract:
> " In addition, this document introduces the Non-IGP Functional
> Capabilities Sub-TLV for advertising IS-IS router's actual non-IGP
> functional capabilities. ELC is one of such non-IGP functional
> capabilities."
>
> It's a matter of opinion but reducing the number of occurrences of "
non-IGP functional
> capabilities" may improve the S/N ration.
>
> 2)
> The format of the Router Non-IGP Functional Capabilities Sub-TLV is
as follows:
>
> 0 1 2 3
> 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
> | Type=TBD1 | Length=4 |
> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
>
>
> The sub-TLV is not hard coded/defined with a length of 4, hence this
value should not be part of
> the definition.
>
> 3)
> "Length: Indicates the length of the value portion in octets and will be a
multiple of 4 octets"
>
> Possibly :s/will/MUST
> Please specify the error handling. (e.g. disregards the whole sub-TLV,
disregards the last 1 to 3
> octets, accept the whole sub-TLV...)
>
>
> 4)
> "One bit of the Non-IGP Functional Capability Bits (Bit 0 is desired)
is to be assigned by the
> IANA for the ELC [RFC6790]."
>
> Since this document defines the new sub-TLV, it can freely do any
allocation itself.
>
> 5)
> "The registration procedure is "Expert Review" as defined in
[RFC8126]."
>
> You may want to read RFC 8126
https://tools.ietf.org/html/rfc8126#section-4.5
> Which, In particular, states:
> " The registry's
> definition needs to make clear to registrants what information is
> necessary.
>
> [...]
>
> The required documentation and review criteria, giving clear guidance
> to the designated expert, should be provided when defining the
> registry. It is particularly important to lay out what should be
> considered when performing an evaluation and reasons for rejecting a
> request. It is also a good idea to include, when possible, a sense
> of whether many registrations are expected over time, or if the
> registry is expected to be updated infrequently or in exceptional
> circumstances only. "
>
> 6)
> "This capability, referred to as Entropy Readable Label Depth (ERLD)
as defined in [I-D.ietf-
> mpls-spring-entropy-label] "
>
> This probably calls for this document to be a normative reference.
>
>
> " A new MSD-type of the Node MSD b-TLV
> [I-D.ietf-isis-segment-routing-msd], called ERLD is defined to
> advertise the ERLD of a given router."
>
> May be adding the reference to the document defining the ERLD:
> OLD: advertise the ERLD
> NEW: advertise the ERLD [I-D.ietf-mpls-spring-entropy-label]
>
> 7)
> "If a router has
> multiple line cards, the router MUST NOT announce the ELC [RFC6790]
> unless all of its linecards are capable of processing ELs."
>
> May be you mean
> OLD: all of its linecards
> OLD: all of the linecards of the links advertised as IS-IS adjacencies.
>
> Regards,
> --Bruno
>
> > -----Original Message-----
> > From: Lsr [mailto:[email protected]] On Behalf Of
[email protected] <mailto:[email protected]>
> > Sent: Tuesday, July 31, 2018 4:07 PM
> > To: [email protected] <mailto:[email protected]>
> > Cc: [email protected] <mailto:[email protected]>
> > Subject: [Lsr] I-D Action: draft-ietf-isis-mpls-elc-05.txt
> >
> >
> > A New Internet-Draft is available from the on-line Internet-Drafts
directories.
> > This draft is a work item of the Link State Routing WG of the IETF.
> >
> > Title : Signaling Entropy Label Capability and
Entropy Readable Label Depth Using
> > IS-IS
> > Authors : Xiaohu Xu
> > Sriganesh Kini
> > Siva Sivabalan
> > Clarence Filsfils
> > Stephane Litkowski
> > Filename : draft-ietf-isis-mpls-elc-05.txt
> > Pages : 7
> > Date : 2018-07-29
> >
> > Abstract:
> > Multiprotocol Label Switching (MPLS) has defined a mechanism to
load
> > balance traffic flows using Entropy Labels (EL). An ingress Label
> > Switching Router (LSR) cannot insert ELs for packets going into a
> > given tunnel unless an egress LSR has indicated via signaling
that it
> > has the capability of processing ELs, referred to as Entropy Label
> > Capability (ELC), on that tunnel. In addition, it would be useful
> > for ingress LSRs to know each LSR's capability of reading the
maximum
> > label stack depth and performing EL-based load-balancing,
referred to
> > as Entropy Readable Label Depth (ERLD), in the cases where stacked
> > LSPs are used for whatever reasons. This document defines
mechanisms
> > to signal these two capabilities using IS-IS. These mechanisms
are
> > useful when the label advertisement is also done via IS-IS. In
> > addition, this document introduces the Non-IGP Functional
> > Capabilities Sub-TLV for advertising IS-IS router's actual non-IGP
> > functional capabilities. ELC is one of such non-IGP functional
> > capabilities.
> >
> >
> > The IETF datatracker status page for this draft is:
> > https://datatracker.ietf.org/doc/draft-ietf-isis-mpls-elc/
> >
> > There are also htmlized versions available at:
> > https://tools.ietf.org/html/draft-ietf-isis-mpls-elc-05
> > https://datatracker.ietf.org/doc/html/draft-ietf-isis-mpls-elc-05
> >
> > A diff from the previous version is available at:
> > https://www.ietf.org/rfcdiff?url2=draft-ietf-isis-mpls-elc-05
> >
> >
> > Please note that it may take a couple of minutes from the time of
submission
> > until the htmlized version and diff are available at tools.ietf.org.
> >
> > Internet-Drafts are also available by anonymous FTP at:
> > ftp://ftp.ietf.org/internet-drafts/
> >
> > _______________________________________________
> > Lsr mailing list
> > [email protected] <mailto:[email protected]>
> > https://www.ietf.org/mailman/listinfo/lsr
>
>
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Ce message et ses pieces jointes peuvent contenir des informations
confidentielles ou privilegiees et ne doivent donc
pas etre diffuses, exploites ou copies sans autorisation. Si vous avez recu
ce message par erreur, veuillez le signaler
a l'expediteur et le detruire ainsi que les pieces jointes. Les messages
electroniques etant susceptibles d'alteration,
Orange decline toute responsabilite si ce message a ete altere, deforme ou
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This message and its attachments may contain confidential or privileged
information that may be protected by law;
they should not be distributed, used or copied without authorisation.
If you have received this email in error, please notify the sender and
delete this message and its attachments.
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_________________________________________________________________________________________________________________________
Ce message et ses pieces jointes peuvent contenir des informations
confidentielles ou privilegiees et ne doivent donc
pas etre diffuses, exploites ou copies sans autorisation. Si vous avez recu ce
message par erreur, veuillez le signaler
a l'expediteur et le detruire ainsi que les pieces jointes. Les messages
electroniques etant susceptibles d'alteration,
Orange decline toute responsabilite si ce message a ete altere, deforme ou
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This message and its attachments may contain confidential or privileged
information that may be protected by law;
they should not be distributed, used or copied without authorisation.
If you have received this email in error, please notify the sender and delete
this message and its attachments.
As emails may be altered, Orange is not liable for messages that have been
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Thank you.
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