Hi Acee,
I also pointed out an inconsistency between the example in section 3.7 and the
normative text in section 3.2.1.4. So, the draft needs a correction anyway.
The question is, which one needs to be corrected – section 3.7, or section
3.2.1.4.
IMHO, we should correct the normative text in section 3.2.1.4 to align with the
example in section 3.7, as the example more closely reflects how OSPFv2
represents the link.
—
Balaji Rajagopalan
From: "Acee Lindem (acee)"
<acee(_at_)cisco(_dot_)com<mailto:acee(_at_)cisco(_dot_)com>>
Date: Wednesday, April 1, 2015 at 11:11 PM
To: Balaji Rajagopalan
<balajir(_at_)juniper(_dot_)net<mailto:balajir(_at_)juniper(_dot_)net>>,
"ietf(_at_)ietf(_dot_)org<mailto:ietf(_at_)ietf(_dot_)org>"
<ietf(_at_)ietf(_dot_)org<mailto:ietf(_at_)ietf(_dot_)org>>, Hannes Gredler
<hannes(_at_)juniper(_dot_)net<mailto:hannes(_at_)juniper(_dot_)net>>
Cc: "idr(_at_)ietf(_dot_)org<mailto:idr(_at_)ietf(_dot_)org>"
<idr(_at_)ietf(_dot_)org<mailto:idr(_at_)ietf(_dot_)org>>
Subject: Re: [Idr] REVISED Last Call: <draft-ietf-idr-ls-distribution-10.txt>
(North-Bound Distribution of Link-State and TE Information using BGP) to
Proposed Standard
Balaji,
This is an implementation issue based on the fact that you are deriving the BGP
LS information from the LSAs rather than having the IGP install the normalized
draft-ietf-idr-ls-distribution links. Given that the draft is with the IESG,
I’m not sure we want to attempt to optimize it to your implementation and
disruptive everyone else’s. If you are maintaining the LSAs in an OSPF LSDB
type structure in BGP, you easily find the Network LSA and extract the
advertising router.
Thanks,
Acee
From: Balaji Rajagopalan
<balajir(_at_)juniper(_dot_)net<mailto:balajir(_at_)juniper(_dot_)net>>
Date: Wednesday, April 1, 2015 at 1:00 PM
To: "ietf(_at_)ietf(_dot_)org<mailto:ietf(_at_)ietf(_dot_)org>"
<ietf(_at_)ietf(_dot_)org<mailto:ietf(_at_)ietf(_dot_)org>>, Hannes Gredler
<hannes(_at_)juniper(_dot_)net<mailto:hannes(_at_)juniper(_dot_)net>>
Cc: "idr(_at_)ietf(_dot_)org<mailto:idr(_at_)ietf(_dot_)org>"
<idr(_at_)ietf(_dot_)org<mailto:idr(_at_)ietf(_dot_)org>>
Subject: Re: [Idr] REVISED Last Call: <draft-ietf-idr-ls-distribution-10.txt>
(North-Bound Distribution of Link-State and TE Information using BGP) to
Proposed Standard
I seek a correction to the following text in section 3.2.1.4.
"
IGP Router ID: <snip> For an OSPFv2 "Pseudonode" representing a LAN,
this contains the 4 octet Router-ID of the designated router (DR)
followed by the 4 octet IPv4 address of the DR's interface to the
LAN (8 octets in total) <snip>"
The reason I seek this change is, the transit link representation in OSPFv2
router-LSA does not contain the router-id of the DR (section 12.4.1.2 of
RFC2328). So, BGP-LS has nowhere to derive Router-ID from.
Below are more details with an example.
The 'IGP router ID' field can appear either in ‘Local Node Descriptor’ or
‘Remote Node Descriptor’. Let’s consider the case in which this field appears
in ‘Remote Node Descriptor’ in the following topology.
R1(1.1.1.1::10.10.10.1) <----L1----> R2 (2.2.2.2::10.10.10.2)
Where,
R1's router-id is 1.1.1.1, and L1 interface IP address is 10.10.10.1.
R2's router-id is 2.2.2.2, and L1 interface IP address is 10.10.10.2.
L1 is a LAN.
R1 is elected as the DR for L1.
There are four distinct unidirectional links in the topology above: R1->DR,
DR->R1, R2->DR, and DR->R2. Let’s consider the link R2->DR. R2’s router LSA
represents R2->DR link as follows: -
Advertising router:2.2.2.2
Link ID: 10.10.10.1
Link data:10.10.10.2
Type:2 (Transit)
Note that the OSPF link representation above does not include the router-id of
the DR, which is 1.1.1.1.
According to the text in section 3.2.1.4, BGP-LS requires us to represent
R2->DR link as follows (considering only node descriptors of relevance to this
discussion, and ignoring the remaining fields) : -
Local Node(IGP-Router-Id:2.2.2.2) -> Remote
Node(IGP-Router-Id:1.1.1.1-10.10.10.1)
However, the OSPF representation of the above link in R2’s router LSA does not
contain 1.1.1.1 at all. Therefore, BGP-LS has nowhere to derive ‘1.1.1.1’ from,
for the link R2->DR.
The example in section 3.7 is at odds with the text in section 3.2.1.4, and
represents the link as follows (which works perfectly): -
Local Node(IGP-Router-Id:2.2.2.2) -> Remote
Node(IGP-Router-Id:10.10.10.1-10.10.10.1)
I suggest rewording the text in 3.2.1.4 as follows:
"
IGP Router ID: <snip> For an OSPFv2 "Pseudonode" representing a LAN,
this contains the 4 octet IPv4 address of the DR's interface to the
LAN, followed by any non-zero 4-octet number (8 octets in total) <snip>”
—
Balaji Rajagopalan
From: The IESG
<iesg-secretary(_at_)ietf(_dot_)org<mailto:iesg-secretary(_at_)ietf(_dot_)org>>
Reply-To: "ietf(_at_)ietf(_dot_)org<mailto:ietf(_at_)ietf(_dot_)org>"
<ietf(_at_)ietf(_dot_)org<mailto:ietf(_at_)ietf(_dot_)org>>
Date: Thursday, March 19, 2015 at 1:10 AM
To: IETF-Announce
<ietf-announce(_at_)ietf(_dot_)org<mailto:ietf-announce(_at_)ietf(_dot_)org>>
Cc: "idr(_at_)ietf(_dot_)org<mailto:idr(_at_)ietf(_dot_)org>"
<idr(_at_)ietf(_dot_)org<mailto:idr(_at_)ietf(_dot_)org>>
Subject: [Idr] REVISED Last Call: <draft-ietf-idr-ls-distribution-10.txt>
(North-Bound Distribution of Link-State and TE Information using BGP) to
Proposed Standard
The IESG has received a request from the Inter-Domain Routing WG (idr) to
consider the following document:
- 'North-Bound Distribution of Link-State and TE Information using BGP'
<draft-ietf-idr-ls-distribution-10.txt> as Proposed Standard
The IESG plans to make a decision in the next few weeks, and solicits
final comments on this action. Please send substantive comments to the
ietf(_at_)ietf(_dot_)org<mailto:ietf(_at_)ietf(_dot_)org> mailing lists by
2015-04-08. Exceptionally, comments may be
sent to iesg(_at_)ietf(_dot_)org<mailto:iesg(_at_)ietf(_dot_)org> instead. In
either case, please retain the
beginning of the Subject line to allow automated sorting.
Abstract
In a number of environments, a component external to a network is
called upon to perform computations based on the network topology and
current state of the connections within the network, including
traffic engineering information. This is information typically
distributed by IGP routing protocols within the network.
This document describes a mechanism by which links state and traffic
engineering information can be collected from networks and shared
with external components using the BGP routing protocol. This is
achieved using a new BGP Network Layer Reachability Information
(NLRI) encoding format. The mechanism is applicable to physical and
virtual IGP links. The mechanism described is subject to policy
control.
Applications of this technique include Application Layer Traffic
Optimization (ALTO) servers, and Path Computation Elements (PCEs).
The file can be obtained via
http://datatracker.ietf.org/doc/draft-ietf-idr-ls-distribution/
IESG discussion can be tracked via
http://datatracker.ietf.org/doc/draft-ietf-idr-ls-distribution/ballot/
The following IPR Declarations may be related to this I-D:
http://datatracker.ietf.org/ipr/1864/
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