TEAS WG A. Deshmukh
Internet-Draft K. Kompella
Intended status: Standards Track Juniper Networks, Inc.
Expires: January 28, 2021 July 27, 2020
RSVP Extensions for RMR
draft-ietf-teas-rsvp-rmr-extension-03
Abstract
Ring topology is commonly found in access and aggregation networks.
However, the use of MPLS as the transport protocol for rings is very
limited today. {{!I-D.ietf-mpls-rmr}} describes a mechanism to
handle rings efficiently using MPLS. This document describes the
extensions to the RSVP-TE protocol for signaling MPLS label switched
paths in rings.
Status of This Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet-
Drafts is at https://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress."
This Internet-Draft will expire on January 28, 2021.
Copyright Notice
Copyright (c) 2020 IETF Trust and the persons identified as the
document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents
(https://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents
carefully, as they describe your rights and restrictions with respect
to this document. Code Components extracted from this document must
include Simplified BSD License text as described in Section 4.e of
Deshmukh & Kompella Expires January 28, 2021 [Page 1]
Internet-Draft RSVP Extensions for RMR July 2020
the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
1.1. Requirements Language . . . . . . . . . . . . . . . . . . 3
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. RSVP Extensions . . . . . . . . . . . . . . . . . . . . . . . 4
3.1. Session Object . . . . . . . . . . . . . . . . . . . . . 4
3.2. SENDER_TEMPLATE,FILTER_SPEC Objects . . . . . . . . . . . 5
4. Ring Signaling Procedures . . . . . . . . . . . . . . . . . . 5
4.1. Differences from regular RSVP-TE LSPs . . . . . . . . . . 5
4.2. LSP signaling . . . . . . . . . . . . . . . . . . . . . . 6
4.2.1. Path Propagation for RMR . . . . . . . . . . . . . . 8
4.2.2. Resv Processing for RMR . . . . . . . . . . . . . . . 8
4.3. Protection . . . . . . . . . . . . . . . . . . . . . . . 9
4.4. Ring changes . . . . . . . . . . . . . . . . . . . . . . 10
4.5. Express Links . . . . . . . . . . . . . . . . . . . . . . 11
4.6. Bandwidth management . . . . . . . . . . . . . . . . . . 11
5. Security Considerations . . . . . . . . . . . . . . . . . . . 13
6. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 13
7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 14
8. References . . . . . . . . . . . . . . . . . . . . . . . . . 14
8.1. Normative References . . . . . . . . . . . . . . . . . . 14
8.2. Informative References . . . . . . . . . . . . . . . . . 14
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 15
1. Introduction
This document extends RSVP-TE [RFC3209] to establish label-switched
path (LSP) tunnels in the ring topology. Rings are auto-discovered
using the mechanisms mentioned in the {{!I-D.ietf-mpls-rmr}}. Either
IS-IS [RFC5305] or OSPF[RFC3630] can be used as the IGP for auto-
discovering the rings.
After the rings are auto-discovered, each node in the ring knows its
clockwise(CW) and anti-clockwise (AC) ring neighbors and its ring
links. All of the express links in the ring also get identified as
part of the auto-discovery process. At this point, every node in the
ring informs the RSVP protocol to begin the signaling of the ring
LSPs.
Section 2 covers the terminology used in this document. Section 3
presents the RSVP protocol extensions needed to support MPLS rings.
Section 4 describes the procedures of RSVP LSP signaling in detail.
Deshmukh & Kompella Expires January 28, 2021 [Page 2]
Internet-Draft RSVP Extensions for RMR July 2020
1.1. Requirements Language
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in BCP
14 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here.
2. Terminology
Assuming there are n nodes in the network, a ring gets formed by a
subset of those n nodes {Ri, Ri+1, Ri+2,...Rn}. We define the
direction from node Ri to Ri+1 as "clockwise" (CW) and the reverse
direction as "anti-clockwise" (AC). As there might be several rings
in a graph, each ring is identified by it's own distinct ring ID -
RID.
R0 . . . R1
. .
R7 R2
Anti- | . Ring . |
Clockwise | . . | Clockwise
v . RID = 17 . v
R6 R3
. .
R5 . . . R4
Figure 1: Ring with 8 nodes
The following terminology is used for ring LSPs:
Ring ID (RID): A non-zero number that identifies a ring; this is
unique in a Service Provider's network. A node may belong to
multiple rings.
Ring node: A member of a ring. Note that a device may belong to
several rings.
Node index: A logical numbering of nodes in a ring, from zero up to
one less than the ring size. Used purely for exposition in this
document.
Ring neighbors: Nodes whose indices differ by one (modulo ring
size).
Ring links: Links that connect ring neighbors.
Deshmukh & Kompella Expires January 28, 2021 [Page 3]
Internet-Draft RSVP Extensions for RMR July 2020
Express links: Links that connect non-neighboring ring nodes.
MP2P LSP: Each LSP in the ring is a multipoint to point LSP such
that LSP can have multiple ingress nodes and one egress node.
3. RSVP Extensions
Due to the new ring LSP semantics, the signaling-message
identification of ring LSPs will be different than the regular RSVP
LSPs. So, a new C-Type is defined here for the SESSION object. This
new C-Type will help to clearly differentiate ring LSPs from regular
LSPs. In addition, new flags are introduced in the SESSION object to
represent the ring direction of the corresponding Path message.
3.1. Session Object
Class = SESSION, LSP_TUNNEL_IPv4 C-Type = TBD
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Ring anchor node address |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Ring Flags | Ring Instance ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Ring ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
SESSION Object
Ring anchor node address: IPv4 address of the anchor node. Each
anchor node creates a LSP addressed to itself.
Ring Instance ID: A 16-bit identifier used in the SESSION. This
Ring Instance ID is useful for graceful ring changes. If a new
node is being added to the ring(resulting in signaling of a larger
ring) or some existing node goes down(resulting in signaling of a
smaller ring), in those cases, anchor node creates a new tunnel
with a different Ring Instance ID.
Ring ID: A 32-bit number that identifies a ring; this is unique in
some scope of a Service Provider's network. This number remains
constant throughout the existence of ring.
Ring Flags: For each ring, the anchor node starts signaling of a
ring LSP. Ring LSP named RLi, anchored on node Ri, consists of
two counter-rotating unicast LSPs that start and end at Ri. One
LSP will be in the clockwise direction and other LSP will be in
Deshmukh & Kompella Expires January 28, 2021 [Page 4]
Internet-Draft RSVP Extensions for RMR July 2020
the anti-clockwise direction. A ring LSP is "multipoint": any
node along the ring can use LSP RLi to send traffic to Ri; this
can be in either the CW or AC directions, or both (i.e., load
balanced). Two new flags are defined in the SESSION object which
define the ring direction of the corresponding Path message.
ClockWise(CW) Direction 0x01: This flag indicates that the
corresponding Path message is traveling in the ClockWise(CW)
direction along the ring.
Anti-ClockWise(AC) Direction 0x02: This flag indicates that the
corresponding Path message is traveling in the Anti-ClockWise(AC)
direction along the ring.
Express Link 0x04: This flag indicates that the corresponding Path
message is traveling along the Express link in the ring.
3.2. SENDER_TEMPLATE,FILTER_SPEC Objects
There will be no changes to the SENDER_TEMPLATE and FILTER_SPEC
objects. The format of the above 2 objects will be similar to the
definitions in RFC 3209. [RFC3209] Only the semantics of these
objects will slightly change. This will be explained in section
Section 4.6 below.
4. Ring Signaling Procedures
A ring node indicates in its IGP updates the ring LSP signaling
protocols that it supports. This can be LDP and/or RSVP-TE.
Ideally, each node should support both. If the ring is configured
with RSVP as the signaling protocol, then once a ring node R_i knows
the RID, its ring links and directions, it kicks off ring RSVP LSP
signaling automatically.
4.1. Differences from regular RSVP-TE LSPs
Ring LSPs differ from regular RSVP-TE LSPs in several ways:
1. Ring LSPs (by construction) form a loop.
2. Ring LSPs are multipoint-to-point. Any ring node can inject
traffic into a ring LSP.
3. The bandwidth of a ring LSP can change hop-by-hop.
4. Ring LSPs are protected without the use of bypass or detour LSPs.
Protection is handled by the ring LSP traversing in the opposite
direction.
Deshmukh & Kompella Expires January 28, 2021 [Page 5]
Internet-Draft RSVP Extensions for RMR July 2020
4.2. LSP signaling
After the ring auto-discovery process, each anchor node creates a LSP
addressed to itself. This ring LSP contains of a pair of counter-
rotating unicast LSPs. So, for a ring containing N nodes, there will
be 2N total LSPs signaled.
There is no need for ERO object in the Path message. The Path
message for ring LSPs has the following format:
<Path Message> ::= <Common Header> [ <INTEGRITY> ]
<SESSION> <RSVP_HOP>
<TIME_VALUES>
<LABEL_REQUEST>
[ <SESSION_ATTRIBUTE> ]
<sender descriptor list>
<sender descriptor list> ::= <sender descriptor>|
<sender descriptor list> <sender descriptor>
<sender descriptor> ::= <SENDER_TEMPLATE> <SENDER_TSPEC>
The anchor node creates 2 Path messages traveling in opposite
directions. The SESSION format MUST be as per the description in
Section 3.1. The anchor node which creates the LSP will insert it's
own address in the "Ring anchor node address" field of the SESSION
object. So effectively, the Path messages are addressed to the
originating node itself.
The SESSION flags of these 2 Path messages are different. The Path
message sent to the CW neighbor MUST have the CW flag set in the
SESSION object to signal the LSP going in the clockwise direction.
The Path message sent to the AC neighbor MUST have the AC flag set to
signal the LSP in the anti-clockwise direction.
When an incoming Path message is received at the ring node Ri, it
consults the results of auto-discovery to find the appropriate ring
neighbor. If the incoming Path message has CW direction flag set,
then Ri includes its own SENDER_DESCRIPTOR in the path message and
forwards the Path message to its CW ring neighbor(Ri+1). Similarly
if the incoming Path message has AC direction flag set, then Ri
includes its own SENDER_TEMPPLATE and forwards that Path message to
it's AC ring neighbor(Ri-1). Thus, there is no need of ERO in the
Path message. The Path message is routed locally at each ring based
on the ring auto-discovery calculations.
Deshmukh & Kompella Expires January 28, 2021 [Page 6]
Internet-Draft RSVP Extensions for RMR July 2020
The RESV message for ring LSPs also uses the new RING_IPv4 SESSION
object. When the Path message originated from the anchor node Ri
reaches back to Ri, Ri generates a Resv message. Note that this
means that anchor node is both Ingress and Egress for the Path
message. The Resv message copies the same ring flags as received in
the corresponding Path message. So, a Resv message for a CW LSP goes
in the AC direction (unlike the Path message, which goes CW). This
is done to correctly match Path and corresponding Resv messages at
transit ring nodes. Upon receiving Resv message with CW flag set,
the ring node will forward the Resv message to its AC neighbor.
Each ring node Ri allocates CW and AC labels for each ring LSP RLx(x
between i..n). As the signaling propagates around the ring, CW and
AC labels are exchanged. When Ri receives CW and AC labels for LSP
RLx from its ring neighbors, primary and fast reroute (FRR) paths for
RLx are installed at Ri.
Consider the following three nodes of the ring, and their signaling
interactions for LSP RL5 originating from anchor node R5:
P5_CW -> P5_CW ->
Q5_CW <- Q5_CW <-
... ------ R7 --------- R8 --------- R9 ------ ...
P5_AC <- P5_AC <-
Q5_AC -> Q5_AC ->
P corresponds to the Path message and Q corresponds to the Resv
message.
As explained above, an RMR LSP consists of two counter-rotating ring
LSPs that start and end at the same node, say R1. As such, this
appears to cause a loop, something that is normally avoided by RSVP-
TE. There are some benefits to this:
Having a ring LSP form a loop allows the anchor node R1 to ping
itself and thus verify the end-to-end operation of the LSP. This, in
conjunction with link-level OAM, offers a good indication of the
operational state of the LSP. Also, having R1 to be the ingress
means that R1 can initiate the Path messages for the two ring LSPs.
This avoids R1 having to coordinate with its neighbors to signal the
LSPs, and simplifies the case where a ring update changes R1's ring
neighbors. The cost of this is a little more signaling and a couple
more label entries in the LFIB. However, we will let experiences
from implementation guide us when we evaluate this approach.
Deshmukh & Kompella Expires January 28, 2021 [Page 7]
Internet-Draft RSVP Extensions for RMR July 2020
4.2.1. Path Propagation for RMR
Ring LSPs are MP2P in nature. It means that every non-egress node is
also an ingress and a merge-point for the LSP. Focussing on ring-
LSP-0 (i.e ring-LSPs starting at R0):
R0---->R1---->R2---->R3---->R4---->R5---->R6--->R7--->R0(CW LSP)
R0---->R7---->R6---->R5---->R4---->R3---->R2--->R1--->R0(ACW LSP)
Each ring node inserts a new SENDER_TEMPLATE object into an incoming
Path message. The procedure for that is as follows:
When a ring node R3 receives a Path message initiated by anchor node
R0(for anchor lsp "lsp0"), R3 SHOULD make a copy of the received Path
message for "lsp0". R3 then inserts a new sender-template object
into the Path message for "lsp0". In the sender-template object, R3
uses the sender address as the loopback address of node R3 and lsp-id
= X. R3 then forwards this modified Path message to it's ring
neighbor.
So at this point, when Path messages heads out at R3, there will be 4
different SENDER_TEMPLATE objects in the outgoing Path message for
lsp0:
-----------------------------------------------------
|SENDER_TEMPLATE_0 : SENDER_ADDRESS = R0, LSP_ID = 1 |
-----------------------------------------------------
|SENDER_TEMPLATE_1 : SENDER_ADDRESS = R1, LSP_ID = 1 |
-----------------------------------------------------
|SENDER_TEMPLATE_2 : SENDER_ADDRESS = R2, LSP_ID = 1 |
-----------------------------------------------------
|SENDER_TEMPLATE_3 : SENDER_ADDRESS = R3, LSP_ID = 1 |
-----------------------------------------------------
4.2.2. Resv Processing for RMR
When Egress node R0 receives the modified Path message, it replies
with the a Resv message containing multiple FLOW_DESCRIPTOR objects.
There should be 1 FLOW_DESCRIPTOR object corresponding to each of the
SENDER_TEMPLATE object in the incoming Path message. The SESSION
object of the Resv message will exactly match with the received Path
message.
RFC 3209[RFC3209] already supports receiving a Resv message with
multiple flow-descriptors in it, as described in section 3.2 in that
document. In each flow-descriptor there is a separate:
Deshmukh & Kompella Expires January 28, 2021 [Page 8]
Internet-Draft RSVP Extensions for RMR July 2020
a. FLOW_SPEC object corresponding to the SENDER_TSPEC that was sent
in the Path message which could be admitted after admission-control
downstream, and
b. FILTER_SPEC object corresponding to SENDER_TEMPLATE that was sent
in the Path message that could be admitted after admission-control
downstream.
Each transit node removes the FLOW-DESCRIPTOR corresponding to itself
from the Resv message before sending the Resv message upstream.
4.3. Protection
In the rings, there are no protection LSPs -- no node or link bypass
LSPs, no standby LSPs and no detours. Protection is via the "other"
direction around the ring, which is why ring LSPs are in counter-
rotating pairs. Protection works in the same way for link, node and
ring LSP failures.
Since each ring LSP is a MP2P LSP, any ring node can inject traffic
onto a LSP whose anchor might be a different ring node. To achieve
the above, an ingress route will be installed as follows at every
ring node J, for a given ring-LSP with anchor Rk (say 1.2.3.4).
1.2.3.4 -> (Push CL_J+1,K, NH: R_J+1) # CW
-> (Push AL_J-1,K, NH: R_J-1) # AC
CL = Clockwise label
AL = Anti-Clockwise label
Traffic will either be load balanced in the CW and AC directions or
the traffic will be sent on just CW or AC lsp based on parameters
such as hop-count, policy etc.
Also, 2 transit routes will be installed for the anchor LSP
transiting from node Rj as follows:
Deshmukh & Kompella Expires January 28, 2021 [Page 9]
Internet-Draft RSVP Extensions for RMR July 2020
CL_J,K -> SWAP(CL_J+1,K, NH: R_J+1) #CW
-> SWAP(AL_J-1,K , NH: R_J-1) #AC
CL = Clockwise label
AL = Anti-Clockwise label
CW NH has weight 1, AC NH has higher-weight.
AL_J,K -> SWAP(AL_J-1,K , NH: R_J-1) #AC
-> SWAP(CL_J+1,K, NH: R_J+1) #CW
CL = Clockwise label
AL = Anti-Clockwise label
AC NH has weight 1, CW NH has higher weight.
Suppose a packet headed in anti-clockwise direction towards R5 and it
arrives at node R7. Lets say that now R7 learns there is a link
failure in the AC direction. R7 reroutes this packet back onto the
clockwise direction. This reroute action is pre-programmed in the
LFIB, to minimize the time between detection of a fault and the
corresponding recovery action.
At this time, R7 also sends a notification to R0 that the AC
direction is not working. R0 modifies it's ingress route(for R5 LSP)
by removing the AC direction LSP's route. Thus, R0 switches traffic
to the CW direction.
These notification propagate CW until each traffic source on the ring
CW of the failure uses the CW direction.For RSVP-TE, this
notification is sent in the form of PathErr message.
To provide this notification, the ring node detecting failure SHOULD
send a Path Error message with error code of "Notify" and an error
value field of ("Tunnel locally repaired"). This Path Error code and
value is same as defined in RFC 4090[RFC4090] for the notification of
local repair.
Note that the failure of a node or a link will not necessarily affect
all ring LSPs. Thus, it is important to identify the affected LSPs
and only switch the affected LSPs.
4.4. Ring changes
A ring node can go down resulting in a smaller ring or a new node can
be added to the ring which will increase the ring size. In both of
Deshmukh & Kompella Expires January 28, 2021 [Page 10]
Internet-Draft RSVP Extensions for RMR July 2020
the above cases, the ring auto-discovery process SHOULD kick in and
it SHOULD calculate a new ring with the changed ring nodes.
When the ring auto-discovery process is complete, IGP will signal
RSVP to begin the MBB process for the existing ring LSPs. For this
MBB process, the anchor node will create a new Path message with a
different Ring Instance ID in the SESSION object. All other fields
in the SESSION Object will remain same as the existing Path
message(before the ring change).
This new Path message will then propagate along the ring neighbors in
the same way as the original Path message. Each ring neighbor SHOULD
forward the Path message to it's appropriate neighbor based on the
new auto-discovery calculations.
For the ring links which are common between the old and new LSPs, the
LSPs will share resources(SE style reservation) on those ring links.
Note that here we are using Ring Instance ID in the SESSION object to
share resources instead of the LSP_ID in the SENDER_TEMPLATE
Object(which is used in RSVP-TE for sharing resources as described in
RFC 3209 [RFC4090]). The LSP_ID use is reserved for a different
functionality as described in section Section 4.6.
4.5. Express Links
Express links are discovered once ring nodes, ring links and
directions have been established. As defined earlier, express links
are links joining non-neighboring ring nodes. Express links are both
clockwise and anti-clockwise.
A ring node with an Express link replicates the incoming Path message
over the Express link. The "Express Link" flag is set in the SESSION
object of the replicated Path message. Also, the ring node Ri
includes an additional SENDER_DESCRIPTOR with a new LSP_ID in the
outgoing PATH message.
When this Path message with Express link flag is received at the
other end of Express link, the other ring node replies with the Resv
message. It does not forward this Path message to any of it's ring
neighbors. Thus, the "Express" LSPs are effectively 1 hop LSPs
formed over the "Express Links".
4.6. Bandwidth management
For RSVP-TE LSPs, bandwidths may be signaled in both directions.
However, these are not provisioned either; rather, one does "reverse
call admission control". When a service needs to use an LSP, the
ring node where the traffic enters the ring attempts to increase the
Deshmukh & Kompella Expires January 28, 2021 [Page 11]
Internet-Draft RSVP Extensions for RMR July 2020
bandwidth on the LSP to the egress. If successful, the service is
admitted to the ring.
. R0 . . . R1
. __________|| .
. / ________| .
R7 / / R2
Anti- | . / / . |
Clockwise | . | / . | Clockwise
v . | \ . v
R6 \ R3
. \ .
R5 . . . R4
Figure 2: BW Management in Ring with 8 nodes
Let's say that Ring node R5 wants to increase the BW for the LSP
whose egress is at node R1. To achieve this BW increase, Ring node
R5 has to increase BW along the LSP anchored at node R1(say lsp1).
R5 makes a copy of the existing ring Path message for lsp1. R5 then
modifies the sender-template object from the copied Path message for
"lsp1". In the sender-template object, R5 uses the sender address as
the loopback address of node R5 and lsp-id = X+1. R5 also modifies
the TSPEC object which represents the BW increase/decrease in this
new Path message. R5 then forwards this new Path message to it's
ring neighbor. The original anchor Path message has sender address
as loopback address of R1.
Now, let's say, node 5 wants to increase BW again for lsp1, then R5
adds a new SENDER_TEMPLATE object in the existing Path message for
"lsp1" with sender address as loopback of node 5 and lsp-id = X+2.
So at this point, there will be 2 different SENDER_TEMPLATE objects
corresponding to node 5 in the outgoing path message.
-----------------------------------------------------
|SENDER_TEMPLATE_0 : SENDER_ADDRESS = R0, LSP_ID = 1 |
-----------------------------------------------------
|SENDER_TEMPLATE_1 : SENDER_ADDRESS = R1, LSP_ID = 1 |
-----------------------------------------------------
| ........ |
-----------------------------------------------------
|SENDER_TEMPLATE_5 : SENDER_ADDRESS = R5, LSP_ID = 1 |
-----------------------------------------------------
|SENDER_TEMPLATE_5 : SENDER_ADDRESS = R5, LSP_ID = 2 |
-----------------------------------------------------
Deshmukh & Kompella Expires January 28, 2021 [Page 12]
Internet-Draft RSVP Extensions for RMR July 2020
Similarly, if node R6 wants to increase the BW for "lsp1", it SHOULD
create a new Path message containing SENDER_TEMPLATE object with
sender address = loopback of node 6 and lsp-id = Y+1. Thus, it
should be noted that each ring-node independently tracks its own lsp-
ID that is currently in-use on a given RMR sub-LSP. This lsp-ID
value will (could) be different for each ring-node for a given ring
sub-LSP.
If sufficient BW is available all the way towards ring node R1, then
this new Path message reaches node R1. R1 generates a Resv message
with the correct FILTER_SPEC object corresponding to the received
SENDER_TEMPLATE object. This Resv message will also have the correct
FLOWSPEC object as per the requested bandwidth.
If sufficient BW is not available at some downstream (say node R9),
then ring node R9 SHOULD generate a PathErr message with the
corresponding Sender Template Object. When node R5 receives this
PathErr message, R5 understands that the BW increase was not
successful. Note that the existing established bandwidths for lsp1
are not affected by this new PathErr message.
When ring node R5 no longer needs the BW reservation, then ring node
R5 SHOULD originate a new Path message with the appropriate Sender
Template Object containing 0 BW as described above. Every downstream
node SHOULD then remove bandwidth allocated on the corresponding link
on receipt of this Path message.
Also, note that as part of this BW increase or decrease process, any
ring node does not actually change any label associated with the LSP.
So, the label remains same as it was signaled initially when the
anchor LSP came up.
5. Security Considerations
It is not anticipated that either the notion of MPLS rings or the
extensions to various protocols to support them will cause new
security loopholes. As this document is updated, this section will
also be updated.
6. Contributors
Ravi Singh
Juniper Networks, Inc.
1133 Innovation Way
Sunnyvale, CA 94089
USA
Email: ravis@juniper.net
Deshmukh & Kompella Expires January 28, 2021 [Page 13]
Internet-Draft RSVP Extensions for RMR July 2020
Santosh Esale
Juniper Networks, Inc.
1133 Innovation Way
Sunnyvale, CA 94089
USA
Email: sesale@juniper.net
Raveendra Torvi
Juniper Networks, Inc.
10 Technology Park Dr
Westford, MA 01886
USA
Email: rtorvi@juniper.net
7. IANA Considerations
Requests to IANA will be made in a future version of this document.
8. References
8.1. Normative References
[I-D.ietf-mpls-rmr]
Kompella, K. and L. Contreras, "Resilient MPLS Rings",
draft-ietf-mpls-rmr-12 (work in progress), October 2019.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/info/rfc2119>.
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
May 2017, <https://www.rfc-editor.org/info/rfc8174>.
8.2. Informative References
[I-D.dai-mpls-rsvp-te-mbb-label-reuse]
Dai, M. and M. Chaudhry, "MPLS RSVP-TE MBB Label Reuse",
draft-dai-mpls-rsvp-te-mbb-label-reuse-01 (work in
progress), September 2015.
[RFC2205] Braden, R., Ed., Zhang, L., Berson, S., Herzog, S., and S.
Jamin, "Resource ReSerVation Protocol (RSVP) -- Version 1
Functional Specification", RFC 2205, DOI 10.17487/RFC2205,
September 1997, <https://www.rfc-editor.org/info/rfc2205>.
Deshmukh & Kompella Expires January 28, 2021 [Page 14]
Internet-Draft RSVP Extensions for RMR July 2020
[RFC3209] Awduche, D., Berger, L., Gan, D., Li, T., Srinivasan, V.,
and G. Swallow, "RSVP-TE: Extensions to RSVP for LSP
Tunnels", RFC 3209, DOI 10.17487/RFC3209, December 2001,
<https://www.rfc-editor.org/info/rfc3209>.
[RFC3630] Katz, D., Kompella, K., and D. Yeung, "Traffic Engineering
(TE) Extensions to OSPF Version 2", RFC 3630,
DOI 10.17487/RFC3630, September 2003,
<https://www.rfc-editor.org/info/rfc3630>.
[RFC4090] Pan, P., Ed., Swallow, G., Ed., and A. Atlas, Ed., "Fast
Reroute Extensions to RSVP-TE for LSP Tunnels", RFC 4090,
DOI 10.17487/RFC4090, May 2005,
<https://www.rfc-editor.org/info/rfc4090>.
[RFC5305] Li, T. and H. Smit, "IS-IS Extensions for Traffic
Engineering", RFC 5305, DOI 10.17487/RFC5305, October
2008, <https://www.rfc-editor.org/info/rfc5305>.
Authors' Addresses
Abhishek Deshmukh
Juniper Networks, Inc.
10 Technology Park Dr
Westford, MA 01886
USA
Email: adeshmukh@juniper.net
Kireeti Kompella
Juniper Networks, Inc.
1133 Innovation Way
Sunnyvale, CA 94089
USA
Email: kireeti@juniper.net
Deshmukh & Kompella Expires January 28, 2021 [Page 15]
