Anycast Segments in MPLS based SPRING
draft-psarkar-spring-mpls-anycast-segments-00
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| Document | Type |
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|---|---|---|---|
| Author | Hannes Gredler | ||
| Last updated | 2015-07-06 | ||
| Replaced by | draft-ietf-spring-mpls-anycast-segments | ||
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draft-psarkar-spring-mpls-anycast-segments-00
SPRING Working Group P. Sarkar, Ed.
Internet-Draft H. Gredler
Intended status: Standards Track Juniper Networks, Inc.
Expires: January 7, 2016 July 6, 2015
Anycast Segments in MPLS based SPRING
draft-psarkar-spring-mpls-anycast-segments-00
Abstract
Instead of forwarding to a specific device or to all devices in a
group, anycast addresses, let network devices forward a packet to (or
steer it through) one or more topologically nearest devices in a
specific group of network devices. [I-D.ietf-spring-segment-routing]
extended the use of anycast addresses to a SPRING network, wherein a
group of SPRING-capable devices can represent a anycast address, by
having the same SRGB label block provisioned on all the devices and
each one of them advertising the same anycast prefix segment (or
Anycast SID).
This document describes a proposal for implementing anycast prefix
segments in SPRING, without the need to have the same SRGB block
(label ranges) provisioned across all the member devices in the
group. Each node can be provisioned with a separate SRGB from the
label range supported by the specfic hardware platform.
Requirements Language
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in RFC 2119 [RFC2119].
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 http://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."
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This Internet-Draft will expire on January 7, 2016.
Copyright Notice
Copyright (c) 2015 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
(http://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
the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Problem Statement . . . . . . . . . . . . . . . . . . . . . . 3
3. Solution . . . . . . . . . . . . . . . . . . . . . . . . . . 6
3.1. Anycast Segment Label . . . . . . . . . . . . . . . . . . 6
3.2. Virtual SID Label Lookup Table . . . . . . . . . . . . . 7
3.3. Label Stack Computation . . . . . . . . . . . . . . . . . 10
3.4. Advertising Anycast Prefix Segments . . . . . . . . . . . 11
3.5. Programming Anycast Prefix Segments . . . . . . . . . . . 12
3.6. Packet Flow . . . . . . . . . . . . . . . . . . . . . . . 12
4. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 13
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 14
6. Security Considerations . . . . . . . . . . . . . . . . . . . 14
7. References . . . . . . . . . . . . . . . . . . . . . . . . . 14
7.1. Normative References . . . . . . . . . . . . . . . . . . 14
7.2. Informative References . . . . . . . . . . . . . . . . . 14
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 15
1. Introduction
Anycast is a network addressing scheme and routing methodology in
which packets from a single source device are forwarded to the
topologically nearest node in a group of potential receiving devices,
all identified by the same anycast address. There are various useful
usecases of anycast addresses, and discussion of the same are outside
the scope of this document.
[I-D.ietf-spring-segment-routing] extended the use of anycast
addresses to SPRING networks. An operator may combine a group of
SPRING-enabled nodes to form a anycast group, by picking a anycast
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address and a segment identifier (hereon referred to as SID) to
represent the group, and then provisioning all the nodes with the
same address and SID. Once provisioned, each device in the group
advertises the corresponding anycast address in it's IGP link-state
advertisements along with the SID provisioned. Source devices on
receiving such anycast prefix segment advertisements, finds out the
topologically nearest device that originated the anycast segment and
forwards packets destined to the same on the shortest-path to the
nearest device.
[I-D.ietf-spring-segment-routing] also requires all devices in a
given anycast group to implement the exact same SRGB block. While
this requirement will always be met in SPRING network deployed over
IPV6 forwarding plane [I-D.previdi-6man-segment-routing-header], the
same may not be easily met in all SPRING deployments over MPLS
dataplane [I-D.ietf-spring-segment-routing-mpls].
In MPLS-based SPRING deployments the segments on a given source
router are actually mapped to a MPLS labels allocated from the local
label pool carved out by the device for accomodating the SRGB block.
In multi-vendor deployments with various types of devices deployed in
the same network topology, such a anycast group may contain a good
combination of devices from different vendors and have different
internal hardware capabilities. In such environments it is not
sufficient to assume that all the devices in a anycast group will be
able to allocate exactly the same range of labels for implementing
the SRGB. In reality, getting a common range of labels among all the
various vendors is not feasible.
This documents provides mechanisms to implement a anycast segments
with any kind of device in a multi-vendor netwrok deployment without
requiring to provision the same exact range of labels for SRGB on all
the devices.
2. Problem Statement
To better illustrate the problem let us consider an example topology
using anycast segments as shown in Figure 1 below.
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+--------------+
| Group A |
| 192.0.1.1/32 |
| SID:100 |
| |
+-----------A1---A3----------+
| | | \ / | | |
SID:10 | | | / | | | SID:30
1.1.1.1/32 | | | / \ | | | 1.1.1.3/32
PE1------R1----------A2---A4---------R3------PE3
\ /| | | |\ /
\ / | +--------------+ | \ /
\ / | | \ /
/ | | /
/ \ | | / \
/ \ | +--------------+ | / \
/ \| | | |/ \
PE2------R2----------B1---B3----+----R4------PE4
1.1.1.2/32 | | | \ / | | | 1.1.1.4/32
SID:20 | | | / | | | SID:40
| | | / \ | | |
+-----+-----B2---B4----+-----+
| |
| Group B |
| 192.0.2.1/32 |
| SID:200 |
+--------------+
Figure 1: Topology 1
In Figure 1 above, there are two groups of transit devices. Group A
consists of devices {A1, A2, A3 and A4}. They are all provisioned
with the anycast address 192.0.1.1/32 and the anycast SID 100.
Similarly, group B consists of devices {B1, B2, B3 and B4} and are
all provisioned with the anycast address 192.0.1.2/32, anycast SID
200. In the above network topology, each PE device is connected to
two routers in each of the groups A and B.
Following are all the possible ECMP paths between the various pairs
of PE devices.
o P1: via {R1, A1, A3, R3}
o P2: via {R1, A1, A4, R3}
o P3: via {R1, A2, A3, R3}
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o P4: via {R1, A2, A4, R3}
o P5: via {R2, B1, B3, R4}
o P6: via {R2, B1, B4, R4}
o P7: via {R2, B2, B3, R4}
o P8: via {R2, B2, B4, R4}
As seen above, there is always eight ECMP paths between each of pair
of PE devices. The network operator may not wish to utilize all
possible ECMP paths for all possible types of traffic flowing between
a given pair of PE devices. It may be more useful for use paths P1,
P2, P3 and P4 for certain types of traffic and use paths P5, P6, P7
and P8 for all other types of traffic between the same PE devices.
If so desired, operators may use these anycast groups A and B and the
corresponding anycast segment to impose a segment-list to forward the
respective traffic flows over the desired specific paths as shown
below. Figure 2 below depicts a expanded view of the paths via group
A. The range labels allocated for SRGB on each of the devices in
group A are also mentioned in this diagram.
+-------------------------+
| Group A |
| 192.0.1.1/32 |
| SID:100 |
|-------------------------|
| |
| SRGB: SRGB: |
SID:10 |(1000-2000) (3000-4000)| SID:30
PE1---+ +-------A1-------------A3-------+ +---PE3
\ / | | \ / | | \ /
\ / | | +-----+ / | | \ /
SRGB: \ / | | \ / | | \ / SRGB:
(7000-8000) R1 | | \ | | R3 (6000-7000)
/ \ | | / \ | | / \
/ \ | | +-----+ \ | | / \
/ \ | | / \ | | / \
PE2---+ +-------A2-------------A4-------+ +---PE4
SID:20 | SRGB: SRGB: | SID:40
|(2000-3000) (4000-5000)|
| |
+-------------------------+
Figure 2: Transit paths via anycast group A
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In the above topology, if device PE1 (or PE2) requires to send a
packet to the device PE3 (or PE4) it needs to encapsulate the packet
in a MPLS payload with the following stack of labels.
o Label allocated R1 for anycast SID 100 (outer label)
o Label allocated by the nearest router in group A for SID 30 (for
destination PE3)
While the first label is easy to compute, in this case since there
are more than one topologically nearest devices (A1 and A2), unless
A1 and A2 implement same exact SRGB, determining the second label is
impossible. In all likeness, devices A1 and A2 may be devices from
different hardware vendors and it may not implement the same exact
SRGB label ranges. In such cases, separate labels are allocated by
A1 and A2 (1030 and 2030 respectively, in the above example). Hence,
PE1 (or PE2) cannot compute an appropriate label stack to steer the
packet exclusively through the group A devices. Same holds true for
devices PE3 and PE4 when trying to send a packet to PE1 or PE2.
3. Solution
3.1. Anycast Segment Label
This document introduces the term 'Anycast Segment Label' to define
the label allocated by a device to advertise reachability for the
specific anycast prefix segment. The value of this label is derived
by applying the SID index associated with the anycast prefix segment
as an offset to the SRGB of the specific device. Table 1 below shows
the labels allocated by the various devices in Figure 2 for the
anycast prefix segment with SID 100.
+-------------+--------+-----------+-----------------------+
| Anycast-SID | Device | SRGB | Anycast-Segment-Label |
+-------------+--------+-----------+-----------------------+
| 100 | R1 | 7000-8000 | 7100 |
| 100 | A1 | 1000-2000 | 1100 |
| 100 | A2 | 2000-3000 | 2100 |
| 100 | A3 | 3000-4000 | 3100 |
| 100 | A4 | 4000-5000 | 4100 |
| 100 | R3 | 6000-7000 | 6100 |
+-------------+--------+-----------+-----------------------+
Table 1: Anycast Segment Label Allocation
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3.2. Virtual SID Label Lookup Table
When a MPLS packet on the wire first hits a device, the forwarding
hardware reads the topmost label in the MPSL header and looks up the
default label lookup table associated with the interface on which the
label has been received. This table is generally called LFIB. The
range of labels found in the LFIB constitutes the default label
space.
This document introduces a separate virtual label lookup table
(hereafter referred to as Virtual LFIB or V-LFIB), that represents a
label space which is also separate from the actual label space
represented by the default LFIB. The label value may be present in
both the default and Virtual LFIB. However the forwarding semantics
associated with the label under the default and Virtual LFIB may not
be same. Following are the fields of a typical entry of this table.
o SID-Index: The SID index assoicated with a prefix segment
originated by another device in the same network. This is also
the key field for this table.
o Forwarding Semantics: This is once again one or more tuples of
following items.
* Outgoing-Label: The label(s) allocated by the neighbor
device(s) on the shortest-path to the topologically nearest
originator(s) of the prefix segment.
* Outgoing-link: The link(s) connecting the device to the
neighbor device(s) on the shortest path to the topologically
nearest originator(s) of the prefix segment.
This document proposes that, any device, when provisioned with one or
more anycast prefix segment (address and SID), it MUST create a
Virtual LFIB table. Such a device MUST add an entry in the Virtual
LFIB for each unicast and anycast prefix segments learnt from a
remote device, if and only if the same prefix has not been
provisioned on the device. The device SHOULD NOT add a entry for any
of the Anycast or Node prefix segments that it has advertised itself.
However if the device has learnt any anycast prefix segment from a
remote device, and the same is not provisioned on this device, the
device MUST include the same in the Virtual LFIB table.
In cases where a prefix segment is reachable via multiple shortest
paths on a given device, the corresponding entry for the prefix SID
MUST have as many forwarding entries in the Virtual LFIB table as the
number of shortest-paths found for the corresponding prefix on the
device. .
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Figure 3 below shows how the Virtual LFIB table on each of devices in
group A should look like. Please note that some of the prefix
segments has multiple forwarding semantics associated with them. For
example, on device A1, the prefix SID 10 (originated by PE3) is
reachable through its neighbors A3 and A4. And as per the SRGB
advertised by A3 and A4, the labels allocated by A3 and A4 are 3030
and 4030 respectively. Hence A1 has added two forwarding entries for
the prefix SID 30 in its Virtual LFIB table.
Also please note that none of the devices in the anycast group have
included the anycast SID 100 in the Virtual LFIB table, since the
same has already been provisioned on these devices.
When a device receives a MPLS packet with the anycast segment label
associated with one of the anycast prefix segments provisioned on the
same device, the device MUST use the Virtual LFIB table to lookup the
next label that follows the anycast segment label in the stack of
labels found in the MPLS header. Refer to Section 3.5 for more
details.
Following forwarding instructions MUST be installed in the MPLS data-
plane for each entry in the Virtual LFIB entry.
o If the label at the top of the stack matches any of the prefix
SIDs in the Virtual LFIB table,
* If there are multiple forwarding tuples associated with
matching table entry,
+ Select one forwarding tuple. (Criteria to select one is
outside the scope of this document.)
* Else,
+ Select the single forwarding tuple available.
* Replace the Prefix SID index found at top of the MPLS label
stack in the packet received, with the 'Outgoing-label' from
the selected forwarding tuple.
* Forward the modified packet onto the 'Outgoing-link' as
specified in the selected forwarding tuple.
* Ensure the next label lookup is launched on the default LFIB
table.
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+========+============+=======+========================+
| | | Forwarding Semantics |
| Device | Prefix SID |--------------------------------|
| | | Outgoing-Label | Outgoing-Link |
+========+============+================+===============+
| A1 | 10 | 7010 | A1->R1 |
| +------------+----------------+---------------+
| | 20 | 7020 | A1->R1 |
| +------------+----------------+---------------+
| | 30 | 3030 | A1->A3 |
| | | 4030 | A1->A4 |
| +------------+----------------+---------------+
| | 40 | 3040 | A1->A3 |
| | | 4040 | A1->A4 |
+========+============+================+===============+
| A2 | 10 | 7010 | A2->R1 |
| +------------+----------------+---------------+
| | 20 | 7020 | A2->R1 |
| +------------+----------------+---------------+
| | 30 | 3030 | A2->A3 |
| | | 4030 | A2->A4 |
| +------------+----------------+---------------+
| | 40 | 3040 | A2->A3 |
| | | 4040 | A2->A4 |
+========+============+================+===============+
| A3 | 10 | 1010 | A3->A1 |
| | | 2010 | A3->A2 |
| +------------+----------------+---------------+
| | 20 | 1020 | A3->A1 |
| | | 2020 | A3->A2 |
| +------------+----------------+---------------+
| | 30 | 6030 | A3->R3 |
| +------------+----------------+---------------+
| | 40 | 6040 | A3->R3 |
+========+============+================+===============+
| A4 | 10 | 1010 | A4->A1 |
| | | 2010 | A4->A2 |
| +------------+----------------+---------------+
| | 20 | 1020 | A4->A1 |
| | | 2020 | A4->A2 |
| +------------+----------------+---------------+
| | 30 | 6030 | A4->R3 |
| +------------+----------------+---------------+
| | 40 | 6040 | A4->R3 |
+========+============+================+===============+
Figure 3: Virtual LFIB Table Setup
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3.3. Label Stack Computation
Any MPLS device that tries to encapsulate any kind of traffic into a
SPRING-based MPLS payload (hereafter referred to as the ingress
device) and steer it through a series of SPRING adjacency and/or
unicast/anycast prefix segments, needs to compute an appropriate
stack of MPLS labels and put it in the outgoing packet.
Alternatively, in a SDN environment, the SDN controller may need to
compute the label stack and install it on the ingress device.
However in both cases, as illustrated in Section 2, for a given
ingress device (e.g. PE1 or PE2), there maybe multiple topolgically
nearest devices in a specific anycast group (e.g. A1 and A2), even
through there is only out-going link from the source device(e.g.
PE1->R1 or PE2-R1). In such case, when the ingress device (or the
SDN controller) wants to steer a packet through the anycast group A,
it can use the anycast segment label advertised by the downstream
neighbor of the ingress device for the specific anycast prefix
segment. Since the packet may reach any one of the multiple devices
in the group and each of them may have a separate SRGB label range,
choosing the MPLS label for the next segment providing reachability
to the final destination. Also, since the packet steered through a
anycast segment can reach of any of the member device in the anycast
group, it is sufficient to assume that the ingress (or the
controller) cannot place an adjacency segment immediately after a
anycast segment in the outgoing packet.
This document proposes the ingress device (or the SDN controller) to
directly use the SID as the label for a prefix segment (can be
another anycast)that immediately follows a given anycast segment
already encoded into the label stack of the outgoing MPLS packet.
The ingress (or the controller) MUST follow the algorithm below to
compute the label-stack it must use to steer a packet through a list
of SPRING segments.
o Set 'last_segment' ==> NONE.
o For [all 'segments' in Segment_List]
* If {'segment'.type == Adjacency_Segment}
+ Set 'label' ==> 'segment'.Adjacency_Segment_Label.
* Else
+ If {'last_segment'.type == Anycast_Prefix_Segment}
- Set 'label' ==> 'segment'.SID_index.
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+ Else
- Set 'label' ==> 'Prefix_Segment_Label'.
o Add 'label' to 'label_stack'.
3.4. Advertising Anycast Prefix Segments
Like unicast prefix segments, anycast prefix segments SHOULD be
advertised in IGP Link-state advertsements using IGP protocol
extension for SPRING specified in
[I-D.ietf-isis-segment-routing-extensions],
[I-D.ietf-ospf-segment-routing-extensions] and
[I-D.ietf-ospf-ospfv3-segment-routing-extensions]. This document
does not propose any protocol extension for advertising anycast
prefix segments.
However when advertising the anycast segments, the originating device
MUST set the corresponding P-Flag(No-PHP) in ISIS Prefix-SID SubTLV
and/or the NP-Flag (No-PHP) in OSPFv2 and OSPFv3 Prefix-SID SubTLV to
1 and the E-Flag in the same SubTLVs to 0. Please refer to following
for more details on usage of these flags.
o ISIS Prefix-SID SubTLV [I-D.ietf-isis-segment-routing-extensions]
o OSPFv2 Prefix-SID SubTLV
[I-D.ietf-ospf-segment-routing-extensions]
o OSPFv3 Prefix-SID SubTLV
[I-D.ietf-ospf-ospfv3-segment-routing-extensions]
The proposal above, ensures that a MPLS packet sent to (or taking
transit through) a given anycast group, always arrives at the
topologically nearest device in the group, with a label that is
derived from the device's SRGB, and the SID associated with the
corresponding anycast prefix segment.
In Figure 2, when PE1 or PE2 intends to steer a packet destined for
PE3 or PE4, through the anycast group A (SID 100), it needs to
forward the packet to R1 (SRGB:7000-8000), after putting the label
7100 (derived from R1's SRGB), at top of the label stack in the MPLS
header. However when the same packet is forwarded to A1 or A2
(topologicaly nearest devices in group A), R1 shall not POP (or
remove) the label 7100. Instead R1 shall replace it with the label
1100 (while forwarding to A1) or 2100 (while forwarding to A2).
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3.5. Programming Anycast Prefix Segments
The proposal specified in Section 3.4, ensures that a MPLS packet
destined to (or steered via) a anycast prefix segment always arrives
at the nearest device in the anycast group with a label derived from
the device's SRGB and the SID associated with the corresponding
anycast prefix segment, as the top-most label label stack in its MPLS
header. If this label is also the bottom-most label (S=1), it means
packet has been destined to the anycast segment, and should be
consumed by the local device. If the label is not the bottom-most
label (S=0), the packet must be forwarded to the next segment, for
which the next label in the stack should be consulted. However
Section 3.3 specifies that the next label in such case, shall be
directly the SID associated with the next segment. Since the SID
associated with a prefix segment may directly collide with another
label in the default LFIB table, Section 3.2 also proposed to have a
Virtual LFIB table to provide a separate label-space for looking up
the next label.
This document specifies that a device provisioned with a given prefix
segment index MUST implement following forwarding semantics for the
anycast segment label (refer to Section 3.1) associated with the
anycast prefix segment.
o If the label at the top the stack is a anycast segment label,
* Pop the label.
* If bottom-most label in the stack (S=1),
+ Send it to host stack for local consumption, as usual.
* Else if not the bottom-most label in the stack (S=0),
+ Set the Virtual LFIB table as the lookup table for the next
label lookup.
+ Launch a lookup for the next label in the stack.
o Else
* Lookup the label in the default LFIB table as usual.
3.6. Packet Flow
Figure 4 below ilustrate how SPRING-based MPLS packets destined for
PE3 and sourced by PE1 are expected to flow theough when PE1
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encapsulates the packet with an appropriate label stack to steer it
through group A devices only
+-------------------------+
| Group A |
| 192.0.1.1/32 |
| SID:100 |
|-------------------------|
| |
| |
---> ---> ---> ---> ---> --->
+----+--+--+ +----+--+--+ +----+--+ +----+--+ +--+ +--+
|7100|30|..| |1100|30|..| |3030|..| |6030|..| |..| |..|
+----+--+--+ +----+--+--+ +----+--+ +----+--+ +--+ +--+
| |
| SRGB: SRGB: |
SID:10 |(1000-2000) (3000-4000)| SID:30
-----PE1---+ +-------A1-------------A3-------+ +---PE3-----
\ / | | \ / | | \ /
\ / | | +-----+ / | | \ /
SRGB: \ / | | \ / | | \ / SRGB:
(7000-8000) R1 | | \ | | R3 (6000-7000)
/ \ | | / \ | | / \
/ \ | | +-----+ \ | | / \
/ \ | | / \ | | / \
-----PE2---+ +-------A2-------------A4-------+ +---PE4-----
SID:20 | SRGB: SRGB: | SID:40
|(2000-3000) (4000-5000)|
| |
---> ---> --->
+----+--+--+ +----+--+ +----+--+
|2100|30|..| |4030|..| |6030|..|
+----+--+--+ +----+--+ +----+--+
| |
| |
+-------------------------+
Figure 4: Packet Flow through MPLS-based SPRING Anycast Segments
4. Acknowledgements
Many many thanks to Shraddha Hegde for her valuable inputs.
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5. IANA Considerations
N/A. - No protocol changes are proposed in this document.
6. Security Considerations
This document does not introduce any change in any of the protocol
specifications. It simply proposes additional inequalities for
selecting LFAs for multi-homed prefixes.
7. References
7.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
7.2. Informative References
[I-D.ietf-isis-segment-routing-extensions]
Previdi, S., Filsfils, C., Bashandy, A., Gredler, H.,
Litkowski, S., Decraene, B., and J. Tantsura, "IS-IS
Extensions for Segment Routing", draft-ietf-isis-segment-
routing-extensions-04 (work in progress), May 2015.
[I-D.ietf-ospf-ospfv3-segment-routing-extensions]
Psenak, P., Previdi, S., Filsfils, C., Gredler, H.,
Shakir, R., Henderickx, W., and J. Tantsura, "OSPFv3
Extensions for Segment Routing", draft-ietf-ospf-ospfv3-
segment-routing-extensions-02 (work in progress), February
2015.
[I-D.ietf-ospf-segment-routing-extensions]
Psenak, P., Previdi, S., Filsfils, C., Gredler, H.,
Shakir, R., Henderickx, W., and J. Tantsura, "OSPF
Extensions for Segment Routing", draft-ietf-ospf-segment-
routing-extensions-04 (work in progress), February 2015.
[I-D.ietf-spring-segment-routing]
Filsfils, C., Previdi, S., Decraene, B., Litkowski, S.,
and R. Shakir, "Segment Routing Architecture", draft-ietf-
spring-segment-routing-03 (work in progress), May 2015.
Sarkar & Gredler Expires January 7, 2016 [Page 14]
Internet-Draft Anycast Segments in MPLS based SPRING July 2015
[I-D.ietf-spring-segment-routing-mpls]
Filsfils, C., Previdi, S., Bashandy, A., Decraene, B.,
Litkowski, S., Horneffer, M., Shakir, R., Tantsura, J.,
and E. Crabbe, "Segment Routing with MPLS data plane",
draft-ietf-spring-segment-routing-mpls-01 (work in
progress), May 2015.
[I-D.previdi-6man-segment-routing-header]
Previdi, S., Filsfils, C., Field, B., and I. Leung, "IPv6
Segment Routing Header (SRH)", draft-previdi-6man-segment-
routing-header-06 (work in progress), May 2015.
Authors' Addresses
Pushpasis Sarkar (editor)
Juniper Networks, Inc.
Electra, Exora Business Park
Bangalore, KA 560103
India
Email: psarkar@juniper.net
Hannes Gredler
Juniper Networks, Inc.
1194 N. Mathilda Ave.
Sunnyvale, CA 94089
US
Email: hannes@juniper.net
Sarkar & Gredler Expires January 7, 2016 [Page 15]