Alcatel-Lucent 7950 SR User Configuration Manual

[Page 1] Alcatel-Lucent 7950 SR

7950 SR OS MPLS Guide Software Version: 7950 XRS OS 11.0 R1 February 2013 Document Part Number: 93-0405-02-01 *93-0405-02-01* ...

[Page 2] Alcatel-Lucent 7950 SR

This document is protected by copyright. Except as specifically permitted herein, no portion of the provided information can be reproduced in any form, or by any means, without prior written permission from Alcatel-Lucent. Alcatel, Lucent, Alcatel-L...

[Page 3] Alcatel-Lucent 7950 SR

7950 SR OS MPLS Configuration Guide Page 3 Table of Contents Preface. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .13 Getting Started Alcatel-...

[Page 4] Alcatel-Lucent 7950 SR

Page 4 7950 SR OS MPLS Configuration Guide Table of Contents Make-Before-Break (MBB) Procedures for LSP/Path Parameter Configuration Change . . . . . . . . . . .78 RSVP-TE LSP Shortcut for IGP Resolution . . . . . . . . . . . . . . . . . . . . . . ....

[Page 5] Alcatel-Lucent 7950 SR

7950 SR OS MPLS Configuration Guide Page 5 Table of Contents Configuring Manual Bypass Tunnels . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .127 Configuring RSVP Parameters . . . . . . . . . . . . ...

[Page 6] Alcatel-Lucent 7950 SR

Page 6 7950 SR OS MPLS Configuration Guide Table of Contents LDP LSP Statistics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .338 TTL Security for BGP and LDP . . . . . . . ...

[Page 7] Alcatel-Lucent 7950 SR

7950 SR OS MPLS Configuration Guide Page 7 Table of Contents Clear Commands . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .395 Debug Commands . . . . . . . . . . . . . . ....

[Page 8] Alcatel-Lucent 7950 SR

Page 8 7950 SR OS MPLS Configuration Guide Table of Contents ...

[Page 9] Alcatel-Lucent 7950 SR

7950 SR OS MPLS Configuration Guide Page 9 List of Tables Table 1: Configuration Process. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .17 MPLS and RSVP Table 2: Packet/Label Field Desc...

[Page 10] Alcatel-Lucent 7950 SR

Page 10 7950 SR OS MPLS Configuration Guide List of Tables ...

[Page 11] Alcatel-Lucent 7950 SR

7950 SR OS MPLS Configuration Guide Page 11 LIST OF FIGURES MPLS and RSVP Figure 1: Label Placement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .22 Figure 2: Label Packet Pl...

[Page 12] Alcatel-Lucent 7950 SR

Page 12 7950 SR OS MPLS Configuration Guide List of Figures ...

[Page 13] Alcatel-Lucent 7950 SR

7950 SR OS MPLS Configuration Guide Page 13 Preface About This Guide This guide describes the services and protocol support provided by the router and presents examples to configure and implement MPLS, RSVP, and LDP protocols. This document is organ...

[Page 14] Alcatel-Lucent 7950 SR

Preface Page 14 7950 SR OS MPLS Configuration Guide List of Technical Publications • 7950 SR OS Basic System Configuration Guide This guide describes basic system configurations and operations. • 7950 SR OS System Management Guide This guide desc...

[Page 15] Alcatel-Lucent 7950 SR

Preface 7950 SR OS MPLS Configuration Guide Page 15 Technical Support If you purchased a service agreement for your router and related products from a distributor or authorized reseller, contact the technical support staff for that distributor or re...

[Page 16] Alcatel-Lucent 7950 SR

Preface Page 16 7950 SR OS MPLS Configuration Guide ...

[Page 17] Alcatel-Lucent 7950 SR

7950 SR OS MPLS Configuration Guide Page 17 GETTING STARTED In This Chapter This chapter provides process flow information to configure MPLS, RSVP, and LDP protocols. Alcatel-Lucent Router Configuration Process Table 1 lists the tasks necessary to co...

[Page 18] Alcatel-Lucent 7950 SR

Getting Started Page 18 7950 SR OS MPLS Configuration Guide ...

[Page 19] Alcatel-Lucent 7950 SR

7950 SR OS MPLS Configuration Guide Page 19 MPLS and RSVP In This Chapter This chapter provides information to configure MPLS and RSVP. • MPLS on page 21  MPLS Label Stack on page 22  Label Switching Routers on page 25 • RSVP on page 39 �...

[Page 20] Alcatel-Lucent 7950 SR

Page 20 7950 SR OS MPLS Configuration Guide • Point-to-Multipoint (P2MP) RSVP LSP on page 101  Application in Video Broadcast on page 101  P2MP LSP Data Plane on page 102  Ingress Path Management for P2MP LSP Packets on page 105  RSVP C...

[Page 21] Alcatel-Lucent 7950 SR

MPLS and RSVP 7950 SR OS MPLS Configuration Guide Page 21 MPLS Multiprotocol Label Switching (MPLS) is a label switching technology that provides the ability to set up connection-oriented paths over a connectionless IP network. MPLS facilitates netw...

[Page 22] Alcatel-Lucent 7950 SR

MPLS Page 22 7950 SR OS MPLS Configuration Guide MPLS Label Stack MPLS requires a set of procedures to enhance network layer packets with label stacks which thereby turns them into labeled packets. Routers that support MPLS are known as Label Switch...

[Page 23] Alcatel-Lucent 7950 SR

MPLS and RSVP 7950 SR OS MPLS Configuration Guide Page 23 A stack can carry several labels, organized in a last in/first out order. The top of the label stack appears first in the packet and the bottom of the stack appears last ( Figure 2). Figure ...

[Page 24] Alcatel-Lucent 7950 SR

MPLS Page 24 7950 SR OS MPLS Configuration Guide Label Values Packets travelling along an LSP (see Label Switching Routers on page 25) are identified by its label, the 20-bit, unsigned integer. The range is 0 through 1,048,575. Label values 0-15 are...

[Page 25] Alcatel-Lucent 7950 SR

MPLS and RSVP 7950 SR OS MPLS Configuration Guide Page 25 Label Switching Routers LSRs perform the label switching function. LSRs perform different functions based on it’s position in an LSP. Routers in an LSP do one of the following: • The rout...

[Page 26] Alcatel-Lucent 7950 SR

MPLS Page 26 7950 SR OS MPLS Configuration Guide previous hop router to this router (strict) or can traverse through other routers (loose). You can control how the path is set up. They are similar to static LSPs but require less configuration. See ...

[Page 27] Alcatel-Lucent 7950 SR

MPLS and RSVP 7950 SR OS MPLS Configuration Guide Page 27 MPLS Facility Bypass Method of MPLS Fast Re-Route (FRR) The MPLS facility bypass method of MPLS Fast Re-Route (FRR) functionality is extended to the ingress node. The behavior of an LSP at an...

[Page 28] Alcatel-Lucent 7950 SR

MPLS Page 28 7950 SR OS MPLS Configuration Guide If dynamic bypass creation is disabled on the node, it is recommended to configure additional manual bypass LSPs to handle the required number of associations. Refer to Configuring Manual Bypass Tunne...

[Page 29] Alcatel-Lucent 7950 SR

MPLS and RSVP 7950 SR OS MPLS Configuration Guide Page 29 6. If the path message for the primary LSP path indicated link protection desired, and no manual bypass was found after step 1, and/or no dynamic bypass LSP was found after performing Step 3...

[Page 30] Alcatel-Lucent 7950 SR

MPLS Page 30 7950 SR OS MPLS Configuration Guide FRR Node-Protection (Facility) The MPLS Fast Re-Route (FRR) functionality enables PLRs to be aware of the missing node protection and lets them regularly probe for a node-bypass. The following descri...

[Page 31] Alcatel-Lucent 7950 SR

MPLS and RSVP 7950 SR OS MPLS Configuration Guide Page 31 Uniform FRR Failover Time The failover time during FRR consists of a detection time and a switchover time. The detection time corresponds to the time it takes for the RSVP control plane prot...

[Page 32] Alcatel-Lucent 7950 SR

MPLS Page 32 7950 SR OS MPLS Configuration Guide Automatic Bandwidth Allocation for RSVP LSPs Enabling and Disabling Auto-Bandwidth Allocation on an LSP This section discusses an auto-bandwidth hierarchy configurable in the config>router>mpls&g...

[Page 33] Alcatel-Lucent 7950 SR

MPLS and RSVP 7950 SR OS MPLS Configuration Guide Page 33 Measurement of LSP Bandwidth Automatic adjustment of RSVP LSP bandwidth based on measured traffic rate into the tunnel requires the LSP to be configured for egress statistics collection at th...

[Page 34] Alcatel-Lucent 7950 SR

MPLS Page 34 7950 SR OS MPLS Configuration Guide default value of sample-multiplier (the value that would result from the no auto-bandwidth- defaults command) is 1, which means the default sample interval is 300 seconds. Over a longer period of time...

[Page 35] Alcatel-Lucent 7950 SR

MPLS and RSVP 7950 SR OS MPLS Configuration Guide Page 35 Periodic Automatic Bandwidth Adjustment Automatic bandwidth allocation is supported on any RSVP LSP that has MBB enabled. MBB is enabled in the config>router>mpls>lsp context using t...

[Page 36] Alcatel-Lucent 7950 SR

MPLS Page 36 7950 SR OS MPLS Configuration Guide • If the current bandwidth is greater than the max bandwidth then the LSP bandwidth is re- signaled to max bandwidth, even if the thresholds have not been triggered. • If the current bandwidth is g...

[Page 37] Alcatel-Lucent 7950 SR

MPLS and RSVP 7950 SR OS MPLS Configuration Guide Page 37 Overflow-Triggered Auto-Bandwidth Adjustment For cases where the measured bandwidth of an LSP has increased significantly since the start of the current adjust interval it may be desirable fo...

[Page 38] Alcatel-Lucent 7950 SR

MPLS Page 38 7950 SR OS MPLS Configuration Guide Manually-Triggered Auto-Bandwidth Adjustment Manually-triggered auto-bandwidth adjustment feature is configured with the tools>perform>router>mpls adjust-autobandwidth [lsp lsp-name [force [b...

[Page 39] Alcatel-Lucent 7950 SR

MPLS and RSVP 7950 SR OS MPLS Configuration Guide Page 39 RSVP The Resource Reservation Protocol (RSVP) is a network control protocol used by a host to request specific qualities of service from the network for particular application data streams or...

[Page 40] Alcatel-Lucent 7950 SR

RSVP Page 40 7950 SR OS MPLS Configuration Guide Figure 6: LSP Using RSVP Path Set Up Figure 6 displays an example of an LSP path set up using RSVP. The ingress label edge router (ILER 1) transmits an RSVP path message (path: 30.30.30.1) downstream ...

[Page 41] Alcatel-Lucent 7950 SR

MPLS and RSVP 7950 SR OS MPLS Configuration Guide Page 41 Using RSVP for MPLS Hosts and routers that support both MPLS and RSVP can associate labels with RSVP flows. When MPLS and RSVP are combined, the definition of a flow can be made more flexible...

[Page 42] Alcatel-Lucent 7950 SR

RSVP Page 42 7950 SR OS MPLS Configuration Guide MD5 Authentication of RSVP Interface When enabled on an RSVP interface, authentication of RSVP messages operates in both directions of the interface. A node maintains a security association with its ...

[Page 43] Alcatel-Lucent 7950 SR

MPLS and RSVP 7950 SR OS MPLS Configuration Guide Page 43 Reservation Styles LSPs can be signaled with explicit reservation styles. A reservation style is a set of control options that specify a number of supported parameters. The style information ...

[Page 44] Alcatel-Lucent 7950 SR

RSVP Page 44 7950 SR OS MPLS Configuration Guide RSVP Overhead Refresh Reduction The RSVP refresh reduction feature consists of the following capabilities implemented in accordance to RFC 2961, RSVP Refresh Overhead Reduction Extensions: • RSVP me...

[Page 45] Alcatel-Lucent 7950 SR

MPLS and RSVP 7950 SR OS MPLS Configuration Guide Page 45 RSVP Graceful Restart Helper This gr-helper command enables the RSVP Graceful Restart Helper feature. The RSVP-TE Graceful Restart helper mode allows the SR OS based system (the helper node) ...

[Page 46] Alcatel-Lucent 7950 SR

RSVP Page 46 7950 SR OS MPLS Configuration Guide Enhancements to RSVP control plane congestion control The RSVP control plane makes use of a global flow control mechanism to adjust the rate of Path messages for unmapped LSP paths sent to the network...

[Page 47] Alcatel-Lucent 7950 SR

MPLS and RSVP 7950 SR OS MPLS Configuration Guide Page 47 RSVP LSP Statistics This feature provides the following counters: • Per forwarding class forwarded in-profile packet count • Per forwarding class forwarded in-profile byte count • Per fo...

[Page 48] Alcatel-Lucent 7950 SR

RSVP Page 48 7950 SR OS MPLS Configuration Guide Configuring Implicit Null The implicit null label option allows a 7x50 egress LER to receive MPLS packets from the previous hop without the outer LSP label. The operation of the previous hop is referr...

[Page 49] Alcatel-Lucent 7950 SR

MPLS and RSVP 7950 SR OS MPLS Configuration Guide Page 49 Using Unnumbered Point-to-Point Interface in RSVP This feature introduces the use of unnumbered IP interface as a Traffic Engineering (TE) link for the signaling of RSVP P2P LSP and P2MP LSP....

[Page 50] Alcatel-Lucent 7950 SR

RSVP Page 50 7950 SR OS MPLS Configuration Guide PathErr message will be sent back to the ingress LER with the "Routing Problem" error code of 24 and an error value of 5 “No route available toward destination”. All MPLS features availa...

[Page 51] Alcatel-Lucent 7950 SR

MPLS and RSVP 7950 SR OS MPLS Configuration Guide Page 51 In addition, the PLR node will include the IPv4 RSVP_HOP object (C-Type=1) or the IF_ID RSVP_HOP object (C-Type=3) in the PATH message if the outgoing interface of the bypass LSP is numbered...

[Page 52] Alcatel-Lucent 7950 SR

Traffic Engineering Page 52 7950 SR OS MPLS Configuration Guide Traffic Engineering Without traffic engineering, routers route traffic according to the SPF algorithm, disregarding congestion or packet types. With traffic engineering, network traffic...

[Page 53] Alcatel-Lucent 7950 SR

MPLS and RSVP 7950 SR OS MPLS Configuration Guide Page 53 TE Metric (IS-IS and OSPF) When the use of the TE metric is selected for an LSP, the shortest path computation after the TE constraints are applied will select an LSP path based on the TE met...

[Page 54] Alcatel-Lucent 7950 SR

Traffic Engineering Page 54 7950 SR OS MPLS Configuration Guide Admin Group Support on Facility Bypass Backup LSP This feature provides for the inclusion of the LSP primary path admin-group constraints in the computation of a Fast ReRoute (FRR) faci...

[Page 55] Alcatel-Lucent 7950 SR

MPLS and RSVP 7950 SR OS MPLS Configuration Guide Page 55 however, that the PLR rules for processing the admin-group constraints can make use of either of the two object admin-group constraints. Procedures at PLR Node The user enables the use of the...

[Page 56] Alcatel-Lucent 7950 SR

Traffic Engineering Page 56 7950 SR OS MPLS Configuration Guide The PLR node then uses the admin-group constraints along with other constraints, such as hop- limit and SRLG, to select a manual or dynamic bypass among those that are already in use. I...

[Page 57] Alcatel-Lucent 7950 SR

MPLS and RSVP 7950 SR OS MPLS Configuration Guide Page 57 Diff-Serv Traffic Engineering Diff-Serv traffic engineering provides the ability to manage bandwidth on a per Traffic Engineering (TE) class basis as per RFC 4124. In the base traffic enginee...

[Page 58] Alcatel-Lucent 7950 SR

Traffic Engineering Page 58 7950 SR OS MPLS Configuration Guide bandwidth against the ‘unreserved bandwidth’ advertised for all links in the path of the LSP for that TE class which consists of a combination of a CT and a priority. Same for the a...

[Page 59] Alcatel-Lucent 7950 SR

MPLS and RSVP 7950 SR OS MPLS Configuration Guide Page 59 Russian Doll Model The RDM model is defined using the following equations: SUM (Reserved (CTc)) <= BCb, where the SUM is across all values of c in the range b <= c <= (MaxCT - 1), and...

[Page 60] Alcatel-Lucent 7950 SR

Traffic Engineering Page 60 7950 SR OS MPLS Configuration Guide Example CT Bandwidth Sharing with RDM Below is a simple example with two CT values (CT0, CT1) and one priority 0 as shown in Figure 7. Figure 7: RDM with Two Class Types Suppose CT1 ban...

[Page 61] Alcatel-Lucent 7950 SR

MPLS and RSVP 7950 SR OS MPLS Configuration Guide Page 61 Figure 8: First LSP Reservation According to the RDM admission control policy: Reserved (CT1, 0) = 50 <= 100 Mbps Reserved (CT0, 0) + Reserved (CT1, 0) = 50 <= 200 Mbps This results in t...

[Page 62] Alcatel-Lucent 7950 SR

Traffic Engineering Page 62 7950 SR OS MPLS Configuration Guide Figure 9: Second LSP Reservation Reserved (CT0, 0) = 120 <= 150 Mbps Reserved (CT0, 0) + Reserved (CT1, 0) = 120 + 50 = 170 <= 200 Mbps Unreserved (CT0, 0) = 150 -120 = 30 Mbps If ...

[Page 63] Alcatel-Lucent 7950 SR

MPLS and RSVP 7950 SR OS MPLS Configuration Guide Page 63 RSVP Control Plane Extensions RSVP will use the Class Type object to carry LSP class-type information during path setup. Eight values will be supported for class-types 0 through 7 as per RFC ...

[Page 64] Alcatel-Lucent 7950 SR

Traffic Engineering Page 64 7950 SR OS MPLS Configuration Guide Diff-Serv TE Configuration and Operation RSVP Protocol Level The following are the configuration steps at the RSVP protocol level: 1. The operator enables Diff-Serv TE by executing the d...

[Page 65] Alcatel-Lucent 7950 SR

MPLS and RSVP 7950 SR OS MPLS Configuration Guide Page 65 b. A mapping of the system forwarding class to CT. The default settings are shown in Table 5. c. Configuration of the percentage of RSVP interface bandwidth each CT shares, for example, th...

[Page 66] Alcatel-Lucent 7950 SR

Traffic Engineering Page 66 7950 SR OS MPLS Configuration Guide interface level and the interface specific configured value overrides the global configured value. The BC value can be changed at any time. The operator can specify the BC for a CT whi...

[Page 67] Alcatel-Lucent 7950 SR

MPLS and RSVP 7950 SR OS MPLS Configuration Guide Page 67 5. The signaled CT, setup priority and holding priority of a detour LSP matches those of the primary LSP path it is associated with. 6. The operator can also configure the setup and holding p...

[Page 68] Alcatel-Lucent 7950 SR

Traffic Engineering Page 68 7950 SR OS MPLS Configuration Guide Diff-Serv TE LSP Class Type Change under Failure An option to configure a main Class Type (CT) and a backup CT for the primary path of a Diff- Serv TE LSP is provided. The main CT is use...

[Page 69] Alcatel-Lucent 7950 SR

MPLS and RSVP 7950 SR OS MPLS Configuration Guide Page 69  Receipt of a PathErr message with error code=25 (Notify) and sub-code=7 (Local link maintenance required) or a sub-code=8 (Local node maintenance required). This invokes the TE Graceful ...

[Page 70] Alcatel-Lucent 7950 SR

Traffic Engineering Page 70 7950 SR OS MPLS Configuration Guide  Consider the following priority of the various MBB types form highest to lowest: Delayed Retry, Preemption, Global Revertive, Configuration Change, and TE Graceful Shutdown. If an ...

[Page 71] Alcatel-Lucent 7950 SR

MPLS and RSVP 7950 SR OS MPLS Configuration Guide Page 71 Bandwidth Sharing Across Class Types In order to allow different levels of booking of network links under normal operating conditions and under failure conditions, it is necessary to allow sh...

[Page 72] Alcatel-Lucent 7950 SR

Traffic Engineering Page 72 7950 SR OS MPLS Configuration Guide It is required that multiple paths of the same LSP share common link bandwidth since they are signaled using the Shared Explicit (SE) style. Specifically, two instances of a primary pat...

[Page 73] Alcatel-Lucent 7950 SR

MPLS and RSVP 7950 SR OS MPLS Configuration Guide Page 73 Downgrading the CT of Bandwidth Sharing LSP Paths Consider a link configured with two class types CT0 and CT1 and making use of the RDM admission control model as shown in Figure 11. Figure ...

[Page 74] Alcatel-Lucent 7950 SR

Traffic Engineering Page 74 7950 SR OS MPLS Configuration Guide Upgrading the CT of Bandwidth Sharing LSP Paths When upgrading the CT the following issue can be apparent. Assume an LSP path X exists with CT0. An attempt is made to upgrade this path ...

[Page 75] Alcatel-Lucent 7950 SR

MPLS and RSVP 7950 SR OS MPLS Configuration Guide Page 75 Advanced MPLS/RSVP Features • Extending RSVP LSP to use Loopback Interfaces Other Than router-id on page 75 • LSP Path Change on page 75 • RSVP-TE LSP Shortcut for IGP Resolution on page...

[Page 76] Alcatel-Lucent 7950 SR

Advanced MPLS/RSVP Features Page 76 7950 SR OS MPLS Configuration Guide The new path must be first configured in CLI or provided via SNMP. The configure router mpls path path-name CLI command is used to enter the path. The command fails if any of th...

[Page 77] Alcatel-Lucent 7950 SR

MPLS and RSVP 7950 SR OS MPLS Configuration Guide Page 77 Manual LSP Path Switch This feature provides a new command to move the path of an LSP from a standby secondary to another standby secondary. The base version of the command allows the path of...

[Page 78] Alcatel-Lucent 7950 SR

Advanced MPLS/RSVP Features Page 78 7950 SR OS MPLS Configuration Guide Make-Before-Break (MBB) Procedures for LSP/Path Parameter Configuration Change When an LSP is switched from an existing working path to a new path, it is desirable to perform t...

[Page 79] Alcatel-Lucent 7950 SR

MPLS and RSVP 7950 SR OS MPLS Configuration Guide Page 79 10. Changing LSP primary or secondary path class-type value and primary path backup-class- type value. 11. Changing LSP level and path level hop-limit parameter value. 12. Enabling/disabling p...

[Page 80] Alcatel-Lucent 7950 SR

Advanced MPLS/RSVP Features Page 80 7950 SR OS MPLS Configuration Guide RSVP-TE LSP Shortcut for IGP Resolution RSVP-TE LSP shortcut for IGP route resolution allows forwarding of packets to IGP learned routes using an RSVP-TE LSP. This is also refer...

[Page 81] Alcatel-Lucent 7950 SR

MPLS and RSVP 7950 SR OS MPLS Configuration Guide Page 81 the LDP-over-RSVP application. Table 6 summarizes the outcome in terms of RSVP LSP role of mixing these configuration options. The resolution and forwarding of IPv6 prefixes to IPv4 IGP shor...

[Page 82] Alcatel-Lucent 7950 SR

Advanced MPLS/RSVP Features Page 82 7950 SR OS MPLS Configuration Guide LSP using the TE-metric and a non-CSPF LSP with a loose or strict hop in the path. A non-CSPF LSP with an empty hop in the path definition returns the IGP cost for the destinati...

[Page 83] Alcatel-Lucent 7950 SR

MPLS and RSVP 7950 SR OS MPLS Configuration Guide Page 83  exclude LSPs with metric higher than underlying IGP cost between the endpoint of the LSP  prefer tunnel next-hop over ip next-hop  within tunnel next-hops: i. select lowest endpoint...

[Page 84] Alcatel-Lucent 7950 SR

Advanced MPLS/RSVP Features Page 84 7950 SR OS MPLS Configuration Guide The forwarding adjacency feature can be enabled independently from the IGP shortcut feature in CLI. If both rsvp-shortcut and advertise-tunnel-link options are enabled for a giv...

[Page 85] Alcatel-Lucent 7950 SR

MPLS and RSVP 7950 SR OS MPLS Configuration Guide Page 85 This feature supports multicast Reverse-Path Check (RPF) in the presence of IGP shortcuts. When the multicast source for a packet is reachable via an IGP shortcut, the RPF check fails since P...

[Page 86] Alcatel-Lucent 7950 SR

Advanced MPLS/RSVP Features Page 86 7950 SR OS MPLS Configuration Guide LFA next-hop will, however, be computed and installed in the unicast RTM for a primary IP next-hop of a prefix. 4. Multicast RTM is a copy of the unicast RTM and is thus populat...

[Page 87] Alcatel-Lucent 7950 SR

MPLS and RSVP 7950 SR OS MPLS Configuration Guide Page 87 Disabling TTL Propagation in an LSP Shortcut This feature provides the option for disabling TTL propagation from a transit or a locally generated IP packet header into the LSP label stack whe...

[Page 88] Alcatel-Lucent 7950 SR

Advanced MPLS/RSVP Features Page 88 7950 SR OS MPLS Configuration Guide RSVP-TE LSP Signaling using LSP Template LSP template can be used for signaling RSVP-TE LSP to far-end PE node that is detected based on auto-discovery method by a client applic...

[Page 89] Alcatel-Lucent 7950 SR

MPLS and RSVP 7950 SR OS MPLS Configuration Guide Page 89 Shared Risk Link Groups Shared Risk Link Groups (SRLGs) is a feature that allows the user to establish a backup secondary LSP path or a FRR LSP path which is disjoint from the path of the pri...

[Page 90] Alcatel-Lucent 7950 SR

Advanced MPLS/RSVP Features Page 90 7950 SR OS MPLS Configuration Guide  Configure primary and secondary LSP paths and enable SRLG on the secondary LSP path. Note that the SRLG secondary LSP path(s) will always perform a strict CSPF query. The s...

[Page 91] Alcatel-Lucent 7950 SR

MPLS and RSVP 7950 SR OS MPLS Configuration Guide Page 91 Figure 13: Shared Risk Link Groups This feature is supported on OSPF and IS-IS interfaces on which RSVP is enabled. SRLG 1 SRLG 2 Primary Path (FRR, node protection) Bypass tunnel taking SRLG ...

[Page 92] Alcatel-Lucent 7950 SR

Advanced MPLS/RSVP Features Page 92 7950 SR OS MPLS Configuration Guide Static Configurations of SRLG Memberships This feature provides operations with the ability to manually enter the link members of SRLG groups for the entire network at any SR OS...

[Page 93] Alcatel-Lucent 7950 SR

MPLS and RSVP 7950 SR OS MPLS Configuration Guide Page 93 The operator enables the use by CSPF of the user SRLG database by entering the user-srlg-db enable command in the config>router>mpls context. When the MPLS module makes a request to CS...

[Page 94] Alcatel-Lucent 7950 SR

Advanced MPLS/RSVP Features Page 94 7950 SR OS MPLS Configuration Guide Least-Fill Bandwidth Rule in CSPF ECMP Selection When multiples equal-cost paths satisfy the constraints of a given RSVP LSP path, CSPF in the router head-end node will select a...

[Page 95] Alcatel-Lucent 7950 SR

MPLS and RSVP 7950 SR OS MPLS Configuration Guide Page 95 Figure 14: Automatic ABR Node Selection for Inter-Area LSP CSPF for an inter-area LSP operates as follows: 1. CSPF in the Ingress LER node determines that an LSP is inter-area by doing a route...

[Page 96] Alcatel-Lucent 7950 SR

Advanced MPLS/RSVP Features Page 96 7950 SR OS MPLS Configuration Guide attempted a path all the way to the last hop in the local area, node E. Instead, CSPF stops the path at node A which will further expand the ERO by including link D-E as part of...

[Page 97] Alcatel-Lucent 7950 SR

MPLS and RSVP 7950 SR OS MPLS Configuration Guide Page 97 Use’ flag set. At the receipt of first of these two messages, the ingress LER will then perform a Global Revertive Make-Before-Break (MBB) to re-optimize the LSP primary path via the ABR w...

[Page 98] Alcatel-Lucent 7950 SR

Advanced MPLS/RSVP Features Page 98 7950 SR OS MPLS Configuration Guide •The srlg option on secondary path is allowed to operate within the scope of the local area of the ingress LER node with the automatic ABR selection feature. •The least-fill...

[Page 99] Alcatel-Lucent 7950 SR

MPLS and RSVP 7950 SR OS MPLS Configuration Guide Page 99 Manual bypass protection works only when a proper completely strict path is provisioned that avoids the area border node. Dynamic bypass protection provides for the automatic computation, si...

[Page 100] Alcatel-Lucent 7950 SR

Advanced MPLS/RSVP Features Page 100 7950 SR OS MPLS Configuration Guide • If a node-protect dynamic bypass cannot be found or signaled, the PLR node attempts a link-protect dynamic bypass LSP. As in existing implementation of dynamic bypass with...