Chapter 4: Cisco MPLS Traffic Engineering

Cisco Press

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RP/0/4/CPU0:Router#show mpls traffic-eng tunnels role head detail 
Signalling Summary:
           LSP Tunnels Process: running
                  RSVP Process: running
                    Forwarding: enabled
       Periodic reoptimization: every 3600 seconds, next in 1244 seconds
        Periodic FRR Promotion: every 300 seconds, next in 173 seconds
   Periodic auto-bw collection: disabled

Name: tunnel-te1 Destination: 172.16.255.2
 Status:
  Admin:  up Oper:  up  Path: valid  Signalling: connected

  path option 10, type explicit PATH1 (Basis for Setup, path weight 3)
  G-PID: 0x0800 (derived from egress interface properties)

 Config Parameters:
  Bandwidth:  30000 kbps (CT1) Priority: 3 3 Affinity: 0x0/0xffff
  Metric Type: TE (default)
  AutoRoute: disabled LockDown: disabled  Loadshare:  30000 bw-based
  Auto-bw: disabled(0/0) 0 Bandwidth Requested:  30000
  Direction: unidirectional
  Endpoint switching capability: unknown, encoding type: unassigned
  Transit switching capability: unknown, encoding type: unassigned

 History:
  Tunnel has been up for: 02:01:00
  Current LSP:
   Uptime: 02:01:00
 Current LSP Info:
  Instance: 9, Signaling Area: ospf DEFAULT area 0
  Uptime: 02:01:00
  Incoming Label: explicit-null
  Outgoing Interface: POS0/3/0/2, Outgoing Label: 33
  Path Info:
   Explicit Route:
    Strict, 172.16.192.3
    Strict, 172.16.192.4
    Strict, 172.16.4.0
    Strict, 172.16.255.2
   Record Route: None
   Tspec: avg rate=30000 kbits, burst=1000 bytes, peak rate=30000 kbits
  Resv Info:
   Record Route:
    IPv4 172.16.255.131, flags 0x2d
    Label 33, flags 0x1
    IPv4 172.16.255.130, flags 0x20
    Label 32, flags 0x1
    IPv4 172.16.255.2, flags 0x20
    Label 0, flags 0x1
   Fspec: avg rate=30000 kbits, burst=1000 bytes, peak rate=30000 kbits
Displayed 1 (of 1) heads, 0 (of 1) midpoints, 0 (of 0) tails
Displayed 1 up, 0 down, 0 recovering, 0 recovered heads
RP/0/4/CPU0:Router#

Examine the information in Table 4-4.

Table 4-4 Flags in the RRO IPv4/IPv6 Subobject

Value (Hexadecimal)

Flag

Description

0x01

Local protection available

Node can protect TE LSP.

0x02

Local protection in use

Node is rerouting the TE LSP through the backup tunnel.

0x04

Bandwidth protection

Node can provide bandwidth protection for the TE LSP.

0x08

Node protection

Node can provide protection against downstream node failure.

0x10

Preemption pending

TE LSP preemption pending. Headend should reroute the TE LSP.

0x20

Node ID

Address represents node ID rather than a link address.

Verifying FRR on the PLR

A PLR will provide the details of the primary TE LSPs it is protecting and what backup tunnel it uses for that purpose.

Example 4-52 shows the output of the show mpls traffic-eng fast-reroute database command in Cisco IOS. If the PLR has selected a backup for a primary TE LSP, the command displays the TE LSP, the input label, the output interface, the output label, the output backup tunnel, and the backup label. The protection status can be ready when a failure has not occurred or active when the node is rerouting the primary TE LSP through the backup.

Example 4-52 Examining the FRR Database on the PLR in Cisco IOS

Router#show mpls traffic-eng fast-reroute database 
Headend frr information:
Protected tunnel       In-label Out intf/label  FRR intf/label  Status

LSP midpoint frr information:
LSP identifier           In-label Out intf/label  FRR intf/label   Status
172.16.255.1 1 [6]       30       PO1/0/0:33      Tu2:implicit-nul ready 
172.16.255.129 1 [9]     33       PO1/0/0:32      Tu1:implicit-nul ready 
Router#
*Nov 10 16:32:52.852: %LINK-3-UPDOWN: Interface POS1/0/0, changed state to down
*Nov 10 16:32:52.856: %OSPF-5-ADJCHG: Process 100, Nbr 172.16.255.130 on POS1/0/0 
from FULL to DOWN, Neighbor Down: Interface down or detached
*Nov 10 16:32:53.852: %LINEPROTO-5-UPDOWN: Line protocol on Interface POS1/0/0, changed state to down
Router#
Router#show mpls traffic-eng fast-reroute database 
Headend frr information:
Protected tunnel         In-label Out intf/label  FRR intf/label  Status

LSP midpoint frr information:
LSP identifier           In-label Out intf/label  FRR intf/label   Status
172.16.255.1 1 [6]       30       PO1/0/0:33      Tu2:implicit-nul active 
172.16.255.129 1 [9]     33       PO1/0/0:32      Tu1:implicit-nul active 
Router#

Cisco IOS XR supports the same command with equivalent information. Example 4-53 shows the command output in Cisco IOS XR. Both examples show the command output before and while the node reroutes the TE LSPs.

Example 4-53 Examining the FRR Database on the PLR in Cisco IOS XR

RP/0/4/CPU0:Router#show mpls traffic-eng fast-reroute database 
LSP midpoint FRR information:
LSP Identifier                Local  Out Intf/        FRR Intf/        Status 
                              Label  Label            Label          
----------------------------- ------ ---------------- ---------------- -------
172.16.255.1 1 [677]          83   PO0/3/0/1:31   tt2:ExpNull4   Ready
RP/0/4/CPU0:Router#
RP/0/4/CPU0:Router#LC/0/3/CPU0:May 2 01:23:29.614 : ifmgr[154]: %PKT_INFRA-LINK-3-
UPDOWN : Interface POS0/3/0/1, changed state to Down 
LC/0/3/CPU0:May 2 01:23:29.615 : ifmgr[154]: %PKT_INFRA-LINEPROTO-5-UPDOWN : Line 
protocol on Interface POS0/3/0/1, changed state to Down 
RP/0/4/CPU0:May 2 01:23:29.643 : ospf[269]: %ROUTING-OSPF-5-ADJCHG : Process 
DEFAULT, Nbr 172.16.255.130 on POS0/3/0/1 from FULL to DOWN, Neighbor Down: 
interface down or detached 

RP/0/4/CPU0:Router#
RP/0/4/CPU0:Router#show mpls traffic-eng fast-reroute database 
LSP midpoint FRR information:
LSP Identifier                Local  Out Intf/        FRR Intf/        Status 
                              Label  Label            Label          
----------------------------- ------ ---------------- ---------------- -------
172.16.255.1 1 [677]          83     tt2:ExpNull4                      Active
RP/0/4/CPU0:Router#

You can use the show mpls traffic-eng tunnels protection command to examine the details of a protected TE LSP on a PLR. You can use the command in Cisco IOS and Cisco IOS XR. Example 4-54 shows a protected TE LSP traversing interface POS1/0/0. The backup selection process has chosen Tunnel2 to protect this TE LSP. See Example 4-41 for the backup tunnel configuration. Example 4-55 shows the equivalent command output in Cisco IOS XR. In that example, the PLR has selected tunnel-te2 to reroute the protected TE LSP. See Example 4-42 for the backup tunnel configuration

Example 4-54 Examining Protected TE LSPs on the PLR in Cisco IOS

Router#show mpls traffic-eng tunnels protection 
NNHOP-BACKUP-40M-CT1
 LSP Head, Tunnel1, Admin: up, Oper: up
 Src 172.16.255.131, Dest 172.16.255.2, Instance 4
 Fast Reroute Protection: None
 Path Protection: None
NNHOP-BACKUP-90M-CT0
 LSP Head, Tunnel2, Admin: up, Oper: up
 Src 172.16.255.131, Dest 172.16.255.2, Instance 1
 Fast Reroute Protection: None
 Path Protection: None
NHOP-BACKUP-90M-ANY-CT
 LSP Head, Tunnel3, Admin: up, Oper: up
 Src 172.16.255.131, Dest 172.16.255.130, Instance 1
 Fast Reroute Protection: None
 Path Protection: None

LSP Tunnel FROM-ROUTER-TO-DST1-FRR-NODEP-BWP is signalled, connection is up
 InLabel : POS2/0/0, 30
 OutLabel : POS1/0/0, 33
 FRR OutLabel : Tunnel2, explicit-null 
 RSVP Signalling Info:
    Src 172.16.255.1, Dst 172.16.255.2, Tun_Id 1, Tun_Instance 6
  RSVP Path Info:
   My Address: 172.16.192.5  
   Explicit Route: 172.16.192.4 172.16.4.0 172.16.255.2 
   Record  Route:  NONE
   Tspec: ave rate=20000 kbits, burst=1000 bytes, peak rate=20000 kbits
  RSVP Resv Info:
   Record  Route: 172.16.255.130(33) 172.16.255.2(0)
   Fspec: ave rate=20000 kbits, burst=1000 bytes, peak rate=20000 kbits

LSP Tunnel FROM-ROUTER-TO-DST1-FRR is signalled, connection is up
 InLabel : POS0/0/0, 33
 OutLabel : POS1/0/0, 32
 FRR OutLabel : Tunnel1, explicit-null 
 RSVP Signalling Info:
    Src 172.16.255.129, Dst 172.16.255.2, Tun_Id 1, Tun_Instance 9
  RSVP Path Info:
   My Address: 172.16.192.5  
   Explicit Route: 172.16.192.4 172.16.4.0 172.16.255.2 
   Record  Route:  NONE
   Tspec: ave rate=30000 kbits, burst=1000 bytes, peak rate=30000 kbits
  RSVP Resv Info:
   Record  Route: 172.16.255.130(32) 172.16.255.2(0)
   Fspec: ave rate=30000 kbits, burst=1000 bytes, peak rate=30000 kbits
Router#

Example 4-55 Examining Protected TE LSPs on the PLR in Cisco IOS XR

RP/0/4/CPU0:Router#show mpls traffic-eng tunnels protection 
NHOP-BACKUP-90M-ANY-CT
 LSP Midpoint, signaled, connection up
 Src: 172.16.255.131, Dest: 172.16.255.130, Instance: 1
 Fast Reroute Protection: None

NHOP-BACKUP-55M-CT0
 LSP Head, Admin: up, Oper: up
 Src: 172.16.255.129, Dest: 172.16.255.130, Instance: 1
 Fast Reroute Protection: None

NNHOP-BACKUP-20M-CT0
 LSP Head, Admin: up, Oper: up
 Src: 172.16.255.129, Dest: 172.16.255.2, Instance: 1
 Fast Reroute Protection: None

NHOP-BACKUP-25M-ANY-CT
 LSP Head, Admin: up, Oper: up
 Src: 172.16.255.129, Dest: 172.16.255.130, Instance: 1
 Fast Reroute Protection: None

FROM-ROUTER-TO-DST1-FRR-NODEP-BWP
 LSP Midpoint, signaled, connection up
 Src: 172.16.255.1, Dest: 172.16.255.2, Instance: 677
 Fast Reroute Protection: Requested
  Inbound: FRR Inactive
   LSP signalling info:
    Original: in i/f: POS0_3_0_0, label: 83, phop: 172.16.0.0
  Outbound: FRR Ready
   Backup tunnel-te2 to LSP nnhop
    tunnel-te2: out i/f: POS0/3/0/2
   LSP signalling info:
    Original: out i/f: POS0/3/0/1, label: 31, nhop: 172.16.192.1
    With FRR: out i/f: tunnel-te2, label: 0
   LSP bw: 20000 kbps, Backup level: CT0 limited, type: CT0 

RP/0/4/CPU0:Router#

The show mpls traffic-eng tunnels backup command enables you to obtain details about the backup tunnels on the PLR. The output shows you how many TE LSPs the backup tunnel is protecting. It also shows you the current allocation of backup bandwidth. Example 4-56 illustrates the command output in Cisco IOS. In this case, Tunnel2 is protecting one TE LSP and has allocated 10,000 kbps of the total 90,000 kbps of backup bandwidth. Example 4-57 shows the equivalent command output in Cisco IOS XR. In that example, te-tunnel2 is protecting one TE LSP and has allocated all its backup bandwidth (20,000 kbps).

Example 4-56 Examining Backup Tunnels on the PLR in Cisco IOS

Router#show mpls traffic-eng tunnels backup 
NNHOP-BACKUP-40M-CT1
 LSP Head, Tunnel1, Admin: up, Oper: up
 Src 172.16.255.131, Dest 172.16.255.2, Instance 4
 Fast Reroute Backup Provided: 
  Protected i/fs: PO1/0/0
  Protected lsps: 1
  Backup BW: sub-pool; limit: 40000 kbps, inuse: 30000 kbps (BWP inuse: 0 kbps)
NNHOP-BACKUP-90M-CT0
 LSP Head, Tunnel2, Admin: up, Oper: up
 Src 172.16.255.131, Dest 172.16.255.2, Instance 1
 Fast Reroute Backup Provided: 
  Protected i/fs: PO1/0/0
  Protected lsps: 1
  Backup BW: global pool; limit 90000 kbps, inuse: 20000 kbps (BWP inuse: 20000 kbps)
NHOP-BACKUP-90M-ANY-CT
 LSP Head, Tunnel3, Admin: up, Oper: up
 Src 172.16.255.131, Dest 172.16.255.130, Instance 1
 Fast Reroute Backup Provided: 
  Protected i/fs: PO1/0/0
  Protected lsps: 0
  Backup BW: any pool; limit: 90000 kbps, inuse: 0 kbps (BWP inuse: 0 kbps)
Router#

Example 4-57 Examining Backup Tunnels on the PLR in Cisco IOS XR

RP/0/4/CPU0:Router#show mpls traffic-eng tunnels backup   

tunnel-te1
 Admin: up, Oper: up
 Src: 172.16.255.129, Dest: 172.16.255.130, Instance: 1
 Fast Reroute Backup Provided:
  Protected LSPs: 0
  Backup BW: CT0; limit: 55000 kbps, Inuse: 0 kbps
  Protected i/fs: POS0/3/0/1
tunnel-te2
 Admin: up, Oper: up
 Src: 172.16.255.129, Dest: 172.16.255.2, Instance: 1
 Fast Reroute Backup Provided:
  Protected LSPs: 1
  Backup BW: CT0; limit: 20000 kbps, Inuse: 20000 kbps
  Protected i/fs: POS0/3/0/1
tunnel-te3
 Admin: up, Oper: up
 Src: 172.16.255.129, Dest: 172.16.255.130, Instance: 1
 Fast Reroute Backup Provided:
  Protected LSPs: 0
  Backup BW: any-class; limit: 25000 kbps, Inuse: 0 kbps
  Protected i/fs: POS0/3/0/1
RP/0/4/CPU0:Router#

Summary

Cisco IOS and Cisco IOS XR provide a comprehensive implementation of MPLS TE. They use tunnel interfaces as an abstraction of TE LSPs. You can perform constraint-based routing using IS-IS or OSPF. RSVP performs the signaling of TE LSPs. You can configure different aspects of the protocol (for instance, graceful restart, reliable messages, authentication) that can influence the scalability and reliability of an MPLS TE implementation. You can use multiple traffic-selection mechanisms to inject traffic into a TE LSP. CBTS enables you to use the MPLS EXP value for this purpose.

DS-TE and FRR extend the basic functionality in Cisco MPLS TE. You can implement DS-TE using the RDM or MAM models. Cisco FRR TE supports link, node, SRLG, bandwidth, and path protection.

References

Osborne, E., and A. Simha. Traffic Engineering with MPLS. Cisco Press; 2003.

Cisco Software Center http://www.cisco.com/go/software

Cisco Software Advisor http://tools.cisco.com/Support/Fusion/FusionHome.do

Cisco IOS Quality of Service Solutions Configuration Guide, Release 12.4 http://www.cisco.com/en/US/products/ps6350/products_configuration_guide_book09186a0080435d50.html

Cisco IOS Software Releases 12.2 S Feature Guides http://www.cisco.com/en/US/products/sw/iosswrel/ps1838/products_feature_guides_list.htmlCisco IOS XR Software Configuration Guides http://www.cisco.com/en/US/partner/products/ps5845/products_installation_and_configuration_guides_list.html

Copyright © 2007 Pearson Education. All rights reserved.

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