Chapter 4: Cisco MPLS Traffic Engineering

Cisco Press

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This section examines node configuration commands for RSVP control authentication, graceful restart, refresh behavior, and hello messages. In Cisco IOS, all RSVP node commands start with the ip rsvp prefix, and you enter them in global configuration. In Cisco IOS XR, you specify the RSVP node configuration under the rsvp configuration mode. All commands are optional in Cisco IOS. In Cisco IOS XR, the interface command is mandatory because it enables RSVP processing on individual interfaces. In addition, Cisco IOS XR uses refresh reduction and reliable messages by default, but the behavior is tunable per interface.

RSVP interface commands are optional in Cisco IOS and Cisco IOS XR. In Cisco IOS, all RSVP interface commands have the ip rsvp prefix and reside under the physical interface. In Cisco IOS XR, all interface commands reside under the submode that the interface command enables under the rsvp configuration mode. The nature of the interface commands differs depending on the operating systems. Cisco IOS XR enables you to tune message rate limiting, refresh reduction, and reliable messages per interface. In Cisco IOS, those features are part of the node configuration. In both operating systems, the MPLS TE tunnel does not require any RSVP configuration. The headend automatically signals the TE LSP when it finds a valid path.

Example 4-23 shows an RSVP configuration in Cisco IOS. In this example, the configuration enables the processing of RSVP signaling on interfaces POS0/1/0 and POS1/0/0 with a maximum reservable bandwidth of 155,000 kbps. As part of the global configuration, this node will use the RSVP reliable messaging and refresh reduction extensions. In addition, the node will act as a helper node for neighbors performing RSVP graceful restarts.

Example 4-23 RSVP TE Configuration in Cisco IOS

interface POS0/1/0
 ip address 172.16.0.0 255.255.255.254
 mpls traffic-eng tunnels
 ip rsvp bandwidth 155000
!
interface POS1/0/0
 ip address 172.16.0.2 255.255.255.254
 mpls traffic-eng tunnels
 ip rsvp bandwidth 155000
!
ip rsvp signalling refresh reduction
ip rsvp signalling hello graceful-restart mode help-neighbor
!

Example 4-24 illustrates an RSVP configuration in Cisco IOS XR. The configuration enables RSVP on interfaces POS0/3/0/0 and POS0/3/0/1 with a bandwidth allocation of 155,000 kbps. The message retransmission timer for reliable message deliver will be 5000 ms on interface POS0/3/0/0. Finally, the configuration enables RSVP graceful restart with a refresh interval of 10,000 ms.

Example 4-24  RSVP TE Configuration in Cisco IOS XR

rsvp
 interface POS0/3/0/0
  bandwidth 155000
  signalling refresh reduction reliable retransmit-time 5000
 !
 interface POS0/3/0/1
  bandwidth 155000
 !
 signalling graceful-restart
 signalling hello graceful-restart refresh interval 10000
!

Verifying RSVP

Many show, clear, and debug commands are available for RSVP in Cisco IOS and Cisco IOS XR. These commands begin with the show ip rsvp, clear ip rsvp, and debug ip rsvp prefixes, respectively. From that group, you can use the show ip rsvp interface command in Cisco IOS and the show rsvp interface command in Cisco IOS XR to examine the RSVP status on a particular interface. In addition, the show ip rsvp counters command in Cisco IOS and the show rsvp counters command in Cisco IOS XR will show you detailed counters on RSVP activity. The next section illustrates some additional verification commands for RSVP. The Cisco IOS and Cisco IOS XR documentation completely describes all commands.

Example 4-25 shows the output of the show ip rsvp interface command in Cisco IOS. The command shows the detailed status for interface POS0/1/0 with the configuration in Example 4-23. In this case, the interface configuration enabled RSVP. The protocol has allocated 10 Mbps out of the total RSVP bandwidth of 155 Mbps. The interface is not using RSVP authentication or generating RSVP hello messages.

Example 4-25 Examine RSVP TE Interface Status in Cisco IOS

Router#show ip rsvp interface detail pos0/1/0

 PO0/1/0:
  RSVP: Enabled
  Interface State: Up
  Bandwidth:
   Curr allocated: 10M bits/sec
   Max. allowed (total): 155M bits/sec
   Max. allowed (per flow): 155M bits/sec
   Max. allowed for LSP tunnels using sub-pools (pool 1): 0 bits/sec
   Set aside by policy (total): 0 bits/sec
  Traffic Control:
   RSVP Data Packet Classification is ON
  Signalling:
   DSCP value used in RSVP msgs: 0x3F
   Number of refresh intervals to enforce blockade state: 4
  Authentication: disabled
   Key chain:  <none>
   Type:    md5
   Window size: 1
   Challenge:  disabled 
  Hello Extension:
   State: Disabled
Router#

Example 4-26 illustrates the information that the show rsvp interface command provides in Cisco IOS XR. The command provides the detailed output for the interface POS0/3/0/0 with the configuration that Example 4-24 described. In this case, RSVP has not allocated any bandwidth out of the total RSVP bandwidth of 155 Mbps. The interface is using RSVP refresh reduction (supporting both summary refresh and bundle messages). RSVP has one neighbor on this interface, with IP address 172.16.0.0, which is using refresh reduction.

Example 4-26 Examine RSVP TE Interface Status in Cisco IOS XR

RP/0/4/CPU0:Router#show rsvp interface pos0/3/0/0 detail 
INTERFACE: POS0/3/0/0 (ifh=0x4000300).
 VRF ID: 0x60000000 (Default).
 BW (bits/sec): Max=155M. MaxFlow=155M.
                Allocated=0 (0%). MaxSub=0.
 Signalling: No DSCP marking. No rate limiting.
 States in: 1. Max missed msgs: 4.
 Expiry timer: Running (every 30s). Refresh interval: 45s.
 Normal Refresh timer: Not running. Summary refresh timer: Running.
 Refresh reduction local: Enabled. Summary Refresh: Enabled (4096 bytes max).
 Reliable summary refresh: Disabled. Bundling: Enabled. (4096 bytes max).
 Ack hold: 400 ms, Ack max size: 4096 bytes. Retransmit: 5000ms.
 Neighbor information:
  Neighbor-IP      Nbor-MsgIds States-out  Refresh-Reduction Expiry(min::sec)
 -------------- -------------- ---------- ------------------ ----------------
   172.16.0.0                1          1            Enabled 14::50

RP/0/4/CPU0:Router#

Example 4-27 illustrates the output of the show ip rsvp counters command in Cisco IOS. The command shows aggregate and per-interface counters for each RSVP message type. In this case, a filter reduces the output to the aggregate counter information. You can verify the number of RSVP messages the node has sent and received. In addition, you find information about disconnect reasons for RSVP sessions.

Example 4-27  Examining RSVP Counters in Cisco IOS

Router#show ip rsvp counters | begin All
All Interfaces     Recv   Xmit                  Recv   Xmit
  Path                0      2   Resv                2     0
  PathError           0      0   ResvError           0     0
  PathTear            0      2   ResvTear            0     0
  ResvConf            0      0   RTearConf           0     0
  Ack               343      3   Srefresh          298   340
  Hello            1112   1111   IntegrityChalle     0     0
  IntegrityRespon     0     0    DSBM_WILLING        0     0
  I_AM_DSBM           0     0    Errors              0     0

Error Distribution    Recv   Xmit
  Authentication         0     0
  Other                  0     0

Recv Msg Queues         Current    Max
  RSVP                        0     1
  Hello (per-I/F)             0     0
  Awaiting Authentication     0     0

States
 Reason for Teardown                    State torn down
                                          Path  Resv-In  Resv-Out
 PathTear arrival                            0        0         0
 ResvTear arrival                            0        0         0
 Local application requested tear            2        1         0
 Output or Input I/F went down               0        0         0
 Missed refreshes                            0        0         0
 Preemption                                  0        0         0
 Backup tunnel failed for FRR Active LSP     0        0         0
 Reroutabilty changed for FRR Active LSP     0        0         0
 Hello RR Client (HST) requested tear        0        0         0
 Graceful Restart (GR) requested tear        0        0         0
 Downstream neighbor SSO-restarting          0        0         0
 Resource unavailable                        0        0         0
 Policy rejection                            0        0         0
 Policy server sync failed                   0        0         0
 Traffic control error                       0        0         0
 Error in received message                   0        0         0
 Unsupported change in Resv                  0        0         0
 Unsupported change in Resv (Label)          0        0         0
 Label programming failed                    0        0         0
 Non RSVP HOP upstream, TE LSP               0        0         0
 Other                                       0        0         0
Router#

Example 4-28 shows how to examine the different RSVP counters in Cisco IOS XR using the show rsvp counters command. The information is almost identical to the Cisco IOS output, with the exception that this command currently obviates the counters for the disconnect reasons of RSVP sessions.

Example 4-28 Examining RSVP Counters in Cisco IOS XR

RP/0/4/CPU0:Router#show rsvp counters messages | begin All
 All RSVP Interfaces   Recv  Xmit                   Recv   Xmit
  Path                    8   647   Resv             717      0
  PathError               0     0   ResvError          0      0
  PathTear                9     8   ResvTear           0      0
  ResvConfirm             0     0   Hello           1190   1595
  Ack                     9   362   SRefresh         355    314
  Retransmit              0         Rate Limited              0
  OutOfOrder              0     
  Bundle                  0     8   AckSubmsg          0      7
  PathSubmsg              0     0   ResvSubmsg         0      8
  PathTearSubmsg          0     0   ResvTearSubmsg     0      0
  PathErrorSubmsg         0     0   ResvErrorSubmsg    0      0

RP/0/4/CPU0:Router#

Verifying Signaling of TE LSPs

Example 4-29 shows the signaling status of a TE LSP using the show mpls traffic-eng tunnels command in Cisco IOS. The successful establishment of a TE LSP results in a signaling status of connected (rather than down). In that case, you will see the output interface and label information for the TE LSP, along with an RSVP section showing the most important Path and Resv details. In this example, you can see that the TE LSP is connected. It uses output interface POS0/1/0 and output label 31. The TE LSP does not show an input label, which evidences that the headend executed the command. The RSVP session has reserved 10 Mbps and signals addresses 172.16.0.1, 172.16.8.0, and 172.16.255.3 in the RSVP explicit route object (ERO).

Example 4-29 Examining TE LSP Signaling Status in Cisco IOS

Router#show mpls traffic-eng tunnels 

Name: FROM-ROUTER-TO-DST1         (Tunnel1) Destination: 172.16.255.3
 Status:
  Admin: up     Oper: up   Path: valid    Signalling: connected
  path option 10, type dynamic (Basis for Setup, path weight 2)

 Config Parameters:
  Bandwidth: 10000  kbps (Global) Priority: 5 5  Affinity: 0x0/0xFFFF
  Metric Type: TE (default)
  AutoRoute: disabled LockDown: disabled Loadshare: 10000  bw-based
  auto-bw: disabled
 Active Path Option Parameters:
  State: dynamic path option 10 is active
  BandwidthOverride: disabled LockDown: disabled Verbatim: disabled


 InLabel : - 
 OutLabel : POS0/1/0, 31
 RSVP Signalling Info:
    Src 172.16.255.1, Dst 172.16.255.3, Tun_Id 1, Tun_Instance 9277
  RSVP Path Info:
   My Address: 172.16.255.1  
   Explicit Route: 172.16.0.1 172.16.8.0 172.16.255.3 
   Record  Route:  NONE
   Tspec: ave rate=10000 kbits, burst=1000 bytes, peak rate=10000 kbits
  RSVP Resv Info:
   Record  Route:  NONE
   Fspec: ave rate=10000 kbits, burst=1000 bytes, peak rate=10000 kbits
 History:
  Tunnel:
   Time since created: 4 days, 1 hours, 20 minutes
   Time since path change: 7 seconds
   Number of LSP IDs (Tun_Instances) used: 9277
  Current LSP:
   Uptime: 7 seconds
  Prior LSP:
   ID: path option 10 [9274]
   Removal Trigger: tunnel shutdown
Router#

Example 4-30 shows the signaling status of a TE LSP using the show mpls traffic-eng tunnels command in Cisco IOS XR. The output format differs slightly when you compare it with Cisco IOS. However, you follow the same approach of verifying the signaling status as connected and then consulting the signaling component of the output.

Example 4-30 Examining TE LSP Signaling Status in Cisco IOS XR

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