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Implementing IP Service Level Agreements
The MPLS echo request packet is sent to a target router through the use of the appropriate label stack associated
with the LSP to be validated. Use of the label stack causes the packet to be forwarded over the LSP itself.
The destination IP address of the MPLS echo request packet is different from the address used to select the
label stack. The destination IP address is defined as a 127.x.y.z/8 address. The 127.x.y.z/8 address prevents
the IP packet from being IP switched to its destination if the LSP is broken.
An MPLS echo reply is sent in response to an MPLS echo request. The reply is sent as an IP packet and it is
forwarded using IP, MPLS, or a combination of both types of switching. The source address of the MPLS
echo reply packet is an address obtained from the router generating the echo reply. The destination address
is the source address of the router that originated the MPLS echo request packet. The MPLS echo reply
destination port is set to the echo request source port.
The MPLS LSP ping operation verifies LSP connectivity by using one of the supported Forwarding Equivalence
Class (FEC) entities between the ping origin and egress node of each FEC. The following FEC types are
supported for an MPLS LSP ping operation:
• LDP IPv4 prefixes (configured with the target ipv4 command)
• MPLS TE tunnels (configured with the target traffic-eng tunnel command)
• Pseudowire (configured with the target pseudowire command)
SUMMARY STEPS
1. configure
2. ipsla operation operation-number
3. type mpls lsp ping
4. output interface type interface-path-id
5. target {ipv4 destination-address destination-mask | traffic-eng tunnel tunnel-interface | pseudowire
destination-address circuit-id}
6. lsp selector ipv4 ip-address
7. force explicit-null
8. reply dscp dscp-bits
9. reply mode {control-channel | router-alert}
10. exp exp-bits
11. ttl time-to-live
12. exit
13. ipsla schedule operation operation-number
14. start-time [hh:mm:ss {day | month day} | now | pending | after hh:mm:ss]
15. commit
16. show ipsla statistics [operation-number]
DETAILED STEPS
Command or Action
Step 1
configure
Cisco ASR 9000 Series Aggregation Services Router System Monitoring Configuration Guide, Release 4.2.x
Configuring IP SLA MPLS LSP Ping and Trace Operations
Purpose
247
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