Traces the path an LSP takes for the specified FEC.
| lsp_name | Specifies the LSP on which to send the MPLS (Multiprotocol Label Switching) echo request. |
| any | Allows the echo request to be sent over any available LSP. |
| host | Specifies the FEC using an ipaddress or hostname. |
| prefix | Specifies a prefix. |
| ipNetmask | Specifies the prefix address. |
| reply-mode | Specifies the reply mode for the MPLS echo response. |
| ip | Requests an IP UDP reply packet. This is the default mode. |
| ip-router-alert | Requests an IP UDP reply packet with the IP Router Alert option. |
| from | Specifies the IP address to be used as the source address in the MPLS echo request. |
| ttl | Specifies the starting TTL hop value. The range is from 1 - 30. The default is 1. |
| hopaddress | Specifies the next-hop address. |
The maximum time-to-live value is 30 seconds.
The FEC can be specified using the ipaddress or hostname via the host parameter. If the optional next-hop is specified, the MPLS echo request is sent along the LSP that traverses the specified node. This option is useful for tracing a specific LSP when multiple LSPs exist to the specified FEC. The lsp keyword may be used to specify a named LSP to trace. The selected LSP is specified by the lsp_name parameter. The any keyword indicates that the switch can trace any available LSP to the specified host.
The optional reply-mode keyword is used to specify the reply mode for the MPLS echo response. When the ip option is specified, the MPLS echo reply is routed back to the sender in a normal IPv4 packet. When the ip-router-alert option is specified, the MPLS echo reply is routed back to the sender in an IPv4 packet with the Router Alert IP option set. Additionally, if the ip-router-alert option is specified and the reply route is via an LSP, the Router Alert Label is pushed onto the top of the label stack. If the reply-mode is not specified, the reply-mode ip option applies.
The optional ttl keyword specifies the starting TTL value in the MPLS echo request packet. Within each router along the path, the TTL value is decremented. When the TTL value reaches zero, the LSR drops the packet and replies with a TTL-expired ICMP (Internet Control Message Protocol) message. The originating LSR responds by displaying the hop for which the TTL expired. To discover all hops to a destination, the originating router repeats the MPLS echo request and increments the TTL start value by one each time until the destination is reached. The maximum TTL is 30, so the traceroute command terminates if the destination is not reached in 30 hops.
If the ttl keyword is omitted, the starting TTL value is 1. If you specify a larger starting TTL value, initial hops are excluded from the traceroute display. For example, if you specify a start TTL value of 5, the TTL value does not decrement to 0 at the first four routers, so the fifth hop router is the first to appear in the traceroute command display.
The from keyword is used to specify the source IP address used in the MPLS echo request. This is the IP address used by the target LSR to send the MPLS echo reply. If not specified, the OSPF (Open Shortest Path First) router ID is used.
The following example shows a sample display for the traceroute command:
# traceroute mpls lsp prefix 11.100.100.10/32 traceroute to 11.100.100.10, 30 hops max 1 11.100.100.8 5 ms 5 ms 2 ms 2 11.100.100.10 2 ms 1 ms 2 ms # traceroute mpls lsp lsp598 traceroute to lsp598, 30 hops max 1 11.100.100.5 6 ms 1 ms 5 ms 2 11.100.100.9 3 ms 2 ms 2 ms 3 11.100.100.8 3 ms 4 ms 3 ms
This command was first available in ExtremeXOS 11.6.
This command is available only on the platforms that support MPLS as described in the ExtremeXOS 22.4 Feature License Requirements document.
Print
this page
Email this topic
Feedback
View PDF
Download EPUB