of the response by a time interval that is limited by the value specified in the Echo
Jitter TLV.
The point-to-multipoint MPLS LSP ping functionality in JUNOSe Software supports a
delay of up to 30 seconds. If the value specified in the Echo Jitter TLV is not within
the supported range, the egress node uses a value within the range as the time to
wait to send the echo response.
IETF draft, Detecting Data Plane Failures in Point-to-Multipoint Multiprotocol Label
Switching (MPLS) - Extensions to LSP Ping, uses a particular type value for the Echo
Jitter TLV. The point-to-multipoint MPLS LSP ping functionality in JUNOSe Software
interprets the suggested type value in the draft to denote the new TLV (Echo Jitter).
Traceroute Overview
The point-to-multipoint LSP ping feature enables the egress node to respond to the
traceroute requests that the ingress node initiates in the same manner as the egress
node responds to a ping request. No additional or separate configuration is needed
to enable the path to the egress nodes to be traced by ingress nodes in
point-to-multipoint LSPs.
Related Topics Point-to-Multipoint LSPs Connectivity Verification at Egress Nodes Overview on
page 237
■
■ TLVs and Sub-TLVs Supported for Point-to-Multipoint LSPs Connectivity
Verification at Egress Nodes on page 239
■ Verifying and Troubleshooting MPLS Connectivity on page 367
TLVs and Sub-TLVs Supported for Point-to-Multipoint LSPs Connectivity Verification
at Egress Nodes
To enable detection of data plane failures using the ping mpls and trace mpls
commands at egress nodes of point-to-multipoint LSPs, JUNOSe Software supports
two new TLVs, Echo Jitter and P2MP Responder Identifier. Also, a sub-TLV, RSVP
P2MP IPv4 Session, is supported in the Target FEC Stack TLV to verify MPLS
connectivity to egress nodes of point-to-multipoint LSPs.
Echo Jitter TLV Operations
The initiator (ingress) of a ping request might require the responding egress to
introduce a random delay (or jitter) before forwarding the response. The delay period
enables the responses from multiple egresses to be spread over a time period. This
mechanism is very useful in situations when the entire LSP tree is being pinged
because it helps the ingress (and nearby routers) node from being flooded with a
number of responses, or from discarding responses if any rate limits are applied on
the incoming traffic.
In JUNOSe Software, the delay is set to a maximum of 30 seconds. The ingress node
informs the egresses of this time interval limitation by supplying a value in the Echo
Jitter TLV in the echo request message. If this TLV is present in the echo request
TLVs and Sub-TLVs Supported for Point-to-Multipoint LSPs Connectivity Verification at Egress Nodes ■ 239
Chapter 2: MPLS Overview
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