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 TLVs and Sub-TLVs Supported for Point-to-Multipoint LSPs Connectivity Verification
at Egress Nodes on page 248
•
• Point-to-Multipoint LSPs Connectivity Verification at Egress Nodes Overview on page 246
• Verifying and Troubleshooting MPLS Connectivity on page 370
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 tracempls 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 packet, the
responding egress node delays sending a response for a random amount of time between
zero milliseconds and 30 seconds that is predefined for this TLV. If the TLV is not
contained in the echo request packet, the responding egress node does not create any
additional delay in responding to the echo request. The Echo Jitter TLV is valid only in an
Copyright © 2010, Juniper Networks, Inc.248
JunosE 11.2.x BGP and MPLS Configuration Guide
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