R2511-HP MSR Router Series MPLS Configuration Guide(V5)

To configure the device to send back an ICMP TTL exceeded message for a received MPLS TTL expired

packet:

Ste

Command

Remarks

1. Enter system view.

system-view N/A

2. Enter MPLS view.

mpls N/A

3. Enable the device to send

back an ICMP TTL exceeded

message when it receives an

MPLS TTL expired packet.

ttl expiration enable

Optional.

Enabled by default.

4. Configure the device to use IP

routes to send back the ICMP

TTL exceeded messages for

TTL-expired MPLS packets that

have only one level of label.

ttl expiration pop

Optional.

By default, an ICMP TTL exceeded

message is sent back along an IP

route when the TTL of an MPLS

packet with a one-level label stack

expires.

This configuration does not take

effect when the MPLS packets carry

multiple levels of labels. ICMP TTL

exceeded messages for such MPLS

packets always travel along the

LSPs.

Configuring LDP GR

MPLS has two separate planes: the forwarding plane and the control plane. Using this feature, LDP

Graceful Restart (GR) preserves the LFIB information when the signaling protocol or control plane fails, so

that LSRs can still forward packets according to LFIB, ensuring continuous data transmission.

A device that participates in a GR process can be a GR restarter or a GR helper.

• GR restarter—Router that gracefully restarts due to a manually configured command or a fault. It

must be GR-capable.

• GR helper—Neighbor of the GR restarter. A GR helper maintains the neighbor relationship with the

GR restarter and helps the GR restarter restore its LFIB information. A GR helper must be

GR-capable.