The ICMP tunneling feature operates in the same way as in a SR-TE LSP. When the label TTL of a traceroute packet of a core IPv4 or IPv6 route or a vpn-ipv4 or vpn-ipv6 route expires at an LSR, the latter generates an ICMP reply packet of type=11- (time exceeded) and injects it in the forward direction of the SR policy. When the packet is received by the egress LER or a BGP border router, SR OS performs a regular user packet route lookup in the data path in the GRT context or in a VPRN context and forwards the packet to the destination. The destination of the packet is the sender of the original packet which TTL expired at the LSR.