What is the effect of the use of the hop-count TLV in cell mode MPLS to the traceroute command?
A.
Traceroute still accurately indicates the number of hops in the MPLS path.
B.
Traceroute will indicate the ingress router to an MPLS domain once for each hop through the
MPLS path and not the core MPLS LSR’s.
C.
Traceroute will accurately indicate each router in the MPLS path.
D.
Traceroute will not indicate any of the MPLS domain routers including the ingress and egress
routers.
Explanation:
Mode MPLS. Page 91 of the reference states “…Although the previous description provides all the
necessary functionality for traceroute to work in a Farme-mode MPLS environment, you also need
to consider the effects of traceroute across an MPLS network that is constructed with ATM-LSRs
in the topology. Chapter 1, “Multiprotocol Lable Switching (MPLS) Architecture Overview,” defines
an ATM-SLR as an LSR with a number
of LC-ATM interfaces that forward cells between these interfaces using labels carried in the
VPI/VCI field. The consequence of this is that TTL is not available in the header of an ATM cell
and, therefore CANNOT BE MANIPULATED AT EACH HOP in the network.
For this reason, when ATM-SLRs are within the path, the ATM portion of the network is TREATED
AS ONE IP HOP.” Reference: MPLS and VPN Architectures (CCIP edition)