Exam JN0-362 topic 1 question 17 discussion

On the ingress of the LSP, if you include the no-decrement-ttl statement, the ingress router negotiates with all downstream routers using a proprietary RSVP object, to ensure all routers are in agreement. If negotiation succeeds, the whole LSP behaves as one hop to transit IP traffic.

Correct answer is A On the ingress of the LSP, if you include the no-decrement-ttl statement, the ingress router negotiates with all downstream routers using a proprietary RSVP object, to ensure all routers are in agreement. If negotiation succeeds, the whole LSP behaves as one hop to transit IP traffic. no-decrement-ttl;

it is ingress LSR, so A or C "the default TTL handling behavior on your Junos device", so, A

It should be A - no-decrement-ttl - ingress LSR use special Label Request object to signal al the routers in LSP (configured only on ingress LSR) - no-propagat-ttl - each router in the path has to be configured with no-propagate-ttl

After reading all comments here, the answer should be A

A is the correct answer. 'no-decrement-ttl': It is Juniper proprietary. Third party devices may not recognize this feature. It is used at the ingress LSR only. It can be globally configured at MPLS protocol definition or per LSP. 'no-propagate-ttl': It is not Juniper proprietary. It exists as an alternative for third party compatibility. It must be used on all LSR in the LSP. It can only be configured at global MPLS configuration. Due above characteristics: Options B and D are immediately discarded. Either 'no-decrement-ttl' or 'no-propagate-ttl' can be configured at the ingress LSR but not at egress LSR ('no-propagate-ttl' can but must be configured on all the path, ingress LSR included). Option C is discarded since 'no-propagate-ttl' cannot be configured per LSP. Is is globally configured at the MPLS protocol.

Answer is C On the ingress router, you can include the no-propagate-ttl statement. The no-propagate-ttl statement applies to all LSPs, regardless of whether they are RSVP-signaled or LDP-signaled. Once set, all future LSPs traversing through this router behave as a single hop to IP packets. LSPs established before you configure this statement are not affected.

"The operation of the no-propagate-ttl statement is interoperable with other vendors’ equipment. However, you must ensure that all routers are configured identically." "no-propagate-ttl" have to be configured on all routers along LSP, not only the ingress. A is correct.

Answer is A. "no-decrement-ttl" on the ingress router and "no-propagate-ttl" on all MPLS routers

The answer should be A as "Configure the no-decrement-ttl parameter for each LSP on the ingress device" The configuration of the "no-propagate-ttl" have to be set on the ingress router including all LSPs. https://www.juniper.net/documentation/en_US/junos/topics/usage-guidelines/mpls-disabling-normal-ttl-decrementing.html

Answer should be A. "no-propagate-ttl" parameter needs to be defined on every LSR to have effect, so option B cannot be answer.