What action is performed for untagged outgoing labels in an MPLS router?
What action is performed for untagged outgoing labels in an MPLS router?
When an MPLS router receives an incoming MPLS packet and the outgoing label is untagged, the router converts the incoming MPLS packet to an untagged packet and then performs a lookup in the Forwarding Information Base (FIB). This lookup determines the next hop and egress interface for the packet. The process involves stripping the MPLS labels and treating the packet as a standard untagged packet before forwarding it.
When an MPLS router receives a packet with an incoming MPLS label and no outgoing label (i.e., an untagged outgoing label), it needs to perform a lookup in the Forwarding Information Base (FIB) to determine the egress interface and next-hop for the packet. The incoming MPLS label is stripped off, and the packet is treated as an untagged packet before performing the FIB lookup. Therefore, option B accurately describes the action performed for untagged outgoing labels in an MPLS router.
It's B
"The non-working state is when R5's LFIB entry for label 16 instructs it to perform a Untagged/No Label operation. Untagged/No Label literally means to strip all of the MPLS labels off the packet and forward the raw IP packet (in this case it's IP). R4 receives a regular IP packet and does a lookup in the FIB." https://www.packetmischief.ca/2015/05/27/mpls-no-label-vs-pop-label/ The first router performs a lookup in LFIB, converts the MPLS packet to IP packet and forwards it to the next hop. Only the next hop performs the FIB lookup.
agree with C, if outbound need to be send untagged, the MPLS part is stripped off
Key words in this questions are "untagged outgoing labels". So yeah its C
its going to be forwarder to the next router
It's about to get forwarded. C is correct.