Select all that apply.

• A

  The total length of an MPLS label is 4 bytes (32 bits).

• B

  The TTL field in an MPLS label has the same meaning as that in an IP packet, and can prevent loops.

• C

  The S field in an MPLS label has 1 bit and is used to identify whether the label is the bottom-ofstack label. If the value is 1, the label is a penultimate-layer label.

• D

  For Ethernet and PPP packets, a label stack is located between the Layer 2 packet header and data; If
  a VLAN tag is available, the label stack is placed before the VLAN tag.