Which of the following are possible criteria for classifying packets at the SAP-ingress? (Choose three)

Question

Options

• AThe EXP bits in the MPLS header.
• BThe packet's source and destination IP addresses.
• CThe service ID of the service to which the SAP belongs.
• DThe dot1p bits in the frame header.
• EThe packet's Ethertype.

• A
  12% (8)
• B
  82% (56)
• C
  6% (4)

Explanation

At the SAP-ingress in Nokia SR OS, classification policies inspect packet fields to assign forwarding class and profile. Source/destination IP addresses (B) are matched using IP criteria entries, dot1p bits (D) - the 3-bit IEEE 802.1p priority field in a VLAN-tagged Ethernet frame - are a common L2 classification tool, and Ethertype (E) identifies the payload protocol (e.g., 0x0800 for IPv4), all of which are valid match fields in a SAP-ingress QoS policy.

Why the distractors are wrong:

• A (MPLS EXP/TC bits): These bits live in the MPLS label stack, which is a network-side construct. SAP-ingress deals with customer-facing (access-side) traffic that arrives before MPLS encapsulation, so EXP bits are not applicable here - they belong in network QoS policies.
• C (Service ID): The service ID is a configuration attribute that identifies which service a SAP belongs to; it is not a field present in the packet itself and cannot be used as a match criterion within an ingress classification policy.

Memory tip: Think "SAP = access side = customer packet fields." At SAP-ingress you're inspecting what the customer sent you - Layer 2 fields (dot1p, Ethertype) and Layer 3 fields (IP addresses, DSCP). MPLS labels are added after classification, so EXP bits don't exist yet; service IDs are router bookkeeping, not packet content.

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