L2 transparency – Multicast

This test verifies transparency for Layer 2 multicast protocols, i.e. checks that the multicast packet are not dropped in the network. The tested protocols are: Spanning Test Protocol, a set of general multicast/broadcast protocols, and MPLS multicast.

Test procedure

Five Ethernet frames with dummy payload are sent on each protocol.

  • If the expected outcome for a protocol is set to Pass, the test fails for that protocol if less than four frames are received with the specified Ethertype and destination MAC.
  • If the expected outcome for a protocol is set to Drop, the test fails for that protocol if at least one frame is received with the specified Ethertype and destination MAC.

Exception: For MPLS multicast, the receiver does not check the destination MAC address; it filters only for the source MAC address and Ethertype.

Protocols tested

Protocol

Destination MAC

Ethertype

STP

01:80:c2:00:00:00

LLC/SNAP 

ARP

ff:ff:ff:ff:ff:ff

0×0806

RARP

ff:ff:ff:ff:ff:ff

0×8035

LLDP

01:80:c2:00:00:0e

0×88cc

Ethernet Configuration Test Protocol

cf:00:00:00:00:00

0×9000

IP local broadcast

ff:ff:ff:ff:ff:ff

0×0800

IP global broadcast

ff:ff:ff:ff:ff:ff

0×0800

MPLS multicast addresses

01:00:5e:80:00:01

0×8848 (see note)
MPLS multicast addresses

01:00:5e:8d:dd:dd

0×8848
MPLS multicast addresses

01:00:5e:8f:ff:01

0×8848

 

Note: Ethertype 0×8848, formerly known as the "MPLS multicast codepoint", is to be used only when an MPLS packet whose top label is upstream-assigned is carried in a multicast Ethernet frame.

Note: Ethernet frames with a value of 1 in the least-significant bit of the first octet of the destination address are treated as multicast frames and are typically flooded to all points on the network. While frames with ones in all bits of the destination address (ff:ff:ff:ff:ff:ff) are sometimes referred to as broadcasts, Ethernet network equipment generally does not distinguish between multicast and broadcast frames.

Limitations

This test can only run on physical or VLAN interfaces (not bridges).

Parameters

General

  • Sender: The sender interface.
  • Receiver: The receiver interface.
  • Wait for ready: Time to wait before starting the test. The purpose of inserting a wait is to allow all Test Agents time to come online and acquire good time sync. Min: 1 min. Max: 24 hours. Default: "Don't wait", i.e. zero wait time.

Advanced

  • Expected outcome for <protocol>: For each protocol, select Pass, Drop, or Don't test. The default is Pass.

Result metrics

  • Pass/fail on Spanning tree, General multicast/broadcast protocols, and MPLS multicast
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