In Bidirectional Forwarding Detection (BFD), periodic packet management (PPM) on the Routing Engine (RE) selects one of the Packet Forwarding Engines (PFEs) as an anchor-PFE when delegating a BFD session that is either a Multihop or Over an Aggregated Ethernet. The anchor PFE is then responsible for maintaining and transmit/receipt of the BFD session. Since the BFD packet can arrive on any interface for these sessions (MHOP or AE), having an anchor PFE ensures that the packets are absorbed at a common point where the sessions are maintained.
Given this benefit, can the anchor PFE feature be used for an AE interface in Operation, Administration, and Maintenance (OAM) Protocols? This article demonstrates the answer with an example.
labroot@jtac-mx480-r2006-re0> show oam ethernet connectivity-fault-management interfaces Interface Link Status Level MEP Neighbors Identifier ae1.10, vlan 10 Up Active 3 101 1
The Distributed attribute is set to FALSE on ae1's member links, which indicates that PPM is running in central mode.
Distributed
FALSE
labroot@jtac-mx480-r2006-re0> show ppm adjacencies detail Protocol: CFM, Hold time: 300, IFL-index: 365 Distributed: FALSE <<< In Do-Dist thread: CFM source key: MAID: 0404test0204test Level: 3 MEP-ID: 101 ack_rdi 0 Protocol: CFM, Hold time: 300, IFL-index: 371 Distributed: FALSE <<<< In Do-Dist thread: CFM source key: MAID: 0405test10205test1 Level: 3 MEP-ID: 102 ack_rdi 0 Adjacencies: 2, Remote adjacencies: 0<<-After release Release 13.3 and above JUNOS release, Connectivity fault management (CFM) sessions operate in distributed mode and can be processed on the Flexible PIC Concentrator (FPC) on aggregated Ethernet interfaces.For example, here ae35.1201 is running CFM:labroot@jtac-MX480-r060-re0> show oam ethernet connectivity-fault-management interfaces Interface Link Status Level MEP Neighbours Identifier ae35.1201 Up Active 5 1 1 labroot@jtac-MX480-r060-re0> show interfaces ae35.1201 |match logical Logical interface ae35.1201 (Index 557) (SNMP ifIndex 2973)
labroot@jtac-MX480-r060-re0> show ppm adjacencies protocol cfm detail
Protocol: CFM, Hold time: 3250, IFL-index: 557Distributed: TRUE <<<-CFM source key: MAID: 0407megapop0209ae35-1201 Level: 5 MEP-ID: 1001 ack_rdi 0Distribution handle: 5107, Distribution address: fpc1
<snip>
labroot@jtac-MX480-r060-re0> show lacp interfaces ae35 Aggregated interface: ae35 LACP state: Role Exp Def Dist Col Syn Aggr Timeout Activity xe-1/0/0 Actor No No Yes Yes Yes Yes Fast Active xe-1/0/0 Partner No No Yes Yes Yes Yes Slow Active xe-3/0/0 Actor No No No No No Yes Fast Active xe-3/0/0 Partner No No No No No Yes Slow Active LACP protocol: Receive State Transmit State Mux State xe-1/0/0(Active) Current Slow periodic Collecting distributing xe-3/0/0(Standby) Current Slow periodic Waiting
labroot@jtac-MX480-r060-re0> show interfaces xe-3/0/0.1201 Logical interface xe-3/0/0.1201 (Index 436) (SNMP ifIndex 2909) Flags: Up SNMP-Traps 0x4000 VLAN-Tag [ 0x8100.1201 ] Encapsulation: ENET2 Input packets : 0 Output packets: 0 Protocol aenet, AE bundle: ae35.1201
labroot@jtac-MX480-r060-re0> show interfaces xe-1/0/0.1201 Logical interface xe-1/0/0.1201 (Index 358) (SNMP ifIndex 2833) Flags: Up SNMP-Traps 0x4000 VLAN-Tag [ 0x8100.1201 ] Encapsulation: ENET2 Input packets : 5242 Output packets: 4884 Protocol aenet, AE bundle: ae35.1201
For link fault management (LFM), all AE child links handle PPM packets. Therefore, there would be no “anchor PFE” in this scenario as well.
labroot@mxvc-r2028-r2029# run show oam ethernet link-fault-management ae19 Interface: ae19 Status: Running, Discovery state: Send Any Transmit interval: 1000ms, PDU threshold: 3 frames, Hold time: 0ms
Here, xe-15/1/0 (ifl 970) and xe-16/1/0 (ifl 971) are child links of ae19, and both of them are handling PPM packets. In this case, PPM runs in distributed mode.
labroot@mxvc-r2028-r2029> show ppm adjacencies detail Protocol: LFM, Hold time: 3000, IFL-index: 970 Distributed: TRUE <<< Distribution handle: 14046, Distribution address: member1-fpc3 Protocol: LFM, Hold time: 3000, IFL-index: 971 Distributed: TRUE <<< Distribution handle: 14048, Distribution address: member1-fpc4 Adjacencies: 2, Remote adjacencies: 2 labroot@mxvc-r2028-r2029# run show interfaces ifl-index 970 Logical interface xe-15/1/0.0 (Index 970) (SNMP ifIndex 2008) ... Protocol aenet, ae bundle: ae19.0 labroot@mxvc-r2028-r2029# run show interfaces ifl-index 971 Logical interface xe-16/1/0.0 (Index 971) (SNMP ifIndex 2009) ... Protocol aenet, ae bundle: ae19.0
2024-11-20 update cfm's default behavior.