- Operations, administration, maintenance
- OAM functions
- Ethernet OAM
- MPLS OAM
- VXLAN OAM
Operations, administration, maintenance
- tracks connectivity, delay, loss, throughput
- defined for Ethernet and MPLS
- entities:
- maintenance entity (ME): logical and physical links
- ME group (MEG): MEs under same administrative control
- ME point (MEP): point where OAM packets are generated and accepted
OAM functions
- continuity check
- unidirectional messages are sent
- opcode = 1
- timeout = 3.5 × period
- loopback (BFD)
- opcode = 3
- reply opcode = 2
- link trace
- alarm indication signal
- remote defect indication
- locked signal
- test signal
- automatic protection switching
- maintenance communications channel
- alarm loss management
- packet loss management
- exchange number of Rx/Tx packets
- opcode = 43
- reply opcode = 42
- delay measurement
- opcode = 47
- reply opcode = 46
- throughput measurement
Ethernet OAM
- IEEE 802.1ag, ITU-T Y.1731 (ITU ∈ IEEE ⇒ compatible)
- EtherType 0x8902
- down MEP:
- OAM is sent to link (not processed by device)
- OAM is received from link
- up MEP:
- OAM is sent towards switching plane (e.g., backplane)
- OAM is received from switching plane
- MEG integration point (MIP):
- can process OAM packets
- does not terminate or generate OAM packets
- OAM can be sent OOB or with service level, assigned to customer
- OAM destination:
- unicast
- MEG level within OAM packet
- mcast
- 0180.c200.003X
- x[0]
- 0 ≡ class 1, to all MEP in MEG
- 1 ≡ class 2, to all MEP and MIP in MEG
- x[1:3]: MEG level
Counter type | Response N | Response N+1 | Delta | Loss |
---|
Query transmit | 1000 | 1500 | 500 | 0 |
Response receive | 800 | 1300 | 500 |
Response transmit | 3400 | 3850 | 450 | 5 |
Query receive | 2100 | 2545 | 445 |
MPLS OAM
- common ping/traceroute may not detect discontiguous LSP because of falling back to IP forwarding
- OAM (RFC 6374): operation, administration and maintenance
- MPLS ping/traceroute:
- UDP 3503
- src: sender IP (IP address of outgoing interface)
- dst: from 127.0.0.0/8 to mitigate IP forwarding
- TTL = 255
- modes:
- default: return reply
- alert:
- each LSR punts packet to CPU: pops label and sends as IP with Router Alert option
- useful for detecting broken LSP
- adds label = 1
- can be used if no MPLS reply received
- no-reply
- uses G-Ach + GAL
; enables MPLS ping and traceroute
(config)# mpls oam
; 3 = draft, 4 = RFC
(config)# mpls echo version 3|4
; includes Cisco TLV into request
(config)# mpls echo vendor-extension
# ping mpls ipv4 <dst IP>/<mask> [repeat <count>] [reply mode <mode>]
# ping mpls pseudowire <PE_IP> <VCID>
# traceroute mpls ipv4 <dst IP> <mask>
VXLAN OAM
- shows path for specific UDP source port ⇒ excludes entropy in outer header for troubleshooting
- can use NVO3 Tissa channel to get extra information: load, egress intf, …
# ping nve ip unknown [vrf <VRF>] payload ip <SRC> <DST> port <SRC> <DST> proto <N> payload-end vni <M>
; ICMP
# traceroute nve ip unknown [vrf <VRF>] payload ip <SRC> <DST> port <SRC> <DST> proto <N> payload-end vni <M>
; NVO3
# pathtrace nve ip unknown [vrf <VRF>] payload ip <SRC> <DST> port <SRC> <DST> proto <N> payload-end vni <M>