Dépanner un en-tête L2 incorrect pour le trafic MPLS de transit
Introduction
Ce document décrit comment dépanner lorsque le chemin de transfert MPLS est rompu en raison de la corruption de l'en-tête L2 sur le noeud NCS4K (6.5.26).
Problème
Dans ce scénario, le tunnel d'ingénierie de trafic (TE) est activé, mais la requête ping MPLS (Multiprotocol Label Switching) ne fonctionne pas via le tunnel MPLS :
tunnel-te5180 10.38.101.62 Up Up default
#ping mpls traffic-eng tunnel-te 5180
Thu Jan 5 21:30:29.245 UTC
Sending 5, 100-byte MPLS Echos to tunnel-te5180,
timeout is 2 seconds, send interval is 0 msec:
Codes: '!' - success, 'Q' - request not sent, '.' - timeout,
'L' - labeled output interface, 'B' - unlabeled output interface,
'D' - DS Map mismatch, 'F' - no FEC mapping, 'f' - FEC mismatch,
'M' - malformed request, 'm' - unsupported tlvs, 'N' - no rx label,
'P' - no rx intf label prot, 'p' - premature termination of LSP,
'R' - transit router, 'I' - unknown upstream index,
'X' - unknown return code, 'x' - return code 0
Type escape sequence to abort.
.....
Success rate is 0 percent (0/5)Vous voyez quelques sauts dans la commande traceroute MPLS :
#traceroute mpls traffic-eng tunnel-te 5180
Thu Jan 5 21:30:49.405 UTC
Tracing MPLS TE Label Switched Path on tunnel-te5180, timeout is 2 seconds
Codes: '!' - success, 'Q' - request not sent, '.' - timeout,
'L' - labeled output interface, 'B' - unlabeled output interface,
'D' - DS Map mismatch, 'F' - no FEC mapping, 'f' - FEC mismatch,
'M' - malformed request, 'm' - unsupported tlvs, 'N' - no rx label,
'P' - no rx intf label prot, 'p' - premature termination of LSP,
'R' - transit router, 'I' - unknown upstream index,
'X' - unknown return code, 'x' - return code 0
Type escape sequence to abort.
0 172.16.61.78 MRU 9582 [Labels: 27769 Exp: 0]
L 1 172.16.61.79 MRU 9582 [Labels: 28136 Exp: 0] 7 ms
. 2 *
. 3 *
. 4 *
. 5 *^CLorsque vous cochez le tunnel MPLS, deux sauts supplémentaires sont signalés pour le routeur explicite (ERO) :
#show mpls traffic-eng tunnels 5180
Thu Jan 5 21:31:11.958 UTC
Name: tunnel-te5180 Destination: 10.38.96.1 Ifhandle:0x80002c4
Signalled-Name: MIVLPAMI-0112003A_t5180
Status:
Admin: up Oper: up Path: valid Signalling: connected
path option 10, type dynamic (Basis for Setup, path weight 3000)
Accumulative metrics: TE 3000 IGP 30 Delay 900000
Path-option attribute: eline-any
Number of affinity constraints: 1
Include bit map : 0x2
Include ext bit map :
Length: 256 bits
Value : 0x::2
Include affinity name : eline(1)
G-PID: 0x0800 (derived from egress interface properties)
Bandwidth Requested: 7 kbps CT0
Creation Time: Thu Nov 10 22:17:55 2022 (7w6d ago)
Config Parameters:
Bandwidth: 0 kbps (CT0) Priority: 5 5 Affinity: 0x0/0xffff
Metric Type: TE (interface)
Path Selection:
Tiebreaker: Min-fill (default)
Hop-limit: disabled
Cost-limit: disabled
Delay-limit: disabled
Path-invalidation timeout: 10000 msec (default), Action: Tear (default)
AutoRoute: enabled LockDown: disabled Policy class: not set
Forward class: 0 (not enabled)
Forwarding-Adjacency: disabled
Autoroute Destinations: 0
Loadshare: 0 equal loadshares
Auto-bw: enabled
Last BW Applied: 7 kbps CT0 BW Applications: 29
Last Application Trigger: Periodic Application
Bandwidth Min/Max: 0-4294967295 kbps
Application Frequency: 60 min Jitter: 0s Time Left: 46m 48s
Collection Frequency: 5 min
Samples Collected: 2 Next: 1m 3s
Highest BW: 0 kbps Underflow BW: 0 kbps
Adjustment Threshold: 10% 10 kbps
Overflow Detection disabled
Underflow Detection disabled
Resignal Last-bandwidth Disabled
Auto-Capacity: Disabled:
Fast Reroute: Enabled, Protection Desired: Any
Path Protection: Not Enabled
BFD Fast Detection: Disabled
Reoptimization after affinity failure: Enabled
Soft Preemption: Disabled
History:
Tunnel has been up for: 7w6d (since Thu Nov 10 22:17:55 UTC 2022)
Current LSP:
Uptime: 15:09:12 (since Thu Jan 05 06:22:00 UTC 2023)
Reopt. LSP:
Last Failure:
LSP not signalled, identical to the [CURRENT] LSP
Date/Time: Thu Jan 05 19:03:33 UTC 2023 [02:27:39 ago]
Prior LSP:
ID: 32 Path Option: 10
Removal Trigger: reoptimization completed
Path info (IS-IS 1 level-2):
Node hop count: 3
Hop0: 172.16.61.79
Hop1: 172.16.57.244
Hop2: 172.16.6.59
Hop3: 10.38.96.1Lorsque vous accédez au premier saut le long du chemin, vous voyez l'entrée correcte LFIB (Label Forwarding Information Base) MPLS pour ce tunnel :
#show mpls forwarding labels 27769
Fri Jan 6 06:13:04.220 UTC
Local Outgoing Prefix Outgoing Next Hop Bytes
Label Label or ID Interface Switched
------ ----------- ------------------ ------------ --------------- ------------
27769 28136 TE: 5180 Hu0/10/0/11/2.4001 172.16.57.244 0
28136 TE: 5180 tt60409 point2point 0 (!)
L'interface de sortie sur ce noeud utilise cette adresse MAC, de sorte que celle-ci peut être utilisée comme adresse MAC source (SRC) dans l'en-tête L2 pour les trames L2 :
#show interfaces hundredGigE 0/10/0/11/2.4001
Fri Jan 6 06:14:45.773 UTC
HundredGigE0/10/0/11/2.4001 is up, line protocol is up
Interface state transitions: 79
Hardware is VLAN sub-interface(s), address is 0c11.67c8.2041
Description: To HundredGigE1/3/0/10/2.PHLAPALO-12121302A:CID:I1001/GE100/PHLAPALO/SLTNPAST
Internet address is 172.16.57.245
MTU 9600 bytes, BW 100000000 Kbit (Max: 100000000 Kbit)
reliability 255/255, txload 0/255, rxload 0/255
Encapsulation 802.1Q Virtual LAN, VLAN Id 4001, loopback not set,
Last link flapped 1w6d
ARP type ARPA, ARP timeout 04:00:00
Last input 00:00:00, output 00:00:00
Last clearing of "show interface" counters never
5 minute input rate 64000 bits/sec, 62 packets/sec
5 minute output rate 2198000 bits/sec, 699 packets/sec
4529877895 packets input, 2267795435148 bytes, 6 total input drops
0 drops for unrecognized upper-level protocol
Received 124 broadcast packets, 0 multicast packets
3926978895 packets output, 1611587340639 bytes, 0 total output drops
Output 0 broadcast packets, 0 multicast packetsMais du côté voisin dans show capture packets ingress location <active LC VM>, vous voyez l'étiquette MPLS correcte, mais totalement incorrecte L2 SRC et les adresses MAC de destination (DST) :
[200] Jan 6 06:10:12.449, len: 103, hits: 1, buffhdr type: 1
i/p i/f: HundredGigE1/3/0/10/2
punt reason: DROP_PACKET
Ingress Headers:
port_ifh: 0x8001ae4, sub_ifh: 0x0, bundle_ifh: 0x0
logical_port: 0x6c1, pd_pkt_type: 3
punt_reason: DROP_PACKET (0)
payload_offset: 21, l3_offset: 21
FTMH:
pkt_size: 0x7e, tc: 0, tm_act_type: 0, ssp: 0x981
PPH:
pph_fwd_code: CPU Trap (7), fwd_hdr_offset: 0
inlif: 0x0, vrf: 0x0, rif: 0x0
FHEI:
trap_code: Rx_UNKNOWN_PACKET (63), trap_qual: 193
[ether dst: 0000.0000.0000 src: 0c11.67c8.2000 type/len: 0x8847]
[MPLS label: 28136, exp 0x6, eos 0, ttl 255] L'adresse MAC DST est uniquement 0 et l'adresse MAC SRC correspond à l'interface de gestion sur le noeud NCS4K :
#show interfaces mgmtEth 0/rp1/emS/0
Fri Jan 6 06:15:59.141 UTC
MgmtEth0/RP1/EMS/0 is down, line protocol is down
Interface state transitions: 0
Hardware is Management Ethernet, address is 0c11.67c8.2000 (bia 0c11.67c8.2000)
Internet address is 10.230.192.86
MTU 1514 bytes, BW 100000 Kbit (Max: 100000 Kbit)
reliability 255/255, txload 0/255, rxload 0/255
Encapsulation ARPA,
Full-duplex, 100Mb/s, unknown, link type is autonegotiation
loopback not set,
ARP type ARPA, ARP timeout 04:00:00
Last input never, output never
Last clearing of "show interface" counters never
5 minute input rate 0 bits/sec, 0 packets/sec
5 minute output rate 0 bits/sec, 0 packets/sec
0 packets input, 0 bytes, 0 total input drops
0 drops for unrecognized upper-level protocol
Received 0 broadcast packets, 0 multicast packets
0 runts, 0 giants, 0 throttles, 0 parity
0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored, 0 abort
0 packets output, 0 bytes, 0 total output drops
Output 0 broadcast packets, 0 multicast packets
0 output errors, 0 underruns, 0 applique, 0 resets
0 output buffer failures, 0 output buffers swapped out
0 carrier transitionsSolution
La cause principale est cette DDTS - ID de bogue Cisco CSCvz99253 
ID de bogue Cisco CSCwa11748 doublon de l'ID de bogue Cisco CSCvz99253 qui est corrigé dans la version 6.5.32 :
++++++++
Dec 23 23:24:58.214 ofa_ipnhgroup_event 0/LC1 3235382# t4839 TP3147224,dnxsdk_l3_fec_create,enter,trans_id,357633649,npu_id,0,is_modify,1,use_eei_encoding,0,dest,0x6052,encap_id,0x4000304a,fec_id,0x2001fe98,
Dec 23 15:10:16.787 ofa_ipnh_event 0/LC1 210586# t5614 TP2061,client_ipnh_create,grid_res_id_alloc_req_success,trans_id,357386085,encap_id,0x304a,alloc_sz,2
Dec 23 15:10:16.787 ofa_ipnh_event 0/LC1 286920# t4857 TP9909,dispatch_ipnh,resolve_refhdl_success,ref_l3intf_trans_id,357386081,hdl,0x87a75238
Dec 23 15:10:16.787 ofa_ipnh_event 0/LC1 172418# t4857 TP9913,dummy_block,trans_id,357386085,wait,duration,time,0.1742
Dec 23 15:10:16.787 ofa_ipnh_event 0/LC1 153352# t4857 TP3149344,srv_ipnh_create,entry,trans_id,357386085,npu_mask,0x100000,l3a_mac_addr,00af.1f18.0043,l3a_intf_id,28,port_id,0
Dec 23 15:10:16.780 ofa_ipnh_event 0/LC1 258284# t5614 TP2061,client_ipnh_create,grid_res_id_alloc_req_success,trans_id,357386077,encap_id,0x3048,alloc_sz,2
Dec 23 15:10:16.780 ofa_ipnh_event 0/LC1 105614# t4857 TP9909,dispatch_ipnh,resolve_refhdl_success,ref_l3intf_trans_id,357383451,hdl,0x87a75238
Dec 23 15:10:16.780 ofa_ipnh_event 0/LC1 172408# t4857 TP9913,dummy_block,trans_id,357386077,wait,duration,time,0.1947
Dec 23 15:10:16.780 ofa_ipnh_event 0/LC1 286912# t4857 TP3149344,srv_ipnh_create,entry,trans_id,357386077,npu_mask,0x100000,l3a_mac_addr,00af.1f18.0043,l3a_intf_id,28,port_id,0
++++++++En tant que méthode de récupération, vous pouvez reconfigurer la sous-interface de sortie affectée.
Historique de révision
| Révision | Date de publication | Commentaires |
|---|---|---|
1.0 |
09-Feb-2023 |
Première publication |
Commentaires