Troubleshooting de Cabeçalho L2 Incorreto para Tráfego MPLS de Trânsito
Introduction
Este documento descreve como solucionar problemas quando o caminho de encaminhamento MPLS é interrompido devido à corrupção do cabeçalho L2 no nó NCS4K (6.5.26).
Problema
Neste cenário, o túnel TE (Engenharia de tráfego) está ativo, mas o ping MPLS (Multiprotocol Label Switching) não funciona através do túnel 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)Você vê alguns saltos no 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 *^CQuando você verifica o túnel MPLS, vê mais dois saltos sendo sinalizados para o Roteador Explícito (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: 10.38.96.1Ao ir para o primeiro salto ao longo do caminho, você verá a entrada correta da LFIB (Label Forwarding Information Base) de MPLS para este túnel:
#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 (!)
A interface de saída nesse nó usa esse endereço MAC, de modo que ele pode ser usado como um MAC de origem (SRC) no cabeçalho L2 para os quadros 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 packetsMas no lado vizinho em show capture packets ingress location <ative LC VM>, você verá o rótulo de MPLS correto, mas os endereços MAC de destino (DST) e SRC de L2 totalmente errados:
[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] O endereço DST Mac é all-0 e o endereço SRC MAC corresponde à interface de gerenciamento no nó 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 transitionsSolução
A causa raiz é este DDTS - ID de bug Cisco CSCvz99253 
ID de bug Cisco CSCwa11748 duplicata do bug da Cisco ID CSCvz99253 que é corrigido na versão 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
++++++++Como um método de recuperação, você pode reconfigurar a subinterface de saída afetada.
Histórico de revisões
| Revisão | Data de publicação | Comentários |
|---|---|---|
1.0 |
09-Feb-2023 |
Versão inicial |
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