Este documento discute sobre a solução de problemas de perda de pacotes em um túnel Dot1Q/L2P devido a um projeto de rede ruim no Cisco IOS® com um estudo de caso.
A Cisco recomenda que você tenha conhecimento destes tópicos:
Conhecimento básico sobre tunelamento Dot1Q
Conhecimento básico do OSPF
Este documento não é restrito a versões de software ou hardware específicas.
The information in this document was created from the devices in a specific lab environment. All of the devices used in this document started with a cleared (default) configuration. If your network is live, make sure that you understand the potential impact of any command.
Consulte as Convenções de Dicas Técnicas da Cisco para obter mais informações sobre convenções de documentos.
Nessa configuração de rede, a interface Gi1/44 e Gi 1/43 do roteador 7600-Core possuem um roteador em uma configuração de stick com Fa0/13 e Fa0/12 do roteador 3400-Metro-1, respectivamente. No switch 7600-Dot1Q, as interfaces Gi9/44 e Gi 9/45 estão habilitadas com o modo de túnel Dot1q. As interfaces de vlan SVI são criadas na borda 3400-Metro e Fa0/13 e Fa0/12 são configuradas como portas de tronco. Os roteadores usam o OSPF para se comunicar entre si.
Núcleo 7609 |
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! version 15.0 hostname 7609-CORE interface GigabitEthernet1/43 mtu 9216 no ip address no ip redirects no ip proxy-arp load-interval 60 carrier-delay 2 flowcontrol send off storm-control broadcast level 1.00 ! interface GigabitEthernet1/43.3503 encapsulation dot1Q 3503 ip address 172.16.41.17 255.255.255.252 no ip redirects no ip proxy-arp ip mtu 1500 ip ospf authentication-key 7 072C0E6B6B272D ip ospf network point-to-point ip ospf hello-interval 3 ip ospf dead-interval 10 ! ! interface GigabitEthernet1/44 mtu 9216 no ip address no ip redirects no ip proxy-arp load-interval 60 carrier-delay 2 flowcontrol send off storm-control broadcast level 1.00 ! interface GigabitEthernet1/44.3803 encapsulation dot1Q 3803 ip address 172.16.73.137 255.255.255.248 secondary ip address 172.16.41.21 255.255.255.252 no ip redirects no ip proxy-arp ip mtu 1500 ip ospf authentication-key 7 072C0E6B6B272D ip ospf network point-to-point ip ospf cost 5 ip ospf hello-interval 3 ip ospf dead-interval 10 !--- Output omitted. ! end |
7609 DOT1Q |
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! version 12.2 ! interface GigabitEthernet9/44 switchport switchport access vlan 24 switchport mode dot1q-tunnel mtu 9216 load-interval 60 carrier-delay 2 flowcontrol send off storm-control broadcast level 1.00 l2protocol-tunnel cdp l2protocol-tunnel stp l2protocol-tunnel vtp no cdp enable spanning-tree portfast disable spanning-tree bpdufilter enable ! ! interface GigabitEthernet9/45 switchport switchport access vlan 24 switchport mode dot1q-tunnel mtu 9216 load-interval 60 carrier-delay 2 flowcontrol send off storm-control broadcast level 1.00 l2protocol-tunnel cdp l2protocol-tunnel stp l2protocol-tunnel vtp no cdp enable spanning-tree portfast disable spanning-tree bpdufilter enable ! !--- Output omitted. ! end |
Metro-1 3400 |
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! version 12.2 ! interface FastEthernet0/3 port-type nni switchport trunk allowed vlan 1052,3503 switchport mode trunk load-interval 60 ! interface FastEthernet0/4 port-type nni switchport trunk allowed vlan 1052,3803 switchport mode trunk load-interval 60 ! ! interface FastEthernet0/12 port-type nni switchport trunk allowed vlan 2-4094 switchport mode trunk ! interface FastEthernet0/13 port-type nni switchport trunk allowed vlan 2-4094 switchport mode trunk ! end |
Borda de 3.400 metros |
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! version 12.2 ! interface FastEthernet0/12 port-type nni switchport mode trunk load-interval 60 storm-control broadcast level 1.00 spanning-tree portfast disable spanning-tree bpdufilter disable ! interface FastEthernet0/13 port-type nni switchport mode trunk load-interval 60 storm-control broadcast level 1.00 spanning-tree portfast disable spanning-tree bpdufilter disable ! ! interface Vlan3503 ip address 172.16.41.18 255.255.255.252 no ip redirects no ip proxy-arp ip ospf authentication-key 7 072C0E6B6B272D ip ospf network point-to-point ip ospf hello-interval 3 ip ospf dead-interval 10 ! interface Vlan3803 ip address 172.16.73.139 255.255.255.248 secondary ip address 172.16.41.22 255.255.255.252 no ip redirects no ip proxy-arp ip ospf authentication-key 7 072C0E6B6B272D ip ospf network point-to-point ip ospf cost 5 ip ospf hello-interval 3 ip ospf dead-interval 10 ! !--- Output omitted. ! end |
Quedas aleatórias de ping ocorrem quando o pacote atravessa o túnel Dot1Q. Mas não há descartes de entrada/saída nas interfaces e também não há sintomas de problemas na camada física. Emita o comando show interface <interface> para verificar as quedas de entrada/saída na interface:
7609-Dot1Q#show interface gi9/44 !--- Output omitted. Input queue: 0/75/0/0 (size/max/drops/flushes); Total output drops: 0 0 input errors, 0 CRC, 1 frame, 0 overrun, 0 ignored 0 output errors, 0 collisions, 1 interface resets 0 lost carrier, 0 no carrier, 0 PAUSE output !--- Output omitted.
Quando um tráfego ICMP de cerca de 100 pings é enviado do Metro-Edge, somente 95 Ecos são recebidos no Núcleo, o que sugere que os pacotes ICMP estão sendo descartados no caminho.
Metro-Edge#ping 172.16.41.21 re 100 Type escape sequence to abort. Sending 100, 100-byte ICMP Echos to 172.16.41.21, timeout is 2 seconds: .....!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! !!!!!!!!!!!!!!!!!!!!!!!!!!!!!! Success rate is 95 percent (95/100), round-trip min/avg/max = ½/9 ms
Observação: o comando show ip traffic no 7609 mostra que somente 95 echos são recebidos, enquanto no Metro-edge e mostra que 100 Echos são enviados.
show ip traffic |
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Em Metro-Edge ICMP statistics: Rcvd: 0 format errors, 0 checksum errors, 0 redirects, 0 unreachable 0 echo, 95 echo reply, 0 mask requests, 0 mask replies, 0 quench 0 parameter, 0 timestamp, 0 info request, 0 other 0 irdp solicitations, 0 irdp advertisements Sent: 0 redirects, 0 unreachable, 100 echo, 0 echo reply 0 mask requests, 0 mask replies, 0 quench, 0 timestamp 0 info reply, 0 time exceeded, 0 parameter problem 0 irdp solicitations, 0 irdp advertisements !--- The above output shows that 100 echos are sent !--- but received 95 replies from 7609-Core.No 7609-Core ICMP statistics: Rcvd: 0 format errors, 0 checksum errors, 0 redirects, 0 unreachable 95 echo, 0 echo reply, 0 mask requests, 0 mask replies, 0 quench 0 parameter, 0 timestamp, 0 info request, 0 other 0 irdp solicitations, 0 irdp advertisements Sent: 0 redirects, 0 unreachable, 0 echo, 95 echo reply 0 mask requests, 0 mask replies, 0 quench, 0 timestamp 0 info reply, 0 time exceeded, 0 parameter problem 0 irdp solicitations, 0 irdp advertisements |
Verifique se os endereços MAC são aprendidos corretamente para solucionar problemas de queda de pacotes.
Use o comando show mac address table para verificar as entradas do endereço MAC.
Para Ping bem-sucedido
7609-DOT1q#sh mac-address-table address E05F.B972.1F00 all Legend: * - primary entry age - seconds since last seen n/a - not available vlan mac address type learn age ports ------+----------------+--------+-----+----------+-------------------------- Active Supervisor: * 24 e05f.b972.1f00 dynamic Yes 0 Gi9/44 !--- This output displays the MAC address learnt !--- and its associated port, in this case the associated !--- port for successful ping is Gi9/44.
Ping de falha
7609-DOT1q#sh mac-address-table address E05F.B972.1F00 all Legend: * - primary entry age - seconds since last seen n/a - not available vlan mac address type learn age ports ------+----------------+--------+-----+----------+-------------------------- Active Supervisor: * 24 e05f.b972.1f00 dynamic Yes 5 Gi9/45 !--- This output displays the MAC address learnt !--- and its associated port, in this case, !--- the port number is Gi9/45.
Para ver a programação detalhada do índice MAC , use o comando show mac-address-table.
7609-DOT1q#sh mac-address-table address E05F.B972.1F00 det MAC Table shown in details ======================================== PI_E RM RMA Type Alw-Lrn Trap Modified Notify Capture Flood Mac Address Age Pvlan SWbits Index XTag ----+---+---+----+-------+----+--------+------+-------+------+--------------+----+------+------+---- Active Supervisor: Yes No No DY No No Yes No No No e05f.b972.1f00 0xE0 24 0 0x22C 0
Emita os comandos Remote login switch e test mcast ltl-info index <Index number> para saber qual número de porta o valor HEX anterior indica.
7609-DOT1q-sp#test mcast ltl-info index 22B index 0x22B contain ports 9/44 7609-DOT1q-sp#test mcast ltl-info index 22C index 0x22C contain ports 9/45 !--- The output shows that hex number 22B !--- points to 9/44 port and hex 22C points to 9/45.
Para o ping com falha, o índice de origem e destino são a mesma porta e, portanto, a queda. Quando habilitado para Mac-move com o comando mac-address-table notification mac-move no 7600, ele mostra os flaps MAC entre duas portas diferentes e esta é a mensagem de erro:
Observação: como o 6500/7600 usa um endereço MAC comum para o switch, o mesmo endereço MAC atribuído entre portas diferentes. O comando show catalyst 6000 chassis-mac-address mostra o endereço MAC do switch reservado.
* Jul 2 10:29:44.011: %MAC_MOVE-SP-4-NOTIF: Host e05f.b972.1f00 in vlan 24 is flapping between port Gi9/45 and port Gi9/44 !--- The previous error message indicates !--- that the same MAC address is assigned between !--- two different ports: Gi9/45 and port Gi9/44.
A rede anterior é uma configuração de rede de malha completa que tem terminais de túnel DOT1Q no mesmo switch. Nesse tipo de configuração de rede, são esperados oscilações de MAC. Para evitar a oscilação de MAC, uma dessas soluções pode ser implementada.
Mova o endpoint do túnel para um switch diferente, por exemplo, o encapsulamento e o desencapsulamento devem ocorrer em um switch diferente.
A remoção de VLAN pode ser feita de modo a regular as VLANS em qualquer uma das portas de tronco.
Revisão | Data de publicação | Comentários |
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1.0 |
06-Nov-2012 |
Versão inicial |