Identificar e Solucionar Problemas de DHCP Externo no EVPN VxLAN Cat9000
Contents
Introdução
Este documento descreve como resolver problemas de DHCP em ambientes EVPN VxLAN externos em plataformas Cat9000.
Pré-requisitos
Requisitos
A Cisco recomenda que você tenha conhecimento destes tópicos:
- LAN virtual extensível em plataformas Cat9000
- Detecção de protocolos de configuração de host em ambientes VxLAN
- Protocolo de gateway de borda (BGP)
Para obter mais informações sobre esses tópicos, consulte:
- Capítulo: Configurando o relé DHCP em um EVPN BGP VXLAN Fabric Cat9300
- Capítulo: Configurando o relé DHCP em um EVPN BGP VXLAN Fabric Cat9400
- Capítulo: Configurando o relé DHCP em um EVPN BGP VXLAN Fabric Cat9500
- Capítulo: Configurando o relé DHCP em um EVPN BGP VXLAN Fabric Cat9600
Componentes Utilizados
As informações neste documento são baseadas no software Cisco IOS XE.
As informações neste documento foram criadas a partir de dispositivos em um ambiente de laboratório específico. Todos os dispositivos utilizados neste documento foram iniciados com uma configuração (padrão) inicial. Se a rede estiver ativa, certifique-se de que você entenda o impacto potencial de qualquer comando.
Diagrama de Rede
Topologia DHCP VxLAN
Casos Práticos 1: Não é possível obter um endereço IP do servidor externo (gateway centralizado dentro da malha)
Essa topologia usa a Camada 2 de VxLAN para a VLAN 250. O host exige endereços IP do servidor DHCP externo.
Verificação Leaf-01
Etapa 1. Na Folha-1, verifique o aprendizado do endereço MAC para os hosts locais.
Etapa 2. Além disso, confirme se o endereço MAC do gateway padrão foi reconhecido. Certifique-se de que os endereços MAC aprendidos e o endereço IP do gateway padrão estejam corretamente instalados como entradas na tabela BGP.
Leaf-1#show mac address-table address 10b3.d68b.3be3 (host mac address)
Mac Address Table
-------------------------------------------
Vlan Mac Address Type Ports
---- ----------- -------- -----
250 10b3.d68b.3be3 DYNAMIC Twe1/0/1
Centralized-Gateway#show interface vlan 250 | include bia (remote mac address)
Hardware is Ethernet SVI, address is 3473.2db8.bee3 (bia 3473.2db8.bee3)
Leaf-1#show bgp l2vpn evpn 10b3.d68b.3be3 (local mac address)
BGP routing table entry for [2][203.0.113.1:250][0][48][10B3D68B3BE3][0][*]/20, version 3
Paths: (1 available, best #1, table evi_250)
Advertised to update-groups:
2
Refresh Epoch 1
Local
0.0.0.0 (via default) from 0.0.0.0 (203.0.113.1)
Origin incomplete, localpref 100, weight 32768, valid, sourced, local, best
EVPN ESI: 00000000000000000000, Label1 10250
Extended Community: RT:10:250 ENCAP:8
Local irb vxlan vtep:
vrf:not found, l3-vni:0
local router mac:0000.0000.0000
core-irb interface:(not found)
vtep-ip:203.0.113.1
rx pathid: 0, tx pathid: 0x0
Updated on Oct 14 2025 22:27:32 UTC
Leaf-1#show bgp l2vpn evpn 3473.2db8.bee3 (remote mac address)
BGP routing table entry for [2][203.0.113.1:250][0][48][34732DB8BEE3][32][192.0.2.254]/24, version 9
Paths: (1 available, best #1, table evi_250)
Flag: 0x100
Not advertised to any peer
Refresh Epoch 4
Local, imported path from [2][203.0.113.4:250][0][48][34732DB8BEE3][32][192.0.2.254]/24 (global)
203.0.113.4 (metric 3) (via default) from 203.0.113.3 (203.0.113.3)
Origin incomplete, metric 0, localpref 100, valid, internal, best
EVPN ESI: 00000000000000000000, Label1 10250
Extended Community: RT:10:250 ENCAP:8 EVPN DEF GW:0:0
Originator: 203.0.113.4, Cluster list: 203.0.113.3
rx pathid: 0, tx pathid: 0x0
Updated on Oct 14 2025 14:48:35 UTC
BGP routing table entry for [2][203.0.113.4:250][0][48][34732DB8BEE3][32][192.0.2.254]/24, version 8
Paths: (1 available, best #1, table EVPN-BGP-Table)
Flag: 0x100
Not advertised to any peer
Refresh Epoch 4
Local
203.0.113.4 (metric 3) (via default) from 203.0.113.3 (203.0.113.3)
Origin incomplete, metric 0, localpref 100, valid, internal, best
EVPN ESI: 00000000000000000000, Label1 10250
Extended Community: RT:10:250 ENCAP:8 EVPN DEF GW:0:0
Originator: 203.0.113.4, Cluster list: 203.0.113.3
rx pathid: 0, tx pathid: 0x0
Updated on Oct 14 2025 14:48:35 UTC
Etapa 3. Validar o aprendizado do endereço MAC entre Leaf-1 e o Default Gateway. A folha 1 aprende endereços MAC locais através da porta de tronco e os endereços MAC remotos através do BGP.
Leaf-1#show l2route evpn mac
EVI ETag Prod Mac Address Next Hop(s) Seq Number
----- ---------- ----- -------------- ---------------------------------------------------- ----------
250 0 L2VPN 10b3.d68b.3b81 Twe1/0/1:250 0
250 0 L2VPN 10b3.d68b.3be3 Twe1/0/1:250 0 (Host local mac address)
250 0 BGP 3473.2db8.bee3 V:10250 203.0.113.4 0 (CGW SVI mac address)
Etapa 4. Verificar o aprendizado do gateway padrão no switch Leaf-1 dentro da instância L2VPN EVPN.
Leaf-1#show l2vpn evpn default-gateway
Valid Default Gateway Address EVI VLAN MAC Address Source
----- --------------------------------------- ----- ----- -------------- -----------
Y 192.0.2.254 250 250 3473.2db8.bee3 203.0.113.4
Etapa 5. Se a perspectiva do VxLAN estiver correta, vá para DHCP para solucionar o problema.
Etapa 6. Confirme o processo DORA a partir da Leaf-1 para o gateway DHCP. Na Folha-01, ative a depuração do pacote de rastreamento ip dhcp e verifique se a descoberta gera entradas de log. Se a geração de log não ocorrer, habilite as capturas de pacotes na interface que se conecta ao PC.
Leaf-1#debug ip dhcp snooping packet
DHCP Snooping Packet debugging is on
Leaf-1#
*Oct 21 19:33:16.358: DHCP_SNOOPING: received new DHCP packet from input interface (TwentyFiveGigE1/0/1)
*Oct 21 19:33:16.358: DHCP Memory dump is printed for process packet
<snip>
*Oct 21 19:33:16.367: DHCP_SNOOPING: process new DHCP packet, message type: DHCPDISCOVER, input interface: Twe1/0/1, MAC da: ffff.ffff.ffff, MAC sa: 10b3.d68b.3be3, IP da: 255.255.255.255, IP sa: 0.0.0.0, DHCP ciaddr: 0.0.0.0, DHCP yiaddr: 0.0.0.0, DHCP siaddr: 0.0.0.0, DHCP giaddr: 0.0.0.0, DHCP chaddr: 10b3.d68b.3be3, efp_id: -1865499306, vlan_id: 250, bootpflag:0x32768(Broadcast)
*Oct 21 19:33:16.367: DHCP_SNOOPING: add relay information option.
*Oct 21 19:33:16.367: DHCP_SNOOPING: Encoding opt82 CID in vlan-mod-port format
*Oct 21 19:33:16.367: DHCP_SNOOPING:VxLAN : vlan_id 250 VNI 10250 mod 1 port 1
*Oct 21 19:33:16.367: DHCP_SNOOPING: Encoding opt82 RID in MAC address format
*Oct 21 19:33:16.367: DHCP_SNOOPING: binary dump of relay info option, length: 26 data:
0x52 0x18 0x1 0xC 0x1 0xA 0x0 0x8 0x0 0x0 0x28 0xA 0x1 0x1 0x0 0x0 0x2 0x8 0x0 0x6 0x4C 0x5D 0x3C 0xEB 0x43 0x40
*Oct 21 19:33:16.367: DHCPS BRIDGE PAK: vlan=250 platform_flags=1
*Oct 21 19:33:16.367: DHCP_SNOOPING: bridge packet get invalid mat entry: FFFF.FFFF.FFFF, packet is flooded to ingress VLAN: (250)
*Oct 21 19:33:16.367: DHCP_SNOOPING: L2RELAY: sent unicast packet to default gw: 3473.2db8.bee3 vlan 0 src intf TwentyFiveGigE1/0/1
*Oct 21 19:33:20.058: DHCP_SNOOPING: received new DHCP packet from input interface (TwentyFiveGigE1/0/1)
*Oct 21 19:33:20.058: DHCP Memory dump is printed for process packet
Etapa 7. Se a depuração não disparar, execute uma captura de pacote para validação. Use a sintaxe especificada para capturar pacotes Discovery de entrada:
monitor capture <name> interface <int> in match ipv4 protocol udp any range 67 68 any range 67 68 start
monitor capture <name> stop
monitor capture export file flash:<name>.pcap
show monitor capture <name> buffer display-filter "eth.addr==[mac address]" detailed
Note: Capture as strings de filtro de exibição que seguem a sintaxe de filtro do Wireshark.
Leaf-1#monitor capture cap interface twe1/0/1 in match ipv4 protocol udp any range 67 68 any range 67 68 start
Started capture point : cap
Leaf-1#
*Oct 21 22:57:04.719: %BUFCAP-6-ENABLE: Capture Point cap enabled.
Leaf-1#
Leaf-1#monitor capture cap stop
Capture statistics collected at software:
Capture duration - 96 seconds
Packets received - 10
Packets dropped - 0
Packets oversized - 0
Bytes dropped in asic - 0
Capture buffer will exists till exported or cleared
Stopped capture point : cap
*Oct 21 22:58:40.810: %BUFCAP-6-DISABLE: Capture Point cap disabled.
Leaf-1#show monitor capture cap buffer display-filter "eth,addr==10:b3:d6:8b:3b:e3" detailed
Starting the packet display ........ Press Ctrl + Shift + 6 to exit
Frame 1: 371 bytes on wire (2968 bits), 371 bytes captured (2968 bits) on interface /tmp/epc_ws/wif_to_ts_pipe, id 0
Interface id: 0 (/tmp/epc_ws/wif_to_ts_pipe)
Interface name: /tmp/epc_ws/wif_to_ts_pipe
Encapsulation type: Ethernet (1)
Arrival Time: Oct 21, 2025 22:57:07.843851000 UTC
[Time shift for this packet: 0.000000000 seconds]
Epoch Time: 1761087427.843851000 seconds
<snip>
[Protocols in frame: eth:ethertype:vlan:ethertype:ip:udp:dhcp]
Ethernet II, Src: 10:b3:d6:8b:3b:e3 (10:b3:d6:8b:3b:e3), Dst: ff:ff:ff:ff:ff:ff (ff:ff:ff:ff:ff:ff)
Destination: ff:ff:ff:ff:ff:ff (ff:ff:ff:ff:ff:ff)
Address: ff:ff:ff:ff:ff:ff (ff:ff:ff:ff:ff:ff)
.... ..1. .... .... .... .... = LG bit: Locally administered address (this is NOT the factory default)
.... ...1 .... .... .... .... = IG bit: Group address (multicast/broadcast)
Source: 10:b3:d6:8b:3b:e3 (10:b3:d6:8b:3b:e3)
Address: 10:b3:d6:8b:3b:e3 (10:b3:d6:8b:3b:e3)
.... ..0. .... .... .... .... = LG bit: Globally unique address (factory default)
.... ...0 .... .... .... .... = IG bit: Individual address (unicast)
Type: 802.1Q Virtual LAN (0x8100)
802.1Q Virtual LAN, PRI: 0, DEI: 0, ID: 250
000. .... .... .... = Priority: Best Effort (default) (0)
...0 .... .... .... = DEI: Ineligible
.... 0000 1111 1010 = ID: 250
Type: IPv4 (0x0800)
<snip>
User Datagram Protocol, Src Port: 68, Dst Port: 67
Source Port: 68
Destination Port: 67
Length: 333
Checksum: 0xdf55 [unverified]
[Checksum Status: Unverified]
[Stream index: 0]
[Timestamps]
[Time since first frame: 0.000000000 seconds]
[Time since previous frame: 0.000000000 seconds]
Dynamic Host Configuration Protocol (Discover)
Message type: Boot Request (1)
Hardware type: Ethernet (0x01)
Hardware address length: 6
Hops: 0
Transaction ID: 0x3bd7aadb
Seconds elapsed: 7
Bootp flags: 0x8000, Broadcast flag (Broadcast)
1... .... .... .... = Broadcast flag: Broadcast
.000 0000 0000 0000 = Reserved flags: 0x0000
Client IP address: 0.0.0.0
Your (client) IP address: 0.0.0.0
Next server IP address: 0.0.0.0
Relay agent IP address: 0.0.0.0
Client MAC address: 10:b3:d6:8b:3b:e3 (10:b3:d6:8b:3b:e3)
Client hardware address padding: 00000000000000000000
Server host name not given
Boot file name not given
Magic cookie: DHCP
Option: (53) DHCP Message Type (Discover)
<snip>
Etapa 8. Validar o encapsulamento de pacotes VxLAN por meio da captura de pacotes. Aplicar vários filtros para esta validação. A VxLAN emprega a porta UDP 4789.
monitor capture cap interface <outgoing interface > out match ipv4 protocol udp any any eq 4789 (Interface that is pointing to the RR or VTEP via BGP)
Leaf-1#show ip bgp all summary
For address family: L2VPN E-VPN
<snip>
Neighbor V AS MsgRcvd MsgSent TblVer InQ OutQ Up/Down State/PfxRcd
203.0.113.3 4 10 4204 4122 365 0 0 2d13h 2
Leaf-1#show ip route 203.0.113.3
Routing entry for 203.0.113.3/32
Known via "ospf 1", distance 110, metric 2, type intra area
Last update from 172.x.x.2 on TwentyFiveGigE1/0/2, 2d13h ago
Routing Descriptor Blocks:
* 172.x.x.2, from 203.0.113.3, 2d13h ago, via TwentyFiveGigE1/0/2
Leaf-1#monitor capture cap interface twe1/0/2 out match ipv4 protocol udp any any eq 4789 start
*Oct 21 23:51:07.689: %BUFCAP-6-ENABLE: Capture Point cap enabled.
Leaf-1#show monitor capture cap buffer display-filter "eth.addr==10:b3:d6:8b:3b:e3" detailed
Starting the packet display ........ Press Ctrl + Shift + 6 to exit
Frame 1: 443 bytes on wire (3544 bits), 443 bytes captured (3544 bits) on interface /tmp/epc_ws/wif_to_ts_pipe, id 0
Interface id: 0 (/tmp/epc_ws/wif_to_ts_pipe)
Interface name: /tmp/epc_ws/wif_to_ts_pipe
Encapsulation type: Ethernet (1)
Arrival Time: Oct 21, 2025 23:51:34.848693000 UTC
[Time shift for this packet: 0.000000000 seconds]
Epoch Time: 1761090694.848693000 seconds
<snip>
[Protocols in frame: eth:ethertype:ip:udp:vxlan:eth:ethertype:ip:udp:dhcp]
Ethernet II, Src: 00:00:00:00:00:00 (00:00:00:00:00:00), Dst: 00:00:00:00:00:00 (00:00:00:00:00:00)
Destination: 00:00:00:00:00:00 (00:00:00:00:00:00)
Address: 00:00:00:00:00:00 (00:00:00:00:00:00)
.... ..0. .... .... .... .... = LG bit: Globally unique address (factory default)
.... ...0 .... .... .... .... = IG bit: Individual address (unicast)
Source: 00:00:00:00:00:00 (00:00:00:00:00:00)
Address: 00:00:00:00:00:00 (00:00:00:00:00:00)
.... ..0. .... .... .... .... = LG bit: Globally unique address (factory default)
.... ...0 .... .... .... .... = IG bit: Individual address (unicast)
Type: IPv4 (0x0800)
Internet Protocol Version 4, Src: 203.0.113.1, Dst: 203.0.113.4
0100 .... = Version: 4
.... 0101 = Header Length: 20 bytes (5)
Differentiated Services Field: 0x00 (DSCP: CS0, ECN: Not-ECT)
0000 00.. = Differentiated Services Codepoint: Default (0)
.... ..00 = Explicit Congestion Notification: Not ECN-Capable Transport (0)
<snip>
User Datagram Protocol, Src Port: 65479, Dst Port: 4789
Source Port: 65479
Destination Port: 4789
Length: 409
[Checksum: [missing]]
[Checksum Status: Not present]
[Stream index: 0]
[Timestamps]
[Time since first frame: 0.000000000 seconds]
[Time since previous frame: 0.000000000 seconds]
Virtual eXtensible Local Area Network
Flags: 0x0800, VXLAN Network ID (VNI)
0... .... .... .... = GBP Extension: Not defined
.... .... .0.. .... = Don't Learn: False
.... 1... .... .... = VXLAN Network ID (VNI): True
.... .... .... 0... = Policy Applied: False
.000 .000 0.00 .000 = Reserved(R): 0x0000
Group Policy ID: 0
VXLAN Network Identifier (VNI): 10250
Reserved: 0
<snip>
User Datagram Protocol, Src Port: 68, Dst Port: 67
Source Port: 68
Destination Port: 67
Length: 359
Checksum: 0x767d [unverified]
[Checksum Status: Unverified]
[Stream index: 1]
[Timestamps]
[Time since first frame: 0.000000000 seconds]
[Time since previous frame: 0.000000000 seconds]
Dynamic Host Configuration Protocol (Discover)
Message type: Boot Request (1)
Hardware type: Ethernet (0x01)
Hardware address length: 6
Hops: 0
Transaction ID: 0xd4c42ec1
Seconds elapsed: 0
Bootp flags: 0x8000, Broadcast flag (Broadcast)
1... .... .... .... = Broadcast flag: Broadcast
.000 0000 0000 0000 = Reserved flags: 0x0000
Client IP address: 0.0.0.0
Your (client) IP address: 0.0.0.0
Next server IP address: 0.0.0.0
Relay agent IP address: 0.0.0.0
Client MAC address: 10:b3:d6:8b:3b:e3 (10:b3:d6:8b:3b:e3)
Client hardware address padding: 00000000000000000000
Server host name not given
Boot file name not given
Magic cookie: DHCP
Verificação do gateway centralizado
Etapa 1. Validar o endereço MAC do host aprendido nas rotas BGP e EVPN L2 (esta etapa espelha o procedimento inicial de verificação Leaf).
Centralized-Gateway#show bgp l2vpn evpn 10b3.d68b.3be3 (remote host mac address)
BGP routing table entry for [2][203.0.113.1:250][0][48][10B3D68B3BE3][0][*]/20, version 12
Paths: (1 available, best #1, table EVPN-BGP-Table)
Not advertised to any peer
Refresh Epoch 1
Local
203.0.113.1 (metric 3) (via default) from 203.0.113.3 (203.0.113.3) (learned via RR)
Origin incomplete, metric 0, localpref 100, valid, internal, best
EVPN ESI: 00000000000000000000, Label1 10250
Extended Community: RT:10:250 ENCAP:8
Originator: 203.0.113.1, Cluster list: 203.0.113.3
rx pathid: 0, tx pathid: 0x0
Updated on Oct 27 2025 17:53:37 UTC
BGP routing table entry for [2][203.0.113.4:250][0][48][10B3D68B3BE3][0][*]/20, version 14
Paths: (1 available, best #1, table evi_250)
Not advertised to any peer
Refresh Epoch 1
Local, imported path from [2][203.0.113.1:250][0][48][10B3D68B3BE3][0][*]/20 (global)
203.0.113.1 (metric 3) (via default) from 203.0.113.3 (203.0.113.3)
Origin incomplete, metric 0, localpref 100, valid, internal, best
EVPN ESI: 00000000000000000000, Label1 10250
Extended Community: RT:10:250 ENCAP:8
Originator: 203.0.113.1, Cluster list: 203.0.113.3
rx pathid: 0, tx pathid: 0x0
Updated on Oct 27 2025 17:53:37 UTC
Centralized-Gateway#show l2route evpn mac mac-address 10b3.d68b.3be3
EVI ETag Prod Mac Address Next Hop(s) Seq Number
----- ---------- ----- -------------- ---------------------------------------------------- ----------
250 0 BGP 10b3.d68b.3be3 V:10250 203.0.113.1 0
Etapa 2. Verificar as informações de retransmissão de DHCP e a configuração de rastreamento de DHCP no gateway centralizado.
Centralized-Gateway#show running-config | section dhcp
ip dhcp-relay source-interface Loopback0
ip dhcp relay information option vpn
ip dhcp relay information option
ip dhcp compatibility suboption link-selection standard
ip dhcp compatibility suboption server-override standard
ip dhcp snooping vlan 250
ip dhcp snooping
Etapa 3. Verificar a conectividade com o servidor DHCP e originar um ping a partir da interface VLAN 250.
Centralized-Gateway#ping 198.51.100.10 source vlan 250
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 198.51.100.10, timeout is 2 seconds:
Packet sent with a source address of 192.0.2.254
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 1/1/1 ms
Etapa 4. Executar uma captura de pacotes para validar se as mensagens de descoberta dos hosts remotos alcançam o gateway centralizado.
Centralized-Gateway#monitor capture cap interface vlan250 in match ipv4 protocol udp any range 67 68 any range 67 68
Centralized-Gateway#monitor capture cap start
Started capture point : cap
Centralized-Gateway#show monitor capture cap buffer display-filter "eth.addr==10:b3:d6:8b:3b:e3" detailed
Starting the packet display ........ Press Ctrl + Shift + 6 to exit
Frame 1: 401 bytes on wire (3208 bits), 401 bytes captured (3208 bits) on interface /tmp/epc_ws/wif_to_ts_pipe, id 0
Interface id: 0 (/tmp/epc_ws/wif_to_ts_pipe)
Interface name: /tmp/epc_ws/wif_to_ts_pipe
Encapsulation type: Ethernet (1)
Arrival Time: Oct 27, 2025 20:43:30.774923000 UTC
[Time shift for this packet: 0.000000000 seconds]
Epoch Time: 1761597810.774923000 seconds
<snip>
[Protocols in frame: eth:ethertype:cmd:ethertype:ip:udp:dhcp]
Ethernet II, Src: 10:b3:d6:8b:3b:e3 (10:b3:d6:8b:3b:e3), Dst: 34:73:2d:b8:be:e3 (34:73:2d:b8:be:e3)
Destination: 34:73:2d:b8:be:e3 (34:73:2d:b8:be:e3)
Address: 34:73:2d:b8:be:e3 (34:73:2d:b8:be:e3)
.... ..0. .... .... .... .... = LG bit: Globally unique address (factory default)
.... ...0 .... .... .... .... = IG bit: Individual address (unicast)
Source: 10:b3:d6:8b:3b:e3 (10:b3:d6:8b:3b:e3)
Address: 10:b3:d6:8b:3b:e3 (10:b3:d6:8b:3b:e3)
.... ..0. .... .... .... .... = LG bit: Globally unique address (factory default)
.... ...0 .... .... .... .... = IG bit: Individual address (unicast)
Type: CiscoMetaData (0x8909)
<snip>
Internet Protocol Version 4, Src: 0.0.0.0, Dst: 255.255.255.255
0100 .... = Version: 4
.... 0101 = Header Length: 20 bytes (5)
Differentiated Services Field: 0x00 (DSCP: CS0, ECN: Not-ECT)
0000 00.. = Differentiated Services Codepoint: Default (0)
.... ..00 = Explicit Congestion Notification: Not ECN-Capable Transport (0)
Total Length: 379
Identification: 0x0230 (560)
Flags: 0x00
0... .... = Reserved bit: Not set
.0.. .... = Don't fragment: Not set
..0. .... = More fragments: Not set
Fragment Offset: 0
Time to Live: 255
Protocol: UDP (17)
Header Checksum: 0xb842 [validation disabled]
[Header checksum status: Unverified]
Source Address: 0.0.0.0
Destination Address: 255.255.255.255
User Datagram Protocol, Src Port: 68, Dst Port: 67
Source Port: 68
Destination Port: 67
Length: 359
Checksum: 0x8f64 [unverified]
[Checksum Status: Unverified]
[Stream index: 0]
[Timestamps]
[Time since first frame: 0.000000000 seconds]
[Time since previous frame: 0.000000000 seconds]
UDP payload (351 bytes)
Dynamic Host Configuration Protocol (Discover)
Message type: Boot Request (1)
Hardware type: Ethernet (0x01)
Hardware address length: 6
Hops: 0
Transaction ID: 0xf23af863
Seconds elapsed: 0
Bootp flags: 0x8000, Broadcast flag (Broadcast)
1... .... .... .... = Broadcast flag: Broadcast
.000 0000 0000 0000 = Reserved flags: 0x0000
Client IP address: 0.0.0.0
Your (client) IP address: 0.0.0.0
Next server IP address: 0.0.0.0
Relay agent IP address: 0.0.0.0
Client MAC address: 10:b3:d6:8b:3b:e3 (10:b3:d6:8b:3b:e3)
Client hardware address padding: 00000000000000000000
Server host name not given
Boot file name not given
Magic cookie: DHCP
Option: (53) DHCP Message Type (Discover)
Length: 1
DHCP: Discover (1)
Option: (57) Maximum DHCP Message Size
Length: 2
Maximum DHCP Message Size: 1200
Option: (61) Client identifier
Length: 27
Type: 0
Client Identifier: cisco-10b3.d68b.3be3-Vl250
<snip>
Etapa 5. Realizar uma captura subsequente de pacotes no switch. Verifique a saída da descoberta e o ingresso da oferta.
Centralized-Gateway#no monitor capture cap
Centralized-Gateway#monitor capture cap interface vlan 75 both match ipv4 protocol udp any range 67 68 any range 67 68
Centralized-Gateway#monitor capture cap start
Started capture point : cap
Centralized-Gateway#monitor capture cap stop
Capture statistics collected at software:
Capture duration - 78 seconds
Packets received - 0
Packets dropped - 0
Packets oversized - 0
Bytes dropped in asic - 0
Etapa 6. Se a captura do pacote não mostrar pacotes, continue com a depuração DHCP e valide o status do pacote na plataforma.
Centralized-Gateway#debug ip dhcp snooping packet
<snip>
*Oct 27 22:20:24.444: DHCP_SNOOPING: process new DHCP packet, message type: DHCPDISCOVER, input interface: Tu0, MAC da: 3473.2db8.bee3, MAC sa: 10b3.d68b.3be3, IP da: 255.255.255.255, IP sa: 0.0.0.0, DHCP ciaddr: 0.0.0.0, DHCP yiaddr: 0.0.0.0, DHCP siaddr: 0.0.0.0, DHCP giaddr: 0.0.0.0, DHCP chaddr: 10b3.d68b.3be3, efp_id: -1137609462, vlan_id: 250, bootpflag:0x32768(Broadcast)
*Oct 27 22:20:24.445: DHCPS BRIDGE PAK: vlan=250 platform_flags=1
*Oct 27 22:20:24.445: DHCP_SNOOPING: Packet destined to SVI Mac:3473.2db8.bee3
*Oct 27 22:20:24.445: DHCP_SNOOPING: bridge packet send packet to cpu port: Vlan250.
*Oct 27 22:20:24.445: DHCP_SNOOPING: bridge packet send packet to port: GigabitEthernet1/0/2, pak_vlan 250.
*Oct 27 22:20:27.952: DHCP_SNOOPING: received new DHCP packet from input interface (Tunnel0)
*Oct 27 22:20:27.952: DHCP Memory dump is printed for process packet.
Centralized-Gateway#debug ip dhcp server packet detail
*Oct 27 22:27:58.009: DHCPD: BOOTREQUEST from 0063.6973.636f.2d31.3062.332e.6436.3862.2e33.6265.332d.566c.3235.30 forwarded to 198.51.100.10.
*Oct 27 22:28:02.008: DHCPD: tableid for 192.0.2.254 on Vlan250 is 0
*Oct 27 22:28:02.008: DHCPD: client's VPN is .
*Oct 27 22:28:02.008: DHCPD: No option 125
*Oct 27 22:28:02.008: DHCPD: Option 124: Vendor Class Information
*Oct 27 22:28:02.008: DHCPD: Enterprise ID: 9
*Oct 27 22:28:02.008: DHCPD: Vendor-class-data-len: 13
*Oct 27 22:28:02.008: DHCPD: Data: 43393330304C2D3234502D3447
*Oct 27 22:28:02.008: DHCPD: Option 125 not present in the msg.
*Oct 27 22:28:02.008: DHCPD: Option 125 not present in the msg.
*Oct 27 22:28:02.008: DHCPD: Looking up binding using address 192.0.2.254
*Oct 27 22:28:02.008: DHCPD: setting giaddr to 192.0.2.254.
*Oct 27 22:28:02.008: DHCPD: relay information option before replacing suboptions
*Oct 27 22:28:02.008: DHCPD: 5218010c010a00080000280a01010000020800064c5d3ceb4340
*Oct 27 22:28:02.008: DHCPD: replacing suboptions in relay information option.
*Oct 27 22:28:02.008: DHCPD: relay information option content (add/replace):
*Oct 27 22:28:02.008: DHCPD: 52060504c00002fe
*Oct 27 22:28:02.008: DHCPD: giaddr changed to 203.0.113.4
Etapa 7. Verificar se as interfaces que se conectam ao servidor DHCP incluem o comando especificado (isso evita a queda do pacote DHCP).
Centralized-Gateway#sh running-config interface gi1/0/2
Building configuration...
Current configuration : 149 bytes
!
interface GigabitEthernet1/0/2
description to L2_switch
switchport trunk allowed vlan 75,250
switchport mode trunk
ip dhcp snooping trust
end
Note: O comando ip dhcp snooping trust aplica-se somente às interfaces de tronco da Camada 2.
Solução para o problema
A configuração do VxLAN funciona conforme esperado. No entanto, o relé do servidor DHCP envia respostas DHCP ao endereço IP 203.0.113.4. O servidor DHCP não tinha acessibilidade a esse endereço IP. Essa falta de conectividade resultou em quedas de pacotes unicast no Gateway Centralizado.
Para resolver esse problema, uma nova interface de Loopback 1 foi configurada e uma rota para o endereço IP foi estabelecida para fornecer conectividade com esse endereço de retransmissão de Loopback.
Logs DHCP:
DHCP-Server#debug ip dhcp server packet detail
DHCP server packet detail debugging is on.
*Oct 28 00:23:43.464: DHCPD: DHCPDISCOVER received from client 0063.6973.636f.2d31.3062.332e.6436.3862.2e33.6265.332d.566c.3235.30 through relay 203.0.113.4.DHCPD: Setting only requested parameters
*Oct 28 00:23:43.464: DHCPD: Option 125 not present in the msg.
*Oct 28 00:23:43.465: DHCPD: egress Interfce GigabitEthernet0/0/4.75
*Oct 28 00:23:43.465: DHCPD: unicasting BOOTREPLY for client 10b3.d68b.3be3 to relay 203.0.113.4.
DHCP-Server#ping 203.0.113.4
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 203.0.113.4, timeout is 2 seconds:
.....
Success rate is 0 percent (0/5)
DHCP-Server#
Gateway centralizado: Configure a conectividade para a nova interface de loopback para a função de retransmissão.
Centralized-Gateway#configure terminal
Enter configuration commands, one per line. End with CNTL/Z.
Centralized-Gateway(config)#interface loopback 1
Centralized-Gateway(config-if)#ip address 198.51.100.25 255.255.255.255
Centralized-Gateway(config-if)#router eigrp 1
Centralized-Gateway(config-router)#network 198.51.100.25 0.0.0.0
Centralized-Gateway(config-router)#exit
Centralized-Gateway(config)#no ip dhcp-relay source-interface Loopback0
Centralized-Gateway(config)#ip dhcp-relay source-interface Loopback1
DHCP-Server#ping 198.51.100.25
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 198.51.100.25, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 1/2/9 ms
DHCP-Server#
Casos Práticos 2: Não é possível obter um endereço IP do servidor externo (gateway centralizado fora da malha)
Essa topologia utiliza a Camada 2 de VXLAN para a VLAN 250. O host obtém seu endereço IP de um servidor DHCP externo localizado fora da estrutura.
Topologia VxLAN de DHCP externo
Verificação Leaf-01
Etapa 1. Em Leaf-1, verifique o anúncio correto no gateway padrão. Como o servidor DHCP está localizado fora da estrutura VxLAN, esse é um requisito importante para a funcionalidade correta da atribuição de endereço IP.
Leaf-1#show l2vpn evpn default-gateway
Valid Default Gateway Address EVI VLAN MAC Address Source
----- --------------------------------------- ----- ----- -------------- -----------
Etapa 2. Se a saída anterior estiver vazia, continue com a solução de problemas do DHCP. Verifique se as configurações relevantes de rastreamento de DHCP estão presentes nos dispositivos Leaf.
Leaf-1#show running-config | section dhcp
ip dhcp relay information option vpn
ip dhcp relay information option
ip dhcp compatibility suboption link-selection standard
ip dhcp compatibility suboption server-override standard
ip dhcp snooping vlan 250
ip dhcp snooping
Leaf-2#show running-config | section dhcp
ip dhcp relay information option vpn
ip dhcp relay information option
ip dhcp compatibility suboption link-selection standard
ip dhcp compatibility suboption server-override standard
ip dhcp snooping vlan 250
ip dhcp snooping
Etapa 3. Se um dispositivo estiver solicitando ativamente um endereço IP usando DHCP, ative o comando de depuração apropriado para validar o status do pacote na plataforma.
*Dec 6 22:42:19.568: DHCP_SNOOPING: received new DHCP packet from input interface (TwentyFiveGigE1/0/1)
*Dec 6 22:42:19.568: DHCP Memory dump is printed for process packet
<snip>
*Dec 6 22:42:19.578: DHCP_SNOOPING: process new DHCP packet, message type: DHCPDISCOVER, input interface: Twe1/0/1, MAC da: ffff.ffff.ffff, MAC sa: 10b3.d68b.3be3, IP da: 255.255.255.255, IP sa: 0.0.0.0, DHCP ciaddr: 0.0.0.0, DHCP yiaddr: 0.0.0.0, DHCP siaddr: 0.0.0.0, DHCP giaddr: 0.0.0.0, DHCP chaddr: 10b3.d68b.3be3, efp_id: 1984524378, vlan_id: 250, bootpflag:0x32768(Broadcast)
*Dec 6 22:42:19.578: DHCP_SNOOPING: add relay information option.
*Dec 6 22:42:19.578: DHCP_SNOOPING: Encoding opt82 CID in vlan-mod-port format
*Dec 6 22:42:19.578: DHCP_SNOOPING:VxLAN : vlan_id 250 VNI 10250 mod 1 port 1
*Dec 6 22:42:19.578: DHCP_SNOOPING: Encoding opt82 RID in MAC address format
*Dec 6 22:42:19.578: DHCP_SNOOPING: binary dump of relay info option, length: 26 data:
0x52 0x18 0x1 0xC 0x1 0xA 0x0 0x8 0x0 0x0 0x28 0xA 0x1 0x1 0x0 0x0 0x2 0x8 0x0 0x6 0x4C 0x5D 0x3C 0xEB 0x43 0x40
*Dec 6 22:42:19.579: DHCPS BRIDGE PAK: vlan=250 platform_flags=1
*Dec 6 22:42:19.579: DHCP_SNOOPING: bridge packet get invalid mat entry: FFFF.FFFF.FFFF, packet is flooded to ingress VLAN: (250)
*Dec 6 22:42:19.579: DHCP_SNOOPING: L2RELAY: cannot find default gw for bd 250: src intf TwentyFiveGigE1/0/1
Note: A mensagem de depuração final indica que o dispositivo não conseguiu identificar o gateway padrão para a VLAN 250.
Verificação Leaf-02
Como a Leaf-2 é a folha de borda ativa dentro do VxLAN Fabric, ela é responsável por encaminhar as informações relacionadas ao gateway padrão.
Etapa 1. Continue para validar a capacidade do EVPN L2VPN de anunciar o gateway padrão.
Leaf-2#show l2vpn evpn summary
L2VPN EVPN
EVPN Instances (excluding point-to-point): 1
VLAN Based: 1
Vlans: 1
BGP: ASN 65000, address-family l2vpn evpn configured
Router ID: 203.0.113.2
Global Replication Type: Ingress
ARP/ND Flooding Suppression: Enabled
Connectivity to Core: UP
MAC Duplication: seconds 180 limit 5
MAC Addresses: 5
Local: 3
Remote: 2
Duplicate: 0
IP Duplication: seconds 180 limit 5
IP Addresses: 2
Local: 2
Remote: 0
Duplicate: 0
Advertise Default Gateway: No
Default Gateway Addresses: 0
Local: 0
Remote: 0
Maximum number of Route Targets per EAD-ES route: 200
Multi-home aliasing: Enabled
Multi-home send proxy MAC/IP: Enabled
Multi-home device ID: 0000.5e00.0101
Global IP Local Learn: Enabled
IP local learning limits
IPv4: 4 addresses per-MAC
IPv6: 12 addresses per-MAC
IP local learning timers
Down: 10 minutes
Poll: 1 minutes
Reachable: 5 minutes
Stale: 30 minutes
Auto route-target: vni-based
Advertise Multicast: No
Global Anycast Gateway MAC: No
Etapa 2. A saída anterior valida que a Leaf-2 não está anunciando o Default-Gateway em direção à outra Leaf-1 dentro da mesma estrutura VxLAN. Continue com a configuração necessária para executar o anúncio correto.
Leaf-2(config)#l2vpn evpn
Leaf-2(config-evpn)#default-gateway advertise
Etapa 3. Depois que a configuração for adicionada, o recurso L2VPN EVPN deve ser habilitado.
Leaf-2#show l2vpn evpn summary
--snip--
Advertise Default Gateway: Yes
Etapa 4. Uma vez habilitado, configure o anúncio adequado do gateway padrão para o outro Leaf dentro do VxLAN Fabric.
Solução de problema 1
A configuração do L2VPN EVPN e do DHCP Snooping funciona conforme esperado. No entanto, o anúncio de gateway padrão não está sendo executado. Portanto, os dispositivos finais conectados à Folha-1 não podem receber um endereço IP do servidor DHCP.
Para resolver esse problema, o anúncio deve ser configurado.
Etapa 1. Configure uma ACL, junto com um mapa de rota para anunciar o gateway padrão via BGP para os outros dispositivos Leaf na rede.
Leaf-2(config)#ip access-list extended GW250
Leaf-2(config-ext-nacl)#10 permit ip host 192.0.2.254 any (permit the IP address if the GW)
Leaf-2(config)#route-map CGW
Leaf-2(config-route-map)#match ip address GW250
Leaf-2(config-route-map)#match evpn route-type 2-mac-ip
Leaf-2(config-route-map)#set extcommunity default-gw
Leaf-2(config)#router bgp 65000
Leaf-2(config-router)#address-family l2vpn evpn
Leaf-2(config-router-af)#neighbor 203.0.113.3 route-map CGW out
Etapa 2. Depois que a configuração anterior for adicionada, verifique Leaf-1 para ver o anúncio correto do gateway padrão.
Leaf-1#show l2vpn evpn default-gateway
Valid Default Gateway Address EVI VLAN MAC Address Source
----- --------------------------------------- ----- ----- -------------- -----------
Y 192.0.2.254 250 250 3473.2db8.bee3 203.0.113.2
Note: No VTEP de borda, verificar o gateway padrão exibe um valor vazio. Esse é o comportamento esperado, pois o gateway centralizado está diretamente conectado ao VTEP de borda.
Leaf-2#show l2vpn evpn default-gateway
Valid Default Gateway Address EVI VLAN MAC Address Source
----- --------------------------------------- ----- ----- -------------- -----------
Agora os dispositivos Leaf estão mostrando corretamente o anúncio do gateway padrão. Verifique se os dispositivos finais estão recebendo corretamente o endereço IP do DHCP.
Verificação do Host 1
Etapa 1. No Host 1, solicite um endereço IP via DHCP:
Host1#show running-config interface vlan 250
Building configuration...
Current configuration : 42 bytes
!
interface Vlan250
ip address dhcp
end
Etapa 2. Validar se o endereço IP foi atribuído corretamente:
Host1#show ip interface brief | include DHCP
Vlan250 unassigned YES DHCP up up
Etapa 3. Se o endereço IP não for atribuído corretamente depois que o gateway padrão tiver sido anunciado corretamente pela folha da borda, continue com a solução de problemas do DHCP.
Verificação da folha 2
Etapa 1. Ative a depuração para DHCP, especificamente para rastreamento de DHCP, para observar como o dispositivo processa pacotes ao encaminhá-los para fora da estrutura de VXLAN.
Leaf-2#debug ip dhcp snooping packet
DHCP Snooping Packet debugging is on
Etapa 2. Reinicie o processo DHCP no dispositivo Host e examine os registros:
Leaf-2#debug ip dhcp snooping packet
*Dec 12 20:11:43.891: DHCP_SNOOPING: received new DHCP packet from input interface (Tunnel0)
*Dec 12 20:11:43.891: DHCP Memory dump is printed for process packet
<snip>
*Dec 12 20:11:43.902: DHCP_SNOOPING: process new DHCP packet, message type: DHCPDISCOVER, input interface: Tu0, MAC da: 3473.2db8.bee3, MAC sa: 10b3.d68b.3be3, IP da: 255.255.255.255, IP sa: 0.0.0.0, DHCP ciaddr: 0.0.0.0, DHCP yiaddr: 0.0.0.0, DHCP siaddr: 0.0.0.0, DHCP giaddr: 0.0.0.0, DHCP chaddr: 10b3.d68b.3be3, efp_id: -2136403878, vlan_id: 250, bootpflag:0x32768(Broadcast)
*Dec 12 20:11:43.902: DHCPS BRIDGE PAK: vlan=250 platform_flags=1
*Dec 12 20:11:43.902: DHCP_SNOOPING: bridge packet output port set is null, packet is dropped.
Etapa 3. Os registros anteriores indicam que o pacote está sendo descartado. Essa mensagem significa que o recurso de rastreamento de DHCP no switch recebeu um pacote DHCP que não pode ser encaminhado porque a porta de saída é inválida. Isso geralmente ocorre quando o rastreamento de DHCP não é capaz de determinar a porta de saída apropriada para encaminhar o pacote DHCP.
Etapa 4. Para resolver esse problema, a interface que aponta para o Gateway centralizado deve ser configurada como confiável.
Leaf-2(config)#interface fortyGigabitEthernet 2/0/1
Leaf-2(config-if)#ip dhcp snooping trust
Etapa 5. Validar se a atribuição de endereço IP via DHCP está funcionando conforme esperado agora.
Leaf-2#debug ip dhcp snooping packet
*Dec 12 20:33:54.156: DHCP Memory dump is printed for process packet
<snip>
*Dec 12 20:33:54.167: DHCP_SNOOPING: process new DHCP packet, message type: DHCPDISCOVER, input interface: Tu0, MAC da: 3473.2db8.bee3, MAC sa: 10b3.d68b.3be3, IP da: 255.255.255.255, IP sa: 0.0.0.0, DHCP ciaddr: 0.0.0.0, DHCP yiaddr: 0.0.0.0, DHCP siaddr: 0.0.0.0, DHCP giaddr: 0.0.0.0, DHCP chaddr: 10b3.d68b.3be3, efp_id: -2136403878, vlan_id: 250, bootpflag:0x32768(Broadcast)
*Dec 12 20:33:54.167: DHCPS BRIDGE PAK: vlan=250 platform_flags=1
*Dec 12 20:33:54.167: DHCP_SNOOPING: bridge packet send packet to port: FortyGigabitEthernet2/0/1, pak_vlan 250.
Etapa 6. A evidência indica que o dispositivo agora identifica corretamente a interface física através do pacote DHCPDISCOVER e deve ser encaminhada à medida que a interface é marcada como confiável a partir da perspectiva de rastreamento de DHCP. No entanto, a atribuição de endereço IP ainda não está funcionando conforme esperado.
Verificação do gateway centralizado
Etapa 1. Com a Border Leaf agora encaminhando pacotes DHCP através da interface apropriada, se a atribuição de endereço IP continuar a falhar, continue com os procedimentos padrão de Troubleshooting de DHCP.
Centralized-Gateway#debug ip dhcp server packet
DHCP server packet debugging is on.
*Dec 12 20:39:36.029: DHCPD: tableid for 192.0.2.254 on Vlan250 is 0
*Dec 12 20:39:36.029: DHCPD: client's VPN is .
*Dec 12 20:39:36.029: DHCPD: No option 125
*Dec 12 20:39:36.029: DHCPD: Option 124: Vendor Class Information
*Dec 12 20:39:36.029: DHCPD: Enterprise ID: 9
*Dec 12 20:39:36.029: DHCPD: Vendor-class-data-len: 13
*Dec 12 20:39:36.029: DHCPD: Data: 43393330304C2D3234502D3447
*Dec 12 20:39:36.029: DHCPD: inconsistent relay information.
*Dec 12 20:39:36.029: DHCPD: relay information option exists, but giaddr is zero
Etapa 2. Com base na saída de depuração do Gateway Centralizado e nos resultados da captura de pacotes, é necessária uma configuração adicional para evitar que o dispositivo descarte pacotes quando o campo giaddr estiver definido como zero.
Quando um pacote DHCP é recebido com a opção de informações de retransmissão presente, mas o endereço IP do gateway (giaddr) está definido somente como zero, o agente de retransmissão DHCP, por padrão, descarta o pacote. Para lidar com esse comportamento, configure o comando ip dhcp relay information trusted.
Etapa 3. Para verificar se o dispositivo está recebendo o pacote, execute uma captura de pacote:
Configure an Access-list to filter the interested traffic.
Extended IP access list dhcp
10 permit udp any any eq 67
20 permit udp any eq 67 any
Configure the capture.
Centralized-Gateway#monitor capture tac interface gigabitethernet1/0/1 both access-list dhcp buffer size 10
Centralized-Gateway#monitor capture cap start
Started capture point : cap
Centralized-Gateway#monitor capture cap stop
Capture statistics collected at software:
Capture duration - 58 seconds
Packets received - 6
Packets dropped - 0
Packets oversized - 0
Bytes dropped in asic - 0
Centralized-Gateway#show monitor capture cap buffer display-filter "eth.addr==10:b3:d6:8b:3b:e3" detailed
Starting the packet display ........ Press Ctrl + Shift + 6 to exit
Frame 1: 397 bytes on wire (3176 bits), 397 bytes captured (3176 bits) on interface /tmp/epc_ws/wif_to_ts_pipe, id 0
Interface id: 0 (/tmp/epc_ws/wif_to_ts_pipe)
Interface name: /tmp/epc_ws/wif_to_ts_pipe
Encapsulation type: Ethernet (1)
Arrival Time: Dec 12, 2025 18:35:21.821468000 UTC
[Time shift for this packet: 0.000000000 seconds]
Epoch Time: 1765564521.821468000 seconds
[Time delta from previous captured frame: 0.000000000 seconds]
[Time delta from previous displayed frame: 0.000000000 seconds]
[Time since reference or first frame: 0.000000000 seconds]
Frame Number: 1
Frame Length: 397 bytes (3176 bits)
Capture Length: 397 bytes (3176 bits)
[Frame is marked: False]
[Frame is ignored: False]
[Protocols in frame: eth:ethertype:vlan:ethertype:ip:udp:dhcp]
Ethernet II, Src: 10:b3:d6:8b:3b:e3 (10:b3:d6:8b:3b:e3), Dst: 34:73:2d:b8:be:e3 (34:73:2d:b8:be:e3)
Destination: 34:73:2d:b8:be:e3 (34:73:2d:b8:be:e3)
Address: 34:73:2d:b8:be:e3 (34:73:2d:b8:be:e3)
.... ..0. .... .... .... .... = LG bit: Globally unique address (factory default)
.... ...0 .... .... .... .... = IG bit: Individual address (unicast)
Source: 10:b3:d6:8b:3b:e3 (10:b3:d6:8b:3b:e3)
Address: 10:b3:d6:8b:3b:e3 (10:b3:d6:8b:3b:e3)
.... ..0. .... .... .... .... = LG bit: Globally unique address (factory default)
.... ...0 .... .... .... .... = IG bit: Individual address (unicast)
Type: 802.1Q Virtual LAN (0x8100)
802.1Q Virtual LAN, PRI: 0, DEI: 0, ID: 250
000. .... .... .... = Priority: Best Effort (default) (0)
...0 .... .... .... = DEI: Ineligible
.... 0000 1111 1010 = ID: 250
Type: IPv4 (0x0800)
Internet Protocol Version 4, Src: 0.0.0.0, Dst: 255.255.255.255
0100 .... = Version: 4
.... 0101 = Header Length: 20 bytes (5)
Differentiated Services Field: 0x00 (DSCP: CS0, ECN: Not-ECT)
0000 00.. = Differentiated Services Codepoint: Default (0)
.... ..00 = Explicit Congestion Notification: Not ECN-Capable Transport (0)
Total Length: 379
Identification: 0x4b04 (19204)
Flags: 0x00
0... .... = Reserved bit: Not set
.0.. .... = Don't fragment: Not set
..0. .... = More fragments: Not set
Fragment Offset: 0
Time to Live: 255
Protocol: UDP (17)
Header Checksum: 0x6f6e [validation disabled]
[Header checksum status: Unverified]
Source Address: 0.0.0.0
Destination Address: 255.255.255.255
User Datagram Protocol, Src Port: 68, Dst Port: 67
Source Port: 68
Destination Port: 67
Length: 359
Checksum: 0x2ae5 [unverified]
[Checksum Status: Unverified]
[Stream index: 0]
[Timestamps]
[Time since first frame: 0.000000000 seconds]
[Time since previous frame: 0.000000000 seconds]
UDP payload (351 bytes)
Dynamic Host Configuration Protocol (Discover)
Message type: Boot Request (1)
Hardware type: Ethernet (0x01)
Hardware address length: 6
Hops: 0
Transaction ID: 0xe9986585
Seconds elapsed: 0
Bootp flags: 0x8000, Broadcast flag (Broadcast)
1... .... .... .... = Broadcast flag: Broadcast
.000 0000 0000 0000 = Reserved flags: 0x0000
Client IP address: 0.0.0.0
Your (client) IP address: 0.0.0.0
Next server IP address: 0.0.0.0
Relay agent IP address: 0.0.0.0
Client MAC address: 10:b3:d6:8b:3b:e3 (10:b3:d6:8b:3b:e3)
Client hardware address padding: 00000000000000000000
Server host name not given
Boot file name not given
Magic cookie: DHCP
Option: (53) DHCP Message Type (Discover)
Length: 1
DHCP: Discover (1)
Option: (57) Maximum DHCP Message Size
Length: 2
Maximum DHCP Message Size: 1200
Option: (61) Client identifier
Length: 27
Type: 0
Client Identifier: cisco-10b3.d68b.3be3-Vl250
Etapa 4. De acordo com a captura anterior do pacote, o pacote DHCP é recebido corretamente pelo dispositivo.
Solução de problema 2
Etapa 1. Com base na saída de depuração do Gateway Centralizado e nos resultados da captura de pacotes, é necessária uma configuração adicional para evitar que o dispositivo descarte pacotes quando o campo giaddr estiver definido como zero.
Quando um pacote DHCP é recebido com a opção de informações de retransmissão presente, mas o endereço IP do gateway (giaddr) está definido somente como zero, o agente de retransmissão DHCP normalmente descarta o pacote.
Para lidar com esse comportamento, configure o comando ip dhcp relay information trusted.
Centralized-Gateway(config)#interface vlan 250
Centralized-Gateway(config-if)#ip dhcp relay information trusted
Etapa 2. Prossiga com a verificação solicitando um endereço IP do Host 1.
Host1#
*Dec 12 21:32:12.659: %DHCP-6-ADDRESS_ASSIGN: Interface Vlan250 assigned DHCP address 192.0.2.1, mask 255.255.255.0, hostname Host1
Leaf-2#
*Dec 12 21:36:03.232: DHCP_SNOOPING: received new DHCP packet from input interface (Tunnel0)
<snip>
*Dec 12 21:36:03.243: DHCP_SNOOPING: process new DHCP packet, message type: DHCPDISCOVER, input interface: Tu0, MAC da: 3473.2db8.bee3, MAC sa: 10b3.d68b.3be3, IP da: 255.255.255.255, IP sa: 0.0.0.0, DHCP ciaddr: 0.0.0.0, DHCP yiaddr: 0.0.0.0, DHCP siaddr: 0.0.0.0, DHCP giaddr: 0.0.0.0, DHCP chaddr: 10b3.d68b.3be3, efp_id: -2136403878, vlan_id: 250, bootpflag:0x32768(Broadcast)
*Dec 12 21:36:03.243: DHCPS BRIDGE PAK: vlan=250 platform_flags=1
*Dec 12 21:36:03.243: DHCP_SNOOPING: bridge packet send packet to port: FortyGigabitEthernet2/0/1, pak_vlan 250.
*Dec 12 21:36:03.245: DHCP_SNOOPING: received new DHCP packet from input interface (FortyGigabitEthernet2/0/1)
<snip>
*Dec 12 21:36:03.255: DHCP_SNOOPING: process new DHCP packet, message type: DHCPOFFER, input interface: Fo2/0/1, MAC da: ffff.ffff.ffff, MAC sa: 3473.2db8.bee3, IP da: 255.255.255.255, IP sa: 192.0.2.254, DHCP ciaddr: 0.0.0.0, DHCP yiaddr: 192.0.2.1, DHCP siaddr: 0.0.0.0, DHCP giaddr: 192.0.2.254, DHCP chaddr: 10b3.d68b.3be3, efp_id: -2136403878, vlan_id: 250, bootpflag:0x32768(Broadcast)
*Dec 12 21:36:03.255: DHCP_SNOOPING: binary dump of option 82, length: 26 data:
0x52 0x18 0x1 0xC 0x1 0xA 0x0 0x8 0x0 0x0 0x28 0xA 0x1 0x1 0x0 0x0 0x2 0x8 0x0 0x6 0x4C 0x5D 0x3C 0xEB 0x43 0x40
*Dec 12 21:36:03.256: DHCP_SNOOPING: binary dump of extracted circuit id, length: 14 data:
0x1 0xC 0x1 0xA 0x0 0x8 0x0 0x0 0x28 0xA 0x1 0x1 0x0 0x0
*Dec 12 21:36:03.256: DHCP_SNOOPING: binary dump of extracted remote id, length: 10 data:
0x2 0x8 0x0 0x6 0x4C 0x5D 0x3C 0xEB 0x43 0x40
*Dec 12 21:36:03.256: actual_fmt_cid OPT82_FMT_CID_VXLAN_MOD_PORT_INTF global_opt82_fmt_rid OPT82_FMT_RID_DEFAULT_GLOBAL global_opt82_fmt_cid OPT82_FMT_CID_DEFAULT_GLOBAL cid: sub_option_length 12
*Dec 12 21:36:03.256: dhcp_snooping_platform_is_local_dhcp_packet: VXLAN-MOD-PORT opt82 vni 10250, vlan_id 250
*Dec 12 21:36:03.256: DHCP_SNOOPING: opt82 data indicates not a local packet
*Dec 12 21:36:03.256: DHCP_SNOOPING: EVPN enabled Ex GW:fabric relay can't parse option 82 data of the message,it is either in wrong format or not inserted by local switch
*Dec 12 21:36:03.256: DHCP_SNOOPING: client address lookup failed to locate client interface, retry lookup using packet mac DA: ffff.ffff.ffff
*Dec 12 21:36:03.256: DHCP_SNOOPING: lookup packet destination port failed to get mat entry for mac: 10b3.d68b.3be3 vlan_id 250
*Dec 12 21:36:03.256: DHCP_SNOOPING: L2RELAY: Ex GW unicast bridge packet to fabric: vlan id 250 from Fo2/0/1
<snip>
*Dec 12 21:36:03.401: DHCP_SNOOPING: process new DHCP packet, message type: DHCPREQUEST, input interface: Tu0, MAC da: 3473.2db8.bee3, MAC sa: 10b3.d68b.3be3, IP da: 255.255.255.255, IP sa: 0.0.0.0, DHCP ciaddr: 0.0.0.0, DHCP yiaddr: 0.0.0.0, DHCP siaddr: 0.0.0.0, DHCP giaddr: 0.0.0.0, DHCP chaddr: 10b3.d68b.3be3, efp_id: -2136403878, vlan_id: 250, bootpflag:0x32768(Broadcast)
*Dec 12 21:36:03.401: DHCPS BRIDGE PAK: vlan=250 platform_flags=1
*Dec 12 21:36:03.401: DHCP_SNOOPING: bridge packet send packet to port: FortyGigabitEthernet2/0/1, pak_vlan 250.
*Dec 12 21:36:03.402: DHCP_SNOOPING: received new DHCP packet from input interface (FortyGigabitEthernet2/0/1)
<snip>
*Dec 12 21:36:03.413: DHCP_SNOOPING: process new DHCP packet, message type: DHCPACK, input interface: Fo2/0/1, MAC da: ffff.ffff.ffff, MAC sa: 3473.2db8.bee3, IP da: 255.255.255.255, IP sa: 192.0.2.254, DHCP ciaddr: 0.0.0.0, DHCP yiaddr: 192.0.2.1, DHCP siaddr: 0.0.0.0, DHCP giaddr: 192.0.2.254, DHCP chaddr: 10b3.d68b.3be3, efp_id: -2136403878, vlan_id: 250, bootpflag:0x32768(Broadcast)
*Dec 12 21:36:03.413: DHCP_SNOOPING: binary dump of option 82, length: 26 data:
0x52 0x18 0x1 0xC 0x1 0xA 0x0 0x8 0x0 0x0 0x28 0xA 0x1 0x1 0x0 0x0 0x2 0x8 0x0 0x6 0x4C 0x5D 0x3C 0xEB 0x43 0x40
*Dec 12 21:36:03.413: DHCP_SNOOPING: binary dump of extracted circuit id, length: 14 data:
0x1 0xC 0x1 0xA 0x0 0x8 0x0 0x0 0x28 0xA 0x1 0x1 0x0 0x0
*Dec 12 21:36:03.413: DHCP_SNOOPING: binary dump of extracted remote id, length: 10 data:
0x2 0x8 0x0 0x6 0x4C 0x5D 0x3C 0xEB 0x43 0x40
*Dec 12 21:36:03.413: actual_fmt_cid OPT82_FMT_CID_VXLAN_MOD_PORT_INTF global_opt82_fmt_rid OPT82_FMT_RID_DEFAULT_GLOBAL global_opt82_fmt_cid OPT82_FMT_CID_DEFAULT_GLOBAL cid: sub_option_length 12
*Dec 12 21:36:03.413: dhcp_snooping_platform_is_local_dhcp_packet: VXLAN-MOD-PORT opt82 vni 10250, vlan_id 250
*Dec 12 21:36:03.413: DHCP_SNOOPING: opt82 data indicates not a local packet
*Dec 12 21:36:03.413: DHCP_SNOOPING: EVPN enabled Ex GW:fabric relay can't parse option 82 data of the message,it is either in wrong format or not inserted by local switch
*Dec 12 21:36:03.413: DHCP_SNOOPING: client address lookup failed to locate client interface, retry lookup using packet mac DA: ffff.ffff.ffff
*Dec 12 21:36:03.413: DHCP_SNOOPING: lookup packet destination port failed to get mat entry for mac: 10b3.d68b.3be3 vlan_id 250
*Dec 12 21:36:03.413: DHCP_SNOOPING: can't find client's destination port, packet is assumed to be not from local switch, no binding update is needed.
*Dec 12 21:36:03.413: DHCP_SNOOPING: client address lookup failed to locate client interface, retry lookup using packet mac DA: ffff.ffff.ffff
*Dec 12 21:36:03.413: DHCP_SNOOPING: lookup packet destination port failed to get mat entry for mac: 10b3.d68b.3be3 vlan_id 250
*Dec 12 21:36:03.413: DHCP_SNOOPING: L2RELAY: Ex GW unicast bridge packet to fabric: vlan id 250 from Fo2/0/1
Etapa 3. O endereço IP foi atribuído corretamente e sugere-se validar o mesmo comportamento da perspectiva do Host 2.
Host2#
*Dec 12 21:13:03.926: %DHCP-6-ADDRESS_ASSIGN: Interface Vlan250 assigned DHCP address 192.0.2.2, mask 255.255.255.0, hostname Host2
Leaf-2#
*Dec 12 22:08:15.417: DHCP_SNOOPING: received new DHCP packet from input interface (FortyGigabitEthernet2/0/2)
<snip>
*Dec 12 22:08:15.428: DHCP_SNOOPING: process new DHCP packet, message type: DHCPDISCOVER, input interface: Fo2/0/2, MAC da: ffff.ffff.ffff, MAC sa: 10b3.d68b.1963, IP da: 255.255.255.255, IP sa: 0.0.0.0, DHCP ciaddr: 0.0.0.0, DHCP yiaddr: 0.0.0.0, DHCP siaddr: 0.0.0.0, DHCP giaddr: 0.0.0.0, DHCP chaddr: 10b3.d68b.1963, efp_id: -2136403878, vlan_id: 250, bootpflag:0x32768(Broadcast)
*Dec 12 22:08:15.428: DHCP_SNOOPING: add relay information option.
*Dec 12 22:08:15.428: DHCP_SNOOPING: Encoding opt82 CID in vlan-mod-port format
*Dec 12 22:08:15.428: DHCP_SNOOPING:VxLAN : vlan_id 250 VNI 10250 mod 2 port 2
*Dec 12 22:08:15.428: DHCP_SNOOPING: Encoding opt82 RID in MAC address format
*Dec 12 22:08:15.428: DHCP_SNOOPING: binary dump of relay info option, length: 26 data:
0x52 0x18 0x1 0xC 0x1 0xA 0x0 0x8 0x0 0x0 0x28 0xA 0x2 0x2 0x0 0x0 0x2 0x8 0x0 0x6 0x68 0x7D 0xB4 0xA8 0xAF 0x0
*Dec 12 22:08:15.428: DHCPS BRIDGE PAK: vlan=250 platform_flags=1
*Dec 12 22:08:15.428: DHCP_SNOOPING: bridge packet get invalid mat entry: FFFF.FFFF.FFFF, packet is flooded to ingress VLAN: (250)
*Dec 12 22:08:15.428: DHCP_SNOOPING: L2RELAY: cannot find default gw for bd 250: src intf FortyGigabitEthernet2/0/2
*Dec 12 22:08:15.430: DHCP_SNOOPING: received new DHCP packet from input interface (FortyGigabitEthernet2/0/1)
<snip>
*Dec 12 22:08:15.440: DHCP_SNOOPING: process new DHCP packet, message type: DHCPOFFER, input interface: Fo2/0/1, MAC da: ffff.ffff.ffff, MAC sa: 3473.2db8.bee3, IP da: 255.255.255.255, IP sa: 192.0.2.254, DHCP ciaddr: 0.0.0.0, DHCP yiaddr: 192.0.2.2, DHCP siaddr: 0.0.0.0, DHCP giaddr: 192.0.2.254, DHCP chaddr: 10b3.d68b.1963, efp_id: -2136403878, vlan_id: 250, bootpflag:0x32768(Broadcast)
*Dec 12 22:08:15.440: DHCP_SNOOPING: binary dump of option 82, length: 26 data:
0x52 0x18 0x1 0xC 0x1 0xA 0x0 0x8 0x0 0x0 0x28 0xA 0x2 0x2 0x0 0x0 0x2 0x8 0x0 0x6 0x68 0x7D 0xB4 0xA8 0xAF 0x0
*Dec 12 22:08:15.440: DHCP_SNOOPING: binary dump of extracted circuit id, length: 14 data:
0x1 0xC 0x1 0xA 0x0 0x8 0x0 0x0 0x28 0xA 0x2 0x2 0x0 0x0
*Dec 12 22:08:15.440: DHCP_SNOOPING: binary dump of extracted remote id, length: 10 data:
0x2 0x8 0x0 0x6 0x68 0x7D 0xB4 0xA8 0xAF 0x0
*Dec 12 22:08:15.440: actual_fmt_cid OPT82_FMT_CID_VXLAN_MOD_PORT_INTF global_opt82_fmt_rid OPT82_FMT_RID_DEFAULT_GLOBAL global_opt82_fmt_cid OPT82_FMT_CID_DEFAULT_GLOBAL cid: sub_option_length 12
*Dec 12 22:08:15.440: dhcp_snooping_platform_is_local_dhcp_packet: VXLAN-MOD-PORT opt82 vni 10250, vlan_id 250
*Dec 12 22:08:15.440: DHCP_SNOOPING: opt82 data indicates local packet
*Dec 12 22:08:15.440: DHCP_SNOOPING: remove relay information option.
*Dec 12 22:08:15.440: DHCP_SNOOPING opt82_fmt_cid_intf OPT82_FMT_CID_VXLAN_MOD_PORT_INTF opt82_fmt_cid_global OPT82_FMT_CID_DEFAULT_GLOBAL cid: sub_option_length 12
*Dec 12 22:08:15.440: DHCP_SNOOPING: VxLAN vlan_id 250 VNI 10250 mod 2 port 2
*Dec 12 22:08:15.440: DHCP_SNOOPING: mod 2 port 2 idb Fo2/0/2 found for 10b3.d68b.1963
*Dec 12 22:08:15.441: DHCP_SNOOPING: calling forward_dhcp_reply
*Dec 12 22:08:15.441: platform lookup dest vlan for input_if: FortyGigabitEthernet2/0/1, is NOT tunnel, if_output: NULL, if_output->vlan_id: 99999, pak->vlan_id: 250
*Dec 12 22:08:15.441: DHCP_SNOOPING opt82_fmt_cid_intf OPT82_FMT_CID_VXLAN_MOD_PORT_INTF opt82_fmt_cid_global OPT82_FMT_CID_DEFAULT_GLOBAL cid: sub_option_length 12
*Dec 12 22:08:15.441: DHCP_SNOOPING: VxLAN vlan_id 250 VNI 10250 mod 2 port 2
*Dec 12 22:08:15.441: DHCP_SNOOPING: mod 2 port 2 idb Fo2/0/2 found for 10b3.d68b.1963
*Dec 12 22:08:15.441: DHCP_SNOOPING: vlan 250 after pvlan check
<snip>
*Dec 12 22:08:15.930: DHCP_SNOOPING: process new DHCP packet, message type: DHCPREQUEST, input interface: Fo2/0/2, MAC da: ffff.ffff.ffff, MAC sa: 10b3.d68b.1963, IP da: 255.255.255.255, IP sa: 0.0.0.0, DHCP ciaddr: 0.0.0.0, DHCP yiaddr: 0.0.0.0, DHCP siaddr: 0.0.0.0, DHCP giaddr: 0.0.0.0, DHCP chaddr: 10b3.d68b.1963, efp_id: -2136403878, vlan_id: 250, bootpflag:0x32768(Broadcast)
*Dec 12 22:08:15.930: DHCP_SNOOPING: add relay information option.
*Dec 12 22:08:15.930: DHCP_SNOOPING: Encoding opt82 CID in vlan-mod-port format
*Dec 12 22:08:15.930: DHCP_SNOOPING:VxLAN : vlan_id 250 VNI 10250 mod 2 port 2
*Dec 12 22:08:15.930: DHCP_SNOOPING: Encoding opt82 RID in MAC address format
*Dec 12 22:08:15.930: DHCP_SNOOPING: binary dump of relay info option, length: 26 data:
0x52 0x18 0x1 0xC 0x1 0xA 0x0 0x8 0x0 0x0 0x28 0xA 0x2 0x2 0x0 0x0 0x2 0x8 0x0 0x6 0x68 0x7D 0xB4 0xA8 0xAF 0x0
*Dec 12 22:08:15.930: DHCPS BRIDGE PAK: vlan=250 platform_flags=1
*Dec 12 22:08:15.930: DHCP_SNOOPING: bridge packet get invalid mat entry: FFFF.FFFF.FFFF, packet is flooded to ingress VLAN: (250)
*Dec 12 22:08:15.930: DHCP_SNOOPING: L2RELAY: cannot find default gw for bd 250: src intf FortyGigabitEthernet2/0/2
*Dec 12 22:08:15.932: DHCP_SNOOPING: received new DHCP packet from input interface (FortyGigabitEthernet2/0/1)
<snip>
*Dec 12 22:08:15.940: DHCP_SNOOPING: process new DHCP packet, message type: DHCPACK, input interface: Fo2/0/1, MAC da: ffff.ffff.ffff, MAC sa: 3473.2db8.bee3, IP da: 255.255.255.255, IP sa: 192.0.2.254, DHCP ciaddr: 0.0.0.0, DHCP yiaddr: 192.0.2.2, DHCP siaddr: 0.0.0.0, DHCP giaddr: 192.0.2.254, DHCP chaddr: 10b3.d68b.1963, efp_id: -2136403878, vlan_id: 250, bootpflag:0x32768(Broadcast)
*Dec 12 22:08:15.943: DHCP_SNOOPING: binary dump of option 82, length: 26 data:
0x52 0x18 0x1 0xC 0x1 0xA 0x0 0x8 0x0 0x0 0x28 0xA 0x2 0x2 0x0 0x0 0x2 0x8 0x0 0x6 0x68 0x7D 0xB4 0xA8 0xAF 0x0
*Dec 12 22:08:15.943: DHCP_SNOOPING: binary dump of extracted circuit id, length: 14 data:
0x1 0xC 0x1 0xA 0x0 0x8 0x0 0x0 0x28 0xA 0x2 0x2 0x0 0x0
<snip>
Histórico de revisões
| Revisão | Data de publicação | Comentários |
|---|---|---|
1.0 |
15-Jun-2026
|
Versão inicial |
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