Catalyst 2960 后面的设备未收到 DHCP 地址

网络工程 思科 转变 dhcp
2021-07-16 01:53:21

我遇到了 DHCP 无法穿越到交换机后面的设备的问题。我部署了许多其他具有几乎相同配置的交换机，它们能够接收 DHCP 地址。在我遇到问题的这个交换机上，大多数设备都有一个静态地址，它们可以访问并且可以从网络访问就好了。我正在尝试将 AP 添加到其中一个端口，作为 UniFi，它需要从服务器获取 DHCP 地址，但无法这样做。当我将 AP 连接到具有相同端口配置的另一台交换机时，它会正确获取 DHCP 地址。在这个有 DHCP 问题的交换机上，如果我分配了一个静态地址，那么我又可以访问网络了。

我想弄清楚为什么 DHCP 没有被正确传递，或者我是否有配置错误。DHCP 服务器是 Windows 服务器，所有其他未连接到此交换机的设备都可以根据需要联系和接收预留或地址。

VLAN 信息由 VTP 向下传递，并且是最新版本。

问题开关配置：

!
! Last configuration change at 19:25:03 UTC Tue Jul 1 2014
! NVRAM config last updated at 19:25:05 UTC Tue Jul 1 2014
!
version 12.2
no service pad
service timestamps debug datetime msec
service timestamps log datetime msec
no service password-encryption
!
boot-start-marker
boot-end-marker
!

!
!
no aaa new-model
switch 1 provision ws-c2960s-24ps-l
authentication mac-move permit
ip subnet-zero
!
!
!
!
spanning-tree mode pvst
spanning-tree etherchannel guard misconfig
spanning-tree extend system-id
!
!
!
!
vlan internal allocation policy ascending
!
!
!
interface FastEthernet0
 no ip address
!
interface GigabitEthernet1/0/1
 description MDF uplink 1/0/20
 switchport mode trunk
!
interface GigabitEthernet1/0/2
 description Fixed Cam
 switchport access vlan 100
 switchport mode access
 spanning-tree portfast
!
interface GigabitEthernet1/0/3
 description PLC
 switchport access vlan 100
 switchport mode access
 spanning-tree portfast
!
interface GigabitEthernet1/0/4
 switchport access vlan 100
 switchport mode access
 spanning-tree portfast
!
interface GigabitEthernet1/0/5
 switchport access vlan 100
 switchport mode access
 spanning-tree portfast
!
interface GigabitEthernet1/0/6
 switchport access vlan 100
 switchport mode access
 spanning-tree portfast
!
interface GigabitEthernet1/0/7
 description IDF Link 1/0/22
 switchport mode trunk
!
interface GigabitEthernet1/0/8
 switchport access vlan 100
 switchport mode access
 spanning-tree portfast
!
interface GigabitEthernet1/0/9
 switchport access vlan 100
 switchport mode access
 spanning-tree portfast
!
interface GigabitEthernet1/0/10
 switchport access vlan 100
 switchport mode access
 spanning-tree portfast
!
interface GigabitEthernet1/0/11
 switchport access vlan 100
 switchport mode access
 spanning-tree portfast
!
interface GigabitEthernet1/0/12
 switchport access vlan 100
 switchport mode access
 spanning-tree portfast
!
interface GigabitEthernet1/0/13
 switchport access vlan 100
 switchport mode access
 spanning-tree portfast
!
interface GigabitEthernet1/0/14
 switchport access vlan 100
 switchport mode access
 spanning-tree portfast
!
interface GigabitEthernet1/0/15
 switchport access vlan 100
 switchport mode access
 spanning-tree portfast
!
interface GigabitEthernet1/0/16
 switchport access vlan 100
 switchport mode access
 spanning-tree portfast
!
interface GigabitEthernet1/0/17
 switchport access vlan 100
 switchport mode access
 spanning-tree portfast
!
interface GigabitEthernet1/0/18
 switchport access vlan 100
 switchport mode access
 spanning-tree portfast
!
interface GigabitEthernet1/0/19
 switchport access vlan 100
 switchport mode access
 spanning-tree portfast
!
interface GigabitEthernet1/0/20
 switchport access vlan 100
 switchport mode access
 spanning-tree portfast
!
interface GigabitEthernet1/0/21
 switchport access vlan 100
 switchport mode access
 spanning-tree portfast
!
interface GigabitEthernet1/0/22
 switchport access vlan 100
 switchport mode access
 spanning-tree portfast
!
interface GigabitEthernet1/0/23
 switchport access vlan 205
 switchport mode access
!
interface GigabitEthernet1/0/24
 description UniFi
 switchport trunk native vlan 200
 switchport mode trunk
!
interface GigabitEthernet1/0/25
!
interface GigabitEthernet1/0/26
!
interface GigabitEthernet1/0/27
!
interface GigabitEthernet1/0/28
!
interface Vlan1
 no ip address
!
interface Vlan205
 ip address 192.168.205.35 255.255.255.0
!
ip default-gateway 192.168.205.1
ip http server
ip http secure-server
ip sla enable reaction-alerts
!
!
line con 0
line vty 0 4
 password ----
 login
line vty 5 15
 login
!
end

VLAN（通过 VTP）

VLAN Name                             Status    Ports
---- -------------------------------- --------- -------------------------------
1    default                            active  Gi1/0/22, Gi1/0/25, Gi1/0/26
                                                Gi1/0/27, Gi1/0/28
99   guest                              active
100  plc                                active  Gi1/0/2, Gi1/0/3, Gi1/0/4
                                                Gi1/0/5, Gi1/0/6, Gi1/0/8
                                                Gi1/0/9, Gi1/0/10, Gi1/0/11
                                                Gi1/0/12, Gi1/0/13, Gi1/0/14
                                                Gi1/0/15, Gi1/0/16, Gi1/0/17
                                                Gi1/0/18, Gi1/0/19, Gi1/0/20
                                                Gi1/0/21
200 wlan                                active
205 Mgmnt                               active  Gi1/0/23

接口： 

Port      Name               Status       Vlan       Duplex  Speed Type
Gi1/0/1   MDF uplink 1/0/20  connected    trunk      a-half  a-100 10/100/1000BaseTX
Gi1/0/2   Fixed Cam          connected    100        a-full  a-100 10/100/1000BaseTX
Gi1/0/3   PLC                connected    100        a-full  a-100 10/100/1000BaseTX
Gi1/0/4                      connected    100        a-full  a-100 10/100/1000BaseTX
Gi1/0/5                      notconnect   100          auto   auto 10/100/1000BaseTX
Gi1/0/6                      notconnect   100          auto   auto 10/100/1000BaseTX
Gi1/0/7   IDF Link 1/0/22    connected    trunk      a-full  a-100 10/100/1000BaseTX
Gi1/0/8                      notconnect   100          auto   auto 10/100/1000BaseTX
Gi1/0/9                      connected    100        a-full a-1000 10/100/1000BaseTX
Gi1/0/10                     notconnect   100          auto   auto 10/100/1000BaseTX
Gi1/0/11                     notconnect   100          auto   auto 10/100/1000BaseTX
Gi1/0/12                     notconnect   100          auto   auto 10/100/1000BaseTX
Gi1/0/13                     notconnect   100          auto   auto 10/100/1000BaseTX
Gi1/0/14                     connected    100        a-full  a-100 10/100/1000BaseTX
Gi1/0/15                     notconnect   100          auto   auto 10/100/1000BaseTX
Gi1/0/16                     notconnect   100          auto   auto 10/100/1000BaseTX
Gi1/0/17                     notconnect   100          auto   auto 10/100/1000BaseTX
Gi1/0/18                     notconnect   100          auto   auto 10/100/1000BaseTX
Gi1/0/19                     notconnect   100          auto   auto 10/100/1000BaseTX
Gi1/0/20                     notconnect   100          auto   auto 10/100/1000BaseTX
Gi1/0/21                     notconnect   100          auto   auto 10/100/1000BaseTX
Gi1/0/22                     notconnect   1            auto   auto 10/100/1000BaseTX
Gi1/0/23                     notconnect   205          auto   auto 10/100/1000BaseTX
Gi1/0/24  UniFi              connected    trunk      a-full  a-100 10/100/1000BaseTX
Gi1/0/25                     notconnect   1            auto   auto Not Present
Gi1/0/26                     notconnect   1            auto   auto Not Present
Gi1/0/27                     notconnect   1            auto   auto Not Present
Gi1/0/28                     notconnect   1            auto   auto Not Present
Fa0                          notconnect   routed       auto   auto 10/100BaseTX

问题切换sh interfaces trunk：

Port        Mode             Encapsulation  Status        Native vlan
Gi1/0/1     on               802.1q         trunking      1
Gi1/0/7     on               802.1q         trunking      1
Gi1/0/24    on               802.1q         trunking      200

Port        Vlans allowed on trunk
Gi1/0/1     1-4094
Gi1/0/7     1-4094
Gi1/0/24    1-4094

Port        Vlans allowed and active in management domain
Gi1/0/1     1,98-111,200-215,300
Gi1/0/7     1,98-111,200-215,300
Gi1/0/24    1,98-111,200-215,300

Port        Vlans in spanning tree forwarding state and not pruned
Gi1/0/1     1,98-111,200-215,300
Gi1/0/7     1,98-111,200-215,300
Gi1/0/24    1,98-111,200-215,300

MDF Gi1/0/20（问题交换机上与Gi1/0/1的连接）：

sh interfaces trunk

Port        Mode             Encapsulation  Status        Native vlan
Gi1/0/20    on               802.1q         trunking      1

Port        Vlans allowed on trunk
Gi1/0/20    1-4094

Port        Vlans allowed and active in management domain
Gi1/0/20    1,98-111,200-215,300

Port        Vlans in spanning tree forwarding state and not pruned
Gi1/0/20    1,98-111,200-215,300



sh run
!
interface GigabitEthernet1/0/20
 description ProblemSwitch gi1/0/1
 switchport mode trunk
!

STP信息

问题切换

sh spanning-tree vlan 200

VLAN0200
  Spanning tree enabled protocol ieee
  Root ID    Priority    24683
             Address     b4a4.e322.7500
             Cost        19
             Port        1 (GigabitEthernet1/0/1)
             Hello Time   2 sec  Max Age 20 sec  Forward Delay 15 sec

  Bridge ID  Priority    32875  (priority 32768 sys-id-ext 200)
             Address     b4a4.e313.2480
             Hello Time   2 sec  Max Age 20 sec  Forward Delay 15 sec
             Aging Time  300 sec

Interface           Role Sts Cost      Prio.Nbr Type
------------------- ---- --- --------- -------- --------------------------------
Gi1/0/1             Root FWD 19        128.1    P2p
Gi1/0/7             Desg FWD 19        128.7    P2p
Gi1/0/24            Desg FWD 19        128.24   P2p


sh spanning-tree interface gi1/0/1

Vlan                Role Sts Cost      Prio.Nbr Type
------------------- ---- --- --------- -------- --------------------------------
VLAN0001            Root FWD 19        128.1    P2p
VLAN0098            Root FWD 19        128.1    P2p
VLAN0099            Root FWD 19        128.1    P2p
VLAN0100            Root FWD 19        128.1    P2p
VLAN0101            Root FWD 19        128.1    P2p
VLAN0102            Root FWD 19        128.1    P2p
VLAN0103            Root FWD 19        128.1    P2p
VLAN0104            Root FWD 19        128.1    P2p
VLAN0105            Root FWD 19        128.1    P2p
VLAN0106            Root FWD 19        128.1    P2p
VLAN01.1            Root FWD 19        128.1    P2p
VLAN0108            Root FWD 19        128.1    P2p
VLAN0109            Root FWD 19        128.1    P2p
VLAN0110            Root FWD 19        128.1    P2p
VLAN0111            Root FWD 19        128.1    P2p
VLAN0200            Root FWD 19        128.1    P2p
VLAN0201            Root FWD 19        128.1    P2p
VLAN0205            Root FWD 19        128.1    P2p
VLAN0211            Root FWD 19        128.1    P2p
VLAN0300            Root FWD 19        128.1    P2p

中密度纤维板开关

sh spanning-tree vlan 200

VLAN0200
  Spanning tree enabled protocol rstp
  Root ID    Priority    24683
             Address     b4a4.e322.7500
             This bridge is the root
             Hello Time   2 sec  Max Age 20 sec  Forward Delay 15 sec

  Bridge ID  Priority    24683  (priority 24576 sys-id-ext 200)
             Address     b4a4.e322.7500
             Hello Time   2 sec  Max Age 20 sec  Forward Delay 15 sec
             Aging Time  300 sec

Interface           Role Sts Cost      Prio.Nbr Type
------------------- ---- --- --------- -------- --------------------------------
Gi2/0/1             Desg FWD 4         128.55   P2p Edge
Gi2/0/2             Desg FWD 4         128.56   P2p Edge
Gi2/0/3             Desg FWD 4         128.57   P2p Edge
Gi2/0/12            Desg FWD 4         128.66   P2p Peer(STP)
Gi2/0/13            Desg FWD 4         128.67   P2p
Gi2/0/18            Desg FWD 19        128.72   P2p Peer(STP)
Gi2/0/24            Desg FWD 19        128.78   P2p
Gi2/0/25            Desg FWD 4         128.79   P2p

Interface           Role Sts Cost      Prio.Nbr Type
------------------- ---- --- --------- -------- --------------------------------

Gi2/0/26            Desg FWD 4         128.80   P2p Peer(STP)
Gi1/0/1             Desg FWD 4         128.1    P2p Edge
Gi1/0/2             Desg FWD 4         128.2    P2p Edge
Gi1/0/3             Desg FWD 4         128.3    P2p Edge
Gi1/0/20            Desg FWD 19        128.20   P2p Peer(STP)
Gi1/0/21            Desg FWD 19        128.21   P2p Peer(STP)
Gi1/0/22            Desg FWD 4         128.22   P2p
Gi1/0/24            Desg FWD 4         128.24   P2p
Gi1/0/25            Desg FWD 4         128.25   P2p Peer(STP)
Gi3/0/1             Desg FWD 4         128.109  P2p Edge
Gi3/0/2             Desg FWD 4         128.110  P2p Edge
Gi3/0/3             Desg FWD 4         128.111  P2p Edge

sh spanning-tree interface gi1/0/20

Vlan                Role Sts Cost      Prio.Nbr Type
------------------- ---- --- --------- -------- --------------------------------
VLAN0001            Desg FWD 19        128.20   P2p Peer(STP)
VLAN0098            Desg FWD 19        128.20   P2p Peer(STP)
VLAN0099            Desg FWD 19        128.20   P2p Peer(STP)
VLAN0100            Desg FWD 19        128.20   P2p Peer(STP)
VLAN0101            Desg FWD 19        128.20   P2p Peer(STP)
VLAN0102            Desg FWD 19        128.20   P2p Peer(STP)
VLAN0103            Desg FWD 19        128.20   P2p Peer(STP)
VLAN0104            Desg FWD 19        128.20   P2p Peer(STP)
VLAN0105            Desg FWD 19        128.20   P2p Peer(STP)
VLAN0106            Desg FWD 19        128.20   P2p Peer(STP)
VLAN0107            Desg FWD 19        128.20   P2p Peer(STP)
VLAN0108            Desg FWD 19        128.20   P2p Peer(STP)
VLAN0109            Desg FWD 19        128.20   P2p Peer(STP)
VLAN0110            Desg FWD 19        128.20   P2p Peer(STP)
VLAN0111            Desg FWD 19        128.20   P2p Peer(STP)
VLAN0200            Desg FWD 19        128.20   P2p Peer(STP)
VLAN0201            Desg FWD 19        128.20   P2p Peer(STP)
VLAN0205            Desg FWD 19        128.20   P2p Peer(STP)
VLAN0211            Desg FWD 19        128.20   P2p Peer(STP)
VLAN0300            Desg FWD 19        128.20   P2p Peer(STP)

我可以毫无问题地从交换机 ping 网关和服务器。在静态分配的 IP 和 DNS 不在本机 VLAN 上的计算机上，我无法 ping 计算机名称，但可以 ping IP 地址。通过分配本地 VLAN ip，我可以 ping 计算机名称。

有人可以帮助弄清楚为什么我无法从这台交换机后面获得 DHCP 地址吗？

编辑：包括整个消毒配置。

2个回答

首先，感谢@AveryAbbot、@Ron、@YLearn 和@DanielYusteAroca 为我解决这个问题提供了极大的帮助。

目前，我已确定问题的原因在于 Ubiquity 的接入点，而不是 Cisco 交换机本身的问题。在进一步研究并与设置此功能的其他一些网络人员交谈后，事实证明该交换机通过 NanoBridge M5 连接到 MDF（我不知道）。也就是说，它不是直线运行，而是以桥接模式连接到 Station 的无线 AP。在此设置中，mac 地址在 AP 端停止，每个传出数据包都获得 AP 的 mac 地址。要解决此问题，您需要在 Ubiquiti 的 Wireless WDS 透明桥接模式下设置 AP 和 Station。在 AP 和 Station 上更改此设置并重新加载交换机后，连接到问题交换机的所有设备现在都会在请求时接收正确的 DHCP 租用。

如果 DHCP 服务器位于不同的 VLAN 上，则您需要使用 ip 助手（DHCP 中继代理）。由于 DHCP 是第 2 层协议，它不能跨越 IP 子网。ip helper 将在执行 vlan 间路由的设备上配置。这通常发生在核心交换机上。

以下是有关使用 ip helper 的信息：

http://www.cisco.com/en/US/docs/ios/12_4t/ip_addr/configuration/guide/htdhcpre.html

此外，调试 DHCP 可以帮助您缩小问题的范围。您需要在运行中继代理的设备上执行此操作。

调试 ip dhcp 服务器数据包

如果中继代理正在工作，您应该会看到类似的内容：

DHCPD：从客户端 015c.260a.4837.95 (192.168.200.201) 收到的 DHCPINFORM。DHCPD：使用地址 192.168.200.1 查找绑定 DHCPD：将 giaddr 设置为 192.168.200.1。DHCPD：从 015c.260a.4837.95 转发到 192.168.206.227 的 BOOTREQUEST

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