两个路由器，一个调制解调器，双 IP，第二个地址偶尔会掉线

网络工程 ipv4 arp
2021-08-03 09:59:16

我们有两个 ER-X 通过非托管交换机连接到 Cisco DPC3010 调制解调器。每个都在不同的块中分配了一个静态 WAN IP：174.79.186.x/27 和 98.187.238.x/27。每隔一段时间（大约一个月一次），我们就会失去第二个 (98.187.238.x/27) IP 上的连接，需要调用我们的 ISP (Cox) 来清除 ARP 缓存，此时连接简历。这可能是我们这边的配置问题，还是仅仅是 ISP 的问题？

编辑：在两个路由器上运行 tcpdump，我可以看到 98.187.238.x/27 地址的 ARP 请求，并且相应的路由器响应，但显然 Cox 没有看到响应，因为请求每隔几秒钟出现一次：

Request who-has 98.187.238.xx tell 98.187.238.65, length 46
78:8a:20:0d:5d:92 > 1c:6a:7a:80:d2:d9, ARP, length 42: Reply 98.187.238.xx is-at 78:8a:20:0d:5d:92, length 28

网络图

路由器配置： 

firewall {
    all-ping enable
    broadcast-ping disable
    group {
    }
    ipv6-receive-redirects disable
    ipv6-src-route disable
    ip-src-route disable
    log-martians enable
    name WAN_IN {
        default-action drop
        description "WAN to internal"
        rule 10 {
            action accept
            description "Allow established/related"
            state {
                established enable
                related enable
            }
        }
        rule 20 {
            action drop
            description "Drop invalid state"
            state {
                invalid enable
            }
        }
    }
    name WAN_LOCAL {
        default-action drop
        description "WAN to router"
        rule 10 {
            action accept
            description "Allow established/related"
            state {
                established enable
                related enable
            }
        }
        rule 20 {
            action drop
            description "Drop invalid state"
            state {
                invalid enable
            }
        }
        rule 21 {
            action accept
            description "Allow eSP"
            log disable
            protocol esp
        }
        rule 22 {
            action accept
            description "Allow L2TP"
            destination {
                port 500,1701,4500
            }
            log disable
            protocol udp
        }
        rule 23 {
            action accept
            description "Allow GRE"
            destination {
            }
            log disable
            protocol gre
        }
        rule 24 {
            action accept
            description "Allow openVPN"
            destination {
                group {
                }
                port 1194
            }
            log disable
            protocol tcp_udp
            state {
                established enable
                invalid disable
                new enable
                related enable
            }
        }
        rule 25 {
            action accept
            destination {
                group {
                    address-group ADDRv4_eth0
                }
            }
            log disable
            protocol icmp
        }
    }
    receive-redirects disable
    send-redirects enable
    source-validation disable
    syn-cookies enable
}
interfaces {
    bridge br0 {
        aging 300
        bridged-conntrack disable
        hello-time 2
        max-age 20
        priority 32768
        promiscuous disable
        stp false
    }
    ethernet eth0 {
        address 174.79.186.xx/27
        description Internet
        duplex auto
        firewall {
            in {
                name WAN_IN
            }
            local {
                name WAN_LOCAL
            }
        }
        mac C0:4A:00:66:49:51
        speed auto
    }
    ethernet eth1 {
        description Local
        duplex auto
        speed auto
    }
    ethernet eth2 {
        description Local
        duplex auto
        speed auto
    }
    ethernet eth3 {
        bridge-group {
            bridge br0
        }
        description Local
        duplex auto
        speed auto
    }
    ethernet eth4 {
        description Local
        duplex auto
        speed auto
    }
    loopback lo {
    }
    openvpn vtun0 {
        bridge-group {
            bridge br0
            cost 100
        }
        description "Pascal phone"
        device-type tap
        encryption aes256
        local-host 174.79.186.xx
        local-port 1194
        mode site-to-site
        openvpn-option --float
        openvpn-option "--auth none"
        openvpn-option "--ping 5"
        remote-port 1194
        shared-secret-key-file *REMOVED*
    }
    switch switch0 {
        address 192.168.1.1/24
        description Local
        mtu 1500
        switch-port {
            interface eth1 {
            }
            interface eth2 {
            }
            interface eth4 {
            }
            vlan-aware disable
        }
    }
}
port-forward {
    auto-firewall enable
    hairpin-nat enable
    lan-interface switch0
    lan-interface eth4.2
    wan-interface eth0
}
protocols {
    static {
    }
}
service {
    dhcp-server {
        disabled false
        hostfile-update disable
        shared-network-name LAN {
            authoritative disable
            subnet 192.168.1.0/24 {
                default-router 192.168.1.1
                dns-server 8.8.8.8
                dns-server 8.8.4.4
                lease 7200
                start 192.168.1.51 {
                    stop 192.168.1.100
                }
                static-mapping Canon_Pixma_MX452 {
                    ip-address 192.168.1.75
                    mac-address 18:0c:ac:f8:0d:4c
                }
                static-mapping SCOTT-PC {
                    ip-address 192.168.1.59
                    mac-address 00:50:8d:9d:3b:f0
                }
            }
        }
        use-dnsmasq disable
    }
    dns {
        forwarding {
            cache-size 150
            listen-on switch0
            listen-on eth4.2
        }
    }
    gui {
        http-port 80
        https-port 443
        older-ciphers enable
    }
    nat {
        rule 5010 {
            description "masquerade for WAN"
            log disable
            outbound-interface eth0
            protocol all
            source {
                address 192.168.1.0/24
            }
            type masquerade
        }
    }
    ssh {
        port 22
        protocol-version v2
    }
    upnp {
        listen-on switch0 {
            outbound-interface eth0
        }
    }
}
system {
    gateway-address 174.79.186.33
    host-name ER-XP
    login {
        user admin {
            authentication {
                encrypted-password ****************
                plaintext-password ****************
            }
            full-name *REMOVED*
            level admin
        }
    }
    name-server 8.8.8.8
    name-server 8.8.4.4
    ntp {
        server 0.ubnt.pool.ntp.org {
        }
        server 1.ubnt.pool.ntp.org {
        }
        server 2.ubnt.pool.ntp.org {
        }
        server 3.ubnt.pool.ntp.org {
        }
    }
    syslog {
        global {
            facility all {
                level notice
            }
            facility protocols {
                level debug
            }
        }
    }
    time-zone America/New_York
}
traffic-control {
}

和

firewall {
    all-ping enable
    broadcast-ping disable
    ipv6-receive-redirects disable
    ipv6-src-route disable
    ip-src-route disable
    log-martians enable
    name LAN_LOCAL {
        default-action accept
        description "Local network isolation"
        rule 1 {
            action drop
            destination {
                address 192.168.1.xx
            }
            log disable
            protocol !icmp
            source {
                address 192.168.44.0/24
            }
        }
    }
    name WAN_IN {
        default-action drop
        description "WAN to internal"
        rule 10 {
            action accept
            description "Allow established/related"
            state {
                established enable
                related enable
            }
        }
        rule 20 {
            action drop
            description "Drop invalid state"
            state {
                invalid enable
            }
        }
    }
    name WAN_LOCAL {
        default-action drop
        description "WAN to router"
        rule 10 {
            action accept
            description "Allow established/related"
            state {
                established enable
                related enable
            }
        }
        rule 30 {
            action drop
            description "Drop invalid state"
            state {
                invalid enable
            }
        }
        rule 31 {
            action accept
            description "Allow ICMP"
            destination {
                group {
                    address-group ADDRv4_eth0
                }
            }
            icmp {
                type 8
            }
            log disable
            protocol icmp
        }
    }
    receive-redirects disable
    send-redirects enable
    source-validation disable
    syn-cookies enable
}
interfaces {
    ethernet eth0 {
        address 98.187.238.xx/27
        description Internet
        duplex auto
        firewall {
            in {
                name WAN_IN
            }
            local {
                name WAN_LOCAL
            }
        }
        speed auto
    }
    ethernet eth1 {
        address 192.168.1.xx/24
        description Mgmt
        duplex auto
        speed auto
    }
    ethernet eth2 {
        description Local
        duplex auto
        speed auto
    }
    ethernet eth3 {
        description Local
        duplex auto
        speed auto
    }
    ethernet eth4 {
        description Local
        duplex auto
        speed auto
    }
    loopback lo {
    }
    switch switch0 {
        address 192.168.44.1/24
        description Webserver_network
        firewall {
            local {
                name LAN_LOCAL
            }
        }
        mtu 1500
        switch-port {
            interface eth2 {
            }
            interface eth3 {
            }
            interface eth4 {
            }
            vlan-aware disable
        }
    }
}
port-forward {
    auto-firewall enable
    hairpin-nat enable
    lan-interface switch0
    rule 1 {
        description HTTPS
        forward-to {
            address 192.168.44.xx
            port 443
        }
        original-port 443
        protocol tcp
    }
    rule 2 {
        description SSH
        forward-to {
            address 192.168.44.xx
            port 22
        }
        original-port *REMOVED*
        protocol tcp_udp
    }
    rule 3 {
        description "HTTP for LE"
        forward-to {
            address 192.168.44.xx
            port 80
        }
        original-port 80
        protocol tcp_udp
    }
    wan-interface eth0
}
service {
    dns {
        forwarding {
            cache-size 150
            listen-on eth1
            listen-on switch0
        }
    }
    gui {
        http-port 80
        https-port 443
        listen-address 192.168.1.xx
        older-ciphers enable
    }
    nat {
        rule 5010 {
            description "masquerade for WAN"
            outbound-interface eth0
            type masquerade
        }
    }
    ssh {
        listen-address 192.168.1.xx
        port 22
        protocol-version v2
    }
    ubnt-discover {
        disable
    }
    unms {
        disable
    }
}
system {
    gateway-address 98.187.238.65
    host-name USXR
    login {
        user *REMOVED* {
            authentication {
                encrypted-password ****************
            }
            level admin
        }
    }
    name-server 8.8.8.8
    name-server 8.8.4.4
    ntp {
        server 0.ubnt.pool.ntp.org {
        }
        server 1.ubnt.pool.ntp.org {
        }
        server 2.ubnt.pool.ntp.org {
        }
        server 3.ubnt.pool.ntp.org {
        }
    }
    syslog {
        global {
            facility all {
                level notice
            }
            facility protocols {
                level debug
            }
        }
    }
    time-zone America/New_York
}
2个回答

我现在认为 192.168.44.0 路由器有缺陷有两个原因：

  1. 登录到 web-gui 上的 cli 需要将近 30 秒。其他相同的路由器没有这种延迟。

  2. 我们的 ISP 能够在 174.79.186.xx/27 块中找到与我们现有主地址相邻的未使用地址。当我在具有 192.168.44.0/24 子网的路由器上配置该地址时，它仍然无法响应 ARP 请求并且从未看到来自网关的 ARP 响应。奇怪的是，当使用旧地址配置时，它的工作时间很短。

编辑：（2/10/2018）

今天我在没有恢复配置的情况下出厂重置 192.168.44.0 并在其上运行基本向导，提供更新的静态 IP。它拒绝查看网关的 ARP 响应：

Request who-has 174.79.186.33 tell 174.79.186.xx, length 46

据说它响应网关的请求：

Request who-has 174.79.186.xx tell 174.79.186.33, length 46
78:8a:20:0d:5d:92 > 1c:6a:7a:80:d2:d9, ARP, length 42: Reply 174.79.186.xx is-at 78:8a:20:0d:5d:92, length 28

但没有成功，因为上述条目每分钟重复多次。

从更新中提供的信息来看，这确实是 ISP 方面的问题。

但是，我会联系 ISP 支持并提供事实信息，解释您在此处告诉我们的内容（连接经常断开，当他们重置设备时返回），向他们提供 tcpdump，并要求他们帮助您解决问题。然后让他们自己得出结论。

这种方法通常比直接说“修复你该死的东西”更成功。有时，当问题实际上出在您的身边时，它可以挽救您的面子。

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