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Newifi-D2逻辑结构探究

发表于 更新于 分类于 Disqus：
本文字数： 2.3k 阅读时长 ≈ 4 分钟

逻辑构造图

先放结论，经过探究，Newifi D2的网络结构图是这样的：

  • 可编程交换机各端口对应关系为
Port Switch Port
Internal (CPU) 6
Internet (WAN) 4
LAN1 3
LAN2 2
LAN3 1
LAN4 0
  • 默认的网络配置为
Interface Name Description Default configuration
br-lan LAN & 2.4GHz WiFi & 5GHz WiFi 192.168.1.1/24
vlan1 (eth0.1) LAN ports(1 - 4) None
vlan2 (eth0.2) WAN port DHCP
wlan0 2.4GHz WiFI Disabled
wlan1 5GHz WiFI Disabled

产品信息

芯片结构

Newifi已经倒闭所以找不到官网产品信息页了，根据MediaTek | MT7621A/N的介绍，MT7621A内嵌 5端口千兆以太网交换机，下面是 MT7621A Datasheet 中的芯片功能模块图，图中也可以看出WAN口和4个LAN口同属于一个Switch，他们都是交换机的端口。除了以太网交换机，芯片还包含了两个以PCIe方式连接的WiFi模块，11n WiFi 和 11ac WiFi，分别用于2.4GHz和5GHz。

内嵌可编程交换机结构

下面是摘自 MT7621 Giga Switch Programming Guide 的交换机功能模块图以及部分寄存器配置截图，该文档描述了 MT7621A 内嵌可编程交换机的结构以及编程方法，可以看到内嵌可编程交换机共有 7 个Port，其中有5个Port引出了网口，根据交换机编程手册，可以配置 CPU_PORT 的 Port Number。

Openwrt for Newifi D2 交换机端口分配方式

我也不懂设备树文件（Device Tree Source）的具体语法，但阅读下面两段代码，大致可以看出Openwrt源码对Newifi D2硬件交换机的配置方式为：

  • 将 Port0 - Port3 记为 lan4 - lan1
  • 将 Port4 记为 wan
  • 将 Port6 定义为 CPU端口

这些都是对 MT7621A 中集成的硬件交换机的配置。

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// From: /target/linux/ramips/dts/mt7621.dtsi
// Url: https://github.com/openwrt/openwrt/blob/master/target/linux/ramips/dts/mt7621.dtsi
ports {
					#address-cells = <1>;
					#size-cells = <0>;
					reg = <0>;

					port@0 {
						status = "disabled";
						reg = <0>;
						label = "lan0";
					};

					port@1 {
						status = "disabled";
						reg = <1>;
						label = "lan1";
					};

					port@2 {
						status = "disabled";
						reg = <2>;
						label = "lan2";
					};

					port@3 {
						status = "disabled";
						reg = <3>;
						label = "lan3";
					};

					port@4 {
						status = "disabled";
						reg = <4>;
						label = "lan4";
					};

					port@6 {
						reg = <6>;
						label = "cpu";
						ethernet = <&gmac0>;
						phy-mode = "rgmii";

						fixed-link {
							speed = <1000>;
							full-duplex;
						};
					};
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// From: /target/linux/ramips/dts/mt7621_d-team_newifi-d2.dts
// Url: https://github.com/openwrt/openwrt/blob/master/target/linux/ramips/dts/mt7621_d-team_newifi-d2.dts
&switch0 {
	ports {
		port@0 {
			status = "okay";
			label = "lan4";
		};

		port@1 {
			status = "okay";
			label = "lan3";
		};

		port@2 {
			status = "okay";
			label = "lan2";
		};

		port@3 {
			status = "okay";
			label = "lan1";
		};

		port@4 {
			status = "okay";
			label = "wan";
			mtd-mac-address = <&factory 0xe006>;
		};
	};
};

查看网络设备

通过 ls /sys/class/net/ -al 可以查看系统中所有的网络设备： 

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root@OpenWrt:~# ls /sys/class/net/ -l
lrwxrwxrwx    1 root     root             0 Jul 22 14:01 br-lan -> ../../devices/virtual/net/br-lan
lrwxrwxrwx    1 root     root             0 Jan  1  1970 eth0 -> ../../devices/platform/1e100000.ethernet/net/eth0
lrwxrwxrwx    1 root     root             0 Jul 22 14:01 eth0.1 -> ../../devices/virtual/net/eth0.1
lrwxrwxrwx    1 root     root             0 Jul 22 14:01 eth0.2 -> ../../devices/virtual/net/eth0.2
lrwxrwxrwx    1 root     root             0 Jan  1  1970 lo -> ../../devices/virtual/net/lo
lrwxrwxrwx    1 root     root             0 Jul 22 14:01 pppoe-wan -> ../../devices/virtual/net/pppoe-wan
lrwxrwxrwx    1 root     root             0 Jul 22 14:01 wlan0 -> ../../devices/pci0000:00/0000:00:01.0/0000:02:00.0/net/wlan0
lrwxrwxrwx    1 root     root             0 Jul 22 14:01 wlan1 -> ../../devices/pci0000:00/0000:00:00.0/0000:01:00.0/net/wlan1

根据符号链接指向的位置，可以分辨出Newifi D2中有三个物理网络设备，五个虚拟网络设备。

物理设备有：

  • eth0
  • wlan0
  • wlan1

虚拟设备有：

  • br-lan
  • eth0.1
  • eth0.2
  • lo
  • pppoe-wan

系统网络信息

接口信息

通过 ip -d addr 可以查看系统中接口以及其IP地址信息：

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1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1000
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00 promiscuity 0 numtxqueues 1 numrxqueues 1 gso_max_size 65536 gso_max_segs 65535
    inet 127.0.0.1/8 scope host lo
       valid_lft forever preferred_lft forever

2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc fq_codel state UNKNOWN group default qlen 1000
    link/ether 20:76:93:44:fe:97 brd ff:ff:ff:ff:ff:ff promiscuity 2 numtxqueues 1 numrxqueues 1 gso_max_size 65536 gso_max_segs 65535

5: br-lan: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue state UP group default qlen 1000
    link/ether 20:76:93:44:fe:97 brd ff:ff:ff:ff:ff:ff promiscuity 0
    bridge forward_delay 200 hello_time 200 max_age 2000 ageing_time 30000 stp_state 0 priority 32767 vlan_filtering 0 vlan_protocol 802.1Q bridge_id 7fff.20:76:93:44:FE:97 designated_root 7fff.20:76:93:44:FE:97 root_port 0 root_path_cost 0 topology_change 0 topology_change_detected 0 hello_timer    0.00 tcn_timer    0.00 topology_change_timer    0.00 gc_timer  100.32 vlan_default_pvid 1 vlan_stats_enabled 0 group_fwd_mask 0 group_address 01:80:c2:00:00:00 mcast_snooping 0 mcast_router 1 mcast_query_use_ifaddr 0 mcast_querier 0 mcast_hash_elasticity 4 mcast_hash_max 512 mcast_last_member_count 2 mcast_startup_query_count 2 mcast_last_member_interval 100 mcast_membership_interval 26000 mcast_querier_interval 25500 mcast_query_interval 12500 mcast_query_response_interval 1000 mcast_startup_query_interval 3125 mcast_stats_enabled 0 mcast_igmp_version 2 mcast_mld_version 1 nf_call_iptables 0 nf_call_ip6tables 0 nf_call_arptables 0 numtxqueues 1 numrxqueues 1 gso_max_size 65536 gso_max_segs 65535
    inet 192.168.2.1/24 brd 192.168.2.255 scope global br-lan
       valid_lft forever preferred_lft forever

6: eth0.1@eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue master br-lan state UP group default qlen 1000
    link/ether 20:76:93:44:fe:97 brd ff:ff:ff:ff:ff:ff promiscuity 1
    vlan protocol 802.1Q id 1 <REORDER_HDR>
    bridge_slave state forwarding priority 32 cost 100 hairpin off guard off root_block off fastleave off learning on flood on port_id 0x8001 port_no 0x1 designated_port 32769 designated_cost 0 designated_bridge 7fff.20:76:93:44:FE:97 designated_root 7fff.20:76:93:44:FE:97 hold_timer    0.00 message_age_timer    0.00 forward_delay_timer    0.00 topology_change_ack 0 config_pending 0 proxy_arp off proxy_arp_wifi off mcast_router 1 mcast_fast_leave off mcast_flood on neigh_suppress off vlan_tunnel off numtxqueues 1 numrxqueues 1 gso_max_size 65536 gso_max_segs 65535

7: eth0.2@eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue state UP group default qlen 1000
    link/ether 20:76:93:44:fe:98 brd ff:ff:ff:ff:ff:ff promiscuity 0
    vlan protocol 802.1Q id 2 <REORDER_HDR> numtxqueues 1 numrxqueues 1 gso_max_size 65536 gso_max_segs 65535

8: pppoe-wan: <POINTOPOINT,MULTICAST,NOARP,UP,LOWER_UP> mtu 1492 qdisc fq_codel state UNKNOWN group default qlen 3
    link/ppp  promiscuity 0
    ppp numtxqueues 1 numrxqueues 1 gso_max_size 65536 gso_max_segs 65535
    inet 100.82.7.242 peer 100.82.0.1/32 scope global pppoe-wan
       valid_lft forever preferred_lft forever
    inet6 2409:8a20:ae02:f845:539:f95a:7989:37c8/64 scope global dynamic noprefixroute
       valid_lft 259059sec preferred_lft 172659sec

9: wlan0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue master br-lan state UP group default qlen 1000
    link/ether 20:76:93:44:fe:96 brd ff:ff:ff:ff:ff:ff promiscuity 1
    bridge_slave state forwarding priority 32 cost 100 hairpin on guard off root_block off fastleave off learning on flood on port_id 0x8002 port_no 0x2 designated_port 32770 designated_cost 0 designated_bridge 7fff.20:76:93:44:FE:97 designated_root 7fff.20:76:93:44:FE:97 hold_timer    0.00 message_age_timer    0.00 forward_delay_timer    0.00 topology_change_ack 0 config_pending 0 proxy_arp off proxy_arp_wifi off mcast_router 1 mcast_fast_leave off mcast_flood on neigh_suppress off vlan_tunnel off numtxqueues 4 numrxqueues 1 gso_max_size 65536 gso_max_segs 65535

10: wlan1: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue master br-lan state UP group default qlen 1000
    link/ether 20:76:93:44:fe:98 brd ff:ff:ff:ff:ff:ff promiscuity 1
    bridge_slave state forwarding priority 32 cost 100 hairpin on guard off root_block off fastleave off learning on flood on port_id 0x8003 port_no 0x3 designated_port 32771 designated_cost 0 designated_bridge 7fff.20:76:93:44:FE:97 designated_root 7fff.20:76:93:44:FE:97 hold_timer    0.00 message_age_timer    0.00 forward_delay_timer    0.00 topology_change_ack 0 config_pending 0 proxy_arp off proxy_arp_wifi off mcast_router 1 mcast_fast_leave off mcast_flood on neigh_suppress off vlan_tunnel off numtxqueues 4 numrxqueues 1 gso_max_size 65536 gso_max_segs 65535

接下来，我们逐一分析一下各个接口所展示的信息，为了便于展示以及分析，忽略IPv6地址（已从输出中删掉）：

  • lo： 虚拟设备，本地回环设备，IPv4地址为 127.0.0.1
  • eth0：物理设备，物理以太网设备，MAC地址为 20:76:93:44:fe:97，无IP地址
  • br-lan：虚拟设备，Linux网桥设备，MAC地址为 20:76:93:44:fe:97，IP地址为 192.168.2.1
  • eth0.1@eth0：虚拟设备，基于 eth0 的VLAN设备，VLAN id为1，MAC地址为 20:76:93:44:fe:97，无IP地址，bridge_slave表示它是网桥的从设备
  • eth0.2@eth0：虚拟设备，基于 eth0 的VLAN设备，VLAN id为2，MAC地址为 20:76:93:44:fe:98，无IP地址
  • pppoe-wan：虚拟设备，PPPoE拨号设备，未显示MAC地址（暂不清楚如何解释，估计是这种虚拟设备就没有MAC，应该是依赖于某个其他设备），IP地址为 100.82.7.242
  • wlan0：物理设备，无线网卡，MAC地址为 20:76:93:44:fe:96，无IP地址，bridge_slave表示它是网桥的从设备
  • wlan1：物理设备，无线网卡，MAC地址为 20:76:93:44:fe:98，无IP地址，bridge_slave表示它是网桥的从设备

桥信息

系统自带了 brctl，通过 brctl show 可以查看系统中的桥信息：

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bridge name     bridge id               STP enabled     interfaces
br-lan          7fff.20769344fe97       no              eth0.1
                                                        wlan0
                                                        wlan1

也可以另外安装 ip-bridge 包，然后使用 bridge 命令进行Linux虚拟网桥操作，比如 bridge link 可以展示桥中的接口： 

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6: eth0.1@eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 master br-lan state forwarding priority 32 cost 100
9: wlan0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 master br-lan state forwarding priority 32 cost 100
10: wlan1: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 master br-lan state forwarding priority 32 cost 100

上面的信息表明，网桥 br-lan 中包含三个设备：eth0.1，wlan0，wlan1

根据上面对各个接口的分析，得知 br-lan 有IP地址，eth0.1，wlan0，wlan1均没有IP地址，而网桥的作用就类似于交换机，可以在桥中各个设备直接交换MAC帧，这三者的关系如下图所示： 

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+--------------------------------------------------------------------+
|                                                                    |
|                          +--------------+                          |
|                          | 192.168.2.1  |                          |
|            +------------→|    br-lan    |←--------------+          |
|            |             +--------------+               |          |
|            |                     ↑                      |          |
|            |                     |                      |          |
|            ↓                     ↓                      ↓          |
|       +---------+           +---------+            +---------+     |
|       | eth0.1  |           |  wlan0  |            |  wlan1  |     |
|       +---------+           +---------+            +---------+     |
|                                                                    |
+--------------------------------------------------------------------+

默认网络配置

网络配置位于 /etc/config/network： 

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config interface 'loopback'
        option ifname 'lo'
        option proto 'static'
        option ipaddr '127.0.0.1'
        option netmask '255.0.0.0'

config globals 'globals'
        option ula_prefix 'fdff:faeb:0d9b::/48'

config interface 'lan'
        option type 'bridge'
        option ifname 'eth0.1'
        option proto 'static'
        option ipaddr '192.168.2.1'
        option netmask '255.255.255.0'
        option ip6assign '60'

config device 'lan_eth0_1_dev'
        option name 'eth0.1'
        option macaddr '20:76:93:44:fe:97'

config interface 'wan'
        option ifname 'eth0.2'
        option proto 'pppoe'
        option password '************'
        option ipv6 'auto'
        option username '************'

config device 'wan_eth0_2_dev'
        option name 'eth0.2'
        option macaddr '20:76:93:44:fe:98'

config interface 'wan6'
        option ifname 'eth0.2'
        option proto 'dhcpv6'

config switch
        option name 'switch0'
        option reset '1'
        option enable_vlan '1'

config switch_vlan
        option device 'switch0'
        option vlan '1'
        option ports '0 1 2 3 6t'

config switch_vlan
        option device 'switch0'
        option vlan '2'
        option ports '4 6t'

网络拓扑汇总

通过查看硬件信息，以及系统中的网络信息，可以大致得知整体的网络拓扑结构为：

参考资料&相关链接