K8s + Flannel 网络架构图

这是Flannel官网给出的网络架构图

这是通过自己的理解画的逻辑结构图

查看bridge

[root@node01 ~]# brctl show
bridge name     bridge id               STP enabled     interfaces
cni0            .0a580af40001       no              veth34bdd66f
                                                        veth374f9b6c
                                                        vethfe4aad1b
docker0         .0242ec6d0fef       no              

查看netns (需要先执行 ln -s /var/run/docker/netns /var/run/netns)

[root@node01 ~]# ip netns list
2ae7b96d0db6 (id: )
21684eef26a3 (id: )
6c568775f2d9 (id: )
default

查看网络接口

[root@node01 netns]# ip -d link show
: lo: <LOOPBACK,UP,LOWER_UP> mtu  qdisc noqueue state UNKNOWN mode DEFAULT qlen
    link/loopback ::::: brd ::::: promiscuity  addrgenmode eui64
: ens33: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu  qdisc pfifo_fast state UP mode DEFAULT qlen
    link/ether :0c::3a:: brd ff:ff:ff:ff:ff:ff promiscuity  addrgenmode eui64
: docker0: <NO-CARRIER,BROADCAST,MULTICAST,UP> mtu  qdisc noqueue state DOWN mode DEFAULT
    link/ether ::ec:6d:0f:ef brd ff:ff:ff:ff:ff:ff promiscuity
    bridge forward_delay  hello_time  max_age  ageing_time  stp_state  priority  vlan_filtering  vlan_protocol .1Q bridge_id 8000.2::ec:6d:f:ef designated_root 8000.2::ec:6d:f:ef root_port  root_path_cost  topology_change  topology_change_detected  hello_timer    0.00 tcn_timer    0.00 topology_change_timer    0.00 gc_timer  241.95 vlan_default_pvid  group_fwd_mask  group_address ::c2::: mcast_snooping  mcast_router  mcast_query_use_ifaddr  mcast_querier  mcast_hash_elasticity  mcast_hash_max  mcast_last_member_count  mcast_startup_query_count  mcast_last_member_interval  mcast_membership_interval  mcast_querier_interval  mcast_query_interval  mcast_query_response_interval  mcast_startup_query_interval  addrgenmode eui64
: flannel.1: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu  qdisc noqueue state UNKNOWN mode DEFAULT
    link/ether 3e:bb:9b::a4: brd ff:ff:ff:ff:ff:ff promiscuity 
    vxlan id 1 local 172.16.65.181 dev ens33 srcport   dstport  nolearning ageing  addrgenmode eui64
: cni0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu  qdisc noqueue state UP mode DEFAULT qlen
    link/ether 0a::0a:f4:: brd ff:ff:ff:ff:ff:ff promiscuity 
    bridge forward_delay  hello_time  max_age  ageing_time  stp_state  priority  vlan_filtering  vlan_protocol .1Q bridge_id .a::a:f4:: designated_root .a::a:f4:: root_port  root_path_cost  topology_change  topology_change_detected  hello_timer    0.00 tcn_timer    0.00 topology_change_timer    0.00 gc_timer   27.93 vlan_default_pvid  group_fwd_mask  group_address ::c2::: mcast_snooping  mcast_router  mcast_query_use_ifaddr  mcast_querier  mcast_hash_elasticity  mcast_hash_max  mcast_last_member_count  mcast_startup_query_count  mcast_last_member_interval  mcast_membership_interval  mcast_querier_interval  mcast_query_interval  mcast_query_response_interval  mcast_startup_query_interval  addrgenmode eui64
: vethfe4aad1b@if3: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu  qdisc noqueue master cni0 state UP mode DEFAULT
    link/ether ::8d:0d:: brd ff:ff:ff:ff:ff:ff link-netnsid  promiscuity
    veth
    bridge_slave state forwarding priority  cost  hairpin on guard off root_block off fastleave off learning on flood on port_id 0x8001 port_no 0x1 designated_port  designated_cost  designated_bridge .a::a:f4:: designated_root .a::a:f4:: hold_timer    0.00 message_age_timer    0.00 forward_delay_timer    0.00 topology_change_ack  config_pending  proxy_arp off proxy_arp_wifi off mcast_router  mcast_fast_leave off mcast_flood on addrgenmode eui64
: veth374f9b6c@if3: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu  qdisc noqueue master cni0 state UP mode DEFAULT
    link/ether 5a::::b3: brd ff:ff:ff:ff:ff:ff link-netnsid  promiscuity
    veth
    bridge_slave state forwarding priority  cost  hairpin on guard off root_block off fastleave off learning on flood on port_id 0x8002 port_no 0x2 designated_port  designated_cost  designated_bridge .a::a:f4:: designated_root .a::a:f4:: hold_timer    0.00 message_age_timer    0.00 forward_delay_timer    0.00 topology_change_ack  config_pending  proxy_arp off proxy_arp_wifi off mcast_router  mcast_fast_leave off mcast_flood on addrgenmode eui64
: veth34bdd66f@if3: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu  qdisc noqueue master cni0 state UP mode DEFAULT
    link/ether d6:f9:c1:4d:4c:af brd ff:ff:ff:ff:ff:ff link-netnsid  promiscuity
    veth
    bridge_slave state forwarding priority  cost  hairpin on guard off root_block off fastleave off learning on flood on port_id 0x8003 port_no 0x3 designated_port  designated_cost  designated_bridge .a::a:f4:: designated_root .a::a:f4:: hold_timer    0.00 message_age_timer    0.00 forward_delay_timer    0.00 topology_change_ack  config_pending  proxy_arp off proxy_arp_wifi off mcast_router  mcast_fast_leave off mcast_flood on addrgenmode eui64 

查看路由

[root@node01 netns]# ip route
default via 172.16.65.2 dev ens33 proto static metric
10.244.0.0/24 dev cni0 proto kernel scope link src 10.244.0.1 
10.244.1.0/24 via 10.244.1.0 dev flannel.1 onlink
10.244.2.0/24 via 10.244.2.0 dev flannel.1 onlink
172.16.65.0/ dev ens33 proto kernel scope link src 172.16.65.181 metric
172.17.0.0/ dev docker0 proto kernel scope link src 172.17.0.1 

参考文章：https://tonybai.com/2017/01/17/understanding-flannel-network-for-kubernetes/