Illustrated Guide To Kubernetes Networking

by Tim Hockin

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Google Cloud Platform An Illustrated Guide to Kubernetes Networking Tim Hockin Senior Staff Software Engineer @thockin

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Google Cloud Platform Layer 2: ethernet

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Google Cloud Platform node-a node-c node-b node-d 192.168.1.1/16 11:22:33:44:55:01 192.168.1.2/16 01:23:45:67:89:02 192.168.1.3/16 11:22:33:44:55:03 192.168.1.4/16 01:23:45:67:89:04 L2 switch

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Google Cloud Platform node-a node-c node-b node-d L2 to: 192.168.1.3 from: 192.168.1.1 GET / 192.168.1.1/16 11:22:33:44:55:01 192.168.1.2/16 01:23:45:67:89:02 192.168.1.3/16 11:22:33:44:55:03 192.168.1.4/16 01:23:45:67:89:04

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Google Cloud Platform node-d node-b node-a node-c L2 to: from: 11:22:33:44:55:01 who has 192.168.1.3? to: 192.168.1.3 from: 192.168.1.1 GET / 192.168.1.1/16 11:22:33:44:55:01 192.168.1.2/16 01:23:45:67:89:02 192.168.1.3/16 11:22:33:44:55:03 192.168.1.4/16 01:23:45:67:89:04 “ARP request”

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Google Cloud Platform node-a node-c node-b node-d L2 to: 192.168.1.3 via: 11:22:33:44:55:03 from: 192.168.1.1 GET / 192.168.1.1/16 11:22:33:44:55:01 192.168.1.2/16 01:23:45:67:89:02 192.168.1.3/16 11:22:33:44:55:03 192.168.1.4/16 01:23:45:67:89:04

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Google Cloud Platform node-a root netns eth0: 192.168.1.1/16 11:22:33:44:55:01 L2 with containers cbr0: 10.0.1.1/24 ctr-1 eth0: 10.0.1.2/24 ctr-2 eth0: 10.0.1.3/24 ctr-3 eth0: 10.0.1.4/24

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Google Cloud Platform node-a 192.168.1.1/16 11:22:33:44:55:01 node-c node-b node-d 192.168.1.2/16 01:23:45:67:89:02 192.168.1.3/16 11:22:33:44:55:03 192.168.1.4/16 01:23:45:67:89:04 L2 ctr-1 10.0.1.2 aa:bb:cc:dd:e1:01 ctr-2 10.0.3.2 aa:bb:cc:dd:e3:02 to: 10.0.3.2 from: 10.0.1.2 GET /

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Google Cloud Platform Layer 3 - IP

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Google Cloud Platform node-a node-c node-b node-d 192.168.1.1/32 192.168.1.2/32 192.168.1.3/32 192.168.1.4/32 L3 gateway

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Google Cloud Platform node-a node-c node-b node-d 192.168.1.1/32 192.168.1.2/32 192.168.1.3/32 192.168.1.4/32 L3 to: 192.168.1.3 from: 192.168.1.1 GET /

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Google Cloud Platform node-a node-c node-b node-d 192.168.1.1/32 192.168.1.2/32 192.168.1.3/32 192.168.1.4/32 L3 to: 192.168.1.3 from: 192.168.1.1 GET /

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Google Cloud Platform node-a node-c node-b node-d 192.168.1.1/32 192.168.1.2/32 192.168.1.3/32 192.168.1.4/32 L3 to: 192.168.1.3 from: 192.168.1.1 GET / routing decision, static or learned (e.g. BGP)

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Google Cloud Platform node-a 192.168.1.1/32 node-c node-b node-d 192.168.1.2/32 192.168.1.3/32 192.168.1.4/32 L3 ctr-1 10.0.1.2 ctr-2 10.0.3.2

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Google Cloud Platform node-a 192.168.1.1/32 node-c node-b node-d 192.168.1.2/32 192.168.1.3/32 192.168.1.4/32 L3 ctr-1 10.0.1.2 ctr-2 10.0.3.2 to: 10.0.3.2 from: 10.0.1.2 GET /

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Google Cloud Platform node-a 192.168.1.1/32 node-c node-b node-d 192.168.1.2/32 192.168.1.3/32 192.168.1.4/32 L3 ctr-1 10.0.1.2 ctr-2 10.0.3.2 to: 10.0.3.2 from: 10.0.1.2 GET /

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Google Cloud Platform node-a 192.168.1.1/32 node-c node-b node-d 192.168.1.2/32 192.168.1.3/32 192.168.1.4/32 L3 ctr-1 10.0.1.2 ctr-2 10.0.3.2 to: 10.0.3.2 from: 10.0.1.2 GET / routing decision, static or learned (e.g. BGP)

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Google Cloud Platform node-a 192.168.1.1/32 node-c node-b node-d 192.168.1.2/32 192.168.1.3/32 192.168.1.4/32 L3 ctr-1 10.0.1.2 ctr-2 10.0.3.2 to: 10.0.3.2 from: 10.0.1.2 GET /

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Google Cloud Platform Overlays Q: When should I use an overlay? A: When nothing else works, or when you have specific reasons to want it (e.g. the added value of management)

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Google Cloud Platform node-a root netns eth0: 192.168.1.1/16 Overlay (e.g. flannel, weave) cbr0: 10.0.1.1/24 ctr-1 eth0: 10.0.1.2/24 ctr-2 eth0: 10.0.1.3/24 ctr-3 eth0: 10.0.1.4/24 flannel0: 10.0.1.254/16

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Google Cloud Platform node-a root netns eth0: 192.168.1.1/16 cbr0: 10.0.1.1/24 ctr-1 eth0: 10.0.1.2/24 ctr-2 eth0: 10.0.1.3/24 ctr-3 eth0: 10.0.1.4/24 flannel0: 10.0.1.254/16 to: 10.0.3.2 from: 10.0.1.2 GET / Overlay (e.g. flannel, weave)

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Google Cloud Platform node-a root netns eth0: 192.168.1.1/16 cbr0: 10.0.1.1/24 ctr-1 eth0: 10.0.1.2/24 ctr-2 eth0: 10.0.1.3/24 ctr-3 eth0: 10.0.1.4/24 flannel0: 10.0.1.254/16 to: 192.168.1.3 from: 192.168.1.1 encap: to: 10.0.3.2 from: 10.0.1.2 GET / Overlay (e.g. flannel, weave)

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Google Cloud Platform node-a 192.168.1.1/16 node-c node-b node-d 192.168.1.2/16 192.168.1.3/16 192.168.1.4/16 ctr-1 10.0.1.2 ctr-2 10.0.3.2 Overlay (e.g. flannel, weave)

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Google Cloud Platform node-c root netns eth0: 192.168.1.3/16 cbr0: 10.0.3.1/24 ctr-4 eth0: 10.0.3.2/24 ctr-5 eth0: 10.0.3.3/24 ctr-6 eth0: 10.0.3.4/24 flannel0: 10.0.3.254/16 to: 192.168.1.3 from: 192.168.1.1 encap: to: 10.0.3.2 from: 10.0.1.2 GET / Overlay (e.g. flannel, weave)

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Google Cloud Platform node-c root netns eth0: 192.168.1.3/16 cbr0: 10.0.3.1/24 ctr-4 eth0: 10.0.3.2/24 ctr-5 eth0: 10.0.3.3/24 ctr-6 eth0: 10.0.3.4/24 flannel0: 10.0.3.254/16 to: 10.0.3.2 from: 10.0.1.2 GET / Overlay (e.g. flannel, weave)

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Google Cloud Platform node-c root netns eth0: 192.168.1.3/16 cbr0: 10.0.3.1/24 ctr-4 eth0: 10.0.3.2/24 ctr-5 eth0: 10.0.3.3/24 ctr-6 eth0: 10.0.3.4/24 flannel0: 10.0.3.254/16 to: 10.0.3.2 from: 10.0.1.2 GET / Overlay (e.g. flannel, weave)

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Google Cloud Platform Overlays - the hard part

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Google Cloud Platform node-a 192.168.1.1/16 node-c non-node node-d 192.168.1.2/16 192.168.1.3/16 192.168.1.4/16 ctr-1 10.0.1.2 ctr-2 10.0.3.2 Overlay (e.g. flannel, weave)

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Google Cloud Platform node-a 192.168.1.1/16 node-c non-node node-d 192.168.1.2/16 192.168.1.3/16 192.168.1.4/16 ctr-1 10.0.1.2 ctr-2 10.0.3.2 to: 10.0.3.2 from: 192.168.1.2 GET / Overlay (e.g. flannel, weave)

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Google Cloud Platform We need a bridge between the physical and overlay networks...

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Google Cloud Platform We need a bridge between the physical and overlay networks... • could: route to nodes • could: route to 1 or more bridge machines • could: run flannel on client machines

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Google Cloud Platform We need a bridge between the physical and overlay networks... • could: route to nodes • could: route to 1 or more bridge machines • could: run flannel on client machines • see “When should I use an overlay?”