++ network readme update

network/README

@@ -58,3 +58,115 @@ Creating a network:
 1) part of the initialisation / demo data (?)
 
 We should probably provide some demo sets that can easily be used.
+
+2) manual/hook based request
+
+- hosts might have different network interfaces (?)
+  -> this will make things very tricky -> don't support it
+- endpoint needs only support
+
+--------------------------------------------------------------------------------
+
+IPAM
+
+IP address management (IPAM) is related to networks, but needs to be
+decoupled to allow pure L2 networks.
+
+From a customer point of view, we probably want to do something like:
+
+- ORDERING an IPv6 network can include creating a virtual network and
+  an IPAM service
+
+Maybe "orders" should always be the first class citizen and ucloud
+internally "hooks" or binds things together.
+
+--------------------------------------------------------------------------------
+
+testing / hacking:
+
+- starting etcd as storage
+
+
+[18:07] diamond:~% etcdctl put /v1/network/200 "{ some_network }"
+OK
+[18:08] diamond:~% etcdctl watch -w=json --prefix /v1/network
+{"Header":{"cluster_id":14841639068965178418,"member_id":10276657743932975437,"revision":6,"raft_term":2},"Events":[{"kv":{"key":"L3YxL25ldHdvcmsvMjAw","create_revision":5,"mod_revision":6,"version":2,"value":"eyBzb21lX25ldHdvcmsgfQ=="}}],"CompactRevision":0,"Canceled":false,"Created":false}
+
+
+--------------------------------------------------------------------------------
+
+Flow for using and creating networks:
+
+- a network is created -> entry in etcd is created
+  -> we need to keep a counter/lock so that 2 processes don't create
+  the same network [Ahmed]
+  -> nothing to be done on the hosts
+- a VM using a network is created
+- a VM using a network is scheduled to some host
+- the local "spawn a VM" process needs to check whether there is a
+  vxlan interface existing -> if no, create it before creating the VM.
+  -> if no, also create the bridge
+  -> possibly adjusting the MTU (??)
+  -> both names should be in hexadecimal (i.e. brff01 or vxlanff01)
+  --> this way they are consistent with the multicast ipv6 address
+  --> attention, ip -6 link ... id XXX expects DECIMAL input
+
+--------------------------------------------------------------------------------
+
+
+
+
+Example
+
+--------------------------------------------------------------------------------
+
+TODOs
+
+- create-vxlan-on-dev.sh -> the multicast group
+  needs to be ff05:: +int(vxlan_id)
+
+--------------------------------------------------------------------------------
+
+Python hints:
+
+>>> vxlan_id = 3400
+>>> b = ipaddress.IPv6Network("ff05::/16")
+>>> b[vxlan_id]
+IPv6Address('ff05::d48')
+
+we need / should assign hex values for vxlan ids in etcd!
+--> easier to read
+
+>>> b[0x3400]
+IPv6Address('ff05::3400')
+
+
+--------------------------------------------------------------------------------
+
+Bridge names are limited to 15 characters
+
+
+Maximum/highest number of vxlan:
+
+>>> 2**24
+16777216
+>>> (2**25)-1
+33554431
+
+>>> b[33554431]
+IPv6Address('ff05::1ff:ffff')
+
+Last interface:
+br1ffffff
+vxlan1ffffff
+
+root@manager:~/ucloud/network# ip -6 link add vxlan1ffffff type vxlan id 33554431 dstport 4789 group ff05::1ff:ffff dev wlp2s0 ttl 5
+Error: argument "33554431" is wrong: invalid id
+
+root@manager:~/ucloud/network# ip -6 link add vxlanffffff type vxlan id 16777215 dstport 4789 group ff05::ff:ffff dev wlp2s0 ttl 5
+
+
+# id needs to be decimal
+root@manager:~# ip -6 link add vxlanff01 type vxlan id ff01 dstport 4789 group ff05::ff01 dev ttl 5
+Error: argument "ff01" is wrong: invalid id
+root@manager:~# ip -6 link add vxlanff01 type vxlan id 65281 dstport 4789 group ff05::ff01 dev wlp2s0 ttl 5