Semester7

Notes of courses done/attended in semester 7 in college

agenda

virt

control removed from each individual switch
What does network admin gets
- an abstract view in form of virtualized n/w
- virtualization achieved by abstraction
- can control and manage the n/w
- can specify behavior in term of control program
  - routing kaise hoga bata sakta
  - access control list
    - who can control to whom
    - maybe ek server kuch hi end points se access karwana
  - traffic engineering rules
    - specify a QoS requirement by applications
      - some apps require more b/w
      - some require least latency path
      - path provisions to the apps is done here
      - for diff flow of packets diff provisions
- all these are specified using a progrmming interface
- then pass it to virtualized view of n/w
- which then compiles topology on these rules
  - validates ki everyth is fine or not
  - all req are done or not
- then push through n/w os into each switch
We can achieve all these things in legacy n/w also but it is a tedious task
centralized view of n/w construct karna padega khud se
and validation part nahi hai, so directly install kardo and bug ho toh resolve karo

nwvi

eg
- data center can move any machine w/o changing addressing space
- in VLAN, switch ports can be virtually grouped irrespective of the physical location
  - machine in FD1 can be put in VLAN with machines in FD2

absts

apps do not worry about managing physical locations and caches, through virtu it gets infi phys memory
file system = os provides it
- h/w me kaise data store ho ra, sector, tracks and all Idc
VM = os abstraction
- app do not have to worryr abt new process scheduling and all

abstraction does not eliminate the complexity
everything is still happening
but OS karra woh jaise file system me
Network Operating System karra yaha
so programmer ko nahi dekhna kya hora
SDN main achievements
- simplifies interface for control program(usere-specific)
- pushed complexity into reusable code(SDN platform)
it works just like compilers
- compiler abstracts the details

control

a new pkt arrives at a port
flow table is maintained
- rules hai isme
- controller se aaye rules
- controller ko n/w programmer ne die
if no rule is matching, pkt sent to controller through a secure channel
controller pushes a rule based on criteria set by n/w admin
either controller can find out action for that
- action = what is to be done with the pkt
  - drop it, or send to diff port
- either he sends directly to that
a pkt which came first time will be sent to controller
Switches are of 2 types
- openflow-only
  - all switches are o/f only
- openflow-hybrid
  - kuch traditional switches and kuch o/f
  - halke halke I will change
there could me multiple flow tables
chained together, they act like filters
say 1st table does firewall operations, then 2nd does layer3 operns, then 3rd table layer 2 operns
table size will be less
a special table = group table
- used to group the flows
- say some common action on some flows
- like sab kuch ISP ko bhejna
- multicast/broadcast karna

ctrl

traditional switch bahut kuch kam karre so complicated
they also have data and ctrl planes
so how SDN wala is different
- are decoupled hai na bhai
- SDN control plane is centralized view but usme distributed

specs

specs2

ports

rsrvd

table