Programmable Networks: Active Networks + SDN

How to Introduce new services

• Overlays: user can introduce what-ever– Ignores physical network perf overhead– Overlay nodes – software routing perf overhead

• Middleboxes: ops can introduce what-ever– Must be placed in a specific location– Must determine apriori what type of MB you want

In the ideal work Ideal

• Anyone can introduce services– So, like overlay

• Can achieve Data-plane throughput– So, like MB

• Can introduce anything– So like Overlay

• Problem:– How to run untrusted code in your environment– We want flexible but need to deal with security, performance, safety

Enter Active Networks• Motivated by advances in RPC• Goal: run mobile code in network

– Code implementation of a new service

• Active Extensions: User ships code to network devices– All packets use the code– No change to packet format

• Active Packets: Each packet carries the code or pointer to the code– Very fine-grain control– Packet is larger – A lot of redundant data

REALITY, MERGE BOTH: The How?

• Entities are a set of pre-installed modules. • The Active packet include the graph of which

entities to use.Active Packet!

Type:Serv 1Type:Serv5Type:Serv6

IP Header

TCP HeaderNetwork Router

Serv 1 Serv 2

Serv 5Serv 6

Serv 7

REALITY, MERGE BOTH: The Why?

• Promotes more modularity and reuse– Entities can be smaller; since packet can be used

to stitch together multiple entities.

• Reduces waste of N/W – A flow multiple packets– If each Packet carries code lot of n/w wasted

• Lots of Waste CPU, load/unloading code• Wasted n/w b/w because of code in pkt

REALITY, MERGE BOTH: End-to-End Picture

Network Router Network RouterActive Packet!

Type: serv1

Serv 1

Global Entity Store

Serv 1 Serv 2 Serv 3

Signs code with specialKey, so routers know to trust the code

The type is an MD5 hashOf the code. This way pkts are treated by the exact code you downloaded from store

REALITY, MERGE BOTH: End-to-End Picture

Network Router Network Router

Active Packet!

Type: serv1

Serv 1

REALITY, MERGE BOTH: End-to-End Picture

Network Router Network Router

Active Packet!

Type: serv1

Serv 1Serv 1

REALITY, MERGE BOTH: End-to-End Picture

Network Router Network Router

Active Packet!

Type: serv1

Serv 1Serv 1

REALITY, MERGE BOTH: End-to-End Picture

Network Router Network Router

Active Packet!

Type: serv1

Serv 1Serv 1 Serv 1

Each router caches the code so that it can be used for Next packet.Packet only caries a pointer to the code.

Active Packet: Capsules

• Recall: OSI layering– A.P. just random modules no need to stick to

layers

Routers: Active Nodes

• A VM (JVM? Language level safety)– Protect code from each other– Prevent for interfering with each other

• A Trusted Operating system– Allow sharing of resources– Need Some that interfaces directly with H/W

Network Router

Linux OS

JVM JVM

Serv 1 Serv 1

Challenges: Performance

• Traffic must be similar + bursty– Or else caching wouldn’t work

• Network has diff types of nodes– Not all can run code at line rate

• Think: Core V Edge• Only run on edge nodes

What impacts Performance of Node

What impacts Performance of Node

• Code distribution– Caching of code minimizes this

• Random management tasks– Cleanup memory (GBC), run normal protocols

• Running code Main performance bottle-neck

Challenges: Security• one code changing with another code's state

– No sharing of state due to sandbox.

• Node O.S. maybe corrupted by code– Sandbox prevents this.

• Sending bad/malicious code to a node– The person signing should catch bad code – (Think Apple’s App store)

• Pkt/Capsule using the wrong code at node– Wrong code will have diff finger print, – so finger print in pkt would make finger print of code at node

Network Router

Linux OS

JVM JVM

Serv 1

100010011001000

100011011101000

GoodServ 1

BadServ 1

Challenges: Resource Sharing

• code using too much resource on a node – Limit resource consumption (also limit code size)– Kill code if it runs for too long

• code using too much resource across a set of nodes: Tricky – – Use TTL to prevents loops.

• If I make copies – then they all get the same TTL

– Divide TTL when making copies • Doesn't work for multicast.

• an app sending too many capsules/pkts– Similiar to today's internet.

Limitation of API

• Fixed assumption that code must work around:– 1. format of IP– 2. resource limits (TTL & size & time)– 3. code distribution – 4. how code types are computed and calculated

Limitation in terms of Architecture

• Things that can't be easily specified:– FW --> since it should work for all flows just not

the flows with the type specified.

– Web-Cache/transcoders --> code is short lived.

Why this Never took off?

• Performance.– Still relatively slow– only at edge

• Complex changes to routers– Routers should run JVM

• Only a few types of networks– ISP and maybe Enterprise networks– So very limited use-cases

A New Problem

A New Problem

Operator’s Goal

NetworkReality

Interface vlan901

ip address 10.1.1.5 255.0.0.0

ospf cost 100

ip access-group 9 out

!Router ospf 1router-id 10.1.2.23network 10.0.0.0 0.255.255.255

!

access-list 9 10.1.0.0 0.0.255.255

23

Old Solution: Programmable NetworksEthane

Sw1Sw2

Sw3Packet

Ethane Drawbacks

• Require complex hardware– Each switch needs to encrypt/decrypt packets

• Performance issues– The controller is involved with every packet

Practical Solution: SDN (e.g. OpenFlow)

If (port == 80) Then Drop

If (port == 22) Then send on if 2

OpenFlow API (0.9)

• Match– IP– Mac– Port– VLAN– TOS

• Action:– Forward/flood on specific interfaces– Drop packet– Rewrite ip or mac headers

Layer 3: (OSPF)1. Matches on IP address2. Forwards on a port

Layer 2: (Spanning Tree)1. Matches on MAC address2. Forwards on a port

OR2. Floods the packet

Layer 3.5: (Firewall/ACL)1. Matches on IP address

OR2. Matches on a port3. Drops or forwards the pkt

Layer 2.5: (Spanning Tree)1. Matches on VLAN2. 2. Floods the packet

OpenFlow API

Layer 3: (OSPF)1. Matches on IP address2. Forwards on a port

Layer 2: (Spanning Tree)1. Matches on MAC address2. Forwards on a port

OR2. Floods the packet

Layer 3.5: (Firewall/ACL)1. Matches on IP address

OR2. Matches on a port3. Drops or forwards the pkt

Layer 2.5: (VLAN)1. Matches on VLAN2. 2. Floods the packet

HP

ACL OSPF VLAN SPT

HP Magic Protocols

Cisco

ACL OSPF VLAN SPT

Cisco Magic Protocols

Juniper

ACL OSPF VLAN SPT

Juniper Magic Protocols

OpenFlow API

Simple Firmware patch

HP

ACL OSPF VLAN SPT

HP Magic Protocols

Cisco

ACL OSPF VLAN SPT

Cisco Magic Protocols

Juniper

ACL OSPF VLAN SPT

Juniper Magic Protocols

OpenFlow Switch

ACL OSPF VLAN SPT

Lesson• A rigid network is impractical

– Doesn’t support new services

• Programmable Networks allow great flexibility– Allows anyone to introduce new services– Into which ever nodes they have access to

• But this flexibility introduces new challenges– Security, performance, Resource control

• For Technological adoption– Minimal overhead for transition is good– New h/w is hard to get created