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 1 Type:Serv5 Type:Serv6 Type:Serv 1 Type:Serv5 Type:Serv6 IP Header TCP Header Network Router Serv 1 Serv 2 Serv 5 Serv 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 Active Packet! Type: serv1 Serv 1 Global Entity Store Serv 1 Serv 2 Serv 3 Signs code with special Key, so routers know to trust the code The type is an MD5 hash Of the code. This way pkts are treated by the exact code you downloaded from store

REALITY, MERGE BOTH: End-to-End Picture Network Router Active Packet! Type: serv1 Serv 1

REALITY, MERGE BOTH: End-to-End Picture Network Router Active Packet! Type: serv1 Serv 1

REALITY, MERGE BOTH: End-to-End Picture Network Router Active Packet! Type: serv1 Serv 1

REALITY, MERGE BOTH: End-to-End Picture Network Router Active Packet! Type: serv1 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 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

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 Serv Good Serv 1 Good Serv 1 Bad Serv 1 Bad Serv 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

Operator’s Goal Network Reality Interface vlan901 ip address ospf cost 100 ip access-group 9 out ! Router ospf 1 router-id network ! access-list

Old Solution: Programmable Networks Ethane Sw1 Sw2 Sw3 Packet

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 address 2. Forwards on a port Layer 3: (OSPF) 1. Matches on IP address 2. Forwards on a port Layer 2: (Spanning Tree) 1. Matches on MAC address 2. Forwards on a port OR 2. Floods the packet Layer 2: (Spanning Tree) 1. Matches on MAC address 2. Forwards on a port OR 2. Floods the packet Layer 3.5: (Firewall/ACL) 1.Matches on IP address OR 1.Matches on a port 2.Drops or forwards the pkt Layer 3.5: (Firewall/ACL) 1.Matches on IP address OR 1.Matches on a port 2.Drops or forwards the pkt Layer 2.5: (Spanning Tree) 1.Matches on VLAN 2.2. Floods the packet Layer 2.5: (Spanning Tree) 1.Matches on VLAN 2.2. Floods the packet

OpenFlow API Layer 3: (OSPF) 1. Matches on IP address 2. Forwards on a port Layer 3: (OSPF) 1. Matches on IP address 2. Forwards on a port Layer 2: (Spanning Tree) 1. Matches on MAC address 2. Forwards on a port OR 2. Floods the packet Layer 2: (Spanning Tree) 1. Matches on MAC address 2. Forwards on a port OR 2. Floods the packet Layer 3.5: (Firewall/ACL) 1.Matches on IP address OR 1.Matches on a port 2.Drops or forwards the pkt Layer 3.5: (Firewall/ACL) 1.Matches on IP address OR 1.Matches on a port 2.Drops or forwards the pkt Layer 2.5: (VLAN) 1.Matches on VLAN 2.2. Floods the packet Layer 2.5: (VLAN) 1.Matches on VLAN 2.2. 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