CONMAN: A STEP TOWARDS NETWORK MANAGEABILITY

Hitesh Ballani, Paul FrancisCornell University

Presented by Lam Chan, Patrick Wong

CURRENT ISSUES Network management requires detailed

knowledge of many different network components

Rising management costs, network downtime. 80% of IT budgets in various enterprises

maintenance 62% of network downtime due to configuration

errors

WHY DOES IT HAPPEN? “Protocols and devices expose their internal

details, leading to a deluge of complexity that burdens the management plane”

Perception differs from reality Error-prone configuration Fragmentation of tools Lack of dependency maintenance

WHY DOES IT HAPPEN? Perception differs from reality Error-prone configuration Fragmentation of tools Lack of dependency maintenance

WHY DOES IT HAPPEN? Perception differs from reality Error-prone configuration Fragmentation of tools Lack of dependency maintenance

WHY DOES IT HAPPEN? Perception differs from reality Error-prone configuration Fragmentation of tools Lack of dependency maintenance

WHY DOES IT HAPPEN? Perception differs from reality Error-prone configuration Fragmentation of tools Lack of dependency maintenance

SOLUTION “The management interface of data-plane

protocols should contain as little protocol-specific information as possible.”

Allows data-plane protocols to have a generic yet simple interface

SOLUTION - CONMAN Complexity Oblivious Network Management

All protocols and devices express their capabilities and functionalities using generic expressions.

Management plane can understand potential of underlying network from these abstractions.

Configures network in line with high-level policies

In other words, restrict protocol complexity to their implementation.

CONMAN – ARCHITECTURE Protocols should not expose their gory details

CONMAN – MODULE ABSTRACTION Switching packets under performance

constraints while filtering unwanted traffic.

CONMAN – MODULE ABSTRACTION Modules may depend on other modules for

doing their job.

CONMAN – MODULE ABSTRACTION Abstractions model the capabilities and

dependencies of modules Applies to almost all data plane modules.

CONMAN – NETWORK MANAGER Network Manager (NM):

Determines the network topology Achieve high-level network configuration goals

by creating/deleting pipes and module components

CONMAN – NETWORK MANAGER (PRIMITIVES) NMs use primitives to facilitate their

management showPotential – returns a list of modules with their

abstractions (determines a device’s capabilities) showActual – returns a state of modules in a device

(pipes, switches, filters) create/delete – creates or deletes pipes, filter rules,

switch rules, and performance enforcement state conveyMessage – allows modules to convey

messages through the NM – this is a ‘module’ command

listFieldsandValues – queries target module for low level fields and values

IMPLEMENTATION GRE Tunneling Protocol that encapsulates a network

protocol in another network protocol

GRE TUNNELING – TODAY’S CONFIGURATION#!/bin/bash # Inserting the GRE-IP kernel module insmod /lib/modules/2.6.10-1/ip_gre.ko # Creating the GRE module with the appropriate keyip tunnel add name greA mode remote 128.84.223.112 local \128.84.222.111 ikey 2001 okey 1001 icsum ocsum iseq oseq ifconfig greA 192.168.1.3 # Enable routingecho 1 > /proc/sys/net/ipv4/ip-forward # Create IP routing state from customer to tunnelecho 202 tun-1-2 > /etc/iproute2/rt_tables ip rule add iff eth0 table tun-1-2 ip route add default dev greA table tun-1-2# Create IP routing state from tunnel to customerecho 203 tun-2-1 > /etc/iproute2/rt_tables ip rule add iff greA table tun-2-1 ip route add default dev eth0 table tun-2-1

GRE TUNNELING – TODAY’S CONFIGURATION#!/bin/bash # Inserting the GRE-IP kernel module insmod /lib/modules/2.6.10-1/ip_gre.ko # Creating the GRE module with the appropriate keyip tunnel add name greA mode remote 128.84.223.112 local \128.84.222.111 ikey 2001 okey 1001 icsum ocsum iseq oseq ifconfig greA 192.168.1.3 # Enable routingecho 1 > /proc/sys/net/ipv4/ip-forward # Create IP routing state from customer to tunnelecho 202 tun-1-2 > /etc/iproute2/rt_tables ip rule add iff eth0 table tun-1-2 ip route add default dev greA table tun-1-2# Create IP routing state from tunnel to customerecho 203 tun-2-1 > /etc/iproute2/rt_tables ip rule add iff greA table tun-2-1 ip route add default dev eth0 table tun-2-1

End point IP addresses

Key Values

GRE TUNNELING Human goal

Create a virtual connectivity between the customer-side interface for Customer-1.

GRE TUNNELING We translate this as a CONMan goal CONMan goal

Configure connectivity between the customer-side interfaces <ETH, A, e> and <ETH, B, e>

GRE TUNNELING – NM IMPLEMENTATION NM gets CONMan abstractions from all the

modules involved < showPotential() > NM maps a path from (1) to (11) that meets

the requirement of the high-level goals

GRE TUNNELING – NM IMPLEMENTATION Configuration at Router A

create (pipe, e, a) create (pipe, a, d) create (switch-state, a, pipe-2, pipe-3) create (pipe, d, b) create (pipe, b, c)

Protocols incorporate the complexity of determining the low-level parameters.

GRE TUNNELING – NM IMPLEMENTATION NM includes a path-finder component that

finds all paths between any two modules in such a graph

Depth-first search, cycle avoiding Choose the path that minimizes the total

number of pipes instantiated in the routers What about other metrics such as security or

performance capabilities of modules? We acknowledge this as an avenue for future

work

GRE TUNNELING – SOME THINGS TO CONSIDER… Humans need not see or write CONMan

scripts Since there is little protocol-specific

information in CONMan scripts… …an automated NM can generate the

commands and other details algorithmically without incorporating protocol-specific knowledge

CONMAN – FUTURE CONSIDERATIONS Abstraction

The abstraction provides just enough information for the NM to build a potential path graph

Scalability NMs can specialize, thus divide and conquer.

Multiple NMs Many NMs with specialized job that can

communicate with each other

CONMAN – FUTURE CONSIDERATIONS (CONT’D) Specifying high-level goals

A more systematic language to describe the goals

Deployment strategies Relatively young project More consideration in the future

THANK YOU