How Can You Have QoS When…

Jennifer RexfordAT&T Labs--Research

How Can You Have QoS When…

• A typographical error by a network operator can bring down your service?

• Routing anomalies and slow convergence might (temporarily) discard your traffic?

• You don’t know how to set the QoS parameters and estimate your bill?

• You can’t tell who is to blame for the QoS violation you have experienced?

A single typo can bring down your network?

• Router configuration problems– Non-standard “assembly language” programming– Configuring individual routers not a network– Complexity in network protocols and mechanisms

• … lead to performance problems– Human error responsible for half of outages– Security holes, resource inefficiency– Delay and cost in configuring and troubleshooting

• … and some research challenges– Models of protocol configuration state– Codifying of best common practices– Tools for error checking and data mining– Systems for automated configuration

The routing system discards your packets?

• Routing problems– Transient instability during routing convergence– Blackholes, route hijacking, policy oscillation,…– Congestion due to sub-optimal routing

configuration

• … lead to performance problems– Packets dropped, discarded, or out-of-order– Forwarding loops consuming extra bandwidth

• … and some research challenges– Faster data-plane convergence– Detection and diagnosis of anomalies– Checking of configuration errors and policy conflicts– Better traffic engineering and capacity planning

Customers don’t know what QoS params to select?

• QoS specification problems– Don’t know the traffic mix by 5-tuple– Can’t accurately map the 5-tuple to

applications– Can’t predict how much their bill will be

• … leads to slow QoS adoption– Customers want QoS but can’t specify it– Customers want QoS but are wary of their bill

• … and some research challenges– Traffic measurement and characterization– Digging below the 5-tuple in the IP/TCP

header– Mapping traffic classes into QoS classes

Customers don’t know who is to blame?

• Finger-pointing problem– Hard to detect QoS violations– Even harder to diagnose them– Even harder to ascribe blame

• … leads to low end-to-end QoS adoption– SLAs based just on basic availability– SLAs only for “on net” traffic in one domain

• … and some research challenges– Measurements for the finger-pointing problem– Techniques for outsourcing the finger-pointing

to a third-party or the provider

Conclusion

• We need to solve these problems!