Hierarchical Broadcast Ring Architecture for High-speed Ethernet Network

1. HSN Workshop 2006 Hierarchical Broadcast Ring Architecture for High-speed Ethernet Network HoRang Jang and Hyong Kim Electrical and Computer Engineering Carnegie Mellon University April 24, 2006

2. HSN Workshop 2006 2/13 Outline Motivation & Background Ethernet Issues Hierarchical Broadcast Ring Architecture Discussion Conclusion

3. HSN Workshop 2006 3/13 Goal of Network Service Providers To create more revenue with lower operational costs More revenue new services (e.g., video, grid computing, etc) but, high competition Lower operational costs capital expenses management costs Ethernet network for MANs low system cost (i.e., capital expenses) low management cost

4. HSN Workshop 2006 4/13 Ethernet Issues for Large Area Networks Simple broadcasting & STP broadcast storm long convergence time link underutilization congestion Flat MAC addressing big forwarding table Virtual LAN same issues in one VLAN limitation of 4094 VLANs a lot of administrative work

5. HSN Workshop 2006 5/13 Proposed Idea Combine the advantages of IP router-based networks and Ethernet switch-based networks Use Ethernet MAC for low system cost Support the standard Ethernet protocols require no cooperation of hosts

6. HSN Workshop 2006 6/13 Proposed Architecture Logical ring topology for broadcast frames no broadcast storm Physical topology for data frames high link utilization

7. HSN Workshop 2006 7/13 Hierarchical Broadcast Ring Switch maintains only MAC addresses of its children, peers, and groups Several hundred MAC addresses can represent millions of hosts

8. HSN Workshop 2006 8/13 Learning: Broadcast (ARP request)

9. HSN Workshop 2006 9/13 Data Forwarding (ARP reply)

10. HSN Workshop 2006 10/13 Discussion: potential issues & solutions The latency of broadcast frames map the current SONET ring to the ring of groups limit the number of switches and the length of a ring does not affect overall application performance the broadcast happens only at the beginning of a traffic flow The amount of broadcast traffic filter out unnecessary broadcasting using hierarchical Proxy ARP increase time-out in the ARP table for frequently used hosts using an aggregation scheme of IP addresses use high-speed Ethernet (e.g., 1GbE, 10GbE) The size of the ARP table reduce the number of IP addresses using the aggregation scheme maintain only the hosts of active flows through the switch use high-density CAM The capacity of a single CAM chip is several million bits

11. HSN Workshop 2006 11/13 Hierarchical Proxy ARP Switch broadcasts the request ONLY to a switch or a group that the destination host belongs to Switch replies on behalf of the destination host only when the request is from its child the request is from a peer and the destination is its child the request is from another group and the destination is in the same group Reduce broadcast traffic and prevent the persistence of old information

12. HSN Workshop 2006 12/13 Aggregation of IP addresses Provide a longer expiration time to frequently used hosts e.g., Mail server, DNS server, File server, Data Center, etc reduce the number of broadcast frames Aggregate IP addresses for the same MAC address e.g., a lot of consecutive IP addresses in a group reduce the size of the ARP table

13. HSN Workshop 2006 13/13 Conclusion Hierarchical architecture for scalability Broadcast ring for broadcasting Shortest path for data forwarding Low management cost self-configuration Low system cost Ethernet MAC hardware