CMULab Quarterly Status Report

Period: Q1 2009

I. Major Accomplishments

A. Milestones Achieved

Tunneling packets from Utah to CMU

This functionality now works, but we had to modify the mechanism from the way initially described. We had planned to use the ProtoGENI GRE tunnels to do IP-in-IP encapsulation, but the CMULab nodes do not have individual public IP addresses. We therefore have switched the implementation of this to use OpenVPN and are coordinating with other GENI projects that are using OpenVPN in a similar manner.

Complete bringing 5 HomeNet nodes up

There are now 5 nodes deployed in Pittsburgh outside of CMU - two in residences, and three distributed in a line through the Intel lab adjacent to the CMU campus towards the residences. The goal of this deployment is to create a connected series of nodes that reach the off-campus apartment building that is our large-scale deployment target; the 5 initial nodes form the base of that line.

Desired node config & boot mgmt functionality

The HomeNet nodes are now functioning. They can receive disk and account updates, inform the central controller when their IP address changes, establish a control network connection using OpenVPN so that they can be managed/accessed when behind firewalls.

The I2 milestone is still pending I2 connectivity establishment.

B. Deliverables made

We continue to keep these changes integrated with the ProtoGENI code, and keep our deployment in sync with the Utah development branch. Patches for all of the above milestones have been submitted to and accepted into the ProtoGENI codebase and are documented on our or the ProtoGENI Wiki.

II. Description of work performed during the last quarter

A. Activities and findings

Our focus this quarter was on finishing the node configuration and beginning to work on node-to-node tunneling. The major shift we made was to move from many of our planned L2 or IP-in-IP tunnels to using OpenVPN. The reason for this was that many of our nodes operate in different administrative, L2, and L3 domains - including many nodes that run behind NATs or firewalls. The CMULab nodes run in one batch of private address space, the Emulator nodes are connected through a series of additional switches to another building on campus, and all but one of the HomeNet nodes must run behind a residential NAT. The L3 (UDP)-based OpenVPN tunneling proved the most robust tunneling mechanism for allowing communication between these disparate groups. We still plan to add optimized L2 tunneling for the CMULab-Emulator link, and when the functionality is available from I2, we will link into the ProtoGENI I2 node as appropriate.

The majority of the time spent this quarter was in dealing with issues revealed by our initial deployment. The HomeNet nodes encountered a variety of perplexing NAT behavior. The nodes at the Intel research lab were behind a firewall that blocked OpenVPN UDP packets. While none of these was a show-stopper, many of them challenged (unstated mental) assumptions that we had had about the connectivity environment for these nodes, and we spent considerable time engineering solutions that were robust across these different environments.

The HomeNet nodes are now usable for experimentation (users can allocate resources and accounts on them), though the node density is not yet high enough to permit large-scale wireless experimentation.

C. Publications (individual and organizational)

None this quarter

D. Outreach activities

The Emulator was used as a core component of the graduate wireless networking course (18-759) at CMU. In addition, it was used as the evaluation environment for several in-submission research papers.

E. Collaborations

As documented in the Utah quarterly report, we have been participating in bi-weekly conference calls with the other members of our cluster. We continue tight integration with the Emulab team and are keeping our source trees in tight synchronization.

We also have frequent discussions with the PSC team, regarding both their GENI activities for user opt-in and with respect to gaining access to the Emulab Internet 2 resources.

At GEC4, we met with several other teams that are also using or interested in using OpenVPN for their control tunnels. We are generalizing our own OpenVPN support and plan to reach out to these groups in the coming quarter.

F. Other Contributions

Last modified 12 years ago Last modified on 04/23/09 15:52:39