title: Traceroute probe method and forward IP path inference

authors: Luckie, Matthew John

subjects: computer science

abstract: Several traceroute probe methods exist, each designed to perform better in a scenario where another fails. This paper examines the effects that the choice of probe method has on the inferred forward IP path by comparing the paths inferred with UDP, ICMP, and TCP-based traceroute methods to (1) a list of routable IP addresses, (2) a list of known routers, and (3) a list of well-known websites. We further compare methods by examining seven months of macroscopic Internet topology data collected by CAIDA's Archipelago infrastructure.
We found significant differences in the topology observed using different probe methods. In particular, we found that ICMP-based traceroute methods tend to successfully reach more destinations, as well as collect evidence of a greater number of AS links. UDP-based methods infer the greatest number of IP links, despite reaching the fewest destinations. We hypothesise that some per-flow load balancers implement different forwarding policies for TCP and UDP, and run a specific experiment to confirm this hypothesis.

text: Traceroute probe method and forward IP path inference Several traceroute probe methods exist, each designed to perform better in a scenario where another fails. This paper examines the effects that the choice of probe method has on the inferred forward IP path by comparing the paths inferred with UDP, ICMP, and TCP-based traceroute methods to (1) a list of routable IP addresses, (2) a list of known routers, and (3) a list of well-known websites. We further compare methods by examining seven months of macroscopic Internet topology data collected by CAIDA's Archipelago infrastructure.
We found significant differences in the topology observed using different probe methods. In particular, we found that ICMP-based traceroute methods tend to successfully reach more destinations, as well as collect evidence of a greater number of AS links. UDP-based methods infer the greatest number of IP links, despite reaching the fewest destinations. We hypothesise that some per-flow load balancers implement different forwarding policies for TCP and UDP, and run a specific experiment to confirm this hypothesis.

year: 2008

title: Expansion dynamics of monospecific, temperate mangroves and sedimentation in two embayments of a barrier-enclosed lagoon, Tauranga harbour, New Zealand

authors: Stokes, Debra J.

subjects: mangrove sedimentation

abstract: In recent years, mangrove expansion has become a coastal management issue in the North Island of New Zealand. Little is known about the spatial evolution and forest structure of temperate mangrove forests in New Zealand or about the associated rates of sedimentation. The extent of mangrove colonization in both a large (Waikareao Estuary) and small (Welcome Bay) embayment within Tauranga Harbour were documented. Forest structure and growth rates were described using tree height, stem density, pneumatophore density, and seedling establishment. Surface elevation changes within mangrove habitat were determined from erosion pin measurements and, on bare intertidal flats, using buried baseplates. Sediment texture and availability was also assessed using sediment traps. Results show that in 1943, mangrove vegetation covered <1% of either embayment, with ongoing expansion resulting in mangrove habitat occupying 9% of Welcome Bay and 6% of Waikareao Estuary in 2003. Mean plant heights were all <1.5 m, with vertical plant growth of 3 cm y−¹ to 7.5 cm y−¹. Pneumatophore densities ranged from  200 per m² to  540 per m², and seedling densities of <1 per m² to 14 per m², with seasonal variation, were documented. Surface elevation changes within mangrove habitat ranged from 0 to +21 mm y−¹, compared with −16 to +15 mm y−¹ on adjacent bare flats. Surface sediment within the mangrove habitat was mostly muddy, whereas bare flats were dominated by fine sand. Sediment-trap results provided accumulation rates of up to 32,000 g m−² mo−¹ on bare flats, and close to 29,000 g m−² mo−¹ within the fringing mangrove vegetation. In this study, mangrove vegetation was found to successfully trap and hold muddy sediments, resulting in increased surface elevation. Rising surface elevation from fine sand deposition is also occurring on bare tidal flats in front of mangrove vegetation at some sites.

text: Expansion dynamics of monospecific, temperate mangroves and sedimentation in two embayments of a barrier-enclosed lagoon, Tauranga harbour, New Zealand In recent years, mangrove expansion has become a coastal management issue in the North Island of New Zealand. Little is known about the spatial evolution and forest structure of temperate mangrove forests in New Zealand or about the associated rates of sedimentation. The extent of mangrove colonization in both a large (Waikareao Estuary) and small (Welcome Bay) embayment within Tauranga Harbour were documented. Forest structure and growth rates were described using tree height, stem density, pneumatophore density, and seedling establishment. Surface elevation changes within mangrove habitat were determined from erosion pin measurements and, on bare intertidal flats, using buried baseplates. Sediment texture and availability was also assessed using sediment traps. Results show that in 1943, mangrove vegetation covered <1% of either embayment, with ongoing expansion resulting in mangrove habitat occupying 9% of Welcome Bay and 6% of Waikareao Estuary in 2003. Mean plant heights were all <1.5 m, with vertical plant growth of 3 cm y−¹ to 7.5 cm y−¹. Pneumatophore densities ranged from  200 per m² to  540 per m², and seedling densities of <1 per m² to 14 per m², with seasonal variation, were documented. Surface elevation changes within mangrove habitat ranged from 0 to +21 mm y−¹, compared with −16 to +15 mm y−¹ on adjacent bare flats. Surface sediment within the mangrove habitat was mostly muddy, whereas bare flats were dominated by fine sand. Sediment-trap results provided accumulation rates of up to 32,000 g m−² mo−¹ on bare flats, and close to 29,000 g m−² mo−¹ within the fringing mangrove vegetation. In this study, mangrove vegetation was found to successfully trap and hold muddy sediments, resulting in increased surface elevation. Rising surface elevation from fine sand deposition is also occurring on bare tidal flats in front of mangrove vegetation at some sites.

year: 2010

title: Tikanga Tainui: Tikanga Whare Wananga

authors: Roa, Tom

subjects: Tainui protocols

abstract: This paper is a preliminary report on an ongoing research project begun in 1999. The project involves consultation with Waikato-Tainui, the tangata whenua of the Waikato region, about the construction of guidelines for University of Waikato staff (both Māori and non-Māori) who are involved in gatherings that call for adherence to Tainui protocols. Here, the emphasis is on guidelines for the conduct of pōwhiri (formal welcomes) on the University Marae.

text: Tikanga Tainui: Tikanga Whare Wananga This paper is a preliminary report on an ongoing research project begun in 1999. The project involves consultation with Waikato-Tainui, the tangata whenua of the Waikato region, about the construction of guidelines for University of Waikato staff (both Māori and non-Māori) who are involved in gatherings that call for adherence to Tainui protocols. Here, the emphasis is on guidelines for the conduct of pōwhiri (formal welcomes) on the University Marae.

year: 2005-09-01