Quality of Service in IN-home digital networks An Architecture for QoS guarantees and Routing in Wireless/Mobile Networks Indu Mahadevany and Krishna M. Sivalingamz

What is the paper about? architecture that provides QoS support in mobile/wireless networks along with support for fast routing during handoffs. use of modified RSVP protocol for QoS support in wireless/mobile networks. routing architecture that includes features of Mobile IP. Goals and contributions of the paper: (a) a hierarchical scalable architecture is proposed for QoS guarantees based on the concept of QoS-regions, (b) a hierarchical architecture is proposed for fast routing based on routing- regions which uses the advantages of Mobile IP and route table changes, (c) The implementation details of QoS guarantees and routing are discussed (d) Experimental testbed, some features of the architecture are supported with results from experiments.

Definition of Concepts Mobile IP Mobile IP uses the concept of a home agent (HA) for every mobile. When a mobile is in a different subnet all data to the mobile are intercepted by the HA. Packets are then encapsulated and sent to the foreign agent (FA) residing in the subnet the mobile is currently located. Advantage: all senders need to know only the address of the home agent, HA keeps track of the current location of the mobile. Disadvantage of this method is that it is better suited for long term mobility. If a mobile is moving frequently - hard to communicate fast with the HA on another subnet. Solution: not contact the HA at every move, change the routing table so that the location of the mobile is known. Current approach: use routing updates locally for faster handoffs and Mobile IP for long range mobility and for a scalable solution.

Definition of Concepts Routing domain A Routing-domain can be any management-specified domain. Ex: a subnet or a number of subnets can constitute a routing domain. Properties: (a) all route changes within the routing-domain is done with the help of route table changes and (b) all routing for mobility between routing-domains is done usingMobile IP.

Definition of Concepts Routing domain Fig aside: architecture with two subnets A and B connected by the router R. A router is the gateway up the hierarchy. The router R can serve a dual purpose: a) as the gateway between subnets A and B b) as a base station.

Definition of Concepts QoS domain A QoS-domain can be any management-specified domain. Ex: a number of cells can constitute a QoS-domain. A system that belongs to two QoS domains is called a router. (Not to be mistaken with the traditional sense of the word) Properties: (a) all passive reservations for mobility within a QoS-domain is done by extending the path of the original reservation (b) all passive reservations for mobility between QoS-domains are done by partial re-routing.

Definition of Concepts Route table changes Mechanism of changing routing tables in a routing-domain: All the base stations in a routing domain register with the routing- domain router. The routing-domain router knows the current location of the mobile. When a mobile moves into another region, the base station in the region informs the routing-domain router about the mobile. The routing-domain router broadcasts this information to all systems in the routing-domain. All hosts in the routing-domain use this information when they want to communicate with the mobile.

The Architecture

The Architecture Routing issues - Scenario Scenario context: Subnet A and B form one routing-domain, subnet C forms another routing-domain. A mobile has a home agent (HA) in the same subnet as the sender. Assumption: routers R1 and R2 can act as a FA. Scenario: HA sends data to a designated host or a router which acts as a foreign agent (FA). The FA is the gateway to a particular routing-domain. Fig. [a] : the mobile M is in the vicinity of subnet A: Routing from the HA to the FA (R1) is done using Mobile IP (represented by (1) in fig.[a]). All mobility within subnets A and B (a routing-domain) is taken care of by local route changes.

The Architecture Routing issues - Scenario Routing from R1 to the mobile is done through the appropriate base stations because the routing tables in the hosts in the subnet A and B keep track of the mobile. When the mobile moves into the region of subnet C (fig. [b]), the home agent will choose R2 as the foreign agent because it belongs to another routing-domain. Any mobility within subnet C is taken care of by routing table changes.

The Architecture Routing issues - Scenario

The Architecture QoS issues Scenario

The Architecture QoS issues - Scenario Context scenario: mobile M initially in cell A. Scenario: The sender makes an active reservation with the router R. The router sends data to BSa ( the base station in this cell ) and resource reservations must be made between BSa and M. When the mobile moves, it could move into any of the other six cells. At this point need to make two kinds of resource reservations that are passive: a) between the current base station Bsa and all other base stations namely BSb, BSc, BSd, BSe, BSf and BSg, b) base stations BSb, BSc etc. make a passive resource reservation on their wireless interfaces to accommodate mobile Ms potential requests.

The Architecture QoS issues - Scenario BSa also informs router R about the addresses of all the neighboring base stations. The router examines these addresses to see if the addresses belong to the same QoS-domain as the current base station or belong to another domain. In fig. (b) mobile M has moved into cell F. The resources that were labeled passive in the wired environment between BSa and BSf are made active and the resources on the wireless interface of BSf is activated to be used for communication between BSf and M. All other resources reserved passively can be deleted now. BSf now sends to router R, the addresses of all the base stations in the neighboring cells. The addresses include address of BSi, BSj and BSk. R realizes that these base stations are in a different QoS domain and hence, R makes passive reservations with BSi, BSj and BSk - fig. (c). Fig.(d) – the mobile has moved into cell I. At this point the reservation between router R and BSi are activated and all other passive reservations are deleted.

The Architecture Dataflow A sender in the Internet wants to send data to a mobile M which is currently in the region of base station BSa (in subnet A). The sender sends the request to the Home Agent (HA) which sends a reservation request to the Foreign agent (FA) (which also happens to be the routing-domain router). The path from the sender to FA uses the mobile IP routing protocol while the path from the FA to the mobile (through BSa) uses the routing table entries on hosts in the same routing-domain which reflect the current location on mobile M. Currently the mobile is in the region of BSa. At this point, passive reservations are to made locally for potential movement of the mobile. BSa informs the QoS domain router the addresses of all its neighboring base stations.

The Architecture Dataflow There are two possible ways of making passive reservations at this point: If all the neighboring base station are in the same QoS-domain, Bsa makes passive reservation with all these neighbors. If some of the neighbors are in a different QoS domain, BSa makes passive reservation with the base stations in the same QoS -domain. The QoS domain router makes passive reservation with the base stations in the neighboring domain. The mobile now moves into region of say BSf. Either: the reservations between BSa and BSf are activated or the reservations between the QoS-domain router and BSf are activated depending on which domain BSf resides. According to the routing followed in the architecture: If the move is local, i.e. within the same routing-domain, the routing tables in the hosts in this domain are changed to indicate that the mobile is now in the location of BSf. If the move is to another routing-domain, the current routing-domain router/FA informs the HA about the move and the HA chooses another QoS domain router the the other subnet as the FA.