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Slide 1: Using Mobility Support for Request-Routing in IPv6 CDNs Arup Acharya and Anees Shaikh TJ Watson Research Center Presented by Renu Tewari
Slide 2: Request-Routing in CDNs  RR directs client HTTP requests to “proximal” server  In IPv4 CDNs, RR primarily via DNS  Key observation: RR is congruent to IP mobility  use mobile IP mechanisms for redirection  no need to overload DNS  In IPv4, mobility requires deployment of “mobility agents”  existing hosts remain unchanged  however, all packets routed via home agent ⇒ triangular routing  IPv6 offers native mobility support  support present in any IPv6 node  direct routing between mobiles and correspondents  RR can use mobility mechanisms without modification
Slide 3: DNS Request Routing (IPv4) CDN servers 63.64.105.4 12.100.104.5 0) modified nameserver = .a bc .c 12 om .1 00 ? .1 04 .5 (T TL root nameserver www.abc.com? client 12.100.104.5 local ns m? c.co ab ww. w ) = 1d TTL om ( bc.c ns.a w w w
Slide 4: RR in IPv6 using mobility support  resolve name to an IP address (IPv) IPv6 RR (IPV) origin server DNS server CDN servers www.abc.com? local NS IPV client
Slide 5: IPv6 Request-Routing (cont.)  RR chooses proximal server (IPL)  forwards SYN pkt to IPL in IP-in-IP tunnel home agent IPv6 RR (IPV) f(IPC, IPV) = IPL SY N src: IPC dest: IPV S TCP TC P YN mobile node correspondent node client (IPC) CDN server (IPL)
Slide 6: IPv6 Request-Routing (cont.)  CDN server sends IPv v IPL mapping to client via a binding update, piggybacked on SYN/ACK  client creates binding cache entry src: IPL dest: IPC HA: IPV bind upd C SYN/A K IPv6 RR (IPV) S TCP YN src: IPC dest: IPV binding cache IPV IPL CDN server (IPL) client (IPC)
Slide 7: IPv6 Request-Routing (cont.)  subsequent client pkts sent to IPL (IPv placed in routing header)  TCP endpoint: < IPc ,IPv> IPv6 RR (IPV) src: IPC dest: IPL RH: IPV binding cache IPV IPL E HTTP G T CDN server (IPL) client (IPC)
Slide 8: Additional remarks  IPv6 mobility provides an alternate mechanism for RR  RR policies and metrics must be implemented at the home agent  Functionality similar to DNS, without some problems  IPv6 RR sees actual client address – improved accuracy  CDN server can use lifetime field in binding cache to control duration of binding  Take advantage of large address space in IPv6  map CDN customers to distinct (virtual) IP addresses  use additional addresses for granular content-based-routing (e.g., streaming, images, etc.)
Slide 9:  correspondents always send pkts via home agent  home agent is in forward data path  home agent tunnels pkts to mobile  mobile can respond directly to correspondent home agent mobility agents correspondent mobile node
Slide 10:  For a home agent to function as a req-router  Require load info about each CDN server, or  A knowledgebase correlating IP addresses with topology/geography: match client and proximal servers
Slide 12: Content Internetworking RRA RRB CDN B CDN A CDN server client