e mobile node. The MIP interdomain handoff time becomes tMIP_inter = 3th + tno + the + tmc (22.14) Note that when the mobile node is located in its home network tmc the. With SIP the interdomain handoff time occurs after C 2009 by Taylor & Francis Group, LLC SIP Security and Quality of Service Performance (a) the times for acquiring new IP address through DHCP and an ARP (4ts + tarp) and (b) the time for the mobile node to send SIP REGISTER message to the home registrar (HR) which is (2th). At this point Internet connectivity is enabled. Then the mobile node re-invites the CN by sending to it an INVITE message. (c) This takes the time (2tmc). Hence the interdomain handoff time is: tSIP_inter = 4ts + tARP + 2th + 2tmc (22.15) In general the choice of tARP is between 1 and 3 ms and tno is about 5 ms. The disruption time increases as the delay distance between the mobile node and CN increases. Since in the case of MIP the mobile node the disruption time is 2ts + 2th + 2tno and tf is about (ts + 2) ms, the disruption time is about 54 ms, which is large enough (for speech sampled at 8 KHz) to drop more than 432 contiguous speech samples which is a significant portion of the speech communication and makes it annoying to listen to. However, MIP outperforms SIP because the mobile terminal starts to receive speech after only about 2ts + 2th + 2tno seconds and the terminal can start to playback some of the speech until the overall handoff is completed. In both interdomain and intradomain handoffs, MIP performance is superior. The intradomain disruption times for both MIP and SIP are relatively flat with increasing delay distance between the mobile node and home network and also always smaller than the interdomain disruption times. The interdomain disruption times increase linearly for both MIP and SIP. At smaller delay separation, the MIP outperforms the SIP performance but only after some time, SIP is advantageous as its disruption time becomes smaller than MIP over larger delays. For both MIP and SIP the interdomain hand