TCP IP Illustrated

That is why dont both ends of the dialup slip link

Info iconThis preview shows page 1. Sign up to view the full content.

View Full Document Right Arrow Icon
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: n Section 3.8 that the destination address of the dialup SLIP link, as shown by the ifconfig command, was 140.252.1.183. The Net-Blazer doesn't require an IP address for its end of each dialup SLIP link. (Doing so would use up more IP addresses.) Instead, it determines which dialup host is sending it packets by which serial interface the packet arrives on, so there's no file:///D|/Documents%20and%20Settings/bigini/Docu...homenet2run/tcpip/tcp-ip-illustrated/arp_addr.htm (9 of 12) [12/09/2001 14.46.39] Chapter 4. ARP: Address Resolution Protocol need for each dialup host to use a unique IP address for its link to the router. All the dialup hosts use 140.252.1.183 as the destination address for their SLIP link. Proxy ARP handles the delivery of datagrams to the router sun, but how are the other hosts on the subnet 140.252.13 handled? Routing must be used to direct datagrams to the other hosts. Specifically, routing table entries must be made somewhere on the 140.252 network that point all datagrams destined to either the subnet 140.252.13, or the specific hosts on that subnet, to the router netb. This router then knows how to get the datagrams to their final destination, by sending them through the router sun. Proxy ARP is also called promiscuous ARP or the ARP hack. These names are from another use of proxy ARP: to hide two physical networks from each other, with a router between the two. In this case both physical networks can use the same network ID as long as the router in the middle is configured as a proxy ARP agent to respond to ARP requests on one network for a host on the other network. This technique has been used in the past to "hide" a group of hosts with older implementations of TCP/IP on a separate physical cable. Two common reasons for separating these older hosts are their inability to handle subnetting and their use of the older broadcasting address (a host ID of all zero bits, instead of the current standard of a host ID with all one bits). 4.7 Gratuitous ARP Another feature of ARP that we can watch is called gratuitous ARP. It occurs when a host sends an ARP request looking for i...
View Full Document

This test prep was uploaded on 04/04/2014 for the course ECE EL5373 taught by Professor Guoyang during the Spring '12 term at NYU Poly.

Ask a homework question - tutors are online