NETWORK ILLUSTRATED TCPIP PHẦN 1 POT

Mỗi ngày 10 phút tìm hiểu TCP/IP (phần 1)TCP/IP là một hệ thống giao thức - một tập hợp các giao thức hỗ trợ việc lưu truyền trên mạng. Và lời giải đáp cho câu hỏi: "Giao thức là gì?" phải được bắt đầu bằng: "Hệ thống mạng là gì?"Phần này sẽ đưa ra định nghĩa về một hệ thống mạn[r]

TCP IP Wiley TCPIP Analysis and Troubleshooting Toolkit Jul03 pdf Cisco Press First Step TCP IP Dec04 chm Addison Wesley TCPIP Illustrated vol02 Jan95 chm Addison Wesley TCPIP Illustrated vol01 Dec93 chm O_reilly_-_Tcpip_Network_Administration._3rd_Ed[r]

packet is sent to 10.10.12.52 (winsvr2). This is how routing works. (Bridges, or direct delivery even in routing, always has frames in which the destination MAC address is the same as the IP address it represents.)How did the source host, wincli1, know the MAC address of the correct router? There co[r]

10.10.12.0 * 255.255.255.0 U 0 0 0 eth0127.0.0.0 * 255.0.0.0 U 0 0 0 lodefault 10.10.12.1 0.0.0.0 UG 0 0 0 eth0[root@lnxclient admin]#The Gateway column has asterisks because we don’t have DNS running and the address is the same as the Destination. Only the default gateway entry (10.10.12.1) is diff[r]

Looking at the table, the fi rst 20 bits are exactly the same in all three entries, as well as the destination address. But which is the longest match? The router will keep compar-ing the addresses in the table to the destination address bit by bit until the table runs out of entries. The last match[r]

root syslogd 72 3 dgram /var/run/log CHAPTER 10 User Datagram Protocol 265The little “echo” port is not listed because it is not running on this host. Note that the syslogd process in FreeBSD listens on both the UDP and TCP ports (in this case, port 514) for clients.What about Windows XP? The comman[r]

request). The sender also includes its own link-layer address with the message.Duplicate IP addresses are always a problem. Before a system can claim an IPv6 address or any other address not constructed by adding a link-local address to a pre-fi x, the system sends a Neighbor Solicitation message ask[r]

private or non-reserved ports. Clients should choose ephemeral port numbers from this range, but many systems do not.Table 10.1 Some Well-Known Ports Used by UDP and TCP Services and FunctionsPort Number Service Meaning7 Echo Used to echo data back to the sender9 Discard Used to discard data at rece[r]

CHAPTERWhat You Will LearnIn this chapter, you will learn about ICMP messages, their types, and (in many cases) the codes used in each type. We’ll look at which ICMP messages are routinely blocked at fi rewalls and which are essential for proper device operation.You will learn about the common ping u[r]

between a source and destination in order to avoid fragmentation. The main reasons today follow:■ Fragmentation is processor intensive. Early routers were hard pressed to both route and fragment. Even today, high link speeds force routers to concentrate on routing and minimize “housekeeping” tasks.■[r]

meaning that it is ordinary bulk data (as FTP should carry) and requires no special handling at devices.Flow Label—A 16-bit field used to label packets belonging to the same flow (those with the same values in several TCP/IP header parameters). The flow label here is 0, but this is common.Payload Le[r]

gling with real data packets. Seeing a small ping getting through reliably is not always helpful.Also, the round-trip times are not often vital information. You expect round-trip times to go up as packet sizes increase, and that’s typically what is observed. The same is true if the network is[r]

2. We’ll confi gure RIPng as the IGP in both ASs, starting with the IPv6 address on the interfaces and show that the routing information about LAN1 and LAN2 ends up everywhere. We will not talk about the role of the EGP in all this until Chapter 15.3. We’ll compare three major IGPs: RIP, OSPF,[r]

lishes groups of parameters based on real world values (e.g., bandwidth at 10, 100, or 1000 Mbps with associated delays), and is offered as a “class” to customers (e.g., bronze, silver, or gold service).Table 13.2 The Six QoS ParametersQoS Parameter Example Values (Typical)Bandwidth (minimum) 1.5 Mb[r]

Internet is a bit less organized than this, although ISPs closer to the core have a higher level of interconnection than those at the edge. This is an interconnected mesh of ISPs and related Internet-connected entities such as government bureaus and learning institutions. Also, keep in mind that in[r]

like split horizon, will not eliminate all cases of routing loops and counting to infi nity. However, triggered updates always help the counting process to reach infi nity much faster.RIPv1A RIP packet must be 512 bytes or smaller, including the header. RIP packets have no implied sequence, and each u[r]

OSPF can be equipped with metrics that can be used to compute the “shortest” path through a group of routers based on link and router characteristics such as highest throughput, lowest delay, lowest cost (money), link reliability, or even more. OSPF is still used very cautiously, with default metric[r]

same sequence and acknowledgment numbers. The server sends an ACK to the FIN and increments the acknowledgment fi eld but not the sequence number. The connec-tion is down.But not really. The “best-effort” nature of the IP network means that delayed dupli-cated could pop out of a router at any[r]

terminology is not correct. It is not the IP packet itself that is fragmented, but the packet content. If the payload is too large to fi t inside a single IP packet (as determined by the IP layer implementation), the content is spread across several packets, each with its own IP header.In some cases,[r]

TCP just by watching it work in a normal, error-free environment. Instead of watching to check whether TCP recovers from lost segments (it does), we’ll just capture the sequence of TCP segments used on various combinations of the three operating system platforms and see what’s going on. Later, we’ll[r]