Notes


1. For connection-oriented protocols such as TCP (to be discussed shortly), error rates have a significant impact on how much of that transmission potential can actually be used to transfer data.

2. That said, the maximum bandwidth for common LAN usage is still 1 Gbps — a transmission rate more than adequate for Web surfing and checking e-mail.

3. ATM, strictly speaking, is an entire protocol stack much like the TCP/IP suite with standards for addressing and path finding. As commonly seen from the point of view of IP, however, ATM simply serves as a layer 2 technology.

4. IPv5 was never released as a production protocol. It was developed for a real-time stream protocol that was never widely adopted.

5. That is 3.4 followed by 68 zeros.

6. To improve performance, many routers will cache routes or use some sort of "express forwarding" mechanism that allows packets to bypass the normal software-based routing table and use an interface-based forwarding table. This is not the same as keeping count of individual packets, however.

7. While IP addresses are represented in decimal for human consumption, MAC addresses are traditionally represented in hexadecimal. Thus, each character of a MAC address represents four binary bits.

8. In NAT terms, a pool can be a range of public IP addresses, or a single IP address.

9. While Cisco sometimes markets EIGRP as a routing protocol with link state characteristics, it is fundamentally a distance vector routing protocol. For those still skeptical, I offer the following exercise: create a small test network using EIGRP and OSPF. Attempt to filter outbound route updates within your autonomous system (EIGRP) or area (OSPF) as appropriate. Note your findings.

10. We will discuss hashing in a bit. For now, consider it a form of one-way encryption.

11. In theory, the ports are random. In practice, some vendors increment the sequence numbers by one for each new connection. So the first source port for packets will be 1024, the second 1025, etc.




Network Perimeter Security. Building Defense In-Depth
Network Perimeter Security: Building Defense In-Depth
ISBN: 0849316286
EAN: 2147483647
Year: 2004
Pages: 119
Authors: Cliff Riggs

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