Vfong's Blog

vfong — Mon, 23 Feb 2009 00:58:07 +0000

Cisco Firewall Specifications
	ASA 5505	ASA 5510	ASA 5520	ASA 5540	ASA 5550	Catalyst 6500 FWSM
Operating System	ASA 7.x, 8.x	ASA 7.x, 8.x	ASA 7.x, 8.x	ASA 7.x, 8.x	ASA 7.x, 8.x	FWSM 2.x, 3.x
Memory	256 MB	256 MB	512 MB	1 GB	4 GB	1 GB
Flash (minimum)	64 MB	64 MB	64 MB	64 MB	64 GB	128 MB
Throughput	150 Mbps	300 Mbps	450 Mbps	650 Mbps	1.2 Gbps	5 Gbps
Concurrent Connections	10,000/25,000^[1]	50,000/130,000^[1]	280,000	400,000	600,000	1 million
Physical Interfaces	Eight 10/100 switch; two Power over Ethernet (PoE)	Five 10/100	Four 10/100/1000, one 10/100	Four 10/100/1000, one 10/100	Eight 10/100 plus 12 10/100 or nine GigabitEthernet	0
Logical Interfaces	Three (no trunking)/20 (trunking)	50/100^[1]	150	200	250	100
Failover	No / Stateless Active/Standby (A/S)^[1]	No / Active/Active (A/A) and A/S	A/A and A/S	A/A and A/S	A/A and A/S	A/A and A/S^[2]
AAA and Cut-Through Proxy	Yes	Yes	Yes	Yes	Yes	Yes
Command-Line Interface	Console, Telnet, Secure Shell (SSH)	Console, Telnet, SSH	Console, Telnet, SSH	Console, Telnet, SSH	Console, Telnet, SSH	Telnet, SSH
GUI	ASDM	ASDM	ASDM	ASDM	ASDM	ASDM
Routing	Static, RIP, EIGRP, OSPF	Static, RIP, EIGRP, OSPF	Static, RIP, EIGRP, OSPF	Static, RIP, EIGRP, OSPF	Static, RIP, EIGRP, OSPF	Static, RIP, OSPF
Security Contexts	0	0 / 2, 5^[1]	2, 20	2, 50	2, 50	100
VPN-Capable	Yes	Yes	Yes	Yes	Yes	No^[3]

^[1] Base license/Security Plus license

^[2] The FWSM supports only LAN-based failover, because it has no physical failover cable connector.

^[3] The FWSM does not support any IPSec VPN features except for a 3DES tunnel that is used for management purposes.

Find information

vfong — Thu, 12 Feb 2009 20:02:48 +0000

My bookmark/tag
Google search for general
Wikipedia for specific
Safari online for more specific/detailed (need to pay?!?) content

Wide Area Networks

vfong — Wed, 04 Feb 2009 18:26:13 +0000

 test

PPP LCP Features
Function	LCP Feature	Description
Looped link detection	Magic number	Detects if the link is looped, and disables the interface, allowing rerouting over a working route.
Error detection	Link Quality Monitoring (LQM)	Disables an interface that exceeds an error percentage threshold, allowing rerouting over better routes.
Multilink support	Multilink PPP	Load-balances traffic over multiple parallel links.
Authentication	PAP and CHAP	Exchanges names and passwords so that each device can verify the identity of the device on the other end of the link.

Likely Reasons for Data-Link Problems on Serial Links
Line Status	Protocol Status	Likely Reason
Up	Down (stable) on both endsor Down (stable) on one end, flapping between up and down on the other	Mismatched encapsulation commands
Up	Down on one end, up on the other	Keepalive is disabled on the end in an up state
Up	Down (stable) on both ends	PAP/CHAP authentication failure

Summary of Symptoms for Mismatched Subnets on Serial Links
Symptoms When IP Addresses on a Serial Link Are in Different Subnets	HDLC	PPP
Does a ping of the other router’s serial IP address work?	No	Yes
Can routing protocols exchange routes over the link?	No	No

 test

Frame Relay configuration steps.

Step 1.	Configure the physical interface to use Frame Relay encapsulation (encapsulation frame-relay interface subcommand).
Step 2.	Configure an IP address on the interface or subinterface (ip address subcommand).
Step 3.	(Optional) Manually set the LMI type on each physical serial interface (frame-relay lmi-type interface subcommand).
Step 4.	(Optional) Change from the default encapsulation of cisco to ietf by doing the following: a. For all VCs on the interface, add the ietf keyword to the encapsulation frame-relay interface subcommand. b. For a single VC, add the ietf keyword to the frame-relay interface-dlci interface subcommand (point-to-point subinterfaces only) or to the frame-relay map command.
Step 5.	(Optional) If you aren’t using the (default) Inverse ARP to map the DLCI to the next-hop router’s IP address, define static mapping using the frame-relay map ip dlci ip-address broadcast subinterface subcommand.

Step 6.	On subinterfaces, associate one (point-to-point) or more (multipoint) DLCIs with the subinterface in one of two ways: a. Using the frame-relay interface-dlci dlci subinterface subcommand b. As a side effect of static mapping using the frame-relay map ip dlci ip-address broadcast subinterface subcommand

 test

TCP/IP internetworking facts

vfong — Wed, 04 Feb 2009 04:21:48 +0000

Fundamentals

Today’s Most Common Types of Ethernet
Common Name	Speed	Alternative Name	Name of IEEE Standard	Cable Type, Maximum Length
Ethernet	10 Mbps	10BASE-T	IEEE 802.3	Copper, 100 m
Fast Ethernet	100 Mbps	100BASE-TX	IEEE 802.3u	Copper, 100 m
Gigabit Ethernet	1000 Mbps	1000BASE-LX, 1000BASE-SX	IEEE 802.3z	Fiber, 550 m (SX) 5 km (LX)
Gigabit Ethernet	1000 Mbps	1000BASE-T	IEEE 802.3ab	100 m

LAN MAC Address Terminology and Features
LAN Addressing Term or Feature	Description
MAC	Media Access Control. 802.3 (Ethernet) defines the MAC sublayer of IEEE Ethernet.
Ethernet address, NIC address, LAN address	Other names often used instead of MAC address. These terms describe the 6-byte address of the LAN interface card.
Burned-in address	The 6-byte address assigned by the vendor making the card.
Unicast address	A term for a MAC that represents a single LAN interface.
Broadcast address	An address that means “all devices that reside on this LAN right now.” – FFFF.FFFF.FFFF
Multicast address	On Ethernet, a multicast address implies some subset of all devices currently on the Ethernet LAN. – 0100.5exx.xxxx

WAN Speed Summary
Name(s) of Line	Bit Rate
DS0	64 Kbps
DS1 (T1)	1.544 Mbps (24 DS0s, plus 8 kb/s overhead)
DS3 (T3)	44.736 Mbps (28 DS1s, plus management overhead)
E1	2.048 Mbps (32 DS0s)
E3	34.064 Mbps (16 E1s, plus management overhead)
J1 (Y1)	2.048 Mbps (32 DS0s; Japanese standard)

All Possible Valid Network Numbers (Classful, ie. no subnet zero)*
Class	First Octet Range	Valid Network Numbers*	Total Number for This Class of Network	Number of Hosts Per Network
A	1 to 126	1.0.0.0 to 126.0.0.0	2⁷–2 (126)	2²⁴–2 (16,777,214)
B	128 to 191	128.1.0.0 to 191.254.0.0	2¹⁴ (16,384)	2¹⁶–2 (65,534)
C	192 to 223	192.0.1.0 to 223.255.254.0	2²¹ (2,097,152)	2⁸–2 (254)

All Possible Valid Network Numbers (Classless)
	Class A	Class B	Class C
First Octet Range	1 to 126	128 to 191	192 to 223
Valid Network Numbers	1.0.0.0 to 126.0.0.0	128.0.0.0 to 191.255.0.0	192.0.0.0 to 223.255.255.0
Number of Networks in This Class	2⁷ – 2	2¹⁴	2²¹
Number of Hosts Per Network	2²⁴ – 2	2¹⁶ – 2	2⁸ – 2
Size of Network Part of Address (Bytes)	1	2	3
Size of Host Part of Address (Bytes)	3	2	1

TCP/IP Transport Layer Features
Function	Description
Multiplexing using ports	Function that allows receiving hosts to choose the correct application for which the data is destined, based on the port number.
Error recovery (reliability)	Process of numbering and acknowledging data with Sequence and Acknowledgment header fields.
Flow control using windowing	Process that uses window sizes to protect buffer space and routing devices.
Connection establishment and termination	Process used to initialize port numbers and Sequence and Acknowledgment fields.
Ordered data transfer and data segmentation	Continuous stream of bytes from an upper-layer process that is “segmented” for transmission and delivered to upper-layer processes at the receiving device, with the bytes in the same order.

Popular Applications and Their Well-Known Port Numbers
Port Number	Protocol	Application
20	TCP	FTP data
21	TCP	FTP control
22	TCP	SSH
23	TCP	Telnet
25	TCP	SMTP
53	UDP, TCP	DNS
67, 68	UDP	DHCP
69	UDP	TFTP
80	TCP	HTTP (WWW)
110	TCP	POP3
161	UDP	SNMP
443	TCP	SSL
16,384–32,767	UDP	RTP-based Voice (VoIP) and Video

LAN Switching

Switch Internal Processing
Switching Method	Description
Store-and-forward	The switch fully receives all bits in the frame (store) before forwarding the frame (forward). This allows the switch to check the FCS before forwarding the frame.
Cut-through	The switch forwards the frame as soon as it can. This reduces latency but does not allow the switch to discard frames that fail the FCS check.
Fragment-free	The switch forwards the frame after receiving the first 64 bytes of the frame, thereby avoiding forwarding frames that were errored due to a collision.

Benefits of Segmenting Ethernet Devices Using Hubs, Switches, and Routers
Feature	Hub	Switch	Router
Greater cabling distances are allowed	Yes	Yes	Yes
Creates multiple collision domains	No	Yes	Yes
Increases bandwidth	No	Yes	Yes
Creates multiple broadcast domains	No	No	Yes

Common Switch Configuration Modes
Prompt	Name of Mode	Context-setting Command(s) to Reach This Mode
hostname(config)#	Global	None—first mode after configure terminal
hostname(config-line)#	Line	line console 0line vty 0 15
hostname(config-if)#	Interface	interface type number

Names and Purposes of the Two Main IOS Configuration Files
Configuration Filename	Purpose	Where It Is Stored
Startup-config	Stores the initial configuration used any time the switch reloads IOS.	NVRAM
Running-config	Stores the currently used configuration commands. This file changes dynamically when someone enters commands in configuration mode.	RAM

SSH configuration steps on a Cisco IOS-based switch:

Step 1.	Change the vty lines to use usernames, with either locally configured usernames or an AAA server. In this case, the login local subcommand defines the use of local usernames, replacing the login subcommand in vty configuration mode.
Step 2.	Tell the switch to accept both Telnet and SSH with the transport input telnet ssh vty subcommand. (The default is transport input telnet, omitting the ssh parameter.)
Step 3.	Add one or more username name password pass-value global configuration commands to configure username/password pairs.
Step 4.	Configure a DNS domain name with the ip domain-name name global configuration command.
Step 5.	Configure the switch to generate a matched public and private key pair, as well as a shared encryption key, using the crypto key generate rsa global configuration command.
Step 6.	Although no switch commands are required, each SSH client needs a copy of the switch’s public key before the client can connect.

Banners and Their Use
Banner	Typical Use
Message of the Day (MOTD)	Shown before the login prompt. For temporary messages that may change from time to time, such as “Router1 down for maintenance at midnight.”
Login	Shown before the login prompt but after the MOTD banner. For permanent messages such as “Unauthorized Access Prohibited.”
Exec	Shown after the login prompt. Used to supply information that should be hidden from unauthorized users.

Cisco IOS switch configuration steps for IP connectivity:

Step 1.	Enter VLAN 1 configuration mode using the interface vlan 1 global configuration command (from any config mode).
Step 2.	Assign an IP address and mask using the ip address ip-address mask interface subcommand.
Step 3.	Enable the VLAN 1 interface using the no shutdown interface subcommand.
Step 4.	Add the ip default-gateway ip-address global command to configure the default gateway.

Actions When Port Security Violation Occurs
Option on the switchport port-security violation Command	Protect	Restrict	Shut Down*
Discards offending traffic	Yes	Yes	Yes
Sends log and SNMP messages	No	Yes	Yes
Disables the interface, discarding all traffic	No	No	Yes

LAN Switch Interface Status Codes
Line Status	Protocol Status	Interface Status	Typical Root Cause
Administratively Down	Down	disabled	The interface is configured with the shutdown command.
Down	Down	notconnect	No cable; bad cable; wrong cable pinouts; the speeds are mismatched on the two connected devices; the device on the other end of the cable is powered off or the other interface is shutdown.
Up	Down	notconnect	An interface up/down state is not expected on LAN switch interfaces.
Down	down (err-disabled)	err-disabled	Port security has disabled the interface.
Up	Up	connect	The interface is working.

Interface Status Codes and Their Meanings
Name	First or Second Status Code	General Meaning
Line status	First status code	Refers to the Layer 1 status—for example, is the cable installed, is it the right/wrong cable, is the device on the other end powered on?
Protocol status	Second status code	Refers generally to the Layer 2 status. It is always down if the line status is down. If the line status is up, a protocol status of down usually is caused by mismatched data link layer configuration.

Organizations That Set or Influence WLAN Standards
Organization	Standardization Role
ITU-R	Worldwide standardization of communications that use radiated energy, particularly managing the assignment of frequencies
IEEE	Standardization of wireless LANs (802.11)
Wi-Fi Alliance	An industry consortium that encourages interoperability of products that implement WLAN standards through their Wi-Fi certified program
Federal Communications Commission (FCC)	The U.S. government agency with that regulates the usage of various communications frequencies in the U.S.

WLAN Standards
Feature	802.11a	802.11b	802.11g
Year ratified	1999	1999	2003
Maximum speed using DSSS	—	11 Mbps	11 Mbps
Maximum speed using OFDM	54 Mbps	—	54 Mbps
Frequency band	5 GHz	2.4 GHz	2.4 GHz
Channels (nonoverlapped)*	23 (12)	11 (3)	11 (3)
Speeds required by standard (Mbps)	6, 12, 24	1, 2, 5.5, 11	6, 12, 24

Different WLAN Modes and Names
Mode	Service Set Name	Description
Ad hoc	Independent Basic Service Set (IBSS)	Allows two devices to communicate directly. No AP is needed.
Infrastructure (one AP)	Basic Service Set (BSS)	A single wireless LAN created with an AP and all devices that associate with that AP.
Infrastructure (more than one AP)	Extended Service Set (ESS)	Multiple APs create one wireless LAN, allowing roaming and a larger coverage area.

FCC Unlicensed Frequency Bands of Interest
Frequency Range	Name	Sample Devices
900 KHz	Industrial, Scientific, Mechanical (ISM)	Older cordless telephones
2.4 GHz	ISM	Newer cordless phones and 802.11, 802.11b, 802.11g WLANs
5 GHz	Unlicensed National Information Infrastructure (U-NII)	Newer cordless phones and 802.11a, 802.11n WLANs

Encoding Classes and IEEE Standard WLANs
Name of Encoding Class	What It Is Used By
Frequency Hopping Spread Spectrum (FHSS)	802.11
Direct Sequence Spread Spectrum (DSSS)	802.11b
Orthogonal Frequency Division Multiplexing (OFDM)	802.11a, 802.11g

WLAN Speed and Frequency Reference
IEEE Standard	Maximum Speed (Mbps)	Other Speeds* (Mbps)	Frequency	Nonoverlapping Channels
802.11b	11 Mbps	1, 2, 5.5	2.4 GHz	3
802.11a	54 Mbps	6, 9, 12, 18, 24, 36, 48	5 GHz	12
802.11g	54 Mbps	Same as 802.11a	2.4 GHz	3

WLAN Vulnerabilities and Solutions
Vulnerability	Solution
War drivers	Strong authentication
Hackers stealing information in a WLAN	Strong encryption
Hackers gaining access to the rest of the network	Strong authentication
Employee AP installation	Intrusion Detection Systems (IDS), including Cisco SWAN
Rogue AP	Strong authentication, IDS/SWAN

WLAN Security Standards
Name	Year	Who Defined It
Wired Equivalent Privacy (WEP)	1997	IEEE
The interim Cisco solution while awaiting 802.11i	2001	Cisco, IEEE 802.1x Extensible Authentication Protocol (EAP)
Wi-Fi Protected Access (WPA)	2003	Wi-Fi Alliance
802.11i (WPA2)	2005+	IEEE

Comparisons of WLAN Security Features
Standard	Key Distribution	Device Authentication	User Authentication	Encryption
WEP	Static	Yes (weak)	None	Yes (weak)
Cisco	Dynamic	Yes	Yes (802.1x)	Yes (TKIP)
WPA	Both	Yes	Yes (802.1x)	Yes (TKIP)
802.11i (WPA2)	Both	Yes	Yes (802.1x)	Yes (AES)

IP Routing

IPv4 Versus IPv6
Feature	IPv4	IPv6
Size of address (bits or bytes per octet)	32 bits, 4 octets	128 bits, 16 octets
Example address	10.1.1.1	0000:0000:0000:0000:FFFF:FFFF: 0A01:0101
Same address, abbreviated	—	::FFFF:FFFF:0A01:0101
Number of possible addresses, ignoring reserved values	2³², (roughly 4 billion)	2¹²⁸, or roughly 3.4 x 10³⁸

Routing Protocol Classes/Algorithms and Protocols that Use Them
Class/Algorithm	IGPs
Distance vector	RIP-1, RIP-2, IGRP
Link-state	OSPF, Integrated IS-IS
Balanced hybrid (also called advanced distance vector)	EIGRP

Comparing Classless and Classful Routing Protocols
Feature	Classless	Classful
Supports VLSM	Yes	No
Sends subnet mask in routing updates	Yes	No
Supports manual route summarization	Yes	No

Interior IP Routing Protocols Compared
Feature	RIP-1	RIP-2	EIGRP	OSPF	IS-IS
Classless	No	Yes	Yes	Yes	Yes
Supports VLSM	No	Yes	Yes	Yes	Yes
Sends mask in update	No	Yes	Yes	Yes	Yes
Distance vector	Yes	Yes	No¹	No	No
Link-state	No	No	No¹	Yes	Yes
Supports autosummarization	No	Yes	Yes	No	No
Supports manual summarization	No	Yes	Yes	Yes	Yes
Proprietary	No	No	Yes	No	No
Routing updates sent to a multicast IP address	No	Yes	Yes	Yes	N/A
Supports authentication	No	Yes	Yes	Yes	Yes
Convergence	Slow	Slow	Very fast	Fast	Fast

IOS Defaults for Administrative Distance
Route Source	Administrative Distance
Connected routes	0
Static routes	1
EIGRP	90
IGRP	100
OSPF	110
IS-IS	115
RIP (V1 and V2)	120
Unknown or unbelievable	255

Determining Whether a Question Allows the Use of the Zero and Broadcast Subnets
Clues in the Question	Subnets Reserved?
Says nothing about it (default for the exam)	No
Lists the ip subnet-zero configuration command	No
Uses a classless routing protocol (RIP-2, EIGRP, OSPF)	No
Lists the no ip subnet-zero configuration command	Yes
Uses a classful routing protocol (RIP-1)	Yes

WAN

Comparing Circuits and Packet Switching
Feature	Circuits	Packet Switching
Service implemented as OSI layer . . .	1	2
Point-to-point (two devices) or more	Point-to-point	Multipoint (more than two)

Interface Status Codes and Typical Meanings When a Ping Does Not Work
Line Status	Protocol Status	Likely Reason/Layer
Administratively down	Down	Interface is shut down
Down	Down	Layer 1
Up	Down	Layer 2
Up	Up	Layer 3

Steps to configure HDLC:

Step 1.	Configure the interface IP address using the ip address interface subcommand.
Step 2.	The following tasks are required only when the specifically listed conditions are true: If an encapsulation protocol interface subcommand that lists a protocol besides HDLC already exists on the interface, use the encapsulation hdlc interface subcommand to enable HDLC. If the interface line status is administratively down, enable the interface using the no shutdown interface subcommand. If the serial link is a back-to-back serial link in a lab (or a simulator), configure the clocking rate using the clock rate speed interface subcommand, but only on the one router with the DCE cable (per the show controllers serial number command).
Step 3.	The following steps are always optional, and have no impact on whether the link works and passes IP traffic: Configure the link’s speed using the bandwidth speed-in-kbps interface subcommand. For documentation purposes, configure a description of the purpose of the interface using the description text interface subcommand.

Routing protocols

vfong — Tue, 03 Feb 2009 19:29:49 +0000

Summary of Interior Routing Protocols

Table 1. Interior IP Routing Protocols Compared
Feature	RIP-1	RIP-2	EIGRP	OSPF	IS-IS
Classless	No	Yes	Yes	Yes	Yes
Supports VLSM	No	Yes	Yes	Yes	Yes
Sends mask in update	No	Yes	Yes	Yes	Yes
Distance vector	Yes	Yes	No	No	No
Link-state	No	No	No	Yes	Yes
Supports autosummarization	Yes	Yes	Yes	No	No
Supports manual summarization	No	Yes	Yes	Yes	Yes
Proprietary	No	No	Yes	No	No
Routing updates sent to a multicast IP address	No	Yes	Yes	Yes	N/A
Supports authentication	No	Yes	Yes	Yes	Yes
Convergence	Slow	Slow	Very fast	Fast	Fast

Basic router configurations

vfong — Tue, 03 Feb 2009 04:47:53 +0000

RIP-2 Configuration

The RIP-2 configuration process takes only the following three required steps, with the possibility that the third step might need to be repeated:

Step 1.	Use the router rip configuration command to move into RIP configuration mode.
Step 2.	Use the version 2 RIP subcommand to tell the router to use RIP Version 2 exclusively.

Step 3.	Use one or more network net-number RIP subcommands to enable RIP on the correct interfaces.
Step 4.	(Optional) As needed, disable RIP on an interface using the passive-interface type number RIP subcommand.

OSPF Configuration

OSPF configuration includes only a few required steps, but it has many optional steps. After an OSPF design has been chosen—a task that may be complex in larger IP internetworks—the configuration may be as simple as enabling OSPF on each router interface and placing that interface in the correct OSPF area.

Step 1.	Enter OSPF configuration mode for a particular OSPF process using the router ospf process-id global command.
Step 2.	(Optional) Configure the OSPF router ID by: a. Configuring the router-id id-value router subcommand. b. Configuring an IP address on a loopback interface.
Step 3.	Configure one or more network ip-address wildcard-mask area area-id router subcommands, with any matched interfaces being added to the listed area.
Step 4.	(Optional) Change the interface Hello and Dead intervals using the ip ospf hello-interval time and ip ospf dead-interval time interface subcommands.

Step 5.	(Optional) Impact routing choices by tuning interface costs as follows: a. Configure costs directly using the ip ospf cost value interface subcommand. b. Change interface bandwidths using the bandwidth value interface subcommand. c. Change the numerator in the formula to calculate the cost based on the interface bandwidth, using the auto-cost reference-bandwidth value router subcommand.
Step 6.	(Optional) Configure OSPF authentication: a. On a per-interface basis using the ip ospf authentication interface subcommand. b. For all interfaces in an area using the area authentication router subcommand.
Step 7.	(Optional) Configure support for multiple equal-cost routes using the maximum-paths number router subcommand.

EIGRP Configuration and Verification

Basic EIGRP configuration closely resembles RIP and OSPF configuration. The router eigrp command enables EIGRP and puts the user in EIGRP configuration mode, in which one or more network commands are configured. For each interface matched by a network command, EIGRP tries to discover neighbors on that interface, and EIGRP advertises the subnet connected to the interface.

Step 1.	Enter EIGRP configuration mode, and define the EIGRP ASN by using the router eigrp as-number global command.
Step 2.	Configure one or more network ip-address [wildcard-mask] router subcommands. This enables EIGRP on any matched interface and causes EIGRP to advertise the connected subnet.
Step 3.	(Optional) Change the interface Hello and hold timers using the ip hello-interval eigrp asn time and ip hold-time eigrp asn time interface subcommands.
Step 4.	(Optional) Impact metric calculations by tuning bandwidth and delay using the bandwidth value and delay value interface subcommands.
Step 5.	(Optional) Configure EIGRP authentication.

Step 6.	(Optional) Configure support for multiple equal-cost routes using the maximum-paths number and variance multiplier router subcommands.

How to copy/clone a GN3 net project, including the start.configs

vfong — Tue, 03 Feb 2009 00:37:05 +0000

New project,
Enter in the new project file name,
Make sure the both the “Save nvram and other disk files” and “Export router configuration files” are checked,
Click on “OK”
A dialog box will pop-up to ask if you want to propagate the change to the current topology, choose “NO“, if choose “Yes”, the new net file will save to startup config file in the existing net/topology, which is not what we want.
Observe in the Dynagen console that the config files are saved to the desired folder/filenames, ie, in a new project folder.

IP Addressing

vfong — Mon, 02 Feb 2009 17:46:47 +0000

Table 1. All Possible Valid Network Numbers^[*]
Class	First Octet Range	Valid Network Numbers^[*]	Total Number for This Class of Network	Number of Hosts Per Network
A	1 to 126 (0000,0001 – 0111,1110)	1.0.0.0 to 126.0.0.0	2⁷ – 2 (126)	2²⁴ – 2 (16,777,214)
B	128 to 191 (1000,0000 – 1011,1111)	128.0.0.0 to 191.255.0.0	2¹⁴ (16,384)	2¹⁶ – 2 (65,534)
C	192 to 223 (1100,0000 – 1101,1111)	192.0.0.0 to 223.255.255.0	2²¹ (2,097,152)	2⁸ – 2 (254)

^[*] The Valid Network Numbers column shows actual network numbers. Networks 0.0.0.0 (originally defined for use as a broadcast address) and 127.0.0.0 (still available for use as the loopback address) are reserved.

Table 2. RFC 1918 Private Address Space
Private IP Networks	Class of Networks	Number of Networks
10.0.0.0	A	1
172.16.0.0 through 172.31.0.0	B	16
192.168.0.0 through 192.168.255.0	C	256

Any organization can use these network numbers. However, no organization is allowed to advertise these networks using a routing protocol on the Internet.

Magic numbers …..

2(7), 128, 128 1000.0000

2(6), 64, 192 1100.0000

2(5), 32, 224 1110.0000

2(4), 16, 240 1111.0000

—–

2(3), 8, 248 1111.1000

2(2), 4, 252 1111.1100

2(1), 2, 254 1111.1110

2(0), 1, 255 1111.1111

Table 3. When to Use Which Formula for the Number of Subnets
Use the 2^s – 2 formula, and avoid the zero and broadcast subnet, if…	Use the 2^s formula, and use the zero and broadcast subnet, if…
Classful routing protocol	Classless routing protocol
RIP Version 1 or IGRP as the routing protocol	RIP Version 2, EIGRP, or OSPF as the routing protocol
The no ip subnet zero command is configured	The ip subnet zero command is configured or omitted (default)
	VLSM is used
	No other clues provided

If a question simply does not give any clues as to whether to allow these two special subnets or not, assume you can use these subnets, and use the 2^s formula.

To find the subnet number (and broadcast) ‘s value for the interesting octet:

a. Calculate the magic number by subtracting the subnet mask’s interesting octet value from 256.

b. Calculate the multiples of the magic number, starting at 0, up through 256.

c. Write down the interesting octet’s value, calculated as follows: find the multiple of the magic number that is closest to, but not greater than, the IP address‘s interesting octet value.

d. Find the broadcast value for the interesting octet by adding the subnet number’s value in the interesting octet to the magic number, and subtract 1.

OSI 7 layers

vfong — Thu, 29 Jan 2009 18:23:40 +0000

All People Seem To Need Data Processing

Application, Presentation, Session, Transport, Network, Data link, Physical

or in reverse order: Please Do Not Tell Sales Person Anything

Linux From Scratch, LFS

vfong — Tue, 27 Jan 2009 23:17:02 +0000

Just went through the whole process of LFS 6.3 book using its LiveCD on VMware workstation 6.5. This is an educational and useful exercise with many advantages for doing so, including:

deep understanding of the linux kernel, how it is built, the related core files, processes and utils
having the source around and be ready to modify and recompile to whatever change I desire to for debugging and understanding (again) helps a lot in understanding the theory of operation of linux
the packages, comprised of C and h include files, are perfect way to brush up on C, linux (unix) is written in C
likewise, the configure, Makefile files are good way to brush up on make, automake and autoconf processes
deep understanding of glibc, binutils, gcc, sysvinit, grub and linux boot processes …

A few useful reminder links, starting wit the LFS main site (from which the various extensions spawn):

One not obvious point (at least for me at first), for each package, it is assumed that the package is untar/uncompressed and that you have cd’ed into the package directory.

What next?

Choose some vital packages like ssh from BLFS to install to make it a usable/friendly linux system. Another direction is to go up the LAMP stack, with Linux from scratch, why not, Apache from scratch, MySQL from scratch and, Python, PHP from scratch. Perl is already built during the LFS. That shows how critical Perl is to the core Linux system.

Vfong's Blog

Cisco Firewall Specifications

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Wide Area Networks

PPP LCP Features

Likely Reasons for Data-Link Problems on Serial Links

Summary of Symptoms for Mismatched Subnets on Serial Links

Frame Relay configuration steps.

TCP/IP internetworking facts

Fundamentals

Today’s Most Common Types of Ethernet

LAN MAC Address Terminology and Features

WAN Speed Summary

All Possible Valid Network Numbers (Classful, ie. no subnet zero)*

All Possible Valid Network Numbers (Classless)

TCP/IP Transport Layer Features

Popular Applications and Their Well-Known Port Numbers

LAN Switching

Switch Internal Processing

Benefits of Segmenting Ethernet Devices Using Hubs, Switches, and Routers

Common Switch Configuration Modes

Names and Purposes of the Two Main IOS Configuration Files

SSH configuration steps on a Cisco IOS-based switch:

Banners and Their Use

Cisco IOS switch configuration steps for IP connectivity:

Actions When Port Security Violation Occurs

LAN Switch Interface Status Codes

Interface Status Codes and Their Meanings

Organizations That Set or Influence WLAN Standards

WLAN Standards

Different WLAN Modes and Names

FCC Unlicensed Frequency Bands of Interest

Encoding Classes and IEEE Standard WLANs

WLAN Speed and Frequency Reference

WLAN Vulnerabilities and Solutions

WLAN Security Standards

Comparisons of WLAN Security Features

IP Routing

IPv4 Versus IPv6

Routing Protocol Classes/Algorithms and Protocols that Use Them

Comparing Classless and Classful Routing Protocols

Interior IP Routing Protocols Compared

IOS Defaults for Administrative Distance

Determining Whether a Question Allows the Use of the Zero and Broadcast Subnets

WAN

Comparing Circuits and Packet Switching

Interface Status Codes and Typical Meanings When a Ping Does Not Work

Steps to configure HDLC:

Routing protocols

Summary of Interior Routing Protocols

Table 1. Interior IP Routing Protocols Compared

Basic router configurations

RIP-2 Configuration

OSPF Configuration

EIGRP Configuration and Verification

How to copy/clone a GN3 net project, including the start.configs

IP Addressing

Table 1. All Possible Valid Network Numbers[*]

Table 2. RFC 1918 Private Address Space

Table 3. When to Use Which Formula for the Number of Subnets

OSI 7 layers

Linux From Scratch, LFS

Table 1. All Possible Valid Network Numbers^[*]