Jaycee's Networking

December 15, 2008

Citrix NetScaler 10010

Filed under: Load Balancing, Netscaler — Tags: — Jaycee @ 4:52 pm

1. single processor, 2U, 2GB memory, either fiber Gigabit Ethernet ports or 10/100/1000 Base-T copper ethernet ports by default.

2. process up to 255,000 HTTP requests per second, and 8,800 SSL requests per second.

3. 4,800 Mbps system throughput(總處理能力), 760 Mbps SSL throughput, and 555 Mbps compression throughput.

4. The unit has the following ports:

(1) 4 10/100/1000-Base-T network interfaces (labeled 1/1, 1/2, 1/3, 1/4)

(2) 1 10/100-Base-T network interface (labeled 0/1)

(3) Serial port (9600 baud, 8 bits, 1 stop bit, No parity)

5. Facing the bezel, the upper LEDs represent connectivity; the lower LEDs represent throughput.


DHCP configuration

Filed under: DHCP, IOS — Tags: — Jaycee @ 11:01 am

1. Excluding IP Address:

Router(config)# ip dhcp excluded-address low-address [high-address]
The IP addresses that the DHCP Server should not assign to DHCP clients.

2.Configuring a DHCP Address Pool:

Router(config)# ip dhcp pool name
Creates a name for the DHCP Server address pool and places you in DHCP pool configuration mode.

3. Configuring the DHCP Address Pool Subnet and Mask:

Router(dhcp-config)# network network-number [mask | /prefix-length]
Specifies the subnet network number and mask of the DHCP address pool.

4. Configuring the Domain Name:

Router(dhcp-config)# domain-name domain
Specifies the domain name for the client.

5. Configuring the IP Domain Name System Servers:

Router(dhcp-config)# dns-server address [address2 address8]
Specifies the IP address of DNS server(s).

6. Configuring the NetBIOS Windows Internet Naming Service (WINS) Servers:

Router(dhcp-config)# netbios-name-server address [address2 address8]
Specifies the NetBIOS WINS server that is available to Microsoft DHCP clients. WINS is a name resolution service that Microsoft DHCP clients use to correlate host names to IP addresses within a general grouping of networks.

7. Configuring the NetBIOS Node Type:

Router(dhcp-config)# netbios-node-type type
The NetBIOS node type can be one of four settings: broadcast, peer-to-peer, mixed, or hybrid.
b-node  Broadcast node
h-node  Hybrid node
m-node  Mixed node
p-node  Peer-to-peer node

8. Configuring the default router:

Router(dhcp-config)# default-router address [address2 address8]

9. Configuring that Address Lease Time:

Router(dhcp-config)# lease {days [hours][minutes] | infinite}
The default is a one-day lease. Use show ip dhcp binding to display the lease expiration time and date of the IP address of the host. An address binding is a mapping between the IP address and MAC address of a client.

10. Configuring DHCP Option for Lightweight Access Points

Router(dhcp-config)# option 60 ascii “VCI string”
Router(dhcp-config)# option 43 hex <hex string>

(1) For VCI Strings, check the table at: http://www.cisco.com/univercd/cc/td/doc/product/wireless/airo1130/1130hig5/113h_g.htm#wp1008197

(2) The hex string is assembled by concatenating the TLC values: Type + Length + Value

a. Type is always f1.

b. Length is the number of controller management IP addresses times 4 in hex.

c. Value is the IP address of the controller listed sequentially in hex.

d. For example, suppose there are 2 controllers with management interface IP addresses: and The length is 2*4 = 8 = 08 (hex). The IP addresses translate to 0a7e7e02 and 0a7f7f02. Assembling the string then yields f1080a7e7e020a7f7f02.

11. Example as below:

ip dhcp excluded-address
ip dhcp pool USER_NET
domain-name jayceechou.com
netbios-node-type b-node
option 43 hex f104.0a05.022a
option 60 ascii “Cisco AP c1130”
lease 30

12. Notes:

When changing DNS server statement, make sure it’s on the top of NETBIOS server statement; otherwise, all machine would ignore the changes and they are not going to get the correct DNS servers.

December 14, 2008

TCP/IP and OSI Layers

Filed under: Information — Jaycee @ 3:50 pm

TCP/IP protocol suite

1. Physical Layer — contains the protocols relating to the physical medium

(1) Electrical/optical protocols describe signal characteristics such as voltage or photonic levels, bit timing, encoding, and signal shape.

(2) Mechanical protocols are specifications such as the dimensions of a connector or the metallic makeup of a wire.

(3) Functional protocols describe what something does. For example, “Request to Send” is the functional description of pin 4 of an EIA-232-D connector.

(4) Procedural protocols describe how something is done. For example, a binary 1 is represented on an EIA-232-D lead as a voltage more negative than 3 volts.

2. Data Link Layer — contains the protocols that control the physical layer:

(1) how the medium is accessed and shared

(2) how devices on the medium are identified

(3) how data is framed before being transmitted on the medium

3. Network Layer / Internet Layer — enabling the routing of data across logical network paths by defining a packet format and an addressing format

4. Transport Layer / Host-to-Host Layer — contains the protocols that control the internet layer

(1) Both the Host-to-Host Layer and Data Link Layer can define such mechanisms as flow and error control.

(2) While Data Link protocols conrol traffic on the Data Link Layer , the physical medium connecting 2 devices

(3) The transport layer controls traffic on the logical link, the end-to-end connection of 2 devices whose logical connection traverses a series of data links.

5. Session Layer + Presentation Layer + Application Layer / Application Layer

(1) some routing protocols such as BGP and RIP reside at this layer, the most common services of the application layer provide the interfaces by which user applications access the network

(2) BGP uses TCP to transport its messages, and RIP uses UDP for the same purposes; thus they are application layer protocols.

(3) Other routing protocols such as OSPF are said to operate at the internet layer because they encapsulate their messages directly into IP packets.

(4) Many applications might use a service at the host-to-host layer, and many services at the host-to-host layer might use the internet layer.

(5) Any other protocol suite is multiplexing b/w layers. Multiple protocol suites (IP, IPX, AppleTalk) can share a physical link via common data-link protocols.

December 10, 2008

ERROR: No snmp response from A.B.C.D (alarm)

Filed under: Information, Nagios, Troubleshoot — Jaycee @ 8:26 am

We’ve got an error message from Nagios after description updating on a switch’s interfaces as below:

ERROR: No snmp response from A.B.C.D (alarm)

If keep repetitively writing to memory,  the processor takes a HUGE hit.
The first things to stop responding would be ICMP and SNMP.

The script were writing to memory every 5 seconds that would have sent up a big red flag.

December 5, 2008

Looking Glass

Filed under: BGP, Information — Tags: — Jaycee @ 3:34 pm

BGP Looking Glass servers are computers on the Internet running one of a variety of publicly available Looking Glass software implementations.  A Looking Glass server (or LG server) is accessed remotely for the purpose of viewing routing info. Essentially, the server acts as a limited, read-only portal to routers of whatever organization is running the lg server. Typically, publicly accessible looking glass servers are run by ISPs or NOCs.

1. BGP Looking Glass Server List:

2. Qwest Looking Glass:


Filed under: Information — Jaycee @ 12:06 pm

CIDR     Dotted Decimal     Inverse Dotted Decimal

December 4, 2008


Filed under: BGP, Information — Jaycee @ 2:16 pm

Step 1. Create your maintainer object.
Step 2. Register AS and Policy Information.
Step 3. Register Routes.

1. Maintainer Template
source: ALTDB

2. Aut-num Template
source: ALTDB

3. Route Template
source: ALTDB

4. Email to:
Only send Maintainer object templates to db-admin@cnacs.occaid.org
Other network information objects including AS, Route, AS-SET, etc must be sent to auto-dbm@irrd.occaid.org

5. WHOIS Lookup:
$ whois -h whois.altdb.net -p 43 [OBJECT]


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