Networking knowledge -- The bullet points

http://computernetworks-jw.blogspot.com

Thread Safe?

"Every function that uses files in some way. This includes printf, scanf, getchar, and putchar (unsafe). The functions sprintf and sscanf are not included (safe)." They (former) need mutex in a certain way to serialize these operations.

• Thread(or task) is an entity in multi-tasking and they can share memory (global variable) with mutex mechanism. / threads are under the same application.
• An application (process) can launch multiple threads.

• Process is a standalone self-contained application and it "cannot" share the global variables. (They run on the different contexts -  属性 ) They can only communicate thru IPC channel.
• Multiple processes can run on a CPU.

C String Lib Reference

http://www.cplusplus.com/reference/clibrary/cstring/

Vlan setting for Ixia

• Check Vlan table

#sh vlan 

Codes: * - Default VLAN, G - GVRP VLANs

Q: U - Untagged, T - Tagged

x - Dot1x untagged, X - Dot1x tagged

G - GVRP tagged, M - Vlan-stack

NUM Status Description Q Ports

* 1 Inactive

2 Inactive U Te 5/0,3

3 Inactive U Te 5/1-2

• Change to L2 mode

#conf

(conf)#int vlan [entry id]

(conf)#int vlan 4

FORMAT: (conf-if-vl-4)#int rang te [slot] /[port] – [port]

(conf-if-vl-4)#int rang te 10/0 - 3

(conf-if-range-te-10/0-3)#no shut

(conf-if-range-te-10/0-3)#sw

03:16:50: %RPM0-P:CP %IFMGR-5-ACTIVE: Changed Vlan interface state to active: Vl 1

(conf-if-range-te-10/0-3)#exit

• Add a new entry to Vlan table

(conf)#int vlan [id]

(conf)#int vlan 4

(conf-if-vl-4)#untag ten 10/0

03:17:38: %RPM0-P:CP %IFMGR-5-ACTIVE: Changed Vlan interface state to active: Vl 4

(conf-if-vl-4)#untag ten 10/3

(conf-if-vl-4)#exit

• Show Vlan Table

(conf)#exit

#03:18:07: %RPM0-P:CP %SYS-5-CONFIG_I: Configured from console by console

#sh vlan

Codes: * - Default VLAN, G - GVRP VLANs

Q: U - Untagged, T - Tagged

x - Dot1x untagged, X - Dot1x tagged

G - GVRP tagged, M - Vlan-stack

NUM Status Description Q Ports

* 1 Active U Te 10/1-2

2 Inactive U Te 5/0,3

3 Inactive U Te 5/1-2

4 Active U Te 10/0,3

• Increase MTU

#conf

FORMAT: (conf)#int range ten  [slot]/[port]  - [port]   // Need space -

(conf)#int range ten 10/0 - 3

(conf-if-range-te-10/0-3)#mtu 9252

(conf-if-range-te-10/0-3)#exit

(conf)#exit

• Check line rate

#sh int tengiga | grep line-rate|TenGi

#sh int tengiga 10 | grep line-rate|TenGi

TenGigabitEthernet 10/0 is up, line protocol is up

Input 9956.00 Mbits/sec, 248909 packets/sec, 99.90% of line-rate

Output 9956.00 Mbits/sec, 248899 packets/sec, 99.90% of line-rate

TenGigabitEthernet 10/1 is up, line protocol is up

Input 9956.00 Mbits/sec, 248898 packets/sec, 99.90% of line-rate

Output 9956.00 Mbits/sec, 248909 packets/sec, 99.90% of line-rate

TenGigabitEthernet 10/2 is up, line protocol is up

Input 9956.00 Mbits/sec, 248909 packets/sec, 99.90% of line-rate

Output 9956.00 Mbits/sec, 248898 packets/sec, 99.90% of line-rate

TenGigabitEthernet 10/3 is up, line protocol is up

Input 9956.00 Mbits/sec, 248898 packets/sec, 99.90% of line-rate

Output 9956.00 Mbits/sec, 248909 packets/sec, 99.90% of line-rate

• Delete an entry in Vlan table

#conf

(conf)#no int vlan [id]

(conf)#end

How to change pattern in Ixia

If Fixed is selected, 4 bytes are inserted. If Repeating is selected, 4 bytes are filled in entire packet payload.

(From this Menu) http://www.flickr.com/photos/78909208@N03/7228247588/lightbox/

• Before create statistic view window, do not forget to create Group View to group the ports of interest.
• May need to clear the “Ownership” of the ports to start traffic

(Menu) Stream Static View

In StatView window

Column B: mouse right click

(Menu) Edit Stream è Pattern (Random/Fix/Repeating), Size (Random/Fix) – (in Frame tab) and Rate (100%) – (in Control tab)

Start/Stop traffic è need to select column

Takes time (5 minutes or so) to reach 100% (99%) line rate

Before create statistic view window, do not forget to create Group View to group the ports of interest.

May need to clear the “Ownership” of the ports to start traffic

SPD spec on Wiki

http://en.wikipedia.org/wiki/Serial_presence_detect#SDR_SDRAM

Check Offset 5: memory type (SDR SDRAM/ DDR SDRAM/ DDR2 SDRAM/ DDR3 SDRAM)

Check # of banks

Check module bank density (512Mb, 1G so on)

DIMM size = module bank density x # of banks

Where is Driver in NetBsd code base

SW-NetBSD/usr/src/sys/arch/evbppc/moduleName/componentKernelDrivers.c

i.e. i2c.c asicA.c fpgaB.c

• contain open/close/ioctl calls and HW init function.
• This level calls real low driver.
• This level does not implements semaphore.
• Device address/offset or register address passed thru via caddr_t structure. Format user definable?