Category: network

Customer IT Support Business Is All About Communication

I remember 20 years ago when I just gone into customer IT support business. Many customers could only rely on fax, phone instead of emails where they actually prefer to communicate face-to-face. As the business was transforming in past years,

communication

Fujitsu Lifebook UH572 Wi-Fi v.s. 3G/UMTS – A Comparison

The Fujitsu Lifebook UH572 provides access to clouds and internet in public locations. Two major internet connectivity options are: Public/local Wi-Fi available in the venue 3G/UMTS through SIM card During one lunch I was at Hayal Kahvesi with friends:

hardware

How to Use “tcpdump” to Log OCFS2 Interconnect (o2net)?

If from the /var/log/messages you are receiving network / o2net related errors and some OCFS2 / system functionality is not available or not working properly, generating a ‘tcpdump’ over the network interconnect may help to diagnose the problem for root cause analysis (RCA).

linux

traceroute Fails with -F (do not fragment bit) Argument

With traceroute-1.4a12-XX the -F argument is used to avoid intra-switch fragmentation. From traceroute(8) manpage: … -F Set the “donâ€™t fragment” bit. … When ‘-F’ is specified the traceroute fails to get connected. Even with localhost:

linux

Extra Data Received on Transport in Urgent Mode (MSG_OOB)

While transmitting data in Urgent Mode at the socket layer: Urgent mode is initiated using send(…, MSG_OOB), Current outgoing queue is longer than MTU Several packets are sent out with the URG flag set. The Urgent Pointer field in the TCP header is not updated correctly. Instead, it stays the same.

kernel

Jumbo Frames and Nagle’s Algorithm (RFC 896)

I really do not like increasing the MTU that large..Some reasons below…

network

Wireless on Dell Latitude D630 with OEL5

I have been referring to linlap for this configuration. The configuration has been made possible via ipw3945 and iwlwifi. To be more precise:

desktop

Xen: How to define the boot order for HVM in vm.cfg

This is done by the boot paramer in vm.cfg. The switches are: * floppy (a) * hard disk (c) * Network (n) * CD-ROM (d) If you use boot = ‘n’ it will be stuck at PXE boot even if there is no dhcp lease and guest will not attempt boot from the Virtual Disk….

network

PXE Boot Config Enterprise Linux

Configuring a PXE boot server Install required packages: # yum install bind dhcp system-config-netboot tftp-server Setup dhcpd: # vi /etc/dhcpd.confddns-update-style interim;ignore client-updates; subnet 10.10.10.0 netmask 255.255.255.0 { option routers 10.10.10.1; option subnet-mask 255.255.255.0; option domain-name-servers 10.10.10.1; option time-offset 7200; range dynamic-bootp 10.10.10.10 10.10.10.15; default-lease-time 21600; max-lease-time 43200; next-server 10.10.10.1; option subnet-mask 255.255.255.0; option broadcast-address 10.10.10.255;…

linux

NIC bonding: having two nics connected to different switches. is that a good idea?

That is actually a good idea .. it handles switch HA in addition to NIC HA .. And having them on different vlans? .. that is actually somehow mandatory .. you cannot have two switches in a LAN (or VLAN) per its function

linux