Troubleshooting link up/down and autonegotiation Recommended Port Configuration (Autonegotiation or Manual Configuration) There are many opinions on the subject of autonegotiation. Previously, many engineers advised customers not to use autonegotiation with any switch-connected device. However, improvements in the interoperation of autonegotiation and the maturity of the technology has recently changed the view of autonegotiation and its use. In… Continue reading Troubleshooting link up/down and autonegotiation

Tcp Zero Window TCP Zero Windows – and Why They Can Be VERY Bad TCP zero windows FIN says “i finished talking to you, but i’ll still listen to everything you have to say until you’re done” RST says “there is no conversation. i won’t say anything and i won’t listen to anything you say” –… Continue reading Tcp Zero Window

tcpattemptfails $ ndd -get /dev/tcp tcp_time_wait_interval 60000 $ ndd -get /dev/tcp tcp_fin_wait_2_flush_interval 16000 $ ndd -get /dev/tcp tcp_rexmit_interval_max 10000 $ ndd -get /dev/tcp tcp_ip_abort_interval 60000 $ ndd -get /dev/tcp tcp_keepalive_interval 90000 $ ndd -get /dev/tcp tcp_conn_req_max_q 16384 $ ndd -get /dev/tcp tcp_conn_req_max_q0 16384 $ ndd -get /dev/tcp tcp_xmit_hiwat 131072 $ ndd -get /dev/tcp tcp_recv_hiwat 131072… Continue reading tcpattemptfails

Spanning Tree Protocol and PortFast

What is Spanning Tree and Portfast, and how can they affect my Altiris environment? During the execution of the Spanning-Tree Algorithm, Spanning-Tree will force the ports to go into five different states: Blocked Listen Learn Forward Disabled The transitioning period from state to state takes the following times by default: From blocking to listening: 20… Continue reading Spanning Tree Protocol and PortFast

Heartbeat and multicast in redhat HA add-on How do I configure cluster nodes to use a dedicated heartbeat interface? Red Hat Enterprise Linux Cluster, High Availability, and GFS Deployment Recommended Practices It is highly recommended to separate the private network for cluster heartbeat from the application network. This should be done wherever possible. Red Hat Clustering in Red Hat Enterprise… Continue reading Heartbeat and multicast in redhat HA add-on

Different register and connection IP

Q: If the database registers to IP1 and the listener listens on both IP1 and IP2. Will the client be able to connect to the database via IP2? A: Yes. Test environment: OS: Redhat Linux 6.3 x86_64 DB: Oracle RAC [grid@bcmsdbs01 admin]$ lsnrctl status LISTENER_TEST LSNRCTL for Linux: Version – Production on 13-MAY-2016… Continue reading Different register and connection IP

ORA-609 with TNS-12537

Question: Does it really mean cnnection was successfully established when you see the following information in listener.log: 12-OCT-2009 10:03:39 * (CONNECT_DATA=(SID=ORCL)) * (ADDRESS=(PROTOCOL=tcp)(HOST=123.456.1.123)(PORT=3158)) * establish * ORCL * 0 12-OCT-2009 10:03:39 * (CONNECT_DATA=(SID=ORCL)) * (ADDRESS=(PROTOCOL=tcp)(HOST=123.456.1.123)(PORT=3159)) * establish * ORCL * 0 Answer: NO!!!! As a big picture, these are the steps for a client connection:… Continue reading ORA-609 with TNS-12537