Troubleshooting Switch Stacks.
So, today in the morning we received this entry in our syslog server:
Feb 27 17:15:58: %STACKMGR-4-STACK_LINK_CHANGE:
Errdisable Port State Recovery on the Cisco IOS
Ports in Cisco switches go into errdisable state for various reasons. some reasons are configured such as arp-inspection, bpdugaurd, psecure-violation, etc. While some are turned on by default such as loopback, link-flap, etc. Following the typical default configuration of cisco switch. Once it...
How to design transparent proxy?
Almost every organization uses proxy. The benefits of proxy servers are countless. Some of these benefits are mentioned:
- Add Accounting
- Add Authorization
- Reduce the load on the external (wan) link
How to subnet?
For any Network Engineer, knowing how to subnet is as important as typing " en " in the CLI. The engineer will have to type access lists that have wild masks, break networks to smaller parts, create vlans, point to point links, and design a whole new enterprise network. Subnetting is part of all...
How to pass ITILv3 Foundation?
For many employees seeking to enhance their career in IT field the certification of ITIL is a very big added advantage. The question is, how to pass it? Questions such as, Do i need to take formal training for ITIL? How much ITIL foundation exam will cost? are valid that go through the...
MPLS VPN tutorial
I would like to post a simple example of how to set up MPLS-VPN for two users. This example was used from the Cisco Press book CCIE Routing and Switching . Although the book...
what is MPLS VPN?
When a service provider connects to sites that belong to one customer that uses private address then SP will advertise those routes within his autonomous systems. This could be handled when he is serving one ogranization. What if the SP is connecting 10 customers each with three sites and all of...
How MPLS works?
MPLS protocol uses a different mechanism to forward packets. Packets are sent based on MPLS lable instead of the conventional packet's destination IP address. It add the ability to make forwarding decisions based on other factors beside the IP address, such as traffic engineering, QoS, and privecy...