There was a strange problem at my costumers site where out of the sudden the Internet speeds were inconsistent. Let me clarify, the main Internet link was 50/50Mbps (provider optics) and speed in the network was sometimes 2/50Mbps and sometimes 45/8Mbps.
Well, this is a short one but convenient as the title says:)
There is a nice little trick or tool in Cisco that we can use when we troubleshoot network problems. It is very simple and useful:)
After the connection between two switches could not be established I went to see the log of the uplink switch and the first thing I have noticed was this: %LINK-3-UPDOWN: Interface FastEthernet0/1, changed state to up %LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet0/1, changed state to up %SPANTREE-7-RECV_1Q_NON_TRUNK: Received 802.1Q BPDU on non trunk FastEthernet0/1 VLAN300. […]
After moving your DHCP server and it doesn’t receive client requests but everything is “OK” with the server, then that could cause a problem in your corporate environment:)
I wanted to use in my test environment an NTP server on Microsoft Windows Server 2008 R2 that would function as a syncing point for my Cisco routers and switches. The starting issue is that Cisco devices will not sync with Windows integrated NTP server and the reason is that Windows use SNTP as network […]
Here are a few notes how to successfully simulate an IPS 6 instance in GNS3. Version 7 is a little tricky to simulate so I suggest you get the IPS Manager Express and practice everything in the demo that is available when you install it.
Although this procedure is written in the official Cisco documentation, I will give you my understanding (example) of it. Command syntax is the only part where I have encountered some problems (errors).
I’ve got used to end a traceroute or a ping sequence on a Cisco IOS device using CTRL+C instead of the unpractical CTRL+Shift+6.
MTU size never crossed my mind until MPLS designed network came to the picture. After adding a switch to the network, OSPF got up, but BGP was going up and down and up and down… That led to the MTU mismatch because bigger frames are needed in a MPLS network.