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[root@monitoring ~]#  snmpwalk -c public -v1 10.0.33.228 End of MIB I was trying to do snmwalk walk for a Cisco Router in GNS3, and was getting only End of MIB after a snmpwalk command.  It turned out that in my Cisco Router configurations I had allowed my SNMP host with ip address with community string "public" but I had not configured the community string separatly with the command  #snmp-server community public This was my configuration mistake but took some time to figure it out

Error while creating node: Docker has returned an error: Cannot connect to host docker:80 ssl:False [No such file or directory] After adding docker template for Alpine Linux in gns3, you get above mentioned message when you want to use alpine linux in GNS3. To get rid of this message you have to install Docker by following below link curl -fsSL https://get.docker.com/ | sh If you do not have curl installed then instal curl first with below command. apt-get install curl After installing Docker you need to add your user name in the docker group with the following command.  $ sudo usermod -aG docker your_username Verify if the docker service is started with following command $ service docker status If docker is not started then start with following command  $ sudo service docker start Logout from GNS3 Virtual Machines and log back. Start gns3 and use alpine linux.

The format of the original 802.1d bridge ID was redefined from two byte priority + MAC address to System ID extension mainly due to the advent of multiple spanning trees as supported by Per VLAN Spanning Tree Plus (PVST+) and IEEE 802.1s Multiple Spanning Trees (MST). With the old-style bridge ID format, a switch’s bridge ID for each STP instance (possibly one per VLAN) was identical if the switch used a single MAC address when building the bridge ID. Having multiple STP instances with the same bridge ID was confusing, so vendors such as Cisco Systems used a different Ethernet BIA for each VLAN when creating the old-style bridge IDs. This provided a different bridge ID per VLAN, but it consumed a large number of reserved BIAs in each switch.  The System ID Extension allows a network to use multiple instances of STP, even one per VLAN,  but without the need to consume a separate BIA on each switch for each STP instance. The System ID E...

In case you are finding it hard to reach default gateway from your newly installed Nexus 1000v virtual machine, here is one quick thing to check and configure before you can reach to the default gateway and other allowed subnets from your Nexus 1000v VM. Configure the management IP Address and default gateway on Nexus 1000v as per below commands conf t interface mgmt 0 ip address 192.168.0.100/24 exit vrf context management ip route 0.0.0.0/0 192.168.0.1 exit copy run start Note: Change the IP address as per your subnet.

Spanning-tree operation requires that each switch have a unique BID (Bridge ID). In the original 802.1D standard, the BID was composed of the bridge priority and the MAC address of the switch, and all VLANs were represented by a CST, Common Spanning Tree. Because Cisco started to use unique instance in PVST+ PVRST+ for each VLAN STP Process, there came need to provide Unique BID for each separate instance of STP per VLAN. So what Cisco Did! divided the Bridge priority field of 16 bits into two parts, 4 bits for priority and 12 bits for VLAN ID and named it as Extended VLAN ID. Now because only left most four bits are reserved for Bridge priority, you can only make the combinations of discrete values in increments of 4096 with those bits.

After I reset my Cisco Router 1841, It started to give error messages like below;  %Error opening tftp://255.255.255.255/network-confg (Timed out) %Error opening tftp://255.255.255.255/cisconet.cfg (Timed out) %Error opening tftp://255.255.255.255/router-config(Timed out) %Error opening tftp://255.255.255.255/ciscotr.cfg (Timed out) Actually these error messages are caused due to default configurations in Cisco IOS Software, which attempts to access the service configuration files from a network Trivial File Transfer Protocol (TFTP) server, and if the router is unable to acces the TFTP Server then it start displaying these messages. Yo can stop displaying these error message by entering following commands at Cisco CLI  Router#config terminal  Enter configuration commands, one per line.  Router(config)#no service  (this is command to stop these error messages) config Router(config)#end Router#write

You need to format the partition on which you want to install Linux Ubuntu and the type of Linux Format is completely different than those of Windows Format types. That's why hard disk partition on which Ubuntu is installed is not view able from Windows Operating System, because windows does not support Linux Ubuntu Formats.  This goes good until you want to both operating systems with dual boot system. When you do not want to use Linux Ubuntu you will have to convert its partition to NTFS or FAT32 in order to access the partition and store and access data from this partition. One method to convert Ubuntu partition to Windows is to convert and format the partition with Free MINITOOL Partition Program. Remember this procedure will only convert to Windows Supported partitions and will ask you to format the partition until you can use it. So you will loose any data on your Ubuntu partition.  See  How to access U...