If you use the article, please cite me:SIP over NAT [SIP cez NAT] / Pavel Segeč. In: Journal of Information, Control and Management Systems. - ISSN 1336-1716. - Vol. 7, No. 1 (2009), p. 89-95.
The Security Device Manager, or SDM is possible to find on www.cisco.com on the following web link
The Cisco Connection online (CCO) user guest account is needed, which we may create for free.
In this article I will describe how to proceed if your firmware upgrade on SRW 248G4 switch failed and the switch then stop working.
I have found only one solution how to recover from this disaster and it is sending a new firmware over PC serial (COM) port using xmodem protocol. A new firmware can be send to the failed switch with the help of Startup menu of the switch. The Startup menu can be entered when the switch is booting.
Sometimes in my lab happens that students delete IOS of the switch from its flash. Unfortunately switches does not have rommon to realize quick IOS recovery over tftp. Only one way is over Xmodem.
Cat 2960 switchIOS recovery
To speed up the process of the recovery we may setup Xmodem speed to higher rate as default 9600 bits:
In this article I will configure, debug and shows the process of RIPv2 authentication.