June 29, 2010

Catalyst 6500 and ASIC issues

Referral news can be found at http://www.networkworld.com/community/blog/asic-issues-delaying-cisco-switch Now keep in mind, I have not read the bulletin published by Rodman & Renshaw, LLC - nor can attest this is the fundamental reasons why the switches have been delayed. As for the lifespan of the Cat 6500 to be fully replaced by the Nexus 7000, remember that Cisco’s Supervisor Engines for Modular Switches have a lifespan of 10 to 12 years, that being said a new 720 Supervisor Engine was just released roughly 1 year and a half ago - you make the math now ;-) ... Read more

June 17, 2010

Cisco IOS Security: Quiet Period Login

Cisco’s IOS Quiet Period refers to the period in which telnet/ssh/http access are disabled for an X amount of time after an Y amount of failed attempt. While it is quite unusual to have router virtual access allowed from the WAN link, it may not hurt to go further by enabling this cisco feature to prevent a potential DOS dictionary attack from the WAN link or possibly as well from the LAN link. ... Read more

April 7, 2010

HSRP Interface Tracking

HSRP stands for “Hot Standby Router Protocol” RCF 2281 defines in detail HSRP - http://tools.ietf.org/html/rfc2281 The purpose of this post isn’t to dive into the details of HSRP but simply to shed light on an HSRP feature often overlook when setting redundant routers for redundant ethernet path. HSRP Election When powering up routers running HSRP, the routers (by default in group 0) starts sending to each other (multicast: 224. ... Read more

October 20, 2009

Cisco IOS - getting out of trouble

As simple as this tip is, you will be amazed on how often it is overlooked during remote night maintenance work. I have therefore decided for that reason to post it here. So, you are sitting at home, editing an IOS configuration of X router during a maintenance window. Your only available remote login is through the wan interface. A bad access list and you can be locked out of the router till you physically go to the office to undo the changes. ... Read more

October 14, 2009

Cisco IOS Tips - cache running-configuration

This is probably one of the most ignored and forgotten feature of IOS since 12.2(25)S and 12.2(27)SBC. I am positing it here as I never stopped coming across routers and switches with this feature not active. Please note you need to enough memory,to use this feature; that is to say, the available space in memory to hold a copy of the interfaces configuration. As you may guess, a router or switch with a monstrous configuration, can take a while to display the running configuration when issuing ... Read more

September 16, 2009

Cisco IOS Configuration boot register - ROMMON

Every cisco routers has a configuration register which is saved in NVRAM and is a 16 bit value. This post will not tackle all the 16 bits of the configuration register, but only the 13th bit which is used to either load IOS or ROMMON. Another post will be made to detail all the 16 bit configuration register. Before continuing, it is important to understand the basic “boot process” of a router. ... Read more

September 15, 2009

Cisco IOS shortcuts

Configuring Cisco IOS shortcuts command are quite easy and neat… just use the exec command “alias”. command structure: alias Example in exec mode: sh ip int br (show ip interface brief) so following, we would get “alias exec s sh ip int br” Example in configure mode: router ospf and we would get “alias configure ro router ospf” More mixed examples [ alias / original command / command to enter ] ... Read more

August 26, 2009

Cisco IOS hidden tools

Hello there, Just a quick overview over a couple of cisco hidden command useful in certain circumstances 1. ttcp ttcp is only available on routers/layer 3 switches (of course ;-) ) For those familiar with iperf, ttcp is a kinda”ish” iperf Start ttcp on one router in point 2 point scenario and ttcp on the other endpoint. One router will be in receiving mode, while the other will be in sending mode… running the command is quite straight forward, thus I will not demonstrate it here. ... Read more

April 25, 2009

Cisco Datacenter Blueprint

If you dream of Cisco Routers and Switches like me If you can’t help it but swear by Cisco (beside their load balancers, let’s be honest it sucks) If you tried to convince your wife to have each room of the house on a different subnet then you need to download this … http://alouche.net/cisco/data-center-poster.pdf **** the following poster is provided and copyrighted freely by Cisco Inc…