FirstDigest » Cisco-switching

InterVLAN routing using Private VLANs

Calin — Fri, 23 Sep 2011 13:04:06 +0000

Private VLANs is one possible solutions for service providers to offer secure connections to their customers and avoid inter-vlan communication in the same switched environment.

I’m sure that you heard (and most probably practice already) InterVLAN routing. When it comes to Private VLANs the routing part may be a bit tricky. Keep in mind that this is not something that I would recommend to use as a standard in a productive environment, but for things like Cisco exams (e.g. CCIE R&S) or last resort solution, [...]

Cisco: Port-channel load-balancing explanation [Part I]

Calin — Mon, 30 Aug 2010 14:26:31 +0000

Port-channel (or etherchannel) is a great way to increase the transport capacity between 2 switches or between a switch and an end device that suport load balancing (e.g. server). Today I don’t want to focus on how the Port-channel are configured, but more on how they load-balance the traffic over the multiple interfaces included in a bundle.

To configure the port-channel load balance, you have to be in the config mode and issue:

port-channel load-balance method

port-channel load-balance method module slot

the method [...]

Cisco: How to use CEF for load-balancing

Calin — Mon, 29 Jun 2009 11:50:59 +0000

According to Cisco’s website, Cisco Express Forwarding (CEF) is advanced, Layer 3 IP switching technology. CEF optimizes network performance and scalability for networks with large and dynamic traffic patterns, such as the Internet, on networks characterized by intensive Web-based applications, or interactive sessions.

The term Load balancing describes a functionality in a router that distributes packets across multiple links based on layer 3 routing information.

Now, putting this two terms together we obtain Load balancing with CEF. Cisco IOS software [...]

Cisco: Layer 2 traffic filtering

Calin — Thu, 27 Nov 2008 06:38:26 +0000

Layer 2 traffic filtering can be very useful when you want to drop packets closer to
the source because you can do this on L2 next-hop which is the switch where the
devices are connected. Based on mac-address, Layer 2 filtering can be apply using
one of the two most common method: Port Security and MAC Access Groups.

Port Security is the more secure method of the two. To use it, map a switch port to the
specific MAC address of [...]

Interface macro command on a Cisco switch

Calin — Sun, 16 Nov 2008 11:42:24 +0000

From the beginning let me tell you that I don’t see very useful this command, as I prefer to use “interface range…” syntax, but since I saw it as a requirement in one of the task for CCIE RS lab exam, and maybe somebody will find it usable in real environment, I said I should put it here in a tutorial.

As many of you already know, you can control a range of interfaces by typing the command “interface range Fa0/1 – 6″ (for example), [...]

Limit traffic on a Cisco switch L2 port with minimal configuration

Calin — Fri, 14 Nov 2008 13:38:18 +0000

Let’s say that somebody (or some task in a test) ask you to limit the inbound traffic on a switch Layer 2 port by using minimal configuration possible. I must say that in the first steps I failed this task miserable, but actually is very simple to do it.

I will use a plain layer 2 Cisco 2950 switch for this task. I observed that I could not implement this on a Cisco 3500XL. I don’t know if the IOS image was wrong, but I [...]