FirstDigest » Cisco-routing

RIPv2 MD5 authentication – routing trick

Calin — Fri, 30 Sep 2011 13:45:58 +0000

I must admit that the following example is more a CCIE exam topic and not a solution that you would add in real network environments.

Let’s assume that we have the following topology:

The Loopback interfaces are there to have some networks which we will advertise into RIPv2. The request [...]

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 [...]

Cisco Easy VPN Router-to-Router

Calin — Fri, 16 Sep 2011 09:17:12 +0000

Cisco Easy VPN is not a new technology. Actually it is pretty old, but still used by many companies or people to connect remote site / remote workers to headquarter.

A few days ago I was looking to connect a remote site in a simple way but still secure and a colleagues suggested me to [...]

Interface software loop

Calin — Tue, 30 Aug 2011 08:13:13 +0000

If you ever worked in an environment where you have to deal with leased / dedicated lines provider by your SP (service provider) then you know that whenever it’s a problem on the line they request, if possible, to put a loop on the line from one end toward the other end, so they can [...]

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 [...]

Cisco: Policy Routing with IP SLA

Calin — Thu, 27 May 2010 12:06:03 +0000

Let’s assume that you have a Cisco router with 2 ISP connection. The first one it’s a 10Mbps connection with a decent latency and the second one it’s a 2Mbps connection with quite high latency.

Since you don’t want to load balance over this 2 connections for the obvious reasons described above, you decide to to use [...]

Cisco: How to configure HSRP

Calin — Fri, 25 Sep 2009 13:59:45 +0000

In this post I proposed to discuss a little bit about Hot Standby Router Protocol and how it can be configured on a Cisco device. For this I have chosen the following topology:

I had in mind this scenario due to the fact that the traffic can take multiple [...]

Cisco: OSPF conditional inject of a Default Route

Calin — Tue, 16 Jun 2009 12:59:01 +0000

I believe most of you are familiar how OSPF is injecting a default route in a normal area. If not, you can find here all the documentation that you need. Please be familiar with this concept before reading this article.

Now, let’s assume [...]

Cisco: How to selective drop packets without using an access-list

Calin — Thu, 05 Mar 2009 13:17:37 +0000

The title actually was a request that I encounter during my CCIE RS preparation. Of course, that in the real world, I would go straight forward and implement an access-list do drop selected packets. But since the lab environment is different for the real one, you might get a task like the above one.

Let’s [...]

Cisco: Engineer’s trick to avoid suboptimal path

Calin — Fri, 16 Jan 2009 09:09:24 +0000

I was explaining in the previous post what is the difference between optimal and suboptimal path and how to avoid the use of not such a good path in your routed environment. Also there I presented this so call “dirty trick” you can use to force the routing protocol [...]