FirstDigest » Routing and Switching

Selective BGP Dampening and parameters tuning

Calin — Fri, 02 Mar 2012 09:42:44 +0000

Some time ago, I wrote about BGP Dampening and how this feature can improve the stability of the network. A lot happened since then and during my experience with different service providers I have seen that BGP dampening can help in the same measure at it can harm [...]

BGP Conditional Advertisement

Calin — Thu, 01 Mar 2012 10:11:10 +0000

BGP Conditional Advertisement – it let the impression of a very complex task. Actually you will find it very easy to implement once you understand it.

In simple words I would say that BGP conditional advertisement it’s a feature that let you advertise a prefix to one of your neighbors if mandatory condition is satisfied. [...]

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 [...]

Draw network diagrams online (with Cisco stencils)

Calin — Sat, 17 Sep 2011 21:15:33 +0000

I’m a Mac and Linux user and if you are like me, then you have the same problems drawing network diagrams. Microsoft Visio does not have a version for this platforms. I’m not saying that there are no alternatives to Visio on Mac or Linux platform, but most of them are either limited in features, [...]

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 II]

Calin — Thu, 30 Sep 2010 12:38:01 +0000

As I promised in Part I of this article, here is the second part covering the port-channel load-balancing method explanation. If you didn’t know what I’m talking about, please be sure that you have read the first part of this article. Everything remains the same in this scenario. We have 3 [...]

Cisco: How can MSS help to solve issues in VPN communication

Calin — Fri, 03 Sep 2010 11:03:35 +0000

Since a week, I’m stretching my brains to solve a communication problem over a VPN connection. The problem was that connections like SSH over VPN were not successfully completed. Imagine site A (Paris – remote end) and site B (Hamburg – local end).

In the back, of this sites, servers and clients. If [...]

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 [...]