IT Issues

Thanks to MED attribute we have influence on how adjacent eBGP router should get into our AS.It is especially helpful if we have 2 or more eBGP entrance into our AS.  Now, we will check how a single eBGP router that  receives MED attribute for the same prefix from many eBGP speakers and different AS…

In this lab from the scratch we will implement fully working MPLS core with Layer 3 VPN and MP-BGP vpnv4 on the provider edge routers. Also we will achieve full connectivity between customers edge routers with routing protocols. At the end we will find out how to implement “extranets” and “shared services”, thanks to which…

In this artcile we will focus on fundamental and crucial features of BGP neighborhood establishing and routes injecting into BGP processes, we also break BGP table down  for better understanding.

The difference between phase 2 and 3 regarding DMVPN is slight at a first glance. In this article we will find out how to properly configure Phase 3, especially we focus on  NHRP protocol and its role. At the end we will establish full reachability between 2 spokes with utilization of EIGRP.

Sham Link feature is necessary if we want to deploy backdoor link between 2 OSPFs domains belong to the same area but split by MPLS. The issue that we will come across is a result that backdoor link will have priority over the MPLS.

We may come across on interesting issue if we get the same prefix from external BGP AS and directly via OSPF process. It may happen if we want to have another link to the destination but not neccesarily via another eBGP link. The problem that we will definetely come across on is just  another variation…

First Hop Redundancy Protocols have been invented for one main reason, providing redundancy for a getaway, but by the occassion they provide load balancing as well. There are 3 FHRP: HSRP, VRRP and GLBP, 2 of them belong to Cisco, VRRP is an opened standard.

If you use VRFs, sometimes you may want to use something what is being called “route leaking”. Route leaking consists in importing and exporting prefixes between VRFs or between VRF and global routing table. In this article I’ll show you how to implement route leaking in 5 different ways.

ACLs can filter traffic at layer 3 and 4. Usually it will be enough, but sometime we need to  subject the trafic to more granular inspection before we reject any host ? Then filtering on access lists will not work and Modular Policy Framework has to be used. But as you see for yourself MPF can do…

Conversion between particular systems seems to be not necessary nowadays, what may be  pernicious. Besides, for any IT guy it’s a shame don’t know how to make simple math that sometimes may be really helpful.

Nowadays, when access layer switches have 1GB ports, increasing the number of an upstream links to the distribution layer is necessary. Let’s have a look on etherchannel feature, the way that we may achieve that and how to configure its on layer 2 and 3.

Spanning Tree Protocol and its variations is responsible for elimination loops and ensuring efficiency at layer 2 . Despite was invented 30 years ago and nowadays very often between Access and Distribution layers routing is utilized, it is still good to know how works and what is responsible for. 

During designing and implementation of wireless network you will come across on Layer 2 and 3 roaming. Both of them improve scalability of the wireless network  and simplify end user life, but work differently.

Since routers and multilayer switches use Cisco Express Forwarding feature, the true that switches are much more faster than routers is not a true anymore. Nowadays routers can make decision with the wirespeed likely switches with ASICS. What is CEF, how works and how helps out the routers in packets routing ?

Usually if we mention about Public Key Infrastructure we think about external Certificate Authority like Verisign or GoDaddy. It turns out, there is a SCEP protocol that enables us running our own CA in Cisco environment and that certificates we may use during ISAKMP IKEv1 or IKv2 authentication.