GLBP Load Balancing

We could use HSRP or VRRP to have a redundant default gateway for our PC/server networks. Although this works well we now have hardware powered-on and just sitting around waiting for its counterpart to fail, we are not actively using it. We could split up networks or use multiple default gateways within the same network but who does that? Well if your router or layer three switch happens to have that Cisco logo on it and a software release of at least 12.2(14)S, please welcome and “slow clap” the Gateway Load Balancing protocol, who has been around since 2002! Continue reading


Inter-VLAN Routing on the Nexus 5k.

Nexus-PLineI previously had the chance to play around with the 5596UP switch, and made some notes on how to configure inter-vlan routing. Since this was a 5596UP switch I needed a layer 3 card to take advantage of it. The next-generation units the 5600 include layer 3 without a card required along with introducing 40GB uplinks! However in this post let’s go back to the basics and configure inter-vlan routing on a nexus switch and in this case I am using a 5596UP.  Continue reading


HDLC and PPP are considered to be in layer 2 of the OSI model. There are some differences between which will be describe in this post, If you would like to learn more about at least the basic configuration of PPP including PAP and CHAP check out the post I wrote about year ago. (Basic PPP Configuration) HDLC was first developed by the ISO Cisco tweaked the protocol sometimes called cHDLC and because of this it only works with Cisco equipment. PPP is defined by RFC 1968 which is an open standard and is able to work on multi-vender equipment. Continue reading

Types of WAN Links

I’ve found this table that I created a while ago and it lists common WAN connections that businesses use. I have used this table like a reference guide to familiar myself into other protocols. People don’t think of it much but the WAN is a different beast compared the LAN as it uses different protocols besides Ethernet. The WAN or wide area network is what connects us to remote locations within a organization. If we have an office in New York and another office in Wyoming  we need these offices to be connected to each other so that they seem to be on the same network even though they are miles away these types of WAN connections and protocols  would do it. Continue reading

Link-State Protocols

Weeks ago and maybe months :), I talked about distance vector protocols and with that you probably got the feeling that when using a distance vector protocol it does not give a full network graphical representation of the entire network. Only the directly connected routes can’t remember? Check out this post Distance Vector Routing. Link state protocols are faster to converge network changes compared to distance vector however when compared to distance vector setup they can be harder to set up, maintain, and troubleshoot when problems arise. Continue reading