BGP: Weight and Local-Preference
It’s important to remember that since BGP is the routing protocol of the internet, there are quite a few attributes that it uses to give preference to a single route out of several redundant paths to a given destination. I was recently contemplating several of these and it occurred to me that two of these attributes in particular are pretty similar. I’d like to compare and contrast them and give reasoning for situations that call upon one or the other.Ticket #18 – Repubished
I am reposting here Lab 18, which was published on ccieflyer.com ...Please follow the instructions found here about how to use the lab file. ...For more mini labs, have a look at the mini labs page.EIGRP Unequal-Cost Load-Balancing
In a previous post, I explored the basics of IP routing, and in the process, we discovered an interesting default feature of OSPF. When there were two OSPF routes in the routing table to a network, and both routes had the same cost, the router performed load balancing between the two. Take, for instance, the following route: 172.16.2.0 [110/12] via 1.1.1.13, 00:09:24, FastEthernet0/0 [110/12] via 1.1.1.2, 00:09:24, FastEthernet0/1 In this example, every packet sent would take one of two routes.EIGRP Unequal-Cost Load-Balancing
In a previous post, I explored the basics of IP routing, and in the process, we discovered an interesting default feature of OSPF. When there were two OSPF routes in the routing table to a network, and both routes had the same cost, the router performed load balancing between the two. Take, for instance, the following route: 172.16.2.0 [110/12] via 1.1.1.13, 00:09:24, FastEthernet0/0 [110/12] via 1.1.1.2, 00:09:24, FastEthernet0/1 In this example, every packet sent would take one of two routes.What’s a Steiner Tree?
Any of you who have worked with VPLS or NG-MVPNs are likely already familiar with using Point-to-Multipoint (P2MP) LSPs to get traffic from a single ingress PE to multiple egress PEs. The reason that P2MP LSPs are desired in these cases is that it can reduce unnecessary replication by doing so only where absolutely required, for example where a given P2MP LSP must diverge in order to reach two different PEs.
However, typically the sub-LSPs which are part of a given P2MP LSP traverse the shortest-path from ingress to egress based on whatever user defined constraints have been configured. While this is fine for many applications, additional optimizations might be required such that additional bandwidth savings can be realized.
We will take a look at something called a Steiner-Tree which can help the network operator to realize these additional savings, when warranted, reducing the overall bandwidth used in the network and fundamentally changing the way in which paths are computed.
Let's start by taking a look at a simple example in which RSVP is used to signal a particular P2MP LSP, but no constraints are defined. All the links in this network have a metric of 10. Continue reading
Changing Gears: Virtual Networking
When it came to networking, my university classes didn’t teach me much more than the basics of network infrastructure, and a little bit of route/switch. Now that I’ve graduated, I continue to learn as I strive for the next steps. So far, it’s been CCNP ROUTE, since I knew I wanted to go for it soon after CCNA. Because of this trend, I’ve been pretty devoted to routing, with a small segway into security as I obtained my Security+ certification.Changing Gears: Virtual Networking
When it came to networking, my university classes didn’t teach me much more than the basics of network infrastructure, and a little bit of route/switch. Now that I’ve graduated, I continue to learn as I strive for the next steps. So far, it’s been CCNP ROUTE, since I knew I wanted to go for it soon after CCNA. Because of this trend, I’ve been pretty devoted to routing, with a small segway into security as I obtained my Security+ certification.The path to certification
Over the last few years I have made the transition at the company I work for, from Support Engineer to Network Engineer. In between this I became a Managed Services Engineer dealing with the configuration, installation and maintenance of Cisco … Continue reading
Virtualizing the OpenBSD Routing Table
Introduction
The OpenBSD routing table can be carved into multiple virtual routing tables allowing complete logical separation of attached networks. This article gives a brief overview of rtables and explains how to successfully leak traffic between virtual routing domains.