Just a little unicorn-y brainstorming today.
This post is in some ways an extension of my earlier post on the importance of QoS in a converged environment like FCoE or VoIP (or both). This will be a good example of a case where SDN very efficiently solves a policy problem that is present in an unfortunately large number of networks today.
For many organizations, large or small, the network is approached with a very siloed, “good enough” mentality - meaning that each portion of an organization’s technology implementation is typically allocated to those that have that particular skillset.
In preparation for an upcoming post, I was reminded about a commonly referred to feature in most IGPs - the concept of Equal-Cost Multipath, or simply ECMP. This is the idea that multiple routes with the same cost to a remote network should get placed in the routing table alongside each other and packets should load-balance over them to use the additional available paths. After all, it’s the same cost, so why not?
For anyone keeping tabs on the storage industry these days, you might have noticed the news today regarding FusionIO’s acquisition of Nexgen - one of a myriad of storage startups that have cropped up in the past few years to address the ever-changing needs of the data center industry. After looking through some of the articles that were published today, I think we all understand the financial details behind the transaction.
This post was initiated by a side conversation I had about iSCSI. From time to time I’m required to implement an iSCSI-based solution, and this is not the first time I’ve heard the question: “So why can’t I route iSCSI traffic?” Most folks with any knowledge of storage protocols will have at some point picked up this informal best practice idea; some will vehemently defend this idea as the word of $deity and shun all those who contradict this truth.
While on my current kick with virtual routing, I stumbled across an interesting concept regarding OSPF, and the flexibility that vendors have in determining the best path through an OSPF network.
The following topology is what I’ve been staring at for the last few days
Pretty simple, right? There’s a single network (192.168.123.0/24) down inside each virtual host where the VMs are to sit. Each host has a router on it (one Cisco CSR 1000v and the other Vyatta Core 6.
I was working on a topology for another post regarding interoperability between the recently released Cisco Cloud Services Router (CSR 1000v) and Vyatta when I ran into an issue regarding vSphere network security policies and First Hop Redundancy Procotols (FHRP) such as VRRP.
This post will serve as a precursor to that overall post, but I want to point out a key configuration piece when performing redundant gateways with a FHRP like VRRP.
I was working on a topology for another post regarding interoperability between the recently released Cisco Cloud Services Router (CSR 1000v) and Vyatta when I ran into an issue regarding vSphere network security policies and First Hop Redundancy Procotols (FHRP) such as VRRP.
This post will serve as a precursor to that overall post, but I want to point out a key configuration piece when performing redundant gateways with a FHRP like VRRP.
As some of you have heard, the Cisco Cloud Services Router (CSR) 1000v has recently been released for download, and I quite literally pounced on it when I first heard the word. For those that haven’t heard, the CSR 1000v is essentially Cisco’s answer to the problem that has existed in datacenters for a while - that the current multi-tenancy mechanisms, especially overlays like VXLAN and yes, even NVGRE, are just not cutting it for everyone.
As some of you have heard, the Cisco Cloud Services Router (CSR) 1000v has recently been released for download, and I quite literally pounced on it when I first heard the word. For those that haven’t heard, the CSR 1000v is essentially Cisco’s answer to the problem that has existed in datacenters for a while - that the current multi-tenancy mechanisms, especially overlays like VXLAN and yes, even NVGRE, are just not cutting it for everyone.
Back to the basics today. I have seen this pop up a few times and wanted to offer some clarification on what seems to be a cloudy issue for CCNP (and some CCIE) candidates. I’ve seen quite a few times now where engineers see a route to Null0 in a Cisco router and assume instantly that the router is “black holing” traffic.
Sometimes, a route to Null0 is inserted into the routing table when performing summarization with nearly every routing protocol in common use today.
I keep having to remind myself that SDN is more about solving a policy problem than a transport problem. This is why the answer to the question “Will SDN solve all of our networking problems?” is always NO. Truth be told, SDN has been around for a while (see SNMP, Perl, Netconf) in various forms, but it’s receiving a lot of attention right now because the mechanisms are starting to mature and frankly, the networking industry hasn’t really seen a lot of groundbreaking innovations lately.
I keep having to remind myself that SDN is more about solving a policy problem than a transport problem. This is why the answer to the question “Will SDN solve all of our networking problems?” is always NO. Truth be told, SDN has been around for a while (see SNMP, Perl, Netconf) in various forms, but it’s receiving a lot of attention right now because the mechanisms are starting to mature and frankly, the networking industry hasn’t really seen a lot of groundbreaking innovations lately.
I’ve done quite a few posts on Quality of Service, particularly on it’s basic concepts, as well as specific implementation details in a Data Center environment. Many of these concepts can be applied to really any use case, since QoS is QoS - just depends on how you classify traffic.
But what do we gain by implementing QoS, especially in a context like Data Center, where a modern core layer is typically at least 10GbE and network congestion is rarely seen?
So you’ve recently changed jobs, and you have a very extensive linux skillset. Your new job doesn’t include or require this skillset. Does that mean that experience will not serve you in this new role?
Absolutely false. The most valuable thing these experiences give us is perspective. The ability to see things from a unique point of view makes you a unique and valuable addition to any team. This is a strong reason for my advocacy of the Unified Skillset.
I am working on an IPv6-related project, and though I think I have enough content to at least get started, I’d like to submit a request to the community at large.
This project is aimed at providing additional awareness around IPv6 in general, but will be geared towards the entire networking community, ranging from those familiar with the protocol, to those that barely know what an 128-bit address is. This material will be publicly available and organized towards the goal of learning and becoming more aware of the new protocol.
Network Virtualization has been a hot button topic for the last few years, particularly in the data center. With trends like SDN, cloud, and unicorns taking off, it’s incredibly important to move towards technologies that improve scalability while preserving proper multi-tenancy.
You may be wondering that all this vendor-supplied, marketing-fueled magic and fairydust is too good to be true. You wouldn’t be too far off - the fact is that none of the solutions provided thus far have addressed the implementation and operation of network virtualization in cases such as a remote datacenter where traditional connectivity like satellite and long-haul fiber is unavailable.
This is one of my favorite times of the year. Despite the terrible weather that Ohio usually affords the month of March, I brave the wet cold and return to my alma mater for this year’s round of senior presentations.
During the five-year IT program, students are required to learn just about anything and everything you can imagine in IT. This ranges from software development of all kinds, database administration, systems administration, network services and even pure route/switch.
The concept of a link-local address is new to some, seeing as the term is not widely talked about in IPv4 circles, despite the fact that some folks see them daily. In IPv4, the range 169.254.1.0 through 169.254.254.255 has been reserved for this purpose. You may see this in the “ipconfig” output of a windows host that failed to pull a DHCP address.
In IPv6, fe80::/10 is reserved for this purpose, though link-local addresses are always configured with a fe80::/64 prefix.
I’ve been running IPv6 on my home network for a while. The solution in place has evolved over time, from terminating tunnels to a linux VM using gogo6 all the way to front-ending with a Cisco ISR using Hurricane Electric, the goal has always been the same - to practice what I preach. Running IPv6 at home and REFUSING to turn it off when problems arise is one of the best ways to learn the protocol.
Ah, the age old question that nearly every CCNA and CCNP candidate asks of themselves and others at some point. We see a minimum of 4 routing protocols in our networking studies, more if you decide to take on the Service Provider track. What makes one routing protocol better than another? I think it’s clear why (at least mostly) these particular two protocols are different, keeping in mind that one is distance vector (yes, distance vector, not hybrid distance vector) and the other is link state.
Keeping It Classless