Posts Tagged ‘multicast’
Edit: For those of you that want to take a look first-hand at these packets, the Wireshark PCAP files referenced in this post can be found here
One of the hottest topics in networking today is Data Center Virtualized Workload Mobility (VWM). For those of you that have been hiding under a rock for the past few years, workload mobility basically means the ability to dynamically and seamlessly reassign hardware resources to virtualized machines, often between physically disparate locations, while keeping this transparent to the end users. This is often accomplished through VMware vMotion, which allows for live migration of virtual machines between sites, or as similarly implemented in Microsoft’s Hyper-V and Citrix’s Xen hypervisors.
One of the typical requirements of workload mobility is that the hardware resources used must be on the same layer 2 network segment. E.g. the VMware Host machines must be in the same IP subnet and VLAN in order to allow for live migration their VMs. The big design challenge then becomes, how do we allow for live migrations of VMs between Data Centers that are not in the same layer 2 network? One solution to this problem that Cisco has devised is a relatively new technology called Overlay Transport Virtualization (OTV).
As a side result of preparing for INE’s upcoming CCIE Data Center Nexus Bootcamp I’ve had the privilege (or punishment depending on how you look at it ) of delving deep into the OTV implementation on Nexus 7000. My goal was to find out exactly what was going on behind the scenes with OTV. The problem I ran into though was that none of the external Cisco documentation, design guides, white papers, Cisco Live presentations, etc. really contained any of this information. The only thing that is out there on OTV is mainly marketing info, i.e. buzzword bingo, or very basic config snippets on how to implement OTV. In this blog post I’m going to discuss the details of my findings about how OTV actually works, with the most astonishing of these results being that OTV is in fact, a fancy GRE tunnel.
One of our most anticipated products of the year – INE’s CCIE Service Provider v3.0 Advanced Technologies Class – is now complete! The videos from class are in the final stages of post production and will be available for streaming and download access later this week. Download access can be purchased here for $299. Streaming access is available for All Access Pass subscribers for as low as $65/month! AAP members can additionally upgrade to the download version for $149.
At roughly 40 hours, the CCIE SPv3 ATC covers the newly released CCIE Service Provider version 3 blueprint, which includes the addition of IOS XR hardware. This class includes both technology lectures and hands on configuration, verification, and troubleshooting on both regular IOS and IOS XR. Class topics include Catalyst ME3400 switching, IS-IS, OSPF, BGP, MPLS Layer 3 VPNs (L3VPN), Inter-AS MPLS L3VPNs, IPv6 over MPLS with 6PE and 6VPE, AToM and VPLS based MPLS Layer 2 VPNs (L2VPN), MPLS Traffic Engineering, Service Provider Multicast, and Service Provider QoS.
Below you can see a sample video from the class, which covers IS-IS Route Leaking, and its implementation on IOS XR with the Routing Policy Language (RPL)
In this short article we’ll take a look at Cisco IOS static multicast routes (mroutes) and the way they are used for RPF information selection. Multicast routing using PIM is not based on propagation of any type of multicast routes – the process that was used say, in DVMRP. Instead, router performs RPF checks based on the contents of unicast routing table, populated by regular routing protocols. The RPF checks could be classified as either data-plane or control-plane. Data-plane RPF check applies when router receives a multicast packet, to validate if the interface and upstream neighbor sending the packet match RPF information. For data-plane multicast, the packet must be received from an active PIM neighbor on the interface that is on the shortest path to the packet source IP address, or RPF check would fail. Control-plane RPF check is performed when originating/receiving control-plane messages, such as sending PIM Join or receiving MSDP SA message. For example, PIM needs to know where to send the Join message for a particular (S,G) or (*,G) tree, and this is done based on RPF lookup for the source IP or RP address. Effectively for PIM, RPF check influences the actual multicast path selection in the “reversed way”: it carves the route that PIM Join message would take and thus affects the tree construction. In both control and data-plane RPF check cases, the process is similar, and based on looking through all available RPF sources.
After working with the December 2010 London Bootcamp on Multicast for the better part of Day 4 in our 12-day bootcamp, I returned to the hotel to find the following post on my Facebook page – “Multicast is EVIL!”
Why do so many students feel this way about this particular technology? I think one of the biggest challenges is that troubleshooting Multicast definitely reminds us of just what an “art” solving network issues can become. And speaking of troubleshooting, in the Version 4 Routing and Switching exam, we may have to contend with fixing problems beyond the scope of our own “self-induced” variety. This is, of course, thanks to the initial 2 hour Troubleshooting section which may indeed include Multicast-related Trouble Tickets.
Your very best defense against any issues in the lab exam regarding this technology – the new 3-Day Multicast technology bootcamp. Also, be sure to enjoy the latest free vSeminar from Brian McGahan – Troubleshooting IP Multicast Routing.
INE is proud to announce the release of our Multicast Class-on-Demand! Taught by myself, this 15-hour Class-on-Demand series covers IPv4 and IPv6 Multicast Routing on Cisco IOS, including both technology lectures and hands-on CLI examples. More information on the Multicast Class-on-Demand can be found here.
To celebrate the release of this new Class-on-Demand, I will be running a free vSeminar on Troubleshooting IP Multicast Routing this Thursday, October 14th, at 10:00 am PDT (17:00 GMT). This free seminar will run about an hour long, and will cover CLI examples of how to troubleshoot common IP Multicast problems, including RPF failure and the use of static multicast routes & mtrace. For those unable to attend, this vSeminar will be available in recorded Class-on-Demand format at a later date. The url to attend is http://ieclass.internetworkexpert.com/tshootipmulticast/
Click here to register for notifications about new upcoming vSeminars.
Hope to see you there!
When we ask students “what are your weakest areas” or “what are your biggest areas of concern” for the CCIE Lab Exam, we typically always here non-core topics like Multicast, Security, QoS, BGP, etc. As such, INE has responded with a series of bootcamps focused on these disciplines.
The IPv4/IPv6 Multicast 3-Day live, online bootcamp, and the associated Class On-Demand version seeks to address the often confounding subject of Multicast. Detailed coverage of Multicast topics for the following certifications is provided:
Cisco Certified Network Professional (CCNP)
Cisco Certified Design Associate (CCDA)
Cisco Certified Design Professional (CCDP)
Cisco Certified Design Expert (CCDE)
Cisco Certified Internetwork Expert Routing & Switching (CCIE R&S)
Cisco Certified Internetwork Expert Service Provider (CCIE Service Provider)
Cisco Certified Internetwork Expert Security (CCIE Security)
To purchase the live and on-demand versions of the course for just an amazing $295 – just click here. The live course runs 11 AM to 6 PM EST US on September 29,30, and October 1.
The preliminary course outline is as follows:
- Module 1 Introduction to Multicast
Lesson 1 The Need for Multicast
Lesson 2 Multicast Traffic Characteristics and Behavior
Lesson 3 Multicast Addressing
Lesson 4 IGMP
Lesson 5 Protocol Independent Multicast
- Module 2 IGMP
Lesson 1 IGMP Version 1
Lesson 2 IGMP Version 2
Lesson 3 IGMP Version 3
Lesson 4 CGMP
Lesson 5 IGMP Snooping
Lesson 6 IGMP Optimization
Lesson 7 IGMP Security
Lesson 8 Advanced IGMP Mechanisms
IPv6 multicast routing is a fun topic, and is often either loved or avoided . Here is a jump-start for all my CCIE candidate friends.
Readers digest version: “Auto-RP is out, Dense-mode is out, IGMP is replaced with Multicast Listener Discovery (MLD). MLDv2 supports SSM. RPs, Bi-directional PIM, SSM, ASM and BSRs are still alive and well, and we can now avoid static RPs and BSR if we choose to use embedded RP within the multicast packets themselves. (Crazy and amazing stuff).
Want a little more? Then read on. In this multi-part blog, we will discuss static RP, BSR, and Embedded RP. This first blog will discuss static RP, with some examples that will assist you in getting started. For those of you who subscribe the open lecture series, I will be including all three RP options in a discussion there as well.
Here is the topology we will use:
Here is some additional info on the topology. Continue Reading
A pretty important topic that is very easy to overlook when studying multicast is the PIM Assert Mechanism. After working with the TechEdit Team in the IEOC it is obvious that more than just a handful of students are confused about what this mechanism does and how it works. In this blog post (the first of many dedicated to multicasting), we will examine the PIM Assert mechanism and put this topic behind us in our preparation in mastering multicast.
In Figure 1, R1 and R4 have a route to the source 188.8.131.52 (the multicast source), and share a multi-access connection to R6. R6’s FastEthernet0/0 interface has joined the multicast group 184.108.40.206.
IPv6 multicast renames IGMP to the Multicast Listener Discovery Protocol (MLP). Version 1 of MLD is similar to IGMP Version 2, while Version 2 of MLD is similar to Version 3 IGMP. As such, MLD Version 2 supports Source Specific Multicast (SSM) for IPv6 environments.
Using MLD, hosts can indicate they want to receive multicast transmissions for select groups. Routers (queriers) can control the flow of multicast in the network through the use of MLD. Continue Reading
IPv6 multicast is an important new blueprint topic for the Version 4.X CCIE R&S Lab Exam as well as the Written Qualification Exam. In this post, we will start at the most logical starting point for this topic – the IPv6 multicast addressing in use.
Like in IP version 4, multicast refers to addressing nodes so that a copy of data will be sent to all nodes that possess the address. Multicast allows for the elimination of broadcasts in IPv6. Broadcasts in IP version 4 were problematic, since the copy of data is delivered to all nodes in the network, whether the node cares to receive the information or not.
Multicast addresses are quickly detected by the initial bit settings. A multicast address begins with the first 8 bits set to 1 (11111111). The corresponding IPv6 prefix notation is FF00::/8.