The Internet of Things (IoT) was a hot topic at Cisco Live last week in Milan. I got to spend a lot of time with customers, partners, and developers, and came home impressed by the tremendous focus on IoT applications. There is an enormous amount of energy directed at building on the foundation Cisco is creating.
If you weren’t able to join us in Milan, here is my list of the week’s highlights.
The opening day keynote Read More »
Tags: big data analytics, Cisco, cisco live, Internet of Everything, internet of things, IoE, IoT, Kip Compton
Given the tremendous interest in VXLAN with MP-BGP based EVPN Control-Plane (short EVPN) at Cisco Live in Milan, I decided to write a “short” technology brief blog post on this topic.
VXLAN (IETF RFC7348) has been designed to solve specific problems faced with Classical Ethernet for a few decades now. By introducing an abstraction through encapsulation, VXLAN has become the de-facto standard overlay of choice in the industry. Chief among the advantages provided by VXLAN; extension of the todays limited VLAN space and the increase in the scalability provided for Layer-2 Domains.
Extended Namespace – The available VLAN space from the IEEE 802.1Q encapsulation perspective is limited to a 12-bit field, which provides 4096 VLANs or segments. By encapsulating the original Ethernet frame with a VXLAN header, the newly introduced addressing field offers 24-bits, thereby providing a much larger namespace with up to 16 Million Virtual Network Identifiers (VNIs) or segments.
While the VXLAN VNI allows unique identification of a large number of tenant segments which is especially useful in high-scale multi-tenant deployments, the problems and requirements of large Layer-2 Domains are not sufficiently addressed. However, significant improvements in the following areas have been achieved:
- No dependency on Spanning-Tree protocol by leveraging Layer-3 routing protocols
- Layer-3 routing with Equal Cost Multi-Path (ECMP) allows all available links to be used
- Scalability, convergence, and resiliency of a Layer-3 network
- Isolation of Broadcast and Failure Domains
IETF RFC7348 – VXLAN: A Framework for Overlaying Virtualized Layer 2 Networks over Layer 3 Networks
Scalable Layer-2 Domains
The abstraction by using a VXLAN-like overlay does not inherently change the Flood & Learn behavior introduced by Ethernet. In typical deployments of VXLAN, BUM (Broadcast, Unicast, Multicast) traffic is forwarded via layer-3 multicast in the underlay that in turn aids in the learning process so that subsequent traffic need not be subjected to this “flood” semantic. A control-plane is required to minimize the flood behavior and proactively distribute End-Host information to participating entities (typically called Virtual Tunnel End Points aka VTEPs) in the same segment – learning.
Control-plane protocols are mostly employed in the layer-3 routing space where predominantly IP prefix information is exchanged. Over the past years, some of the well-known routing protocols have been extended to also learn and exchange Layer-2 MAC addresses. An early technology adoption with MAC addresses in a routing-protocol was Cisco’s OTV (Overlay Transport Virtualization), which employed IS-IS to significantly reduce flooding across Data Center Interconnects (DCI).
Multi-Protocol BGP (MP-BGP) introduced a new Network Layer Reachability Information (NLRI) to carry both, Layer-2 MAC and Layer-3 IP information at the same time. By having the combined set of MAC and IP information available for forwarding decisions, optimized routing and switching within a network becomes feasible and the need for flood to do learning get minimized or even eliminated. This extension that allows BGP to transport Layer-2 MAC and Layer-3 IP information is called EVPN – Ethernet Virtual Private Network.
EVPN is documented in the following IETF drafts
Integrated Route and Bridge (IRB) – VXLAN-EVPN offers significant advantages in Overlay networking by optimizing forwarding decision within the network based on Layer-2 MAC as well as Layer-3 IP information. The decision on forwarding via routing or switching can be done as close as possible to the End-Host, on any given Leaf/ToR (Top-of-Rack) Switch. The Leaf Switch provides the Distributed Anycast Gateway for routing, which acts completely stateless and does not require the exchange of protocol signalization for election or failover decision. All the reachability information available within the BGP control-plane is sufficient to provide the gateway service. The Distributed Anycast Gateway also provides integrated routing and bridging (IRB) decision at the Leaf Switch, which can be extended across a significant number of nodes. All the Leaf Switches host active default gateways for their respective configured subnets; the well known semantic of First Hop Routing Protocols (FHRP) with active/standby does not apply anymore.
Summary – The advantages provided by a VXLAN-EVPN solution are briefly summarized as follows:
- Standards based Overlay (VXLAN) with Standards based Control-Plane (BGP)
- Layer-2 MAC and Layer-3 IP information distribution by Control-Plane (BGP)
- Forwarding decision based on Control-Plane (minimizes flooding)
- Integrated Routing/Bridging (IRB) for Optimized Forwarding in the Overlay
- Leverages Layer-3 ECMP – all links forwarding – in the Underlay
- Significantly larger Name-Space in the Overlay (16M segments)
- Integration of Physical and Virtual Networks with Hybrid Overlays
- It facilitates Software-Defined-Networking (SDN)
Simply formulated, VXLAN-EVPN provides a standards-based Overlay that supports Segmentation, Host Mobility, and High Scale.
VXLAN-EVPN is available on Nexus 9300 (NX-OS 7.0) with Nexus 7000/7700 (F3 linecards) to follow in the upcoming major release. Additional Data Center Switching platforms, like the Nexus 5600, will follow shortly after.
A detailed whitepaper on this topic is available on Cisco.com. In addition, VXLAN-EVPN was featured during the following Cisco Live! Sessions.
Do you have appetite for more? Post a comment, tweet about it and have the conversation going … Thanks for reading and Happy Networking!
Tags: #CLEUR, Cisco, cisco live, Cisco Nexus, Cisco Nexus 9000, data center, EVPN, ietf, network, nexus, rfc7348, SDN, VXLAN
Change happens either with us, by us or to us. Especially during the 3 Day IT Management Track at Cisco Live in Milan. We heard many things about leadership, disruption, change and innovation, and why it is the most important for leaders to listen, while sending the right signals to the audience. As Kevin Murray from the Good Relationship group stated: “People are afraid of ‘change’ but love to ‘innovate’ – so tell me the difference between ’change’ and ‘innovation’ – there is none!” If 60% of the companies’ assets are intangible, representing USD 35 trillion in total, leaders can really make a difference by valuing the people around them. Read More »
Tags: 2015, Cisco IT, cisco live, cisco on cisco, IT, IT management, itm, milan
The Cisco® Remote Integrated Services Engine (RISE) allows both physical and virtual external service appliances to be attached to the Cisco Nexus® 7000 Series Switches and gain the same benefits as if the appliances were directly connected to the switch backplane like a dedicated service module. Cisco RISE provides a bidirectional control plane for tightly coupling network services to data center switching. Cisco RISE establishes a communication path between the network data plane and the service appliance, simplifying deployment and optimizing data paths with better traffic visibility in the data center. RISE is supported Cisco Prime NAM, Citrix NetScaler 1000v, Citrix NetScaler VPX, Citrix NetScaler MPX, Citrix NetScaler SDX etc.
Interested in knowing more about Cisco® RISE . The engineering team will showcase demos of some of the innovative features being designed for the Nexus 2K to 7K platforms. These are 15-30min Software Demos performed by our technical leaders. Please stop by our booth or visit the Nexus Data Center Whisper suites to watch the live demo and get some free goodies. Email questions to: email@example.com
Tags: cisco live, cisco prime, Cisco Prime NAM, citrix, Citrix NetScaler 1000V, Citrix NetScaler VPX, CLIVE, milan, NetScaler, Remote integrated Service Engine, RISE, whisper suite sessions
Whether you are among the 8,000 attendees participating at Cisco Live Milan in-person or among our many virtual attendees catching the live web broadcast, you’ll find lots to help you with your mobility-related projects.
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Tags: #CLEUR, 11ac, 802.11ac, byod, Cisco CMX, cisco live, innovation, meraki, Meraki Challenge, milan, Milano, mobile, mobility, technology, wi-fi, wlan, workspace