This chapter has covered a lot of topics, ranging from software to hardware. It’s important to understand how the software and hardware are designed to work in conjunction with each other. This combination creates carrier-class routers that are able to solve the difficult challenges networks are facing with the explosion of high-speed and high-density Ethernet services.
Junos has a very simple and elegant design that allows for the clear and distinct separation of the control and data planes. Juniper has a principle of “distribute what you can and centralize what you must” There are a handful of functions that can be distributed to the data plane to increase performance. Examples include period packet management such as Hello packets of routing protocols and point of local repair (PLR) features such as MPLS Fast Reroute (FRR) or Loop Free Alternate (LFA) routes in routing protocols. By distributing these types of features out to the data plane, the control plane doesn’t become a bottleneck and the system is to scale with ease and can restore service in under 50 ms.
The MX Series ranges from a small 2U router to a giant 44U chassis that’s able to support 20 line cards. The Trio chipset is the pride and joy of the MX family; the chipset is designed for high-density and high-speed Ethernet switching and routing. Trio has the unique ability to provide inline services directly within the chipset without having to forward the traffic to a special service module. Example services include NAT, GRE, IP tunneling, port mirroring, and IP Flow Information Export (IPFIX).
The Juniper MX is such a versatile platform that it’s able to span many domains and use cases. Both Enterprise Environments (EE) and Service Providers have use cases that are aligned with the feature set of the Juniper MX:
Data centers that need to provide services to multiple tenants require multiple learning domains, routing instances, and forwarding separation. Each instance is typically mapped to a specific customer and a key requirement is collecting accounting and billing information.
As the number of data centers increase, the transport between them must be able to deliver the services mandated by the business. Legacy applications, storage replication, and VM mobility may require a common broadcast domain across a set of data centers. MPLS provides two methods to extend a broadcast domain across multiple sites: Virtual Private LAN Service (VPLS) and Ethernet VPN (E-VPN).
As enterprise customers grow, the number of data centers, branch offices, and campuses increase and create a requirement to provide transport between each entity. Most customers purchase transport from a Service Provider, and the most common provider edge (PE) to customer edge (CE) routing protocol is BGP.
The core of a Service Provider network requires high-density and high-speed interfaces to switch MPLS labels. Features such as LFA in routing protocols and MPLS FRR are a requirement to provide PLR within 50 ms.
The edge of Service Provider networks requires high scale in terms of routing instances, number of routing prefixes, and port density to support a large number of customers. To enforce customer service level agreements (SLA) features such as policing and hierarchical class of service (H-CoS) are required.
Multiplay and triple play services require high subscriber scale and rich features such as authentication, authorization, and accounting (AAA); change of authorization (CoA); and dynamic addressing and profiles per subscriber.
The number of cell phones has skyrocketed in the past 10 years and is placing high demands on the network. The varying types of service require class of service to ensure that voice calls are not queued or dropped, interactive applications are responsive, and web browsing and data transfer is best effort. Another key requirement is packet-based timing support features such as E-Sync and 1588v2.
The Juniper MX supports a wide variety of line cards that have Ethernet interfaces such as 1GE, 10GE, 40GE, and 100GE. The MPC line cards also support traditional time-division multiplexing (TDM) MICs such as T1, DS3, and OC-3. The line cards account for the bulk of the investment in the MX family, and a nice investment protection is that the line cards and MICs can be used in any Juniper MX chassis.
Each chassis is designed to provide fault protection through full hardware and software redundancy. All power supplies, fan trays, switch fabric boards, control boards, routing engines, and line cards can be host-swapped and do not require downtime to replace. Software control plane features such as graceful routing engine switchover (GRES), non-stop routing (NSR), and non-stop bridging (NSB) ensure that routing engine failures do not impact transit traffic while the backup routing engine becomes the new master. The Juniper MX chassis also supports In Service Software Upgrades (ISSU) that allows you to upgrade the software of the routing engines without impacting transit traffic or downtime. Junos high availability features will be covered in Chapter 9. The Juniper MX is a phenomenal piece of engineering that’s designed from the ground up to forward packets and provide network services at all costs.