Cisco IOS Admin
Cisco IOS vs. Juniper JUNOS: The technical differences
IOS traditionally is a monolithic operating system, which means it runs as a single operation and all processes share the same memory space. Because of the latter feature, bugs in one operation can have an impact on or corrupt other processes. In addition, if a user wishes to add features or functions to the operating system, IOS has to be deactivated while a completely new version with the desired features is loaded.
JUNOS, on the other hand, was constructed as a modular operating system. The kernel is based on the open source FreeBSD operating system, and processes that run as modules on top of the kernel are segregated in exclusive, protected, memory space. Users thus can add features and functions to the version of JUNOS running on their systems without disabling the entire operating system — a characteristic known as in-service software upgrades that also enhances uptime and availability.
"The major difference is operational," says Jeff Doyle, president of IP consultancy Jeff Doyle and Associates, who has worked with both operating systems. "The reality is, IOS is pretty old. [JUNOS] was architecturally designed differently. It's more modern and modular, meaning bug fixes are easier and functional failures tend to be not as impactful as they are with as IOS."
Administrative Distance (AD) values in Cisco & Juniper AD value is a reliability or trustworthiness of a protocol, for selecting routes to be placed in routing table. If a router has routes to same destination from two different protocols it will prefer the protocol with lowest AD value, and its routes will be installed in the Routing / Forwarding table. Cisco and Juniper use different values of AD for their selection criteria.
IOS traditionally is a monolithic operating system, which means it runs as a single operation and all processes share the same memory space. Because of the latter feature, bugs in one operation can have an impact on or corrupt other processes. In addition, if a user wishes to add features or functions to the operating system, IOS has to be deactivated while a completely new version with the desired features is loaded.
JUNOS, on the other hand, was constructed as a modular operating system. The kernel is based on the open source FreeBSD operating system, and processes that run as modules on top of the kernel are segregated in exclusive, protected, memory space. Users thus can add features and functions to the version of JUNOS running on their systems without disabling the entire operating system — a characteristic known as in-service software upgrades that also enhances uptime and availability.
"The major difference is operational," says Jeff Doyle, president of IP consultancy Jeff Doyle and Associates, who has worked with both operating systems. "The reality is, IOS is pretty old. [JUNOS] was architecturally designed differently. It's more modern and modular, meaning bug fixes are easier and functional failures tend to be not as impactful as they are with as IOS."
Administrative Distance (AD) values in Cisco & Juniper AD value is a reliability or trustworthiness of a protocol, for selecting routes to be placed in routing table. If a router has routes to same destination from two different protocols it will prefer the protocol with lowest AD value, and its routes will be installed in the Routing / Forwarding table. Cisco and Juniper use different values of AD for their selection criteria.