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August 31, 2004

Juniper OS :: JUNOS and JUNOSe

junos_293_thumb.gif I'm intersted in oprating system it means their managements for instance process management,memory management and so on also on deadlock detection/avoidance,file system,scheduling strategies and .... I think freeBSD has the best managements and works properly although other OS like SUN Solaris is powerful but FreeBSD is categurised in non-commercial operating system and it comes with full source code. in fact i wanna talk about JUNOS that based on the FreeBSD , first of all please don't pronounce JUN-OS ,you should pronounce just in one syllable.Juniper appliances have JUNOS as operating system which based on the FreeBSD they've modified the freeBSD,extracted some modules and imported specially modified modules and some engines on it. the JUNOS has some parts contain : JKernel (The operating system package) JRoute (The routing engine software) JPFE (The PFE software) JDocs (Updated online reference documentation) Jcrypto (Security software (U.S. domestic only)) Jbase (Additions to JUNOS) Totally they called Jbundle.

Juniper Networks releases several new versions of JUNOS software each year. you can see some feature of JUNOS : - Modularity - JUNOS software employs a modular software design, providing superior resilience and ensuring that new capabilities such as IPv6 can be easily integrated - Routing expertise - Juniper Networks IP routing expertise delivers a full complement of production-hardened routing protocols - Standards-based - thoughtful adherence to industry standards for routing, MPLS, and availability mechanisms such as Protocol Graceful Restart translates to improved stability and reduced operational complexity for customers - Security - JUNOS software combines intelligent packet processing with superior performance to offer customers a potent IP security toolkit - Service richness - whether individual subscriber, enterprise business, or service provider, JUNOS IP services portfolio enables customers to deliver assured experiences to end users of any profile - Policy and control - Juniper Networks SDX and NMC platforms allow customer to invoke and control these powerful JUNOS capabilities; in addition, Juniper Networks JUNOScript XML interface simplifies and accelerates OSS integration Modular software architecture The Juniper appliences load JUNOS from flash memory but they have hard disk for other purpose like syslogs,Backup and so on thereby when they want to become shutdown they should be manually turned off from OS it means execute halt command (request system halt). there isn't any concern about blackout without the shutting down command because at next boot , maybe it takes a few time for checking file system on hard disk drive so if it fails in the worst situation the applience will boot successfully and works properly because the JUNOS is on flash and in this case we don't have backup and logs and so on. Another OS from Juniper is JUNOSe,it's the operating system that powers Juniper Networks market-leading E-series family of edge routers.the Juniper web site said "twenty of the top twenty-five service providers in the world use JUNOSe in their production networks, delivering profitable service to end-user customers. Major publicly announced deployments include: Bell Canada, Cable & Wireless, Deutsche Telekom, France Telecom, Korea Telecom, PCCW, Telstra, Telefonica, XO, and many others.JUNOSe is specifically architected to help service providers migrate from traditional “best effort” IP services to enhanced IP services based on the infranet model." Totally JUNOSe is specifically architectured to address and overcome the challenges that's service provider face at the edge. Some new service in JUNOSe : - Hierarchical QoS capabilities to deliver a voice and data service. - Virtual router and MPLS 2547 VPN technologies. - rolling out IPTV and Video on Demand - A service provider using the per-VLAN queuing, rate limiting, and policy. and .... You can get more information about JUNOS and JUNOSe at the Juniper web site : http://www.juniper.net

Posted by Mehrdad at 10:29 PM

August 18, 2004

Virtual Private LAN service

As you know Ethernet is simple,flexible and scaleable bandwith also it has been revolition in MetroEthernet.Virtual Private LAN service (VPLS) allows service providers to deliver VPN service base on ethernet and it's one of the most inovation of providing Ethernet/MPLS VPN.
it uses Martini encapsulation standard and empowers service providers Ethernet networks with scalability and availability. Without VPLS, the scalability of Ethernet networks is limited to the number of unique identifiers or VLAN IDs used to provide services, and the availability of Ethernet networks is limited by the poor resiliency characteristics of mechanisms such as Spanning Tree Protocol.Some limitation such as QinQ solves and VPLS networks can support over a million unique identifiers.
VPLS is based on an Internet Engineering Task Force (IETF) draft called Lasserre-V. Kompella, written by Marc Lasserre of Riverstone Networks Inc. and Vach Kompella of TiMetra Networks, now owned by Alcatel. VPLS is expected to be a fully ratified standard by the end of this year, but several service providers are already deploying the service because they feel it’s stable enough for commercial use, says Newell.

Posted by Mehrdad at 12:11 PM

August 11, 2004

Fragment Collision

Today one of my friends ask a question about Fragment Collision (short/runt frames) so i'm going to write brief of it in this section.
As you know a collision occurs when two stations begin transmission simultaneously when they detect silence on the network so at that time they stop transmission and send a JAM signal and back off for a while (Random amount of time)
The mechanism requires that stations be close enough together for each station to see any possible attempted transmisstion before the first 64 bytes of its frame have been transmitted.(This is because 64 bytes is the minimum frame size for an Ethernet network).
The IEEE specification defines the term fragment collision for that .
the below picture is a frame as Fragment collision .
fragmentcol.jpg

Posted by Mehrdad at 01:31 PM

August 08, 2004

IEEE 802.1Q-in-Q VLAN Tag (QinQ)

The IEEE 802.1Q-in-Q VLAN Tag is purpose to expand the VLAN space by tagging the tagged packets, thus producing a "double-tagged" frame. The expanded VLAN space allows the service provider to provide certain services, such as Internet access on specific VLANs for specific customers, and yet still allows the service provider to provide other types of services for their other customers on other VLANs.

qinq.jpg

For more information you can see the below link :
IEEE 802.1Q-in-Q VLAN Tag Termination

Posted by Mehrdad at 05:07 PM