Learning IOS and JUNOS

Cisco Announces New Service Provider Operations Track Built on the growing demand for dedicated professionals who can manage, maintain and troubleshoot complex service provider IP NGN core network infrastructures, Cisco is introducing a new Service Provider (SP) Operations track. This new track is focused on developing associate, professional and expert-level capabilities to operate large, complex SP networks. These new, first of their kind certifications are designed specifically for Cisco Service Provider Customers, Partners and Cisco Networking Engineers. Over the coming months Cisco will release new CCIE, CCNP, and CCNA SP Operations courses and exams. In addition, the written exam topics for the CCIE SP Operations certification are now available on the Cisco Learning Network. The CCIE SP Operations written exam is scheduled for release in the second quarter of 2010. CCIE SP Operations Certification The  Cisco CCIE SP Operations  certification assesses and validates...

經過了兩三個月的時間，我儘了最大的努力找出所有SP CCIE Written可能相關"主題"的文章摘要，並且用紅色字體標註"重點"，希望對各位了解題意有幫助，順便可以知道原來的文章出處及更詳盡的內容意義。 今天已經完成了第一階段的SP CCIE Written考試，接下來就是要準備第二階段SP CCIE Lab的部份了，我會邊作Lab邊將個人心得紀錄在這個blog中，希望我的經歷可以讓各位更輕鬆地準備SP CCIE! 祝各位CCIE Candiates好運! 一起克服大魔王!

Introduction A common problem when using Open Shortest Path First (OSPF) is routes in the database don't appear in the routing table. In most cases OSPF finds a discrepancy in the database so it doesn't install the route in the routing table. Often, you can see the Adv Router is not-reachable message (which means that the router advertising the LSA is not reachable through OSPF) on top of the link-state advertisement (LSA) in the database when this problem occurs. Here is an example: Adv Router is not-reachable LS age: 418 Options: (No TOS-capability, DC) LS Type: Router Links Link State ID: 172.16.32.2 Advertising Router: 172.16.32.2 LS Seq Number: 80000002 Checksum: 0xFA63 Length: 60 Number of Links: 3 There are several reasons for this problem, most of which deal with mis-configuration or a broken topology. When the configuration is corrected the OSPF database discrepancy goes away and the routes appear in the routing table. This document explains some of the more common rea...

...(略) To demonstrate how traffic engineering addresses the problem of underutilized links, we will take an example in Figure 3-18 by first defining the traffic engineer terminology: Head-End—A router on which a TE tunnel is configured (R1) Tail-End—The router on which the TE tunnel terminates (R3) Mid-point—A router through which the TE tunnel passes (R2) LSP—The label-switched path taken by the TE tunnel; here it's R1-R2-R3 Downstream router—A router closer to the tunnel tail Upstream router—A router farther from the tunnel tail (so R2 is upstream to R3's downstream, and R1 is upstream from R2's downstream) Continuing the traffic engineering building block, information distribution is done via a link state protocol, such as IS-IS or OSPF. The link state protocol is required only for traffic engineering, not for the implementation of Layer 3 VPNs. A link state protocol is required to ensure that information gets flooded and to build a topology of the entire network. Inform...

IEEE 802.17 Resilient Packet Ring Feature Guide This feature guide describes how to configure the Cisco implementation of the IEEE 802.17 Resilient Packet Ring (RPR) protocol on supported Cisco routers and includes information about the benefits of the feature, supported platforms, related publications, and so on. RPR is similar but not identical to the Spatial Reuse Protocol (SRP), the underlying technology used in the Cisco Dynamic Packet Transfer (DPT) family of products. Throughout this document, this feature is referred to as RPR. This document covers the use of the RPR feature. It does not include hardware installation and initial configuration information. Refer to the appropriate router installation and configuration note for information on how to configure the hardware and prepare it for use with RPR. Information About RPR Resilient Packet Ring (RPR), as described in IEEE 802.17, is a metropolitan area network (MAN) technology supporting data transfer among stations interconne...

…(略) ICRQ -> Mandatory AVP's: Message Type Assigned Session ID Call Serial Number …(略)

Two main types of video traffic exist: Interactive-Video (videoconferencing) and Streaming-Video (both unicast and multicast). Each type of video is examined separately. Interactive-Video When provisioning for Interactive-Video (video conferencing) traffic, the following guidelines are recommended: Interactive-Video traffic should be marked to DSCP AF41; excess videoconferencing traffic can be marked down by a policer to AF42 or AF43. Loss should be no more than 1 percent. One-way latency should be no more than 150 ms. Jitter should be no more than 30 ms. Assign Interactive-Video to either a preferential queue or a second priority queue (when supported); when using Cisco IOS LLQ, overprovision the minimum-priority bandwidth guarantee to the size of the videoconferencing session plus 20 percent. (For example, a 384-kbps videoconferencing session requires 460 kbps of guaranteed priority bandwidth.)

Using OSPF in PE-CE Router Connections In an MPLS VPN configuration, the OSPF protocol is one way you can connect customer edge (CE) routers to service provider edge (PE) routers in the VPN backbone. OSPF is often used by customers that run OSPF as their intrasite routing protocol, subscribe to a VPN service, and want to exchange routing information between their sites using OSPF (during migration or on a permanent basis) over an MPLS VPN backbone. Figure 1 shows an example of how VPN client sites that run OSPF can connect over an MPLS VPN backbone. Figure 1 OSPF Connectivity Between VPN Client Sites and an MPLS VPN Backbone When OSPF is used to connect PE and CE routers, all routing information learned from a VPN site is placed in the VPN routing and forwarding (VRF) instance associated with the incoming interface. The PE routers that attach to the VPN use the Border Gateway Protocol (BGP) to distribute VPN routes to each other. A CE router can then learn the routes to other sites in ...

The IP Event Dampening feature introduces a configurable exponential decay mechanism to suppress the effects of excessive interface flapping events on routing protocols and routing tables in the network. This feature allows the network operator to configure a router to automatically identify and selectively dampen a local interface that is flapping. Restrictions for IP Event Dampening Subinterface Restrictions Only primary interfaces can be configured with this feature. IP Event Dampening does not track the flapping of individual subinterfaces on an interface. Virtual Templates Not Supported Copying a dampening configuration from virtual templates to virtual access interfaces is not supported because dampening has limited usefulness to existing applications that use virtual templates. Virtual access interfaces are released when an interface flaps, and new connections and virtual access interfaces are acquired when the interface comes up and is made available to the network. Since dampe...

WHY IS QoS NEEDED? The primary goal of QoS is to provide priority for traffic flows to and from specific devices. In this context, priority means providing lower latency and higher bandwidth connections with more controlled jitter. An underlying principle of Fibre Channel switching is that the network guarantees that no frames will be dropped. If this is the case, why do we need QoS at all? Switches today provide high-performance, non-blocking, non-oversubscribed crossbar switch fabrics. The Cisco MDS 9513 Multilayer Director can switch more than a billion frames per second. Why would users ever need QoS when a switch fabric provides seemingly endless amounts of frame-switching capacity? The answer is simple: congestion. Congestion occurs for two basic reasons: • Congestion will occur if multiple senders are contending with a smaller number of receivers. If the aggregate rate of traffic transmitted by senders exceeds the size of the connection to the receivers, blocking will occur (Fig...

Feature Overview Any Transport over MPLS (AToM) is a solution for transporting Layer 2 packets over an MPLS backbone. AToM enables service providers to supply connectivity between customer sites with existing data link layer (Layer 2) networks by using a single, integrated, packet-based network infrastructure — a Cisco MPLS network. Instead of separate networks with network management environments, service providers can deliver Layer 2 connections over an MPLS backbone. With Cisco AToM technology, provisioning and connecting is straightforward. A customer using Ethernet in a building or campus in one location can connect through a service provider offering Ethernet over MPLS to the customer's Ethernet networks in remote locations. AToM provides a common framework to encapsulate and transport supported Layer 2 traffic types over an MPLS network core. Service providers can use a single MPLS network infrastructure to offer customers connectivity for supported Layer 2 traffic, as well ...

White Paper -------------------------------------------------------------------------------- Layer 2 Tunneling Protocol Version 3 Enables Layer 2 Services for IP Networks The competitive environment for service providers has changed considerably since the Internet became a global force in the 1990s. Enterprises are no longer signing up for new IP-based services for the novelty or out of fear of being left behind by the competition. The challenge for service providers today is to grow their businesses by expanding their customer base and service revenue in a more cautious spending environment. Most enterprises are taking a more conservative approach to network investments. New IP-based services give enterprises an opportunity to improve their productivity and competitiveness while lowering their existing network expenses. Service providers that offer these services and savings can grow their customer base and service revenue. This white paper focuses on one such opportunity—offering tra...

1.0 Overview Cisco Nonstop Forwarding with Stateful Switchover (NSF with SSO) is a Cisco innovation for routers with dual route processors. Cisco NSF with SSO allows a router that has experienced hardware or software failure of an active route processor to maintain data link layer connections and continue forwarding packets during the switchover to the standby route processor. This forwarding can continue despite lost routing protocol peering arrangements with other routers. Routing information is recovered dynamically, in the background, while packet forwarding proceeds uninterrupted. Cisco NSF for BGP is a combination of internal system modifications to the various NSF-capable hardware platforms, and external enhancements to the BGP-4 protocol. The modifications to the BGP protocol (BGP Graceful Restart) have been submitted to the Internet Engineering Task Force (IETF): http://www.ietf.org/internet-drafts/draft-ietf-idr-restart-06.txt1 This document will detail specific changes to th...