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STUDY GUIDES SAMPLE TESTS FORUMS AUDIO TRAINING VIDEO TRAINING EXAMSHEETS HELP US OUT LINKS DIRECTORY NEWSLETTERS COLLEGE DEGREES FAQ ARTICLES BOOK REVIEWS ADVERTISE TIPS/TRICKS TOPSITES CONTACT		640-504 BCMSN (Building Cisco Multilayer Switched Networks) This study guide is developed to provide you with an overview of the Cisco 504 Switching subject. You are suggested to use this study guide to give yourself a “bird eye view” of the exam. For further study and more in-depth coverage of the topics, the following books are recommended: Cisco CCNP Preparation Library, Second Edition (Cisco Career Certifications) -- Diane Teare, et al; Hardcover CCNP: Switching Study Guide -- Todd Lammle, et al; Hardcover CCIE Professional Development : Cisco Lan Switching (The Cisco Press Ccie Professional Development Series) -- Kennedy Clark, Kevin Hamilton; Textbook Binding Cisco Catalyst LAN Switching CCIEPrep.com -- Louis R. Rossi(Preface), et al; Paperback Cisco IOS Switching Services by Inc Cisco Systems (Paperback) CISCO Interactive Mentor LAN Switching (With CD-ROM) by Systems, Inc. Cisco(Editor) (Software) CCIE Fundamentals: Network Design and Case Studies, Second Edition (Certification) (Hardcover) Knowledge measured according to Cisco Campus network models Cisco Hierarchical Internetworking Model OSI LAN Switching and hardware Remote Monitoring Multi-layer switching Layer-2 Switching Layer-3 Switching Layer-4 Switching Tag Switching Virtual LANs Trunking VTP Spanning Tree Protocol Multicasting Protocol Independent Multicast Dial-on-Demand Routing Hot Standby Routing Protocol PortFast UplinkFast BackboneFast =========================================================== Do NOT use this study guide as your sole study resource. Successful completion of the 504 exam requires both practical experience as well as lots and lots of reading. On the actual exam you will encounter questions on IOS commands as well as many terms. For the commands, Cisco’s original documentation has very detailed coverage. You may follow the links we provide to read these original Cisco documents for more information on the commands. We figured out that the best way to present the study material for 504 is to describe the key terms that will be covered in the exam. Here you go…. =========================================================== Readings from the Cisco Web Site Configuring VLANs http://www.cisco.com/univercd/cc/td/doc/product/lan/cat5000/rel_2_3/config/09vlans.htm Configuring VLAN Trunks http://www.cisco.com/univercd/cc/td/doc/product/lan/c2900xl/29_35sa6/eescg/masctrnk.htm Configuring VTP http://www.cisco.com/univercd/cc/td/doc/product/lan/cat5000/rel_4_2/config/vlans.htm VTP White Paper http://www.cisco.com/warp/public/473/21.html IOS Switching commands http://www.cisco.com/univercd/cc/td/doc/product/software/ios120/12cgcr/switch_r/xrswcmd.htm Configuring STP http://www.cisco.com/warp/public/473/5.html Configuring IP MLS http://www.cisco.com/univercd/cc/td/doc/product/lan/cat5000/rel_5_2/layer3/mls.htm MLS Commands http://www.cisco.com/univercd/cc/td/doc/product/software/ios120/12cgcr/switch_r/xrmls.htm HSRP http://www.cisco.com/warp/public/619/index.shtml Configuring IP services http://www.cisco.com/univercd/cc/td/doc/product/software/ios120/12cgcr/np1_c/1cprt2/1cip.htm IP Multicast Commands http://www.cisco.com/univercd/cc/td/doc/product/software/ios113ed/113ed_cr/np1_r/1rmulti.htm Configuring Multicast Services http://www.cisco.com/univercd/cc/td/doc/product/lan/cat5000/rel_2_3/config/10multi.htm Campus Network In the past, the primary target of local workstations would be workgroup servers in the same neighborhood Nowadays, performance of Layer 3 device is critical Nowadays, resources are shared mostly in the core layer of the Cisco Hierarchical Model 20/80 Rule 80 % of the campus traffic will traverse the core while 20 % will stay local with the LANs The new trend for the networking world when we have a high percentage of traffic destined for the enterprise server farm 80/20 rule 80 % of the network traffic should be local, while 20 % of the network traffic should move across the backbone This is the “old school of thought” Not suitable for nowadays web based environment where activities and processing are consolidated to central servers ASICs Short for application-specific integrated circuits Uses high-speed hardware implementation for efficient routing Cisco Hierarchical Internetworking Model This refers to the network design where we have 3 different layers: Core Distribution Access This model facilitates scalability, performance and troble-shooting Core Layer High-speed switching backbone Designed to switch packets as fast as possible Does not perform packet manipulation Distribution Layer Boundary definition Packet manipulation Address or area aggregation Departmental or workgroup access Broadcast or multicast domain definition VLAN routing Security Access Layer Allows local end users into the network Uses access lists to filter the needs of a particular set of users Shared / switched bandwidth MAC layer filtering Microsegmentation OSI Layers and Protocols You should memorize the following relationships between the layers and the protocols / formats: Application Layer – Telnet, SMTP, FTP Presentation – ASCII, MPEG, GIF, JPEG Transport –TCP, SPX Network - IP, IPX Cisco Switches in the different layers: Access Layer 1900 2800 2900 4000 5000 5500 Distribution Layer 2926G 5000 5500 6000 Core Layer 5000 5500 6500 8500 Switches Interfaces and Management The 5000/6000/6500 series switches use a set based CLI similar to the Unix csh style interface. The most commonly used commands are Set (for configuration changes), Show ( for showing config information) and Clear (for removing config settings). You may manage the switches with In-band management, meaning you do it through telnet or SNMP through modem or line module. You may also manage with Out-of-band management, meaning you are doing it via the console port directly connected to the Supervisor module. You may seek help from Cisco by approaching Cisco’s Technical Assistance Center TAC. TAC has Customer Support Engineers CSEs to help you out Support may also be obtained via Cisco Connection Online in Cisco web site RMON Short for Remote Monitoring 4 groups available for different functions: Statistics Group - monitoring port utilization and providing error statistics History Group – providing periodic statistics Alarm Group - sampling interval / threshold Event Group - logging events Layer 2 Switching Hardware-based bridging Frame forwarding handled by ASICs Has the same characteristics and limitations as bridging Has the limitations of slow convergence and blocked links with STP For creating flatter network Layer 3 Switching Hardware-based routing Can use Netflow switching Packet-by-packet Layer 3 switches support standards-based packet header rewrite and time-to-live decrement Layer 4 Switching Hardware-based routing Packet forwarding handled by ASICs Can use Netflow switching Control traffic based on Layer 4 information with extended access lists Provide granular Layer 4 accounting of flows with NetFlow switching - NetFlow feature card performs Layer 3 / 4 switching in hardware Prioritization by applications MLS Short for Multi Layer Switching Route once switch many Provides high-performance Layer 3 switching for Catalyst 5000 series Switches IP data packets between subnets using ASIC Offload routers from forwarding unicast IP data packets over the Ethernet Provides traffic statistics for identifying traffic characteristics for administration, planning, and troubleshooting Catalyst 5000 series switch uses the Route Switch Module RSM to perform route processing, although routing services can also be provided by external router For MLS to work, you need to have Multilayer Switching Switch Engine (MLS-SE), Multilayer Switching Route Processor (MLS-RP) and also the Multilayer Switching Protocol (MLSP) It is important to realize that: Know the difference of collision VS broadcast domain Bridges limit collision domains only, not broadcast domains. Routers can limit broadcast domains Blocks 5 different types of block available: Core Blocks –Connect multiple switch blocks together Switch Blocks – access layer switches are connected with distribution layer devices WAN Blocks – connect to single or multiple ISPs with multiple connections Server Blocks – server group in a subnet Mainframe Blocks – form centralized network services Tag Switching Deployed in a multicast environment Works at the data link layer Forwarding mechanism similar to label swapping All tag switches that belongs to a common multicast tree on the same sub-network agree on a common tag to make forwarding of multicast packets to the downstream possible The Forwarding component uses the tag information included in the packets as well as those maintained by the tag switch to perform packet forwarding. The Control component will ensure that tag information are correctly maintained by the switches. Support QOS in a sense that it marks packets as a member of a particular class VLAN Short for Virtual LAN Similar to an extended bridged network Enable Layer 2 switching across the campus Distribution layer will route traffic between VLANs Each VLAN functions as a separate broadcast domain Membership based on switch port number most of the time, and can be static or dynamic Membership remains the same even when the user is re-located to another location To build up a VLAN, you need to assign the ports, configure the ports for trunking, verify the configuration and then remove the trunk finally Frame tagging deploys IEEE 802.1Q for identifying VLANs through inserting VLAN identifier into frame header VTP Short for VLAN Trunk Protocol Maintain VLAN configuration consistency of the network VTP version 1 works with supervisor engine software release 2.1 or later and ATM software release 3.1 or later VTP version 2 works with supervisor engine software release 3.1 and later All switches in the same VTP domain must run the same VTP version VTP domain = VLAN management domain VTP domain made up of interconnected switches sharing the same domain name A switch can belong to only one domain A password must b configured on each switch in the management domain when it is running in secure mode Advertisement information includes VTP domain name, VTP configuration revision number, MTU size, Frame format, VLAN Ids, Emulated LAN names for ATM LANE, 802.10 SAID values for FDDI 3 VTP modes: You use client mode when there are other Catalyst switches in the domain. You use transparent mode when the switch will not share VLAN information with any other switch on the network. You use server mode when this is the first switch in your management domain 5 trunk modes: The On mode forces a port to become a trunk port, while the Off mode does the exact opposite. The Desirable mode causes the port to actively try to set a link to a trunk, while the Auto mode makes a port available as a trunk link. With the Nonegotiate mode the port will be set in a permanent trunking mode. Pruning For VTP Increases available bandwidth Restricts flooded traffic to trunk links that the traffic must use to access the appropriate network devices Only prune traffic from VLANs that are pruning-eligible VLAN 1 is not pruning-eligible VLANs 2 - 1000 are pruning-eligible You are not encouraged to use VTP pruning on Catalyst series switches attached to Emulated Local Area Network ISL Encapsulation Short for Inter-Switch Link Cisco only protocol Interconnect multiple switches Maintain VLAN information as traffic goes between switches A frame is encapsulated with a header that transports VLAN IDs VLAN ID is added to a frame only when the frame is destined for a remote network IEEE 802.1Q Open standard on trunking encapsulation Does not change the size of the frame during encapsulation Sometime being referred to as dot1q STP Short for Spanning Tree Protocol Prevent loops in a bridged environment in Layer 2 VLAN + STP = ability to control forwarding paths per subnet = configuration flexibility and layer 2 redundancy Bridge ID = 2byte priority (same for all switches) + 6byte Media Access Control address of the switch / bridge BPDU is for electing root switch for STP BPDU timer is for forcing ports to wait for topology information during propagation delays STP looks at the path cost to determine which port should forward and which port should block Path cost = sum of all port costs Catalyst LAN switches maintain separate instance of Spanning Tree for each active VLAN configured Bridge ID and priority are associated with each instance of Spanning Tree Switch with lowest bridge priority becomes the root switch for an instance of a spanning tree For a switch that acts as a secondary root, spanning-tree bridge priority is modified from the default value of 32768 to 16384 You can change the global port priority of switch ports, since you can have a possible priority range of 0 through 63 Port with lowest priority value forwards frames for all VLANs If all ports have same priority, port with lowest port number forwards frames You can change the global port cost of switch ports, since you can have a possible cost range of 1 to 65535 Ports with lower port costs will most likely be chosen to forward frames for all VLANs You should assign lower numbers to ports attached to faster media You should assign higher numbers to ports attached to slower media The progress flow of a port: Blocking –>Listening –>Learning –> Forwarding –>Disabled Note that a port in blocking state does not forward frames Also note that a port in learning state is getting ready but not actually forward frames Spanning Tree Timers Hello timer determines how often the switch will broadcast Hello messages Forward delay timer determines the amount of time a port will remain in the listening and learning states Maximum age timer determines how long the protocol information received on a port will be stored by the switch PVST, PVST+ and CST PVST stands for Per VLAN Spanning Tree CST stands for Common Spanning Tree PVST increases network scalability by load balancing across different VLANs PVST convergence time is smaller than that for the larger STP topology for the entire switch PVST+ = PVST with Cisco enhancements PVST+ supports 802.1Q trunks PVST+ supports the mapping of multiple spanning trees to single spanning tree of the 802.1Q switches PVST+ architecture distinguishes regions of the following types: PVST region, PVST+ region, and MST region. Each region has a homogenous type of switch. Also note that all PVSTs are tunneled through the MST region Default CST is the PVST of VLAN 1, which is known as the Native VLAN CST allows for fewer BPDUs to consume bandwidth Fast EtherChannel Builds upon 802.3 full-duplex Fast Ethernet Supports full duplex auto-negotiation and auto-sensing Bandwidth scalability at increments of 200 Mbps to 800 Mbps currently Will support multiples of Gigabit Ethernet in the future Can support Gigabit EtherChannel Uses multiple Fast Ethernet links for load balancing traffic across multiple links Automatic recovery for link loss through redistributing loads across remaining links Convergence transparent to end users ISL VLAN trunking protocol can carry multiple VLANs across a Fast EtherChannel Routers attached to the Fast EtherChannel trunks can provide full multiprotocol routing with HSRP HSRP Short for Hot Standby Routing Protocol One router will automatically assume the function of the second router when the second router fails Active router forwards packets to virtual router Standby router monitors HSRP group status Standby router takes over packet-forwarding responsibility when the active router fails Interface tracking enables automatic priority adjustment based on the availability of the router interfaces Does not support DDR directly 3 types of multicast messages: Hello---sent every three seconds. Coup---sent when a standby router assumes the function of the active router Resign---sent when a router is about to shut down or when a router with a higher priority sends a hello message. HSRP-configured router states: Active Standby Speaking and listening Listening Speaking = sending Hello packets Listening = receiving Hello packets DDR Short for Dial-on-Demand Routing Pretend that full-time connectivity is still available, although what really happens is that the network is using Dialer interfaces to connect. Will filter out interesting packets defined by the access list Encapsulation Methods supported are PPP, HDLC, SLIP and X.25 IRDP Short for ICMP Router Discovery Protocol Allows router to dynamically learns about routes to other networks Multicast Send one copy of each packet to a group of computers Need a network-layer address for communicating with the group - the Class D addresses Need a dynamic registration mechanism for a computer to join the group – uses IGMP IOS supports of IP multicast routing includes CGMP Cisco Group Management Protocol, PIM Protocol Independent Multicast, DVMRP Distance Vector Multicast Routing Protocol and IGMP Internet Group Management Protocol By enabling PIM on an interface you also enable IGMP on that interface. An interface with PIM can be configured to be in dense mode, sparse mode, or sparse-dense mode. You must enable PIM in one of these modes for IP multicast routing to work. When populating a multicast routing table, dense-mode interfaces are always added to the table. When populating a multicast routing table, sparse-mode interfaces are added to the table only when periodic Join messages are received from downstream routers, or when there is a member directly connected on the interface. In the situation where forwarding from a LAN occurs, sparse-mode operation will start if there is an RP known for the group. Otherwise, packet will be flooded in dense-mode Dense mode is for environment where the multicast group members are densely distributed throughout the network Use dense mode when bandwidth is sufficient. Dense mode PIM floods multimedia packet to all routers and prune routers that do not support the group members RP Short for Rendezvous Point One or more routers must be RPs for sparse mode to work – routers will learn to be RPs themselves RPs are used by senders to announce their existence RPs are also used by receivers to learn about new senders RP address is used by first-hop routers to send PIM register messages on behalf of a sending host RP address is also used by last-hop routers to send PIM join/prune messages to the RP for informing about group membership A single PIM router can be a RP for more than one group A group can have more than one RP BackboneFast Cisco proprietary Used at the Distribution layer Also exists at the Core layer Useful in a situation where there are multiple switches connected together Requires the availability of multiple paths to the same root bridge Can detect indirect link failures Increase the speed of recovery when there is a failure with a STP active link UplinkFast Cisco proprietary Can detect direct link failures Used at the Access layer only Provides fast convergence after a spanning tree topology change Provides load balancing between redundant links by deploying uplink groups PortFast Cisco proprietary Prevents loops in a network Works on nontrunking access ports only Spanning tree loops can still occur if BPDUs are being transmitted and received on ports with portfast enabled CDP Short for Cisco Discovery Protocol Cisco only Works at Data Link layer Passes information between Cisco devices Uses multicast address with no protocol ID nor network layer field You cannot filter CDP ATM Short for Asynchronous Transfer Mode Cells are fixed at 53 bytes 5 bytes header 48 bytes payload Capable of transmitting voice and data at the same time at high speed Supports QoS This study guide is developed in Year 2001 by Yu Chak Tin Michael. His personal web site is located at: http://michaelyu.freeservers.com. You may also email him at: ycthk@i-cable.com Copyright 2000 http://www.CERTguide.com/