Cramsession for CCDA® Exam

Note: The CCDA® exam builds on information in the CCNA® exam. Please refer to the CCNA Cramsession for further OSI and related info.

LAN Devices

Hub – Multi–port Repeater, doesn't change the address or data. Cannot filter packets
Bridges – Reads destination MAC to determine if local; will not forward if local. If not local, will forward to all connected networks. Can generate broadcast storms.¹
Switches – Analogous to fast multi–port bridge; filters and forwards frames based on the destination address of each frame. Works at Data Link Layer of OSI model
Routers – Can filter via hardware and network address. Economic as data is forwarded to correct recipient, not all connected networks as per bridge.
Gateways – Software used to link different programs or protocols. Examines the entire packet.
ATM Switches – High speed cell switching. Requires high speed medium eg., Fiber

WAN Devices

Router – Offers both Wan and internetworking interfaces
X25 and Frame Relay – Connects over public data circuits using digital signal
Modem – Connects using analog signals
CSU/DSU (Channel Service Unit/Data Service Unit)– Used to connect DTE to digital circuit, such as T1 or E1.
Communications Servers – Dial in/out eg., AS5200
Multiplexors – Allow more than one signal over one physical circuit – called a mux.

OSI Model

Encapsulation is the process of adding information to data received from an upper layer as the data travels down the protocol stack. To exchange information, each layer uses protocol data units to control information to the headers and trailers of user data as it is encapsulated.

LAN Technologies

Ethernet – Most Common, contention based uses CSMA/CD eg., 802.3, 802.2 and Ethernet II
FDDI – Employs token passing technology using dual counter rotating rings operating at 100Mb. One ring active at any one time. Some stations are attached to both rings. Long distance capability, expensive but secure
Token ring – More resilient than Ethernet 802.5. One station is always an active monitor to ensure that there's only one token
ATM – High speed WAN technology. Fixed 53 byte cells instead of frames

Why Segment the Network?

To reduce Collisions and make better use of bandwidth:

Bridge – Works at Layer 2; looks at MAC Address and forwards to all connected networks.
Router – Works at Layer 3; looks at Logical Address and forwards using best known route. Table kept for all protocols on network.
Switch – Think of it as a multi–port bridge; works with MAC address

Three different switching terms:

• Port configuration switching – Port assigned to physical network segment via software
• Frame Switching – used to increase bandwidth on network; allows multiple parallel transmissions –Catalyst Switches use this.
• Cell Switching – ATM used by all CISCO Lightstream Switches

Modes

• Store and Forward – Reads entire frame then computes CRC. Slowest Catalyst 5000 Default.
• Cut–through – Only copies destination address; then forwards. If too many errors reverts to Store and Forward until error rate drops to acceptable level. Quickest.
• Fragment Free – Waits for Collision window to pass before forwarding.

Spanning Tree Protocol – 802.1d designed to prevent routing loops on network. Works by determining best path through network and blocking all other paths that could cause loops.

VLAN – Grouping ports into logical groups by restricting the broadcast domain to designated VLAN member ports. VLANs are also called switched domains and autonomous switching domains. Communication between VLANs requires a router.

TCP/IP

TCP – Connection Oriented; full duplex built–in reliability means increased overhead and router bandwidth requirement.
UDP – Connectionless; unreliable, low overhead
IP – Software logical address
ARP – Broadcasts to resolve specified IP address to MAC address
RARP – Broadcasts to resolve specific MAC address to IP address
MAC – Physically burnt into the NIC; assigned in unique blocks to NIC manufacturers
BOOTP – Used by diskless workstations to learn IP address and server info; forerunner to DHCP
ICMP – Used by PING; returns Dest unreachable, hops, buffer full etc.,

Local Resolution

Checks to see if IP address is local (on the same subnet); if it is, tries to resolve from ARP cache. If not found in cache, a broadcast is issued which requests the MAC address of the target machine. Updates cache and establishes communication.

Remote Resolution

Checks IP address to see if local (on the same subnet). If not, checks route table for path to remote network. Resolves MAC address of default gateway either from cache or via broadcast to default gateway IP address. Router resolves MAC address of destination host or another router, if host is more than one hop away.

IPX/SPX

IPX – Controls addressing, packet delivery, and routing decisions (note: it is connectionless). Uses sockets to communicate to upper layers.
SPX – Adds connection-oriented communication; works by creating unique virtual circuits between machines.
RIP – A Distance Vector Routing protocol; uses ticks and hops to determine metric.
SAP– Service Advertising Protocol, which is the glue of IPX/SPX communication, advertises services and request services.
NLSP – Netware Link State Protocol; replacement for RIP and SAP
NCP – Netware Core Protocol controls all client access to server resources.

IPX/SPX can support large internetworks. Strict client/server relationship: clients rely on servers to locate all resources, and servers use SAP to build SAP Table of all known resources. CISCO routers act as NetWare servers and can respond from their SAP tables.

Cisco's Small/medium Sized Business Solution Framework

Broken into three Categories:

1. Media Problems – eg., high collision rate, high utilization
2. Protocol Problems – eg., protocol generating high level of broadcasts
3. Transport Problems – eg., bandwidth requirements

Analyzing Customer Requirements falls into two areas:

Administrative Data – What the company does, who the contacts are, who has authorization to sign off on approval, what the company growth forecast is, whether or not a solution has been attempted before.

Technical Data – Analysis of information flow, shared data, locations, network traffic between segments.

Cisco's 12 Customer Inventory Items

1. Existing Apps – Determine how much data flows over the LAN, eg., Email vs Accounting Systems
2. Existing Network – List all protocols in use.
3. Network Topology – Create a High Level Topology of the customer's network.
4. Potential Bottlenecks – Develop a profile of Internal/External Network Traffic
5. Business Constraints – Determine monetary, political, or other constraints
6. Current Network Availability – Determine Mean Time Between Failures (MTBF) and cost of failures.
7. Current Network Performance – Determine network latency; measure response from key servers.
8. Current Network Reliability – CRCs, Runts, Giants, Collisions, Broadcasts
   
9. Current Network Utilization – Determine network utilization using a Protocol Analyzer
10. Status of Current Routers – Memory and CPU utilization, Media errors
11. Current Network Management Systems – All Tools and what platform
12. Overall Network Health – Compare results to Cisco's recommendations below

• Ethernet segments should not exceed 40% Network Utilization
• Token Ring should not exceed 70% Network Utilization
• WAN Links should not exceed 70% Network Utilization
• Response time should be less than 100ms
• Broadcasts/Multicasts should be no more than 20% of all network traffic
• On Ethernet there should be no more than 1 CRC error per 1million bytes of data
• Cisco Router CPU Utilization should not exceed 75%

Determine percentage of availability by dividing the MTBF by the Mean Time to Repair (MTTR).

When analyzing the network you would make heavy use of a protocol analyzer.

Customer Expectations

You need to manage the customer's expectations and take into consideration business and security constraints. Consider what is required by the customer for applications, performance and manageability.

Hierarchical Topologies

Cisco defines a three–layered approach:

1. CORE - the backbone of the network. If there is a problem here everyone is likely to be affected. Key issues: Bandwidth, Fault Tolerance, no workgroup access at this level
2. DISTRIBUTION - this is where the management really takes place. At this level you would implement filtering, security policies, routing and other support functions
3. ACCESS - this is where users connect to the internetworks. Some functions of this layer are creation of collision domains, access control, and policies. Examples of technology at this layer are DDR and Ethernet switching

Redundant LAN Examples

TCP/IP

• HSRP – Hot Standby Router Protocol. Creation of Phantom Router that does not exist physically but does have MAC and IP address. Users are pointed at the Phantom Router. The phantom address is passed between two or more routers. If the active router fails, the user does not notice because requests are dealt with automatically by another router (standby)
• Proxy ARP – Changes the client so that they send ARP requests for every IP device either local or not. Any router hearing this request that can get to the desired IP address will respond with its own MAC address. Note this is enabled by default on all CISCO routers.

AppleTalk / IPX

Both of these protocols will automatically be able to find their way on a network with more than one path. This is due to the nature of their routing. Appletalk workstations listen for RTMP routing updates which are broadcast every 10 seconds. IPX clients can issue a find network number request and have a router respond dynamically.

Redundant Wan Connections

• Full Mesh – All nodes have a direct link to each other. Very redundant, lacks efficiency and hard to scale.
• Partial Mesh – Each node has a redundant link to the layer above it. Scalable and able to load balance.
• DDR Backup – This can be used to make a redundant link come live upon demand, either due to load or a failure. Can be a cost effective way of adding redundancy.
• Load balancing – With most IP protocols this is automatic, but there can be problems with pinhole congestion:

Pinhole Congestion – Caused by routing protocols that don't understand capacity as a metric, so they load balance evenly across both paths until the lower capacity path is completely used and the faster path is only partially used. This would be avoided by EIGRP.

IPX and AppleTalk don't load balance by default; however, load balancing can be achieved through the maximum paths command.

Topology Security

Three–Part Firewall

Two routers are deployed to protect the Internal LAN. One router is connected to the Internet and a De-Militarized Zone (DMZ). The other router is connected to internal LAN and the DMZ. Servers that need to be seen externally, such as the Mail, Web, and DNS servers, are placed in the DMZ.

CISCO Hardware

Model	Features
1900	Very low cost per port, limited in performance
2820	Has modules for ATM and FDDI
2900	Not in exam
3000	Incorporates WAN Links, stack ability includes InterSwitchLayer
3900	Token Ring Switch designed to interconnect to Core Token ring Switch
4000	Not Covered
5000	1.2Gb back plane, 5 Slots
5500	13 Slots4, 3.6Gb Back plane for Frame Switching, 5Gbps for ATM Cell Switching
5502	Two Slot suited to smaller networks
5505	Five Slot capable of redundant supervisor engines (Must be in slot two)
6500	Not in exam

Series	Features
1600	Small Office, Ethernet, ISDN and Serial Connections
2500	Remote Office, Specific, Ethernet, Token, ISDN, Serial
3600	Modular, dial access, WAN, T1, E1, Most Network Interfaces
4000	Modular, All network interfaces, large office
7000	Large Wan Use, redundant PSU, Many processors, CxBus5, Many Processors, VIP, SSP
7500	Large Wan Use, CyBus, Redundant PSU, Lots Memory, Sonet Support
12000	Gigabit, Not Covered in Exam

Routing Process

Routers work at Layer 3 of the OSI Model. Requires path determination and interface switching eg., inbound to outbound. For routers to share this info with other nearby routers, a routing protocol must be used.

Router Switching

• Process Switching – Packet gets copied to process buffer, address is looked up, packet is encapsulated and forwarded on appropriate outbound interface. Cache is updated and further packets to the same address are handled on cached info. Most processor intensive.
• Silicon Switching – Only 7000 Series + SSP⁶. The SSP is a dedicated switch processor that takes over from the router processor. Fast solution.
• Optimum Switching – Fast than both Fast and Netflow Switching, replaces fast switching on high end routers.
• Fast Switching – Is used when no entries exist in more efficient caches; on by default in low end routers; sometimes necessary to disable due to memory limits or to aid troubleshooting.
• Autonomous Switching – Compares packets against autonomous switching cache. When packet arrives the interface checks the switching cache closest to it. Only found on 7000 and AGS+ series routers.
• Distributed Switching – Happens on VIP (Versatile Interface Processor), very efficient. Gets more efficient as more VIP cards added. No need to use router processor.
• Netflow Switching – Admin tool, increases overhead; gathers stat data, port, protocol, and user info that can be sent to a management station.

Cisco Express Forwarding Layer 3 Switching Function

Advantages

High end, stable, faster than fast and optimum switching. Does not rely on cache info, checks the forwarding information base (copied from routing table) and the adjacency table layer–two MAC addresses of adjacent routers, ie., next hop.

Can Load Balance – Per destination (default), Per packet. Can gather stat info.

Disadvantages

Memory intensive processor - 128Mb, Line cards - 32Mb. Doesn't support ATM DXI, Token Ring, NAT, SMDS, Multipoint PPP or Policy routing.

WAN Networks

Bandwidth is split into Digital Streams (DS) each representing 64K. Some common standards are:

T1 – 1.54 Mbps	T3 – 44.763 Mbps
E1 – 2.048 Mbps	E3 – 34.064 Mbps
J1 – 2.048 Mbps

• Dedicated Leased Lines – CSU/DSU to CSU/DSU point to point serial link
• Asynchronous Dial–in – Modem connection over normal phone line
• DDR – Over ISDN, Modem etc.,
• Packet Switched Services – Frame Relay, X25, ATM

Wan Protocols

• SDLC (Synchronous Data Link Control)– Main SNA link layer protocol. PTP, Half, full duplex. Two node types: Primary Stations control other stations, setup and manage links. Secondary stations can only transmit to the primary and only after permission.
• HDLC (High-Level Data Link Control) – Link layer protocol for Serial links. Cisco Default. Supports the following modes: Normal Response Mode – as per Secondary under SDLC, Asynchronous Response Mode allows secondary to communicate without permission, Asynchronous Balanced mode combines the two stations. Lower overhead than LAPB but less error checking.
• LAPB (Link Access Procedure, Balanced)– Operates at Layer 2. Integrated into X25. Router can be DTE or DCE. HDLC confined to ABM transmission. Job is to make sure that frames are error free. Three different frame types: Information frames - flow control, error detection. S Frames - requesting and suspending communications. U Frames - link setup, disconnecting, error reporting. High overhead, but good error checking
• ISDN – Supports data, text, voice, music. BRI 2 B and 1 D Channel. PRI 23B + 1D or in Europe 30 B + 1D.
• ISDN Terminals – TE1 – Terminals that understand ISDN Standards, TE2 precedes ISDN standard have to use a terminal adapter. ISDN has four reference points to define logical interfaces R = TE2 to TA, S = Terminal and NT2, T= NT1 to NT2, U = NT1 and line termination equipment
• ISDN Protocols – E = Existing Network; Q = Switching and signaling; I = Concepts, terminology and service
• PPP = Used over ISDN or modem. Multiple protocol support ie Appletalk, IP, IPX, DECnet etc. Slip only supports IP. To enable multi–link requires dialer–list command on router.

Frame Relay (layer 2 protocol)

Establishes a Frame relay Virtual Circuit which is a connection between two DTE devices. Two circuit types: Permanent (PVC) and switched (SVC) identified by DLCI

Multi–protocol support eg., IP, DECnet, Appletalk, IPX, XNS, ISO. More efficient and faster than X25 because of less error checking.

Default encapsulation on CISCO is CISCO or can be IETF. Use IETF if connecting to non–Cisco devices with frame relay.

DLCI – Data link connection identifier – IP addresses need to be mapped to DLCI's to communicate over a virtual circuit. Can be done dynamically with IARP⁷ or manually though the map command
Example : Myrouter(config–if) frame–relay interface–dlci x ( where x is your number)

Local Management Interface – gives DLCI global rather than local significance. Makes entire frame relay network appear as typical LAN. Manages status providing info on keep–alives, multicasting, addressing and status of virtual circuit. With version 11.2 of IOS, auto–sensed.

Three LMI types Cisco (default) ANSI and q933a. Subinterfaces allow you to route IP on one virtual circuit and IPX on the other.
Example: Myrouter(config)#encapsulation frame–relay
Example: Myrouter(config)#int s0.x (where x is any number to limit).

Note: some routers have limits, eg., 2500 can handle max of 255. Two types of sub interface Point–to–point and multipoint.

Frame Relay Congestion Control

• DE – Discard Eligibility used to identify traffic importance
• FECN (Forward Explicit Congestion Notification) – To tell others the path is congested
• BECN (Backward Explicit Congestion Notification) – Goes back to sending router to tell it to slow down
• CIR (Committed Information Rate) – Minimum bandwidth guaranteed. Choose realistic level; can choose zero if retransmission is acceptable. Can be by BC or committed burst size that allows customers to exceed CIR for limited time

NETWORK ADDRESSING

Variable Length subnet masks (VSLM) – Network length depicted by adding /x to represent number of bits that define network portion. More flexibility in Addressing. Allows for more than one subnet per network. Discontigous addressing should be avoided as the networks we are working with should be physically connected to the same router. There are some routing protocols that cannot handle VLSM eg., RIP v1, but RIP v2, and OSPF can take advantage of VLSM (and CIDR).

Private Addressing

10.0.0.0	255.0.0.0	1 Class A
172.16.0.0	255.240.0.0	16 Class B
192.168.0.0	255.255.0.0	256 Class C

NAT (Network Address Translation)

Maps private addresses to unique external IP addresses. Enable it on border router. The border router then handles all communication between internal and external parties; border router acts on behalf of internal client.

ROUTE SUMMARISATION

Contiguous networks are grouped together and advertised as a single entity called a supernet. Move network prefix to the left (ie, borrow bits from network portion of address) to describe a single route to contiguous block of IP addresses (Classless Inter–Domain Routing or CIDR). This can only be done using contiguous IP addresses.

Note: Classful routing uses Class A,B,C addresses.

ROUTER / SERVER ADDRESSING

Basic method is to choose a range of addresses for routers and servers and use them consistently. Specifying interface order is also beneficial to allow admin to know where they are.

DHCP/Client Addressing

Remember broadcasts do not pass a router by default. Cisco routers can forward DHCP requests by using a helper address. IP helper address converts the broadcast message into a unicast broadcast destined for appropriate server. This will also forward:

• TFTP (69) NetBIOS datagram service (138)
• DNS (53) NetBIOS name service (137)
• Time (37) BOOTP (67,68)
• TACACS (49)

To restrict what is forwarded, use the forward–protocol command in conjunction with above to restrict on an interface.

CISCO DNS/DHCP Manager

Ensures IP address mapping to DNS name remains consistent. Includes such things as TFTP, NTP, Syslog server.

IPX Numbering Considerations

If you are able to specify an IPX network address, and your network includes IP, then you should hex your IP address and use that for your IPX network address to create a single addressing scheme.

Network Naming Schemes

Use names that represent roles if possible and keep consistent i.e. MAIL1, MAIL2

ROUTING

Static Routing –– manually assigned by Admin
Dynamic Routing –– Generated/Determined by Routing Protocol

DYNAMIC

With Dynamic Routing, routers pass information between each other so that routing tables are regularly maintained. The routers then determine the correct paths packets should take to reach their destinations. Information is passed only between routers. A routing domain is called an Autonomous System as it is a portion of the internetwork under common admin authority. Consists of routers that share information over the same protocol. Can be split into routing areas.

DISTANCE VECTOR PROTOCOLS

Used in smaller networks that are less than 100 routers. Easy to configure and use. As routers increase in number, you need to consider CPU utilization, convergence time, bandwidth utilization. Convergence is due to routing updates at set intervals eg., 90 seconds. When router recognizes change, updates routing table and sends whole table to all of its neighbours.

LINK–STATE PROTOCOLS

Maintains Topology Database. Routers have formal neighbour relationship. Exchange LSA (Link State Advertisement) or hello packets with directly connected interfaces. These are exchanged at short intervals (typically 10 sec). Only new info is exchanged. Scales well; only downside is that link–state protocols are more complex.

INTERIOR ROUTING PROTOCOLS – Used within AS

Examples: RIP, RTMP (for Appletalk), IGRP, OSPF, EIGRP.

Two categories: Distance Vector and Link State.

Distance vector

Update intervals:

• IP RIP – 30 sec
• IPX RIP – 60 sec
• IGRP – 90 sec
• RTMP 10 sec

Uses hops; the lower the better, but can make bad decisions. Routing loops or counting to infinity occur because of the delay in sending updates. Can be fixed with:

• Split Horizon - Info cannot be sent back on the interface it was received from
• Route Poisoning - When network goes down, route gets set to 16 or unreachable until back up
• Hold–Downs - Prevents routes from changing too rapidly in order to determine if link has really failed, or is backed up

Link State

Maintains a more complex table of the topology info. Uses topological databases, the SPF algorithim and a routing table. Forms tree structure with itself as route. Understands bandwidth, load etc.

Convergence – The router that becomes aware of the change either sends it to all other routers or to a designated router.

Cons – Must have more CPU power. Requires more memory and more bandwidth initially.

Enter the Hybrid

Best of both worlds: IS–IS, EIGRP.

EIGRP

Mixture of Distance vector and link state. Allows for load balancing, incremental routing updates, formal neighbour relationships. Uses DUAL for metric calculation.

Features:

• Route Tagging – Distinguishes routes learned via session
• Classless Routing – Supports VLSM, and subnet info
• Configurable Metrics, equal cost load balancing

Uses three databases: Route, Topology, and Neighbour. Can use these for each protocol it supports––up to 9 databases considering concurrent use of IPX, Appletalk and IP.

Route Tagging –Can have multiple sessions of EIGRP running on a single router. Each distinguished by the AS number assigned to it.

Neighbour Relationship – Uses hello packet to establish and maintain relationships with directly connected routers.

Route Calculation and Updates – Faster Than IGRP. Calculation is where effects router locally, eg., eth0 congested router then sent to neighbours. Update is where routers notice link congestion and update each other.

• Calculation and Selection - Topology database stores all routes and metrics for adjacent routers. Six can be stored for each destination network. Must select primary and backup route. When in state of being chosen in active state; once it decides is passive. Looks at bandwidth, delay

  Adds feasible cost and advertised cost and chooses lowest. Remaining options get added to topology database for potential future use.

• Updates and Changes - Propagates only changes. If better path found only an update; if path down, then full check of alternates; if path not found, query neighbours to produce alternative.

Configuring EIGRP - can use IP, IPX or AppleTalk

IP – Must define AS for each session. Router eigrp autonomous–system–number must then define network network – network number.

Example:

myrouter# config t
Myrouter(config)# router EIGRP x ( where x is AS Number)
Myrouter(config–router)# network x.x.x.x (Network number)

Note: EIGRP assumes serial links to be T1. Can have slower connection to do this; need to specify bandwidth in kilobits, eg., bandwidth 56000

Related IPX IOS Commands:

• ipx routing
• Ipx router eigrp x
• Network x
• Ipx router rip
• No network x (to stop Rip over IPX)

Related Appletalk IOS Commands:

• AppleTalk routing eigrp router–number
• Appletalk Eigrp–bandwidth–percent (set bandwidth limit)
• Appletalk Eigrp–splithorizon (enables split horizon)
• Appletalk Eigrp–timers (sets hello and holdtime timers)

OSPF (Open Shortest Path First)

Pure link state protocol. Open standard. Fast convergence and has formal relationships with neighbours (adjacent routers). Each multi–access network with more than one router has a DR (designated router) and a BR (backup router) elected by OSPF hello protocol. The router with the highest router priority wins; you can set this variable with the IOS command ip ospf priority x.

OSPF uses three databases – topology, which stores all route info; route; and adjacency. Best routes end up in route database.

• Backbone – Used to connect multiple areas; accepts all LSA's
• Stub – Does not accept any external routing update but summary LSA's. Used when route tables get too big. Only works with intra- and inter-area routes; all others go to default 0.0.0.0
• Totally Stub – Cannot accept any external or summary LSA's; only deals with intra area. Anything but internal goes to 0.0.0.0
• Standard – normal area that accepts internal or external LSA's.

Link State Types:

• Autonomous System Entry – Comes from the ASBR (Autonomous System Boundary Router) and contains info on external networks
• Summary Entry – Type 3 Info for internal networks sent to backbone routers, type 4 contains info about ABSR. Summary info is sent by ABR to all backbone routers
• Network Entry – DR multicasts to all area routers network specific info
• Router Link Entry – Contains all default link state info broadcast within a defined area

Router Types:

• Internal – All interfaces in the same area
• External – Has at least one interface assigned to area 0
• ABR – Connected to multiple OSPF areas
• ABSR – Has an interface connected to external network or different AS

Metric – bandwidth

Can be manually set by defining cost: ip ospf cost and distance: Distance ospf (1–255, with 0 directly connected)

Commands

Internal – requires process id and area assignment.

Example myrouter (config)# router ospf x (where x is the process id)
Myrouter (config–router)# network x.x.x.x y.y.y.y area x (y.y.y.y is the wildcard–mask)

Wildcard Mask

Work out all the 1s	255.255.255.255
Your mask i.e./20	255.255.240.0
Wildcard	0.0.15.255

Note: an OSPF network must have a backbone Area 0, which is the CORE layer.

Creates a single data–link, flat network

• Transparent Bridging – Connects two or more Ethernet segments. Learns MAC address of all devices and then starts filtering.
• Integrated Routing/Bridging – Allows you to route and bridge the same protocol by using a virtual bridge–group interface
• Source–Route Bridging – Knows the entire route to destination before sends data. Not designed for large networks.
• Source–Route Transparent Bridging – Use this when you have to go across bridging domains. Affects spanning tree as packets cannot cross domains therefore you cannot have multiple paths between these domains.

3 Main tasks – Implementation & Change, monitoring and diagnosis, design and optimization.

Makes use of SNMP – Uses UDP, IP, IPX to communicate. Has three devices – Managed, Agents, Network Management System. 4 operations – Get, Getnext, Set, trap. Cisco has introduced support for SNMP v2 since IOS 10.2; incorporates security and two additional messages – Getbulkrequest and informrequest.

RMON – Used to provide more information and can happen offline in continuous manner. Mainly used to monitor packet and traffic patterns on LAN Segments.

CISCOWORKS

SNMP based management software comprehensive suite of network tools. Device Setup, Management, Health Monitor, can set thresholds via RMON.

CSWI

Used for Switched Internetworks.

CISCOVIEW

Gives you exactly that remote physical view of the Cisco device eg., LED's.

TRAFFIC DIRECTOR

Has the Rmon features of monitoring traffic, user definable thresholds, multidomain view

NETSYS

Policy based network management, Diagnostics, troubleshooting and What if features

CISCOWORKS BLUE

Used for managing SNA and TCP/IP environments. Graphical Layout, Problem Determination, Management Tools

Access Lists – Recall Numbers from CCNA Cram. Key points to remember implicit deny at end of list; list is processed until first hit, then no more access info is considered; you can speed up by moving most used access line to top of the list.

• Cisco Routers can act on behalf of other devices to reduce WAN traffic
• IPX GNS response can come from Router
• IPX Watchdog Spoofing router can respond rather than client

Compression / Encryption

• Header – Used for Apps eg., Telnet
• Payload – Generally used with Frame relay, X.25, ATM
• Link – Combination of above requires PPP or LAPB

Encryption requires IOS 11.2 or newer and currently only supports IP although you can encapsulate IPX and AppleTalk in IP.

Should not be used if CPU utilization is greater than 65%.

QUEUING

• FIFO – First in first out Weighted Fair Queuing – divides bandwidth across queues of traffic based on weights. WFQ ensures that all traffic is treated fairly, given its weight. Low volume is given precedence.
• Priority – packets belonging to one priority class of traffic are transmitted before all lower priority traffic
• Custom – Set bandwidth on traffic type; useful on slow interfaces.
• Frame Relay Traffic Shaping – Can throttle traffic by using BECN, FECN.
• RSVP – Reserves bandwidth for traffic that cannot tolerate delay (eg. Video)

Responding to an RFP (Request for Proposal)

The recommendation is that you respond with a document in Five Parts:

1. Executive Summary – 1–2 pgs precis of Purpose, Recommendations, considerations and benefits.
2. Design Requirements – Existing Network, customer requirements.
3. Design Solution – Proposed Network, hardware, media, protocols.
4. Summary – How Solution meets customer requirements.
5. Appendices – Contain Technical Info referred to in proposal. Schedule, results of prototype or pilot. Contact info.

Remember Prototype is larger in scale than Pilot.

Notes:

¹Broadcast Storms are generated when a network segment event is sent in a perpetual loop until that segment becomes overloaded.

²ASN.1 – Abstract Syntax Notation is the standard data syntax used by the presentation layer ie SNMP

³ARP Cache Life in Windows 95 is 2 Minutes, 10 minutes for NT and 4hrs for CISCO by default.

⁴Slot 13 Unavailable for Frame switching

⁵CxBus = 533 Mbps, Cybus 1.067Gb note 7513, 7507, 7576 can have dual Cybuses.

⁶SSP – Silicon Switch Processor