Ca Ex S2m02 Static Routing

CCNA – Semester 2

Chapter 2 - Static Routing CCNA Exploration 4.0

Objectives • Define the general role a router plays in networks. • Describe the directly connected networks, different router • • • • •

interfaces Examine directly connected networks in the routing table and use the CDP protocol Describe static routes with exit interfaces Describe summary and default route Examine how packets get forwarded when using static routes Identify how to manage and troubleshoot static routes

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Routers and Network

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Role of the Router • The router is a special-purpose computer that plays a key role in the operation of any data network. Routers are primarily responsible for interconnecting networks by: – Determining the best path to send packets – Forwarding packets toward their destination

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Introducing the topology • Topology Lab

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Introducing the topology • Topology Lab

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Reference: Cisco router 1841’s Component Product

Description

Quantity

CISCO1841

Modular Router w/2xFE, 2 WAN slots, 32 FL/128 DR

1

CAB-ACE

Power Cord Europe

1

S184IPB-12406T

Cisco 1841 IOS IP BASE W/O CRYPTO

1

WIC-2T

2-Port Serial WAN Interface Card

1

CAB-SS-V35FC

V.35 Cable, DCE Female to Smart Serial, 10 Feet

2

CAB-SS-V35MT

V.35 Cable, DTE Male to Smart Serial, 10 Feet

2

MEM1800-32CF

32MB Cisco 1800 Compact Flash

1

ROUTER-SDM-CD

CD for SDM software

1

CON-OSPCISCO1841

ONSITE 24X7X4 Modular Router w/2xF

1

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Cable Standards

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Cable for LAN/WAN interfaces

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Examining the Connections of the Router • Serial Connectors

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– DB-60 port and Smart port: five-in-one serial port: • EIA/TIA-232, EIA/TIA-449, V.35, X.21, and EIA/TIA530 standards Ethernet Connectors – 2 types of connectors can be used: Straight through and Cross-over  Straight through used to connect: • Switch-to-Router, Switch-to-PC, Router-to-Server, Hub-to-PC, Hub-to-Server  Cross-over used to connect: • Switch-to-Switch, PC-to-PC, Switch-to-Hub, Hub-toHub, Router-to-Router 10

Router Configuration Review

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Examining Router Interfaces •

Examining Router Interfaces – show ip route command – used to view routing table – show interfaces command – used to show status of an interface – show ip interface brief command – used to show a portion of the interface information – show running-config command – used to show configuration file in RAM

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Configuring an Ethernet Interface •

Configuring an Ethernet interface – By default all serial and Ethernet interfaces are down – To enable an interface use the no shutdown command

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Configuring an Ethernet Interface • Verifying Ethernet interface

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– Show interfaces for fastEthernet 0/0 – command used to show status of fast Ethernet port – Show ip interface brief – Show running-config Ethernet interfaces participate in ARP

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Logging Synchronous Command • In order to keep the unsolicited output separate from your input, enter line configuration mode for the consoled port and add the logging synchronous command.

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Configuring a Serial Interfaces •

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Configuring a Serial interface – Enter interface configuration mode – Enter in the ip address and subnet mask – Enter in the no shut down command Example: – R1(config)#interface serial 0/0 – R1(config-if)#ip address 172.16.2.1 255.255.255.0 – R1(config-if)#no shutdown

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Examining Router Interfaces •

Examining Router Interfaces – Physically connecting a WAN Interface. – A WAN Physical Layer connection has sides:  Data Circuit-terminating Equipment (DCE) – This is the service provider. CSU/DSU is a DCE device.  Data Terminal Equipment (DTE) – Typically the router is the DTE device.

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Examining Router Interfaces • Configuring serial links in a lab environment  One side of a serial connection must be considered a DCE  This requires placing a clocking signal – use the clock rate command.  Example: • R1(config)#interface serial 0/0 • R1(config-if)#clockrate 64000  Serial Interfaces require a clock signal to control the timing of the communications.

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Note: Wic-2a/s support maximum clock rate is 128000 bps

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Examining Router Interfaces • Verifying the Serial Interface Configuration – – – – –

show interfaces command show ip interface brief command show running-config ping command show ip route

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Verifying Changes to the Routing Table • The routing table consists of a list of "known" network addresses - that is, those addresses that are directly connected, configured statically, and learned dynamically.

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Verifying Changes to the Routing Table • Observing Routes as They are Added to the Routing Table – debug ip routing command will let us see any changes that the router performs when adding or removing routes.

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Devices on Directly Connected Networks • When a router only has its interfaces configured, and the routing table contains the directly connected networks but no other routes, only devices on those directly connected networks are reachable.

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Devices on Directly Connected Networks

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Cisco Discovery Protocol (CDP) Network discovery with CDP • CDP is an information-gathering tool used by network administrators to get information about directly connected Cisco devices. • CDP is a proprietary tool that enables you to access a summary of protocol and address information about Cisco devices that are directly connected. • These advertisements contain information such as the types of devices that are connected, the router interfaces they are connected to, the interfaces used to make the connections, and the model numbers of the devices. • Concept of neighbors – 2 types of neighbors  Layer 3 neighbors  Layer 2 neighbors 24

Cisco Discovery Protocol (CDP) CDP Operation • CDP runs at the Data Link layer connecting the physical media to the

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upper-layer protocols (ULPs). Cisco network devices, such as routers that support different Network layer protocols (for example, IP and Novell IPX), can learn about each other CDP provides the following information about each CDP neighbor device: – Device identifiers – Address list – Port identifier – Capabilities list – Platform

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Default Setting

Feature CDP global state CDP interface state CDP holdtime (packet holdtime in seconds)

Default Setting Enabled Enabled 180

CDP timer (packets sent every x seconds)

60

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Using CDP for Network Discovery • The information gathered by the CDP protocol can be examined with the show cdp neighbors command.

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Using CDP for Network Discovery Field Device ID

Local Intrfce Holdtme

Definition The name of the neighbor device and either the MAC address or the serial number of this device. The protocol being used by the connectivity media. The remaining amount of time (in seconds) the current device will hold the CDP advertisement from a sending router before discarding it.

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Using CDP for Network Discovery Capability (Capability Codes)

Capability (type of routing device) of the listed neighboring device. The capability types that can be discovered are: R—Router T—Transparent bridge B—Source-routing bridge S—Switch H—Host I— device is using IGMP r—Repeater

Platform

The product number of the device.

Port ID

The protocol and port number of the device. 29

Using CDP for Network Discovery

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CDP Commands

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CDP Commands

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CDP Commands

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CDP Commands

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Static Routes with “Next Hop” Addresses

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Purpose and Command Syntax of ip route • Static routes are commonly used when routing from a network to a stub network. – A stub network is a network accessed by a single route.

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Purpose and Command Syntax of ip route

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Configuring Static Routes • Installing a Static Route in the Routing Table

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Verifying Static Route Commands Configuring Routes to Two More Remote Networks

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Routing Table Principles and Static Routes

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Routing Table Principles and Static Routes

• Applying the Principles

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Resolving to an Exit Interface

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Resolving to an Exit Interface • Exit Interface is down

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Static Routes with Exit Interface

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Configuring a Static Route with an Exit Interface • Static routes can be configured with an exit interface, which allows the routing table to resolve the exit interface in a single search instead of two searches.

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Configuring a Static Route with an Exit Interface

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Static Route and an Exit Interface

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Modifying Static Routes •

There are times when a previously configured static route needs to be modified: – The destination network no longer exists, and therefore the static route should be deleted. – There is a change in the topology, and either the intermediate address or the exit interface has to be changed.

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Verifying the Static Route Configuration •

Use the following commands  Step 1: show running-config  Step 2 verify static route has been entered correctly  Step 3: show ip route  Step 4 verify route was configured in routing table  Step 5 issue ping command to verify packets can reach destination and that Return path is working

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Static Routes with Ethernet Interfaces •

Ethernet interfaces and ARP. – If a static route is configured on an Ethernet link, if the packet is sent to the next-hop router then • the destination MAC address will be the address of the next hop’s Ethernet interface • This is found by the router consulting the ARP table – If an entry isn’t found then an ARP request will be sent out

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Static Routes with Ethernet Interfaces Static routes and Ethernet exit interfaces • With Ethernet networks, may be many different devices sharing the same multi-access network so the router does not know the next-hop IP address and it cannot determine the destination MAC address for the Ethernet frame.

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Summary and Default Static Routes

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Summary Static Routes • •

Summarizing Routes to Reduce the Size of the Routing Table Route Summarization: Multiple static routes can be summarized into a single static route if: – The destination networks can be summarized into a single network address, and – The multiple static routes all use the same exit-interface or nexthop IP address

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Summary Static Routes • Configuring a Summary Route: Step 1: Delete the current static route Step 2: Configure the summary static route Step 3: Verify the new static route

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Default Static Route •

A default static route is a route that will match all packets. Default static routes are used: – When no other routes in the routing table match the packet's destination IP address. In other words, when a more specific match does not exist. A common use is when connecting a company's edge router to the ISP network. – When a router has only one other router to which it is connected. This condition is known as a stub router.

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Default Static Route • Verifying a Default Static Route

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Managing and Troubleshooting Static Route

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Static Routes and Packet Forwarding • Static Routes and Packet Forwarding

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Static Routes and Packet Forwarding

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Static Routes and Packet Forwarding

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Static Routes and Packet Forwarding

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Static Routes and Packet Forwarding

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Static Routes and Packet Forwarding

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Static Routes and Packet Forwarding

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Troubleshooting a Missing Route • Tools that can be used to isolate routing problems include: – ping– tests end to end connectivity – traceroute– used to discover all of the hops (routers) along the path between 2 points – show IP route – used to display routing table & ascertain forwarding process – show ip interface brief - used to show status of router interfaces – show cdp neighbors detail – used to gather configuration information about directly connected neighbors

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Solving the Missing Route •

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Finding a missing or miss-configured route requires methodically using the correct tools – Start with ping. If ping fails then use traceroute to determine where packets are failing to arrive Issue: show ip route to examine routing table. – If there is a problem with a miss-configured static route remove the static route then reconfigure the new static route

Solving: – R2(config)#no ip route 172.16.3.0 255.255.255.0 serial0/0/1 – R2(config)#ip route 172.16.3.0 255.255.255.0 serial 0/0/0 65

Basic Static Route Configuration Lab

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Challenge Static Route Configuration Lab

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Summary

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