PACE-IT: Introduction_to Routing Concepts (part 2) - N10 006

Introductionto routing concepts II.

Instructor, PACE-IT Program – Edmonds Community College

Areas of Expertise Industry Certifications

PC Hardware

Network Administration

IT Project Management

Network Design

User Training

IT Troubleshooting

Qualifications Summary

Education

M.B.A., IT Management, Western Governor’s University

B.S., IT Security, Western Governor’s University

Entrepreneur, executive leader, and proven manger with 10+ years of experience turning complex issues into efficient and effective solutions.

Strengths include developing and mentoring diverse workforces, improving processes, analyzing business needs and creating the solutions required— with a focus on technology.

Brian K. Ferrill, M.B.A.

Introduction to routing concepts II.PACE-IT.

– Routing metrics.

– Route aggregation.

– High availability.

Routing metrics.Introduction to routing concepts II.

There may be more than one route available to a remote network. Routing protocols use metrics to determine which route is the best route to use.

Each routing protocol will use its own set of metrics in determining which routes to which networks are placed in its routing table.

The same basic metric may be used by different routing protocols. When this occurs, the metric is usually implemented in a different manner through the use of different algorithms.



– Hop count.» The number of routers between two end points.

• Determined from the sending router’s perspective.

– Maximum transmission unit (MTU).» The maximum allowed size of a packet, measured in

bytes.• The standard MTU for Ethernet is 1500 bytes.

» Packets that exceed the MTU must be fragmented into small pieces, leading to more packets, leading to slower connection.

– Bandwidth.» A measure of the speed of the network connection.

• The speed can be measured in Kbps, Mbps, or Gbps.

– Latency.» A measure of time that a packet takes to traverse a

link.• When implemented by routing protocols, the total

amount of latency (or delay) to go end to end between two points is used.


– Administrative distance (AD).» The believability of a routing protocol’s advertised

routes.• Different routing protocols are considered to be more

believable (trustworthy) than others.» Routers use the AD to help determine which routing

protocol to use when more than one protocol is installed on the router.

» The lowest AD of an advertised route will determine the protocol used.

» Common standard ADs:• Directly connected route = 0 (no protocol required).• Statically configured route = 1 (no protocol required).• E-BGP = 20.• Internal EIGRP = 90.• OSPF = 110.• IS-IS = 115.• RIP = 120.• External EIGRP = 170.• I-BGP = 200.• Unknown = 255 (not believable).

Route aggregation.Introduction to routing concepts II.

Without some mechanism put in place, routing tables soon become very large and highly inefficient.

Through careful planning, network administrators use a process called route aggregation to condense the size of routing tables. They do so through the use of Classless Inter-Domain Routing (CIDR) to summarize routes to different networks. Route aggregation is common in networking.



– Example of route aggregation.» Networks connected to interface S/0/1:

• 10.1.1.0/24.• 10.1.17.0/24.• 10.1.32.0/24.• 10.1.128.0/24.

» These routes could be summarized (aggregated) by a common CIDR entry in a routing table:

• 10.1.0.0/16.

– Warning on route aggregation.» Route aggregation takes careful planning during the

network design phase.• The above example would not work if interface s/1/1

on the same router was connected to network 10.1.2.0 (this is an example of non-contiguous networks).

High availability.Introduction to routing concepts II.

Part of a network administrator’s job is to ensure that networks remain up and active for the maximum amount of time.

In an effort to ensure that networks don’t go down, administrators often remove single points of failure.

A single point of failure in a network is the point where a single failure will cause the network to cease functioning. Network administrators often use high availability techniques in order to remove those single points of failure. An example of a high availability technique is the use of redundant links to outside networks.



– Hot Standby Router Protocol (HSRP).

» HSRP is a proprietary Cisco method of creating a fault tolerant link using two or more routers with connections outside of the local subnet.

• The two routers are connected together as well as having connections outside of the local network.

• A virtual IP address is created and shared between the routers.

• Devices on the network are configured to use the virtual IP address as the default gateway for packets leaving the network.

• If a router goes down, the link outside of the network is still available.

– Virtual Router Redundancy Protocol (VRRP).

» VRRP is an IETF (Internet Engineering Task Force) standard that is similar in operation to HSRP.

Routing protocols use metrics to determine which route is the best route to use to reach remote networks. Routing protocols can use the same metrics, but will use different algorithms to populate their routing tables. Common metrics include: hop count, MTU, bandwidth, latency, and AD.

Topic

Routing metrics.

Summary

Without some planning, routing tables can become large and inefficient. Route aggregation is a method of summarizing routes to different networks through the use of CIDR. Care and caution must be used when non-contiguous networks are present.

Route aggregation.

Network technicians use high availability techniques in an effort to remove single points of failure from networks. HSRP and VRRP are examples of high availability techniques that are implemented to reduce the chances that a single router going offline will create a problem for the network.

High availability.

What was covered.Introduction to routing concepts II.

THANK YOU!

This workforce solution was 100 percent funded by a $3 million grant awarded by the U.S. Department of Labor's Employment and Training Administration. The solution was created by the grantee and does not necessarily reflect the official position of the U.S. Department of Labor. The Department of Labor makes no guarantees, warranties, or assurances of any kind, express or implied, with respect to such information, including any information on linked sites and including, but not limited to, accuracy of the information or its completeness, timeliness, usefulness, adequacy, continued availability or ownership. Funded by the Department of Labor, Employment and Training Administration, Grant #TC-23745-12-60-A-53.

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PACE-IT: Introduction_to Routing Concepts (part 2) - N10 006

Education

Transcript of PACE-IT: Introduction_to Routing Concepts (part 2) - N10 006