Troubleshooting Accouterments and Cabling

Troubleshooting Accouterments and Cabling

The best important affair to bethink in troubleshooting is to accouterment your

problems logically so you don’t absence any important apparatus or steps.You

must affirm the bloom of all the apparatus that accomplish up the firewall.When

addressing PIX firewall problems, you would be best served application the OSI model

to adviser your efforts.This archetypal was created to adviser development efforts in

networking by adding functions and casework into alone layers. Per the OSI

model, associate layers acquaint with anniversary other. For example, the arrangement layer

at one host communicates with the arrangement band at addition host.

The admission advocated in this affiliate is based on the OSI archetypal credible in

Figure 10.1. Problems are tackled starting at the everyman layer, such as validating

hardware and cabling at the concrete layer. Alone back the apparatus at the

lower band accept been accurate do you about-face your absorption to apparatus at a

higher layer.

Troubleshooting and Performance Ecology • Affiliate 10 555

Figure 10.1 The OSI Model

Provides the user/application

an interface into the network.

Converts and restores abstracts in a

format that can be transported

between arrangement devices.

Example protocols include

ASCII or EBCDIC.

Manages and synchronizes the

sessions amid devices.

Segments and reassembles data

for the Session and Arrangement l

ayers. Establishes connections

and provides breeze control.

Addresses and routes abstracts on

a network. IP and IPX are

examples of arrangement protocols.

OSPF, EIGRP, and added routing

protocols accomplish at this layer.

Assembles raw abstracts into

acceptable formats for the

Physical and the Arrangement layers.

802.3 and HDLC are example

protocols.

Addresses capacity of

connecting to physical

media such as 10BaseT cable.

Application

Presentation

Session

Transport

Network

Data Link

Physical

7

6

5

4

3

2

1

Access List

Conduit

NAT/PAT/Static

Global

IPsec/VPN

Routing

Hardware

Cabling

556 Affiliate 10 • Troubleshooting and Performance Monitoring

This affiliate organizes troubleshooting efforts by the OSI model. Initial

troubleshooting starts at Band 1, the concrete layer. Once all concrete components

have been validated, the troubleshooting focus is confused to the abstracts articulation layer

components, and so on, up the OSI stack.This controlled admission ensures that

we do not absence any angle of our aegis agreement area the botheration could

be.

Our aboriginal accomplish in troubleshooting alpha with concrete band issues. In the

context of the PIX firewall, concrete apparatus accommodate the firewall hardware

and cabling.We alpha our altercation with a quick overview of the PIX firewall

hardware architectonics and cabling.

This affiliate focuses on troubleshooting PIX firewalls. Once you accept mastered

its command syntax and basal firewall operations, the PIX is a almost simple

device to configure. Its library of commands is baby compared to that of Cisco

routers and switches. In antecedent chapters, we covered the PIX firewall in detail,

from the assorted models in the artefact band to simple and avant-garde configurations.

This book contains advice on how to accommodate the PIX firewall into

your absolute network. As acceptable as your PIX agreement is, problems will still

crop up, and you charge to apperceive how to boldness them.The purpose of this chapter

is to present a alignment that you can use to advance these problems and avoid

missing analytical troubleshooting steps.

Hardware and cabling problems can be a affliction to an contrarily well-functioning

network. A accouterments botheration becomes credible if you apperceive which indicators

to monitor.The bound cardinal of cable types that the PIX supports eases

our cable troubleshooting considerably.This affiliate provides abstruse information

about these cables so you can validate them.

The PIX firewall is an IP device. Granted, it is a awful specialized accessory that

performs basic aegis functions, but it is still an IP device. As such, it needs to

know area to accelerate traffic.We highlight some accepted connectivity problems

and how you can abode them. A admired action of the PIX firewall is its

ability to conserve IP abode amplitude and adumbrate arrangement capacity via Network

Address Translation (NAT). If you accept problems with NAT, you charge be able to

isolate and annihilate them.

The PIX firewall provides several admission ascendancy mechanisms, from simple

access lists to circuitous aqueduct statements.These admission mechanisms accept simultaneous

loose/tight backdrop in that assertive cartage is accustomed while added cartage is

denied.Your troubleshooting will not alone seek to boldness admission problems but

also acquisition the appropriate antithesis amid allowing and abstinent traffic.

Entire books accept been accounting on IPsec, and for acceptable reason. IPsec can protect

your cartage from end to end after accepting to be implemented at every hop

along the way. IPsec agreement can be complex.You charge be intimately

familiar with IPsec operations in adjustment to abutment and troubleshoot it.This chapter

covers several key aspects of IKE and IPsec to aid your ecology and support.

Capturing arrangement packets on the PIX firewall can accredit you to troubleshoot

more effectively.The PIX firewall offers several appearance that you can use to

capture cartage for assay and botheration isolation.Available accoutrement accommodate built-in PIX

commands as able-bodied as third-party accoutrement for arrangement abduction and packet decode.

www.syngress.com

www.syngress.com

How do you apperceive if your PIX firewall is assuming as able-bodied as it should? How

would you apperceive if it was overloaded? You charge to adviser firewall performance

and bloom proactively.The ambition of ecology is to anticipate accessory glitches from

turning into above problems.The achievement of your ecology efforts can be quite

dense and arcane, so you charge to apperceive how to adapt what you are monitoring.