My Lines, My Lines!

In the last section we left off with Frame Relay. In this section we will explore even more transport media such as DSL and ISDN, and others.



Acronym of the Moment:



DSLAM: Digital Subscriber Line Access Multiplexer (Concentrates multiple DSL connections together)

ADSL: Asymmetrical Digital Subscriber Line

POTS: Plain Old Telephone Service

SHDSL: Symmetric High speed Digital Subscriber Line

PPPoE: Point to Point Over Ethernet



DSL is one of the most popular connection media for consumers and companies alike. DSL runs over existing POTS wiring with the use of a DSL modem. This connection feeds into a telephone company's DSLAM. Some J-Series routers have support for ADSL using PPPoE over ATM applications. The interfaces will appear to be ATM connections, but do not support native ATM, only ATM over DSL. Let's take a look at the following example:
[edit]
labuser@labrouter#show interfaces
at-6/0/0 {
encapsulation ethernet-over-atm;
atm-options {
vpi 0;
}
dsl-options {
operating-mode auto;
}
unit 0; {
encapsulation ppp-over-ether-over atm-llc;
vci 0.39;
}
}
Our J-Series Lab router has an ADSL Annex A PIM installed on slot 6. (Annex A is DSL over POTS, Annex B is DSL over ISDN respectively.) The lab router will be a client to our phone company's DSL multiplexer so that the Lab router can act as a DSL modem. As shown in the example above, we are using PPPoe over ATM for our DSL. We need configuration for the physical interface at-6/0/0. and a logical interface. You will notice in our configuration that there is a vci and vpi statement.
VPI is Virtual Path Identifier and VCI is a Virtual Channel Identifier and these must be the same as what is configured at the DSLAM. The remainder of the parameters can be learned from the DSLAM with the operating mode auto statement.

"On to Our Logical Interface...."

Now that we have our ATM interface, we now will configure an internal PPPoE interface and its' mappings. We need to map our physical interface where PPPoE will be running, the access server, and underlying requested services. See Below:

pp0{
unit 0{
pppoe-options{
underlying-interface at-6/0/0.0;
access-concentrator labisp;
service-name pppserv@labisp;
auto-reconnect 5;
}
family inet{
negotiate-address
}
}
}
}
You can verify your new connection with run show pppoe interfaces.

ISDN is a protocol designed to run over the public telephone network. Like Frame Relay, ISDN is seeing less deployment with the emergence of DSL and other broadband technologies. Just like in our previous example, ISDN on a Juniper router requires a logical interface and a physical one. Our physical interface, br which will contain the dialing number and switch type. In our lab router br-0/0/4 will be configured with a switch type of etsi for Europe NET3. Also, a dial pool we create will map our physical interface to a logical unit in our dialer interface. First we configure our physical interface:

[edit interfaces]
br-0/0/4{
isdn-options{
switch-type etsi;
}
dialer-options{
pool labpool1;
}
}
Now on to the dialer interface which contains our number we need a number to dial, an IP address, and our pool mapping our logical interface to br-0/0/4... dl0 will be our dialer interface and we will set up our "dialer filter" to establish a connection only when there is "interesting traffic" (More on this in a moment.)

dl0{
unit 0{
dialer-options{
pool labpool1;
dial-string 5559999;
}
family inet{
filter{
dialer dial_filter;
}
address 12.12.20.1/24;
}
}
}

Here is our simple dialer filter "dial_filter" that brings up our connection any time packets are destined for 12.12.20.2 using the note action. All other destinations are ignored in term b without a corresponding from statement.

[edit]
firewall{
family inet{
dialer-filter dial_filter{
term a{
from{
destination-address{
12.12.20.1/24
}
}
then note;
}
term b{
then ignore;
}
}
}
}

ISDN is commonly used as a backup link for other interfaces if they fail. To configure the ISDN as backup, the dl0 interface can be mapped to our interface requiring backup. The interface we are backing up is fe-0/0/1:

[edit interfaces fe-0/0/1 unit 0]
backup-options{
interface dl0.0;
}
Presumably, the ISDN interface would stay up even if the entire path is not reachable. It is also wise to configure a list of reachable IP networks when interfaces are working normally. In our lab example, a single network of 13.13.20.0/24 is used to verify connectivity with the use of a watch list.

dl0{
unit 0{
dialer-options{
pool labpool1;
dial-string 5559999;
watch-list{
13.13.20.0/24;
}
}
family inet{
address 13.13.20.1/24;
}
}
}
You can make calls between ISDN devices. To accept a call, an incoming dialer map can be configured on dl0:
dl0{
unit 0{
dialer-options{
pool labpool1;
incoming-map;
watch-list{
caller 384030;
}
}
family inet{
address 12.12.20.1/24;
}
}
}
You can use the show isdn and show dialer commands to verify the interface is working. show isdn will verify Layers 1-3 connectivity and switch type. show dialer will indicate per channel status.

Logical Versus Physical

All interfaces in JUNOS and most other networking devices have two properties; logical and physical. Physical properties belong to an entire physical port, whereas logical properties correspond to the portion of the interface represented by a unit or channel number. Depending on the type of physical port installed, a large number of properties can be configured. We will detail some of the most common here:

• Clocking: Aligns bits as they are transmitted out of the interface. A clock signal can be supplied by a Service Provider or by the router.



• Encapsulation: Layer 2 encapsulation used on the interface. Examples include Frame Relay, Point to Point Protocol or PPP, and Cisco Highlevel Data Link Control or HDLC



• MTU: Maximum Transmission Unit, which is the maximum size of the frame transmitted from the interface.



• Keepalives: Used to verify the operation of the interface. Most encapsulations enable keepalives by default, but they can be disabled to aid troubleshooting.



• Layer 1/2 Options: Various bit and byte settings for the interface media such as framing, flow control, and source address filters

All router interfaces sending and recieving traffic or packets require a logical unit to be configured. This way, an interface may be divided into multiple logical interfaces (subinterfaces in Cisco) This division then could be used to create multiple Virtual Local Area Networks or VLANs with their own logical unit. Note: Many router vendors do not require a subinterface or logical unit on every physical interface but a Juniper router does. Even point-to-point interfaces and non VLAN tagged interfaces need a logical unit to be configured.

In JUNOS, unit numbers MUST be configured before any other logical configuration is applied. Here are some of the common logical properties that can be configured.

• Protocol Family refers to the Layer 3 protocols that can be sent and recieved on this interface. The most common is family inet. Other protocol amilies include IPv6, Multi Protocol Label Switching or MPLS, and ISO (Intermediate System to Intermediate System IS-IS)



• Protocol Address: Layer 3 family address such as family inet (IP address)



• Virtual Circuit Address: Circuit identifier use when an interface is divided logically. Logical interfaces include VLAN IDs, Frame Relay Data Link Connection Identifier or DLCI, or ATM virtual path/Virtual Connection Identifiers (VP/VCI)



• Logical unit numbers can range from 0-16,385



• The best practice is to keep circuit address the same as the unit number for ease of toubleshooting.



• Note: If you are configuring a point to point interface the unit number MUST be zero!

"More Interface Configuration Examples"

Let's demonstrate configuring a Fast Ethernet interface in JUNOS:

Note: Remember interfaces in JUNOS are 'automatically enabled' when the physical connection is wired. So, after cabling up, we check the status of our Fast Ethernet Interface:

1. root@routername> show interfaces terse fe-2/0/1


2. Once we determine that the interface is up, we enter configuration mode: root@routername#configure
   
3. We are brought to the [edit] hierarchy and now, to edit our interface: root@routername# edit interfaces fe-2/0/1


4. Establish the unit: root@routername#set unit 0 family inet address 10.10.20.122/24


5. JUNOS software requires a mask for every IP address in the classless CIDR notation (Classless Inter Domain Routing). This is denoted by the / (slash)


6. Execute a show command: root@routername#show to verify our newly created interface


7. Activate our new changes with commit: root@routername# commit-and-quit


8. Let's verify our newly created interface with ping: root@routername#ping 10.10.20.121 count 3

The reason for the count command with ping is, a Juniper router will send an endless number of pings unless a number of packets is specified or you use Ctrl-C

Notes and Exam Topics 1

Exam Topics Breakdown for JNCIA-ER (JNO-342)

Audience Considerations: Operating Juniper Networks Routers in the Enterprise

The prerequisite is a basic understanding of the TCP/IP protocols.
While not required, familiarity with the command-line interface of a routing platform or UNIX system is helpful.

Exam Objectives

list line of enterprise routers
describe transit and host processing
packet flow differences between M7i/M10 and J-Series routers
key differences between the M7i/M10 and J-Series routers
configuration management
JUNOS CLI features (modes, prompts, auto-complete, EMACS keystrokes, and pipe
commands used in configuration mode (edit, set, delete, and commit)
manipulation of saved configuration files (rollback and load, and rollback file locations)
describe the configuration hierarchy
describe active, candidate, and rollback configurations

Acronyms of the Moment:

RE: Routing Engine
FRU: Field Replaceable Units
ASIC: Application Specific Integrated Circuit
PIC: Physical Interface Card
FPC: Flexible Physical Interface Card Concentrator
PFE: Packet Forwarding Engine
PIM: Physical Interface Module
BSD: Berkeley Software Development
OJRE: Operating Juniper Routers in the Enterprise
CLI: Command Line Interface
GUI: Graphical User Interface
BGP: Border Gateway Protocol
MPLS: Multi-Protocol Label Switching (Traffic Shaped/Engineered Networks)
ISP: Internet Service Provider

We love our High-End Hardware!
M-Series and T-Series Selling Points: Your Network Core

Runs JUNOS, the Operating system found on Juniper Networks routers
JUNOS is derived FreeBSD Unix for software stability
Hardware based packet forwarding through the use of ASICs
Separate forwarding and Control Planes (More on this later!)
Web-based GUI management in addition to CLI
Rescue Configuration Option: rollback rescue
Supports multiple different physical media types in a single chassis

Where Exactly Do We Put Our M or T Router?
M and T platforms usually service large company enterprises and Internet Service Providers. These and other large companies comprise what is called “the backbone of the Internet.”

More notes coming soon!!!

Welcome to My Juniper Blog!

Hello Everyone,

This is my Juniper Networks certification and resource blog! I will post my study notes, thoughts and caveats on Juniper and the JNCIA-ER. Feel free to offer up resources that you feel would be helpful to those persuing Juniper Certifications.

Enjoy!