Awesome – BE

Todd is in the UK for a series of talks and seminars – which kicked off in London. I have known Todd for a few years now, speaking via email and his forum http://www.lammle.com. In many ways i owe him for where i am today as his books, advise and friendship have helped me every step of the way. There is an old sigma/saying that “you should never meet your idols, as they will disappoint you” – in this meeting this was most certainly wrong. Todd is an awesome guy, he is just like he is in his writing style.

I was also able to introduce Todd to my wife and son as they met us at the end of the day- he was most gracious to both her and our little boy.

BE.

A few terms to know –

assured forwarding (AF)
CoS packet forwarding class that provides a group of values you can define and includes four subclasses, AF1, AF2, AF3, and AF4, each with three drop probabilities, low, medium, and high.

behavior aggregate (BA) classifier
Feature that can be used to determine the forwarding treatment for each packet. The behavior aggregate classifier maps a code point to a forwarding class and loss priority. The loss priority is used later in the work flow to select one of the two drop profiles used by random early detection (RED).

best effort (BE)
CoS packet forwarding class that provides no service profile. For the BE forwarding class, loss priority is typically not carried in a code point, and random early detection (RED) drop profiles are more aggressive.

class of service (CoS)
Method of classifying traffic on a packet-by-packet basis, using information in the type-of-service (ToS) byte to assign traffic flows to different service levels.

Differentiated Services (DiffServ)
Services based on RFC 2474, Definition of the Differentiated Services Field (DS Field) in the IPv4 and IPv6 Headers. The DiffServ method of CoS uses the type-of-service (ToS) byte to identify different packet flows on a packet-by-packet basis. DiffServ adds a Class Selector code point (CSCP) and a DiffServ code point (DSCP).

DiffServ code point (DSCP) values
Values for a 6-bit field defined in IP packet headers that can be used to enforce class-of-service (CoS) distinctions.

drop profile
Drop probabilities for different levels of buffer fullness that are used by random early detection (RED) to determine when to drop packets from a given J-series or SRX-series device scheduling queue.

expedited forwarding (EF)
CoS packet forwarding class that provides end-to-end service with low loss, low latency, low jitter, and assured bandwidth.

multifield (MF) classifier
Firewall filter that scans through a variety of packet fields to determine the forwarding class and loss priority for a packet and polices traffic to a specific bandwidth and burst size. Typically, a classifier performs matching operations on the selected fields against a configured value.

network control (NC)
CoS packet forwarding class that is typically high priority because it supports protocol control.

PLP bit
Packet loss priority bit. Used to identify packets that have experienced congestion or are from a transmission that exceeded a service provider’s customer service license agreement. A J-series or SRX-series device can use the PLP bit as part of a congestion control strategy. The bit can be configured on an interface or in a filter.

policer
Feature that limits the amount of traffic passing into or out of an interface. It is an essential component of firewall filters that is designed to thwart denial-of-service (DoS) attacks. A policer applies rate limits on bandwidth and burst size for traffic on a particular J-series device interface.

policing
Applying rate and burst size limits to traffic on an interface.

random early detection (RED)
Gradual drop profile for a given class, used for congestion avoidance. RED attempts to anticipate congestion and reacts by dropping a small percentage of packets from the tail of the queue to prevent congestion.

rule
Guide that the device follows when applying services. A rule consists of a match direction and one or more terms.

BE.

I have had some great fun with these – to download here is the link.

http://www.visguy.com/2011/08/16/crayon-visio-network-shapes-revisited

BE.

TTL down one
the end nearer with each hop
little packet, poof.

My session is dead:
Forgot to commit confirm.
Where are my car keys?

What fun!

BE.

The above picture shows a binary to powers of a decimal chart, to help with understanding the structure of the J-Tree. For example, the binary sequence 0100 000 equates to a decimal 64, whereas 0110 0000 codes a decimal 96. In this example, bit 8, which has the decimal power of 128, represents the second set of nodes from the top of the tree. The top of the tree represents no bit, and the first pair of nodes down represents a test of the MSB, which is bit 8 in this example, as either 0 (0), or 1 (128).

Once you grasp the J tree all is clear!

BE.

I cannot wait to get all over these bad boys!
Currently i am reading through the Junos Enterprise Routing, 2nd Edition book. It is a great book and has clear information and is well written with add of humour from the author along the way.
The first three chapters were good and i was getting full marks on the example questions at the end of the chapters. Then chapter four decided to turn it up a bit and i found i had to re-read some parts twice over to fully understand what was being said. Chapter five started in the same way with a lot of information to get into, thankfully as the chapter progresses everything is broken down more with example.

BE.

I was trying to buy “The Official Study Guide for JNCIA Certification and Junos Administration”, but for some reason the book has been cancelled by the publishers. I have “JUNOS Enterprise Routing” instead & “Junos Cookbook”. Junos looks and feels great – although on the “Junos as a Second Language-WBT” you cannot use tab complete and have to use the space bar, which after so many years of IOS takes some getting used to. Thankfully on new Junos you can use the tab complete. In my next post i will add some differences in commands from Junos to IOS.

BE.

I will be taking the JNCIA- Junos & JNCIS-ENT exams, if time permits the JNCIS-SP also.
My work is implementing a number of large Juniper routers for a new data centre they are building – and i will get to play/work with them it makes good sense to get some knowledge. First off all the learning materials i need for JNCIA are free from Junipers website. Plus there is an online test engine, that if you pass the pre-exam you get 50% of the exam fee.

Ok the question is how do i get my lab pratice in? I looked at Olive, seemed a little complicated for me, i looked at GNS3 and came to the same conclusion. So my work call Juniper and they agree to send me some routers and switches.