D IAGNÓSTICO DE LA MEJORA DE PROCESO EN LA INGENIERÍA DE SOFTWARE EN LA EMPRESA S OFTEL

The editors received quite a ew tips about groups and are elated to se e so many users enjoy using the eature. Conguration groups are

indeed powerul, but we ound that most o the groups examples submitted could be improved in some way. So, instead o inserting our pithy comments throughout several groups tips, we’ve combined the best tips with some o our own best pract ices to produce a little primer on groups. It’s a template that you can useully apply to various

network administration scenarios.

C

Conguration groups are a great way to apply common conguration to multiple parts o the conguration. The interface-rangeeature allows you to perorm some o the same tasks or interace congura-tion, but the^groupseature may still be the most appropriate way to handle some interace conguration, and it is the only way (sho rt o 

 Junos Automation scripts) to apply common settings to pieces o the conguration other than interaces.

One o the big dierences between theinterface-rangecommand and conguration groups is that theinterface-range command will

actually result in the interace being congured, even i the interace is not separately listed in the conguration. On the other hand, a

conguration group with a match condition only applies to things that are already congured. So, a conguration group that applies to

ge-0/0/*will only aect an interace that has a name beginning with

ge-0/0/and that is already listed in the conguration. On the other hand, an interace-range command that applies to ge-0/0/0 through ge-0/0/23 will actually congure those 24 interaces as i you had individually congured them. You can see this using theshow config-uration | display inheritance command. Thereore, i you want to congure a large number o interaces, you may want to use the

interface-rangeconguration. On the other hand, i you want to dene some deault conguration that will apply to interaces that you congure individually, a conguration group is probably more

appropriate.

For those who are curious, you can mix interface-rangecommands and conguration groups. The sotware expandsinterface-range

commands rst, and then it applies the statements rom conguration groups to matching interaces.

You dene conguration groups in the [edit groups] hierarchy. You can have multiple groups. Each group has a name. You can congure the router to apply one or more groups at various levels o the ration. Unless you congure the router to apply a group to the congu-ration, that conguration group will have no eect.

groups { BFD_BGP {

protocols { bgp {

group <*> {

neighbor <10.100.1.*> { bfd-liveness-detection {

minimum-interval 300;

26 DayOne:JunosTips,Techniques,andTemplates2011

multiplier 3;

} } } } } }

INTERFACE_DEFAULTS { interfaces {

<*-*> {

unit <*> {

family mpls;

family iso;

} } } }

DEFAULT_SYSTEM_SETTINGS { system {

services { ssh;

telnet;

} } } }

You can congure conguration groups with or without match conditions. I you do not use match conditions (such as shown here with theDEFAULT_SYSTEM_SETTINGSgroup), Junos will simply merge the conguration rom the group into the conguration when you apply the group to a level o the conguration hierarchy.

When you do use match conditions (as in the two preceding examples) and you apply the groups to a level o the hierarchy, the sotware

examines that level o the hierarchy (as well as everything underneath it) or matching conguration entries. When it nds a match, it applies the listed conguration.

You can use angle brackets to dene matches based on wildcards. An asterisk (*) matches any zero or more characters and a question mark (^?) matches a single character. (This is similar to the way a DOS or UNIX shell deals with wildcard matches.)

You can also use character classes. Here, you place a list o characters within square brackets. Junos nds a match i any o those characters exist in the string it is examining. For example, < ^[afgxc]e*> matches

any interace name that begins with ae, e, ge, xe, or ce. You can also speciy a range o characters or numbers (such as [A-Za-z0-9]that would match any alphanumeric character).

You can only match on user-dened strings. (For example, theunit

keyword is not a user-dened string, but the number that ollows it is a user-dened string. Likewise, the^address keyword is not a user-dened string, but the address itsel is a user-de ned string.) It is important to note that the match conditions in angle brackets must exactly match the entire user-de ned string. You can use the asterisk to match those parts o the string that are unimportant or your purposes.

Here is an example o using matches in a group. Note that the group matches any interace name with a dash (which excludes the xp 0, me0, vme, and similar interaces).

On its surace, this seems like a good tip, because it automatically excludes the management interaces. However, note that it also

excludes Aggregated Ethernet (ae) interaces, which may not be what you want. A better solution may be to use the apply-groups-except

statement in the management interace conguration. This tells Junos not to apply that group to that interace, even i the g roup is applied at a higher level o the hierarchy.

Also, note that the group matches the unit number with *. This matches absolutely any string (and, certainly, any unit number):

groups {

INTERFACE_DEFAULTS { interfaces {

<*-*> {

unit <*> {

family mpls;

family iso;

} } } } }

Here is another example o groups. In this case, it looks at IP address-es. BFD parameters are applied to all BGP neighbors that have an IP address beginning with^10.100.1. :

groups { BFD_BGP {

protocols { bgp {

28 DayOne:JunosTips,Techniques,andTemplates2011

group <*> {

neighbor <10.100.1.*> {

bfd-liveness-detection { minimum-interval 300;

multiplier 3;

} } } } } } }

Now let’s extend the previous example and only apply the BFD parameters to any BGP group that starts with the name^CUST_GOLD_.  Junos will only apply these BFD parameters to BGP neighbors with an

IP address beginning with^10.100.1.and which are in a group with a name that begins withCUST_GOLD_:

groups { BFD_BGP {

protocols { bgp {

group <CUST_GOLD_*> { neighbor <10.100.1.*> {

bfd-liveness-detection { minimum-interval 300;

multiplier 3;

} } } } } } }

This is only a small introduction to these wildcard expressions. It is worth noting that this type o match is also used elsewhere. For example, theinterface-rangecommand will take a similar kind o 

wildcard match. Also, you can use these wildcard matches to select interace names in theshow interfacesCLI command. The only big dierence is that the angle-brackets (< >) are only used to surround matches in the [edit groups] conguration hierarchy; elsewhere, you just use the text o the match (or example,show interfaces ge-0/0/*).

Once you have dened the groups and applied them at the appropriate hierarchy levels, you can use thedisplay inheritancepipe command to show the way the conguration looks with the group commands applied.

The display inheritancepipe command has a ew side-eects. It also expands interace ranges, it does not show conguration groups or interace ranges themselves, and it also hides any piece o the congu-ration marked as inactive. Even i you are not using groups, it can be a good way to exclude deactivated congurations rom the con gura-tion display.

Here is an example o using groups to perorm a specic thing, namely addingfamily mplsto every unit on any transit interace (but not^fxp0,

me0,^vme, or any other interace without a dash):

groups { mpls {

interfaces {

<*-*> {

unit <*> {

family mpls;

} } } } }

apply-groups [ mpls ];

interfaces { ge-0/0/3 {

unit 0 {

family inet {

address 172.18.2.2/30;

} } }

ge-0/0/4 {

vlan-tagging;

unit 102 { vlan-id 102;

family inet {

address 172.20.102.1/24;

} }

unit 202 { vlan-id 202;

family inet {

address 172.20.202.1/24;

} } } }

[edit]

lab@srxA-2# show interfaces | display inheritance

30 DayOne:JunosTips,Techniques,andTemplates2011

## 'mpls' was inherited from group 'mpls'

##

## 'mpls' was inherited from group 'mpls'

##

## 'mpls' was inherited from group 'mpls'

##

family mpls;

} }

In this next example, Junos sets the VRRP priority to 200 on any VRRP group congured or any unit numbered 500-599. It will also set the VRRP priority to 50 on any VRRP group congured or any unit numbered 600-699. You might use such a conguration in a load-balancing situation where one router is supposed to be the primary VRRP router or one set o VLANs and the backup VRRP router or another set o VLANs:

groups {

priority 200;

} } } }

unit <6??> { family inet {

address <*> {

vrrp-group <*> { priority 50;

} } } } } } } }

Now, let’s apply BFD to OSPF interaces. This conguration applies dierent settings or WAN and LAN interaces, based on the interace name: <^[fgxca]e> matches any transit Ethernet interace, and <*>

matches any interace. When a piece o conguration matches multiple match conditions in a group, the values rom the rst-matched section override conficting values rom later matches. In this example, that means that or Ethernet interaces, the values rom the rst interace specication will override the second one. Non-Ethernet interaces should only match the second interace specication, so they will inherit those values:

groups {

BFD_OSPF { protocols {

ospf {

area <*> {

interface "<[fgxca]e*>" { bfd-liveness-detection {

minimum-interval 50;

multiplier 3;

} }

interface <*> {

bfd-liveness-detection { minimum-interval 300;

multiplier 3;

} } } } }

32

root@srxA-1# show srxA-1# show protocols ospf| diprotocols ospf| displsplay inheritanceay inheritance ar

## 'bfd-liveness-detection' was iveness-detection' was inherited froinherited from grom group 'BFD_OSPF'up 'BFD_OSPF'

#

### bfd-l

bfd-liveness-detection iveness-detection {{

#

###

## '50

## '50' wa' was inherited fros inherited from grom group 'BFD_OSPFup 'BFD_OSPF''

#

### minimu

minimum-interval 50m-interval 50;;

#

###

## '3

## '3' wa' was inherited fros inherited from grom group 'BFD_OSPFup 'BFD_OSPF''

#

## 'bfd-liveness-detection' was iveness-detection' was inherited froinherited from grom group 'BFD_OSPF'up 'BFD_OSPF'

#

### bfd-l

bfd-liveness-detection iveness-detection {{

#

###

## '300

## '300' wa' was inherited fros inherited from groum group 'BFD_OSPFp 'BFD_OSPF''

#

### minimu

minimum-interval m-interval 300;300;

#

###

## '3

## '3' wa' was inherited fros inherited from grom group 'BFD_OSPFup 'BFD_OSPF''

#

While this has been a whirlwind tour through Junos conguhas been a whirlwind tour through Junos conguratiorationn groups, mostly because our ed

groups, mostly because our editor in chie was literally pacing outsideitor in chie was literally pacing outside our lab door demanding the nal manuscript

our lab door demanding the nal manuscript, you , you can see that theycan see that they are powerul when used corre

are powerul when used correctly. Tctly. To get maximum beneo get maximum benet romt rom groups, you need to understand the match conditions. A

groups, you need to understand the match conditions. Also, don’lso, don’tt

orget to use the

orget to use the^displdisplay inheritanay inheritancecepipe command beore youpipe command beore you commit in order to veriy that the groups are applied as you e commit in order to veriy that the groups are applied as you expecxpectt beore you commit the changes. BTW:

beore you commit the changes. BTW:Day One: Confguring JunosDay One: Confguring Junos Basics

Basicshas a good introduction on groups: wwhas a good introduction on groups: www.w.juniper.net/dayone.juniper.net/dayone.

In document Modelo para la organizacion de la mejora continua en la ingenieria de software en softel (página 46-54)