Difference between revisions of "EBGP JUNOS Projekt"

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m (added Category:BGP using HotCat)
m (→‎Load Balancing)
 
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</source>
 
</source>
 
De tidligere eksempler ovenfor viser at det virker.
 
De tidligere eksempler ovenfor viser at det virker.
 +
 +
==Load Balancing==
 +
Default loadbalancer juniper pr. prefix, det vil sige at hvis en routes har flere next-hops med samme metric vælger den en forwarder ud fra hash af prefixen. Alle pakker til det samme prefix vil så løbe over det samme link.<br/>
 +
Har man nok routes i sin routing tabel vil man opleve en loadbalancing, men fordelingen af trafik vil ikke altid blive ligeligt.<br/>
 +
Ved at konfigurere routeren til "pr. pakke" loadbalancing vil den istedet lave en hash af hver pakke og balancere pr. flow istedet for destinations prefix<br/>
 +
Prefix loadbalancing over næsten den samme next-hop 10.255.0.21
 +
<source lang=cli>
 +
root@SRX240> <input>show route table PE2.inet.0 10.205.0.0/16</input>
 +
 +
PE2.inet.0: 66 destinations, 91 routes (66 active, 0 holddown, 0 hidden)
 +
+ = Active Route, - = Last Active, * = Both
 +
 +
10.205.0.0/16      *[BGP/170] 00:50:32, localpref 100
 +
                      AS path: 65001 65004 65006 I
 +
                    > to <notice>10.255.0.6</notice> via lt-0/0/0.5
 +
                    [BGP/170] 00:50:32, localpref 100
 +
                      AS path: 65003 65004 65006 I
 +
                    > to 10.255.0.21 via lt-0/0/0.22
 +
10.205.0.0/24      *[BGP/170] 00:50:32, localpref 100
 +
                      AS path: 65003 65004 65006 I
 +
                    > to <notice>10.255.0.21</notice> via lt-0/0/0.22
 +
                    [BGP/170] 00:50:32, localpref 100
 +
                      AS path: 65001 65004 65006 I
 +
                    > to 10.255.0.6 via lt-0/0/0.5
 +
10.205.1.0/24      *[BGP/170] 00:50:32, localpref 100
 +
                      AS path: 65003 65004 65006 I
 +
                    > to <notice>10.255.0.21</notice> via lt-0/0/0.22
 +
                    [BGP/170] 00:50:32, localpref 100
 +
                      AS path: 65001 65004 65006 I
 +
                    > to 10.255.0.6 via lt-0/0/0.5
 +
10.205.2.0/24      *[BGP/170] 00:50:32, localpref 100
 +
                      AS path: 65003 65004 65006 I
 +
                    > to <notice>10.255.0.21</notice> via lt-0/0/0.22
 +
                    [BGP/170] 00:50:32, localpref 100
 +
                      AS path: 65001 65004 65006 I
 +
                    > to 10.255.0.6 via lt-0/0/0.5
 +
10.205.10.0/24    *[BGP/170] 00:50:32, localpref 100
 +
                      AS path: 65003 65004 65006 I
 +
                    > to <notice>10.255.0.21</notice> via lt-0/0/0.22
 +
                    [BGP/170] 00:50:32, localpref 100
 +
                      AS path: 65001 65004 65006 I
 +
                    > to 10.255.0.6 via lt-0/0/0.5
 +
10.205.20.0/24    *[BGP/170] 00:50:32, localpref 100
 +
                      AS path: 65003 65004 65006 I
 +
                    > to <notice>10.255.0.21</notice> via lt-0/0/0.22
 +
                    [BGP/170] 00:50:32, localpref 100
 +
                      AS path: 65001 65004 65006 I
 +
                    > to 10.255.0.6 via lt-0/0/0.5
 +
</source>
 +
Som vi ser her vil de fleste pakker tage den samme vej. For 10.204.0.0 netværkene vil 10.255.0.6 blive brugt istedet
 +
<source lang=cli>
 +
root@SRX240> <input>show route table PE2.inet.0 10.204.0.0/16</input>
 +
 +
PE2.inet.0: 66 destinations, 91 routes (66 active, 0 holddown, 0 hidden)
 +
+ = Active Route, - = Last Active, * = Both
 +
 +
10.204.0.0/16      *[BGP/170] 01:47:43, localpref 100
 +
                      AS path: 65001 65004 I
 +
                    > to <notice>10.255.0.6</notice> via lt-0/0/0.5
 +
                    [BGP/170] 01:45:25, localpref 100
 +
                      AS path: 65003 65004 I
 +
                    > to 10.255.0.21 via lt-0/0/0.22
 +
10.204.0.0/24      *[BGP/170] 01:47:43, localpref 100
 +
                      AS path: 65001 65004 I
 +
                    > to <notice>10.255.0.6</notice> via lt-0/0/0.5
 +
                    [BGP/170] 01:45:25, localpref 100
 +
                      AS path: 65003 65004 I
 +
                    > to 10.255.0.21 via lt-0/0/0.22
 +
10.204.1.0/24      *[BGP/170] 01:47:43, localpref 100
 +
                      AS path: 65001 65004 I
 +
                    > to <notice>10.255.0.6</notice> via lt-0/0/0.5
 +
                    [BGP/170] 01:45:25, localpref 100
 +
                      AS path: 65003 65004 I
 +
                    > to 10.255.0.21 via lt-0/0/0.22
 +
10.204.2.0/24      *[BGP/170] 01:47:43, localpref 100
 +
                      AS path: 65001 65004 I
 +
                    > to <notice>10.255.0.6</notice> via lt-0/0/0.5
 +
                    [BGP/170] 01:45:25, localpref 100
 +
                      AS path: 65003 65004 I
 +
                    > to 10.255.0.21 via lt-0/0/0.22
 +
10.204.10.0/24    *[BGP/170] 01:47:43, localpref 100
 +
                      AS path: 65001 65004 I
 +
                    > to <notice>10.255.0.6</notice> via lt-0/0/0.5
 +
                    [BGP/170] 01:45:25, localpref 100
 +
                      AS path: 65003 65004 I
 +
                    > to 10.255.0.21 via lt-0/0/0.22
 +
10.204.20.0/24    *[BGP/170] 01:47:43, localpref 100
 +
                      AS path: 65001 65004 I
 +
                    > to <notice>10.255.0.6</notice> via lt-0/0/0.5
 +
                    [BGP/170] 01:45:25, localpref 100
 +
                      AS path: 65003 65004 I
 +
                    > to 10.255.0.21 via lt-0/0/0.22
 +
</source>
 +
Og den ene route bliver ikke brugt
 +
<source lang=cli>
 +
root@SRX240> <input>show route table PE2.inet.0 protocol bgp detail 10.205.0.0/24</input>
 +
 +
PE2.inet.0: 66 destinations, 91 routes (66 active, 0 holddown, 0 hidden)
 +
10.205.0.0/24 (2 entries, 1 announced)
 +
        <notice>*BGP</notice>    Preference: 170/-101
 +
                Next hop type: Router, Next hop index: 847
 +
                Address: 0x15b9ef0
 +
                Next-hop reference count: 39
 +
                Source: 10.255.0.21
 +
                Next hop: 10.255.0.21 via lt-0/0/0.22, selected
 +
                <notice>State: <Active Ext></notice>
 +
                Local AS: 65002 Peer AS: 65003
 +
                Age: 1:00:46
 +
                Task: BGP_65003_65002.10.255.0.21+51141
 +
                Announcement bits (2): 1-KRT 3-BGP_RT_Background
 +
                AS path: 65003 65004 65006 I
 +
                Accepted
 +
                Localpref: 100
 +
                Router ID: 10.255.255.3
 +
        BGP    Preference: 170/-101
 +
                Next hop type: Router, Next hop index: 814
 +
                Address: 0x15b9a30
 +
                Next-hop reference count: 42
 +
                Source: 10.255.0.6
 +
                Next hop: 10.255.0.6 via lt-0/0/0.5, selected
 +
                <notice>State: <Ext>
 +
                Inactive reason: Active preferred</notice>
 +
                Local AS: 65002 Peer AS: 65001
 +
                Age: 1:00:46
 +
                Task: BGP_65001_65002.10.255.0.6+179
 +
                AS path: 65001 65004 65006 I
 +
                Accepted
 +
                Localpref: 100
 +
                Router ID: 10.255.255.1
 +
</source>
 +
===Konfigurer Multipath===
 +
Aktiver multipath for naboskaberne
 +
<source lang=cli>
 +
[edit routing-instances PE2]
 +
root@SRX240# <input>set protocols bgp group EXT-PEERS multipath</input>
 +
 +
[edit routing-instances PE2]
 +
root@SRX240# <input>commit</input>
 +
commit complete
 +
</source>
  
 
=Links=
 
=Links=
Line 310: Line 450:
  
 
[[Category:BGP]]
 
[[Category:BGP]]
 +
[[Category:Juniper]]

Latest revision as of 13:12, 5 November 2014

Prøv at konfigurer følgende setup på en Juniper SRX: BGP Demo Setup

Opgave

Grundlæggende forbindelser

  • Konfigurer IP Adresser på alle Logical Tunnel interfaces
    • De skal ligge i 10.255.0.X/30 netværkene
    • LT interfacet skal have samme unit nummer som .4 oktet i op adressen(10.255.0.2 = lt-0/0/0.2)
  • Configurer lo så de passer med <routernummer>x10. og en management adresse(PE1 = Lo0.10:10.255.255.1/32)

Konfiguration

Konfigurer de logiske interfaces og forbind dem 

root@SRX240> <input>show configuration interfaces lt-0/0/0.2</input>
<notice>encapsulation ethernet;
peer-unit 1;</notice>
family inet {
    address 10.255.0.2/30;
}

root@SRX240> <input>show configuration interfaces lt-0/0/0.1</input>
<notice>encapsulation ethernet;
peer-unit 2;</notice>
family inet {
    address 10.255.0.1/30;
}
root@SRX240> <input>show configuration interfaces lo0.10</input>
family inet {
    address 10.255.255.1/32;
}

Opret en virtual router instance og forbind lt interfaces til instancen. 

root@SRX240> <input>show configuration routing-instances PE2</input>
instance-type virtual-router;
<notice>interface lt-0/0/0.2;
interface lt-0/0/0.5;
interface lt-0/0/0.22;
interface lo0.20;</notice>

Verificering

Kontroller at routerne har sat alle interfaces og IP adresser 

root@SRX240> <input>show interfaces routing-instance PE2 terse</input>
Interface               Admin Link Proto    Local                 Remote
<notice>lt-0/0/0.2              up    up   inet     10.255.0.2/30
lt-0/0/0.5              up    up   inet     10.255.0.5/30
lt-0/0/0.22             up    up   inet     10.255.0.22/30
lo0.20                  up    up   inet     10.255.255.2        --> 0/0</notice>

Kontroller at de virtuelle routere kan pinge hinanden. 

root@SRX240> <input>ping 10.255.0.2 routing-instance PE5</input>
PING 10.255.0.2 (10.255.0.2): 56 data bytes
<notice>64 bytes from 10.255.0.2: icmp_seq=0 ttl=64 time=1.132 ms
64 bytes from 10.255.0.2: icmp_seq=1 ttl=64 time=1.068 ms
64 bytes from 10.255.0.2: icmp_seq=2 ttl=64 time=1.012 ms</notice>
^C
--- 10.255.0.2 ping statistics ---
3 packets transmitted, 3 packets received, 0% packet loss
round-trip min/avg/max/stddev = 1.012/1.071/1.132/0.049 ms

BGP opsætning

  • Lav en export regl til bgp
  • Konfigurer lo0 interfacets ip adresse som router-id
  • konfigurer eBGP imellem alle routerne.

Konfiguration

Lav en export regl i global routing instance 

root@SRX240> <input>show configuration policy-options policy-statement VR-EBGP-EXPORT</input>
term 1 {
    from {
        protocol direct;
    }
    then accept;
}

Konfigurer router-id og ASN under den virtuelle router. 

[edit routing-instances]
root@SRX240# <input>show</input>
PE1 {
    routing-options {
        <notice>router-id 10.255.255.1;
        autonomous-system 65001;</notice>
    }
}

Lav eBGP under den virtuelle router 

[edit]
root@SRX240# <input>show routing-instances PE1 protocols bgp</input>
group EXT-PEERS {
    type external;
    export VR-EBGP-EXPORT;
    neighbor 10.255.0.5 {
        peer-as 65002;
    }
    neighbor 10.255.0.10 {
        peer-as 65004;
    }
}

Verificering

Kontroller BGP naboer kommer op i Established state og der bliver udvækslet routes 

root@SRX240> <input>show bgp summary instance PE1</input>
Groups: 1 Peers: 2 Down peers: 0
Table          Tot Paths  Act Paths Suppressed    History Damp State    Pending
PE1.inet.0            54         43          0          0          0          0
PE1.mdt.0              0          0          0          0          0          0
Peer                     AS      InPkt     OutPkt    OutQ   Flaps Last Up/Dwn State|#Active/Received/Accepted/Damped...
10.255.0.5            65002        127        128       0       0       54:27 <notice>Establ</notice>
  <notice>PE1.inet.0: 25/36/36/0</notice>
10.255.0.10           65004        124        126       0       0       54:19 <notice>Establ</notice>
  <notice>PE1.inet.0: 18/18/18/0</notice>

root@SRX240> <input>show bgp neighbor 10.255.0.5</input>
Peer: 10.255.0.5+64085 AS 65002 Local: 10.255.0.6+179 AS 65001
  Type: External    State: <notice>Established</notice>    Flags: <Sync>
  Last State: OpenConfirm   Last Event: RecvKeepAlive
  Last Error: None
  Export: <notice>[ VR-EBGP-EXPORT ]</notice>
  Options: <Preference PeerAS Refresh>
  Holdtime: 90 Preference: 170
  Number of flaps: 0
  Peer ID: 10.255.255.2    Local ID: 10.255.255.1      Active Holdtime: 90
  Keepalive Interval: 30         Peer index: 0
  BFD: disabled, down
  Local Interface: lt-0/0/0.6
  NLRI for restart configured on peer: inet-unicast
  NLRI advertised by peer: inet-unicast
  NLRI for this session: inet-unicast
  Peer supports Refresh capability (2)
  Stale routes from peer are kept for: 300
  Peer does not support Restarter functionality
  NLRI that restart is negotiated for: inet-unicast
  NLRI of received end-of-rib markers: inet-unicast
  NLRI of all end-of-rib markers sent: inet-unicast
  Peer supports 4 byte AS extension (peer-as 65002)
  Peer does not support Addpath
  Table PE1.inet.0 Bit: 30000
    RIB State: BGP restart is complete
    RIB State: VPN restart is complete
    Send state: in sync
    <notice>Active prefixes:              25
    Received prefixes:            36
    Accepted prefixes:            36
    Suppressed due to damping:    0
    Advertised prefixes:          32</notice>
  Last traffic (seconds): Received 27   Sent 2    Checked 48
  <notice>Input messages:  Total 140    Updates 9       Refreshes 0     Octets 3107
  Output messages: Total 142    Updates 8       Refreshes 0     Octets 3133</notice>
  Output Queue[2]: 0

Kontroller der bliver modtaget routes 

root@SRX240> <input>show route receive-protocol bgp 10.255.0.10</input>

inet.0: 65 destinations, 65 routes (65 active, 0 holddown, 0 hidden)

PE1.inet.0: <notice>63 destinations, 74 routes (63 active, 0 holddown, 0 hidden)</notice>
  Prefix                  Nexthop              MED     Lclpref    AS path
* 10.202.0.0/16           10.255.0.10                             65004 65003 I
* 10.202.0.0/24           10.255.0.10                             65004 65003 I
* 10.202.1.0/24           10.255.0.10                             65004 65003 I
* 10.202.2.0/24           10.255.0.10                             65004 65003 I
* 10.202.10.0/24          10.255.0.10                             65004 65003 I
* 10.202.20.0/24          10.255.0.10                             65004 65003 I
* 10.204.0.0/16           10.255.0.10                             65004 I
* 10.204.0.0/24           10.255.0.10                             65004 I
* 10.204.1.0/24           10.255.0.10                             65004 I
* 10.204.2.0/24           10.255.0.10                             65004 I
* 10.204.10.0/24          10.255.0.10                             65004 I
* 10.204.20.0/24          10.255.0.10                             65004 I
* 10.205.0.0/16           10.255.0.10                             65004 65006 I
* 10.205.0.0/24           10.255.0.10                             65004 65006 I
* 10.205.1.0/24           10.255.0.10                             65004 65006 I
* 10.205.2.0/24           10.255.0.10                             65004 65006 I
* 10.205.10.0/24          10.255.0.10                             65004 65006 I
* 10.205.20.0/24          10.255.0.10                             65004 65006 I

Og her kontrollerer vi en bestemt route i tabellen på PE1 

root@SRX240> <input>show route table PE1.inet.0 protocol bgp detail 10.202.0.0/24</input>

PE1.inet.0: 63 destinations, 74 routes (63 active, 0 holddown, 0 hidden)
10.202.0.0/24 (2 entries, 1 announced)
        *BGP    Preference: 170/-101
                Next hop type: Router, Next hop index: 820
                Address: 0x15b9ac8
                Next-hop reference count: 39
                <notice>Source: 10.255.0.10</notice>
                <notice>Next hop: 10.255.0.10 via lt-0/0/0.9, selected</notice>
                State: <Active Ext>
                Local AS: 65001 Peer AS: 65004
                Age: 1:05:54
                Task: BGP_65004_65001.10.255.0.10+179
                <notice>Announcement bits (2): 1-KRT 3-BGP_RT_Background
                AS path: 65004 65003 I</notice>
                Accepted
                Localpref: 100
                Router ID: 10.255.255.4
         BGP    Preference: 170/-101
                Next hop type: Router, Next hop index: 815
                Address: 0x15b9a7c
                Next-hop reference count: 64
                Source: 10.255.0.5
                Next hop: 10.255.0.5 via lt-0/0/0.6, selected
                State: <Ext>
                Inactive reason: Active preferred
                Local AS: 65001 Peer AS: 65002
                Age: 1:03:36
                Task: BGP_65002_65001.10.255.0.5+64085
                AS path: 65002 65003 I
                Accepted
                Localpref: 100
                Router ID: 10.255.255.2

Se hvad vi sender til vores naboer: 

root@SRX240> <input>show route advertising-protocol bgp 10.255.0.10</input>

PE1.inet.0: <notice>63 destinations, 74 routes</notice> (63 active, 0 holddown, 0 hidden)
  Prefix                  Nexthop              MED     Lclpref    AS path
* 10.50.0.0/16            Self                                    65002 65005 65099 I
* 10.99.6.0/24            Self                                    65002 65005 65099 I
* 10.99.20.0/24           Self                                    65002 65005 65099 I
* 10.99.31.0/24           Self                                    65002 65005 65099 I
* 10.99.62.0/24           Self                                    65002 65005 65099 I
* 10.99.99.1/32           Self                                    65002 65005 65099 I
* 10.99.99.2/32           Self                                    65002 65005 65099 I
* 10.99.114.0/24          Self                                    65002 65005 65099 I
* 10.99.152.0/24          Self                                    65002 65005 65099 I
* 10.99.199.0/24          Self                                    65002 65005 65099 I
* 10.99.207.0/24          Self                                    65002 65005 65099 I
* 10.99.212.0/24          Self                                    65002 65005 65099 I
* 10.200.0.0/16           Self                                    65002 65005 I
* 10.200.0.0/24           Self                                    65002 65005 I
* 10.200.1.0/24           Self                                    65002 65005 I
* 10.200.2.0/24           Self                                    65002 65005 I
* 10.200.10.0/24          Self                                    65002 65005 I
* 10.200.20.0/24          Self                                    65002 65005 I
* 10.201.0.0/16           Self                                    65002 I
* 10.201.0.0/24           Self                                    65002 I
* 10.201.1.0/24           Self                                    65002 I
* 10.201.2.0/24           Self                                    65002 I
* 10.201.5.0/24           Self                                    65002 I
* 10.201.10.0/24          Self                                    65002 I
* 10.201.20.0/24          Self                                    65002 I
* 10.203.0.0/16           Self                                    I
* 10.203.0.0/24           Self                                    I
* 10.203.1.0/24           Self                                    I
* 10.203.2.0/24           Self                                    I
* 10.203.5.0/24           Self                                    I
* 10.203.10.0/24          Self                                    I
* 10.203.20.0/24          Self                                    I

Kontroller om der er performance problemer på udstyret 

root@SRX240> <input>show chassis routing-engine</input>
Routing Engine status:
    <notice>Temperature                 38 degrees C / 100 degrees F</notice>
    CPU temperature             39 degrees C / 102 degrees F
    Total memory               512 MB Max   410 MB used ( 80 percent)
      Control plane memory     336 MB Max   302 MB used ( 90 percent)
      Data plane memory        176 MB Max   107 MB used ( 61 percent)
    CPU utilization:
      User                       3 percent
      Background                 0 percent
      Kernel                     1 percent
      Interrupt                  0 percent
      Idle                      96 percent
    Model                          RE-SRX240B
    Serial ID                      AAAF3940
    Start time                     2014-11-05 11:11:44 CET
    Uptime                         1 hour, 25 minutes, 7 seconds
    Last reboot reason             0x1:power cycle/failure
    <notice>Load averages:                 1 minute   5 minute  15 minute
                                       0.11       0.05       0.01</notice>

Route Summering

  • Konfigurer de forskellige netværk på lo0 interfacet hvis de ikke allerede er konfigureret
  • Konfigurer en aggregate route der dækker hele /16 netværket
  • Tillad den i export politikken

Konfiguration

Her konfigurerer vi en aggregated route for at indskyde den i BGP opdateringerne, men alligevel smide alt trafik til summeringen væk, hvis der ikke findes en mere specifik route i den lokale routing tabel[1] 

root@SRX240> <input>show configuration routing-instances PE1 routing-options</input>
aggregate {
    route 10.203.0.0/16;
}

Exporter også aggregate routes 

root@SRX240> <input>show configuration policy-options policy-statement VR-EBGP-EXPORT</input>
term 1 {
    from {
        protocol [ direct <notice>aggregate</notice> ];
        route-filter 10.128.0.0/9 orlonger;
    }
    then accept;
}

De tidligere eksempler ovenfor viser at det virker.

Load Balancing

Default loadbalancer juniper pr. prefix, det vil sige at hvis en routes har flere next-hops med samme metric vælger den en forwarder ud fra hash af prefixen. Alle pakker til det samme prefix vil så løbe over det samme link.
Har man nok routes i sin routing tabel vil man opleve en loadbalancing, men fordelingen af trafik vil ikke altid blive ligeligt.
Ved at konfigurere routeren til "pr. pakke" loadbalancing vil den istedet lave en hash af hver pakke og balancere pr. flow istedet for destinations prefix
Prefix loadbalancing over næsten den samme next-hop 10.255.0.21 

root@SRX240> <input>show route table PE2.inet.0 10.205.0.0/16</input>

PE2.inet.0: 66 destinations, 91 routes (66 active, 0 holddown, 0 hidden)
+ = Active Route, - = Last Active, * = Both

10.205.0.0/16      *[BGP/170] 00:50:32, localpref 100
                      AS path: 65001 65004 65006 I
                    > to <notice>10.255.0.6</notice> via lt-0/0/0.5
                    [BGP/170] 00:50:32, localpref 100
                      AS path: 65003 65004 65006 I
                    > to 10.255.0.21 via lt-0/0/0.22
10.205.0.0/24      *[BGP/170] 00:50:32, localpref 100
                      AS path: 65003 65004 65006 I
                    > to <notice>10.255.0.21</notice> via lt-0/0/0.22
                    [BGP/170] 00:50:32, localpref 100
                      AS path: 65001 65004 65006 I
                    > to 10.255.0.6 via lt-0/0/0.5
10.205.1.0/24      *[BGP/170] 00:50:32, localpref 100
                      AS path: 65003 65004 65006 I
                    > to <notice>10.255.0.21</notice> via lt-0/0/0.22
                    [BGP/170] 00:50:32, localpref 100
                      AS path: 65001 65004 65006 I
                    > to 10.255.0.6 via lt-0/0/0.5
10.205.2.0/24      *[BGP/170] 00:50:32, localpref 100
                      AS path: 65003 65004 65006 I
                    > to <notice>10.255.0.21</notice> via lt-0/0/0.22
                    [BGP/170] 00:50:32, localpref 100
                      AS path: 65001 65004 65006 I
                    > to 10.255.0.6 via lt-0/0/0.5
10.205.10.0/24     *[BGP/170] 00:50:32, localpref 100
                      AS path: 65003 65004 65006 I
                    > to <notice>10.255.0.21</notice> via lt-0/0/0.22
                    [BGP/170] 00:50:32, localpref 100
                      AS path: 65001 65004 65006 I
                    > to 10.255.0.6 via lt-0/0/0.5
10.205.20.0/24     *[BGP/170] 00:50:32, localpref 100
                      AS path: 65003 65004 65006 I
                    > to <notice>10.255.0.21</notice> via lt-0/0/0.22
                    [BGP/170] 00:50:32, localpref 100
                      AS path: 65001 65004 65006 I
                    > to 10.255.0.6 via lt-0/0/0.5

Som vi ser her vil de fleste pakker tage den samme vej. For 10.204.0.0 netværkene vil 10.255.0.6 blive brugt istedet 

root@SRX240> <input>show route table PE2.inet.0 10.204.0.0/16</input>

PE2.inet.0: 66 destinations, 91 routes (66 active, 0 holddown, 0 hidden)
+ = Active Route, - = Last Active, * = Both

10.204.0.0/16      *[BGP/170] 01:47:43, localpref 100
                      AS path: 65001 65004 I
                    > to <notice>10.255.0.6</notice> via lt-0/0/0.5
                    [BGP/170] 01:45:25, localpref 100
                      AS path: 65003 65004 I
                    > to 10.255.0.21 via lt-0/0/0.22
10.204.0.0/24      *[BGP/170] 01:47:43, localpref 100
                      AS path: 65001 65004 I
                    > to <notice>10.255.0.6</notice> via lt-0/0/0.5
                    [BGP/170] 01:45:25, localpref 100
                      AS path: 65003 65004 I
                    > to 10.255.0.21 via lt-0/0/0.22
10.204.1.0/24      *[BGP/170] 01:47:43, localpref 100
                      AS path: 65001 65004 I
                    > to <notice>10.255.0.6</notice> via lt-0/0/0.5
                    [BGP/170] 01:45:25, localpref 100
                      AS path: 65003 65004 I
                    > to 10.255.0.21 via lt-0/0/0.22
10.204.2.0/24      *[BGP/170] 01:47:43, localpref 100
                      AS path: 65001 65004 I
                    > to <notice>10.255.0.6</notice> via lt-0/0/0.5
                    [BGP/170] 01:45:25, localpref 100
                      AS path: 65003 65004 I
                    > to 10.255.0.21 via lt-0/0/0.22
10.204.10.0/24     *[BGP/170] 01:47:43, localpref 100
                      AS path: 65001 65004 I
                    > to <notice>10.255.0.6</notice> via lt-0/0/0.5
                    [BGP/170] 01:45:25, localpref 100
                      AS path: 65003 65004 I
                    > to 10.255.0.21 via lt-0/0/0.22
10.204.20.0/24     *[BGP/170] 01:47:43, localpref 100
                      AS path: 65001 65004 I
                    > to <notice>10.255.0.6</notice> via lt-0/0/0.5
                    [BGP/170] 01:45:25, localpref 100
                      AS path: 65003 65004 I
                    > to 10.255.0.21 via lt-0/0/0.22

Og den ene route bliver ikke brugt 

root@SRX240> <input>show route table PE2.inet.0 protocol bgp detail 10.205.0.0/24</input>

PE2.inet.0: 66 destinations, 91 routes (66 active, 0 holddown, 0 hidden)
10.205.0.0/24 (2 entries, 1 announced)
        <notice>*BGP</notice>    Preference: 170/-101
                Next hop type: Router, Next hop index: 847
                Address: 0x15b9ef0
                Next-hop reference count: 39
                Source: 10.255.0.21
                Next hop: 10.255.0.21 via lt-0/0/0.22, selected
                <notice>State: <Active Ext></notice>
                Local AS: 65002 Peer AS: 65003
                Age: 1:00:46
                Task: BGP_65003_65002.10.255.0.21+51141
                Announcement bits (2): 1-KRT 3-BGP_RT_Background
                AS path: 65003 65004 65006 I
                Accepted
                Localpref: 100
                Router ID: 10.255.255.3
         BGP    Preference: 170/-101
                Next hop type: Router, Next hop index: 814
                Address: 0x15b9a30
                Next-hop reference count: 42
                Source: 10.255.0.6
                Next hop: 10.255.0.6 via lt-0/0/0.5, selected
                <notice>State: <Ext>
                Inactive reason: Active preferred</notice>
                Local AS: 65002 Peer AS: 65001
                Age: 1:00:46
                Task: BGP_65001_65002.10.255.0.6+179
                AS path: 65001 65004 65006 I
                Accepted
                Localpref: 100
                Router ID: 10.255.255.1

Konfigurer Multipath

Aktiver multipath for naboskaberne 

[edit routing-instances PE2]
root@SRX240# <input>set protocols bgp group EXT-PEERS multipath</input>

[edit routing-instances PE2]
root@SRX240# <input>commit</input>
commit complete

Links

  1. ↑ http://networkenhancers.blogspot.dk/2011/05/difference-between-static-aggregate-and.html
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