isis attached bit

10.01 2020 | by massimiliano

isis attached bit Di default informazioni di routing tra differenti livelli L1 ed L2 non sono ammessi. Quindi un […]

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isis attached bit

Di default informazioni di routing tra differenti livelli L1 ed L2 non sono ammessi.

Quindi un router L1 non ha nessuna prefix conosciuta rispetto ad un altra area e l’unico modo che ha di comunicare con essa, attraverso un router L1/L2, è quello di affidarsi ad un bit conosciuto come attached-bit

ISIS LSP ha un byte filed in cui gli 8 bit rappresentano:

bit 8: utilizzato per partial bit

bit from 4 to 7: sono conosciuti come attached bit dove:

– bit 4: default metric
– bit 5: delay metric
– bit 6: expance metric
– bit 7: error metric

bit 3: overload

bit 1 e 2: IS Type

Attached bit indica che il nodo è collegato ad un’altra area o meglio ad un Level-2 backbone; questi sono settati attraverso L1-L2 attached LSP generati da un router L1/L2.

ARCHITETTURA LAB DI TEST CON ROUTER JUNOS:

isis lab attached bit

Premesso:

– JUNOS-3 e JUNOS-5 hanno il ruolo di L1 L2 router

– JUNOS-1, JUNOS-2, JUNOS-6, JUNOS-7 hanno ruolo L1 router
– Due aree ISIS 49.0000 e 49.0001
– Attached Bit Enabled (default route 0.0.0.0)

CONFIGURATION GUIDE

Si riporta solo la configurazione di un Router L1 ed un router L1/L2 (gli altri router hanno la medesima configurazione con i relativi propri indirizzi IF ed ISO)

root@JUNOS1>; show configuration
## Last commit: 2014-02-13 09:51:32 UTC by root
version 10.1R1.8; system {
host-name JUNOS1;
root-authentication {
encrypted-password “$1$5Ns2jTZU$MNb26tfWTe8yG9T9Y3RWo1”; ## SECRET-DATA
}

interfaces {
em0 {
unit 0 {
description LAN1;
family inet {
address 10.10.10.1/24;
}
family iso;
}
em1 {
unit 0 {
description “to J2”;
family inet {
address 1.1.1.1/30;
}
family iso;
}
em3 {
unit 0 {
description “to J3”;
family inet {
address 2.2.2.1/30;
}
family iso;
}
lo0 {
unit 0 {
description RID;
family inet {
address 192.168.1.1/32;
}
family iso {
address 49.0000.0019.2168.1100.00;
}
protocols {
isis {
level 2 disable;
interface em0.0 {
passive;
}
interface em1.0 {
point-to-point;
}
interface em3.0 {
point-to-point;
}
interface lo0.0;
}

L1/L2 router

root@JUNOS5>; show configuration
## Last commit: 2014-02-02 10:49:39 UTC by root
version 10.1R1.8;
system {
host-name JUNOS5;
}

interfaces
{
em0 {
unit 0 {
description “to J3 L2”;
family inet {
address 5.5.5.2/30;
}
family iso;
}
em1 {
unit 0 {
description “to J6”;
family inet {
address 6.6.6.1/30;
}
family iso;
}
em3 {
unit 0 {
description “to J7”;
family inet {
address 7.7.7.1/30;
}
family iso;
}
lo0 {
unit 0 {
description RID;
family inet {
address 172.16.100.1/32;
}
family iso {
address 49.1111.1721.6100.1000.00;
}
protocols {
isis {
interface em0.0 {
point-to-point;
level 1 disable;
}
interface em1.0 {
point-to-point;
level 2 disable;
}
interface em3.0 {
point-to-point;
level 2 disable;
}
interface lo0.0 {
level 1 disable;
}

VERIFICA TABELLE DI ROUTING:

Router L1:

root@JUNOS1>; show route

inet.0: 12 destinations, 12 routes (12 active, 0 holddown, 0 hidden)
+ = Active Route, – = Last Active, * = Both

0.0.0.0/0 *[IS-IS/15] 00:06:52, metric 10
> to 2.2.2.2 via em3.0 1

iso.0: 1 destinations, 1 routes (1 active, 0 holddown, 0 hidden)
+ = Active Route, – = Last Active, * = Both

49.0000.0019.2168.1100/72
*[Direct/0] 00:12:48
> via lo0.0

root@JUNOS1>; show isis route

IS-IS routing table Current version: L1: 8 L2: 0
IPv4/IPv6 Routes
—————-
Prefix L Version Metric Type Interface NH Via
0.0.0.0/0 1 8 10 int em3.0 IPV4 JUNOS3

root@JUNOS1>; show isis database

IS-IS level 1 link-state database:
LSP ID Sequence Checksum Lifetime Attributes

JUNOS1.00-00 0x4 0x71c6 1023 L1
JUNOS2.00-00 0x4 0x70ec 974 L1
JUNOS3.00-00 0x4 0x2901 619 L1 L2 Attached
3 LSPs

IS-IS level 2 link-state database:
0 LSPs

root@JUNOS1>; show isis overview

Instance: master
Router ID: 192.168.1.1
Adjacency holddown: enabled
Maximum Areas: 3
LSP life time: 1200
Attached bit evaluation: enabled
SPF delay: 200 msec, SPF holddown: 5000 msec, SPF rapid runs: 3
IPv4 is enabled, IPv6 is enabled
Traffic engineering: enabled
Restart: Enabled
Restart duration: 210 sec
Helper mode: Enabled
Level 1
Internal route preference: 15
External route preference: 160
Wide metrics are enabled, Narrow metrics are enabled
Level 2
Internal route preference: 18
External route preference: 165
Wide metrics are enabled, Narrow metrics are enabled

root@JUNOS1>; show isis interface

IS-IS interface database:
Interface L CirID Level 1 DR Level 2 DR L1/L2 Metric
em0.0 0 0x1 Passive Passive 10/10
em1.0 1 0x1 Point to Point Disabled 10/10
em3.0 1 0x1 Point to Point Disabled 10/10
lo0.0 0 0x1 Passive Passive 0/0

root@JUNOS1>; ping 30.30.30.1
PING 30.30.30.1 (30.30.30.1): 56 data bytes
64 bytes from 30.30.30.1: icmp_seq=0 ttl=62 time=2.003 ms
64 bytes from 30.30.30.1: icmp_seq=1 ttl=62 time=2.050 ms
^C
— 30.30.30.1 ping statistics —
2 packets transmitted, 2 packets received, 0% packet loss
round-trip min/avg/max/stddev = 2.003/2.026/2.050/0.023 ms

root@JUNOS1>; ping 40.40.40.1
PING 40.40.40.1 (40.40.40.1): 56 data bytes
64 bytes from 40.40.40.1: icmp_seq=0 ttl=62 time=2.363 ms
64 bytes from 40.40.40.1: icmp_seq=1 ttl=62 time=2.528 ms
64 bytes from 40.40.40.1: icmp_seq=2 ttl=62 time=1.309 ms
^C
— 40.40.40.1 ping statistics —
3 packets transmitted, 3 packets received, 0% packet loss
round-trip min/avg/max/stddev = 1.309/2.067/2.528/0.540 ms

Router L1/L2:

root@JUNOS3>; show route

inet.0: 20 destinations, 20 routes (20 active, 0 holddown, 0 hidden)
+ = Active Route, – = Last Active, * = Both

1.1.1.0/30 *[IS-IS/15] 00:18:32, metric 20
to 2.2.2.1 via em1.0
> to 3.3.3.1 via em3.0
2.2.2.0/30 *[Direct/0] 00:19:30
> via em1.0
2.2.2.2/32 *[Local/0] 00:19:30
Local via em1.0
3.3.3.0/30 *[Direct/0] 00:19:30
> via em3.0

3.3.3.2/32 *[Local/0] 00:19:30
Local via em3.0
5.5.5.0/30 *[Direct/0] 00:19:30
> via em0.0

5.5.5.1/32 *[Local/0] 00:19:30
Local via em0.0
6.6.6.0/30 *[IS-IS/18] 00:13:43, metric 20
> to 5.5.5.2 via em0.0
7.7.7.0/30 *[IS-IS/18] 00:13:43, metric 20
> to 5.5.5.2 via em0.0
8.8.8.0/30 *[IS-IS/18] 00:13:36, metric 30
> to 5.5.5.2 via em0.0

10.10.10.0/24 *[IS-IS/15] 00:18:32, metric 20
> to 2.2.2.1 via em1.0
20.20.20.0/24 *[IS-IS/15] 00:19:17, metric 20
> to 3.3.3.1 via em3.0
30.30.30.0/24 *[IS-IS/18] 00:13:13, metric 30
> to 5.5.5.2 via em0.0
40.40.40.1/32 *[IS-IS/18] 00:13:36, metric 30
> to 5.5.5.2 via em0.0
172.16.100.1/32 *[IS-IS/18] 00:13:43, metric 10
> to 5.5.5.2 via em0.0
172.16.100.2/32 *[IS-IS/18] 00:13:36, metric 20
> to 5.5.5.2 via em0.0
172.16.100.3/32 *[IS-IS/18] 00:13:13, metric 20
> to 5.5.5.2 via em0.0
192.168.1.1/32 *[IS-IS/15] 00:00:36, metric 10
> to 2.2.2.1 via em1.0
192.168.1.2/32 *[IS-IS/15] 00:19:17, metric 10
> to 3.3.3.1 via em3.0
192.168.1.3/32 *[Direct/0] 00:19:30
> via lo0.0

iso.0: 1 destinations, 1 routes (1 active, 0 holddown, 0 hidden)
+ = Active Route, – = Last Active, * = Both

49.0000.0019.2168.1300/72
*[Direct/0] 00:19:30
> via lo0.0

root@JUNOS3>; show isis database

IS-IS level 1 link-state database:
LSP ID Sequence Checksum Lifetime Attributes

JUNOS1.00-00 0x7 0xf0b6 1018 L1
JUNOS2.00-00 0x4 0x70ec 585 L1
JUNOS3.00-00 0x5 0x2702 1078 L1 L2 Attached
3 LSPs

IS-IS level 2 link-state database:
LSP ID Sequence Checksum Lifetime Attributes

JUNOS3.00-00 0x6 0x64b6 1019 L1 L2
JUNOS5.00-00 0x4 0x7470 260 L1 L2
2 LSPs

root@JUNOS3>; show isis overview

Instance: master
Router ID: 192.168.1.3
Adjacency holddown: enabled
Maximum Areas: 3
LSP life time: 1200
Attached bit evaluation: enabled
SPF delay: 200 msec, SPF holddown: 5000 msec, SPF rapid runs: 3
IPv4 is enabled, IPv6 is enabled
Traffic engineering: enabled
Restart: Enabled
Restart duration: 210 sec
Helper mode: Enabled
Level 1
Internal route preference: 15
External route preference: 160
Wide metrics are enabled, Narrow metrics are enabled
Level 2
Internal route preference: 18
External route preference: 165
Wide metrics are enabled, Narrow metrics are enabled