MPLS-LDP-RSVP-TE protocol difference between JUNOS and CISCO

24.11 2020 | by massimiliano

MPLS-LDP-RSVP-TE protocol difference between JUNOS and CISCO LDP Label distribution protocol LDP (RFC 5036) è un protocollo di […]

https://www.ingegnerianetworking.com/wp-content/uploads/2020/11/junos-cisco-ex-design-mpls-401.PNG

LDP Label distribution protocol

LDP (RFC 5036) è un protocollo di segnalazione (non è un protocollo di routing) con il compito di distribuire un label-mapping ed in grado di poter creare i seguenti LSP (label switch path):

– MP2P: Multipoint to Point (from any to one) con LSP di tipo unidirezionali

– P2MP: Point to Multipoint (from one to any) con LSP di tipo unidirezionale

– MP2MP: Multipoint to Multipoint (from any to any) con LSP non di tipo unidirezionale

Viceversa da RSVP, LDP non crea LSP di tipo P2P (Point to Point) e non implementa funzionalità di TE (Traffic Engineering);

Traffico unicast quindi, viene trasportato generalmente in un LSP di tipo MP2P dove parte da Ingress Router Edge (PE head-end) per arrivare ad un dato Egress Router Edge (PE tail-end).

Si riporta per completezza una configurazione base sia Junos che Cisco:

PE1 JUNOS

PE3 CISCO

set interfaces em0 unit 0 family mpls

set interfaces em1 unit 0 family inet address 10.0.0.13/30

set interfaces em1 unit 0 family mpls

set interfaces lo0 unit 0 family inet address 10.255.255.11/32

set routing-options router-id 10.255.255.11

set protocols mpls interface em0.0

set protocols mpls interface em1.0

set protocols ospf area 0.0.0.0 interface lo0.0 passive

set protocols ospf area 0.0.0.0 interface em0.0

set protocols ospf area 0.0.0.0 interface em1.0

set protocols ldp track-igp-metric

set protocols ldp interface em0.0

set protocols ldp interface em1.0

ip cef

mpls label protocol ldp

mpls ldp router-id Loopback0

interface Loopback0

ip address 10.255.255.33 255.255.255.255

ip ospf 1 area 0

interface GigabitEthernet0/0

ip address 10.0.0.17 255.255.255.252

ip ospf 1 area 0

mpls ip

interface GigabitEthernet0/1

ip address 10.0.0.14 255.255.255.252

ip ospf 1 area 0

mpls ip

router ospf 1

router-id 10.255.255.33

Il comando track-igp-metric accoppia LDP ed IGP ad utilizzare lo stesso valore di metrica (route metric default LDP = 1) ed è una best practice per loop avoidance.

E’ importante poi configurare il router-ID con lo stesso valore della loopback che deve essere raggiungibile altrimenti la sessione LDP non può attivarsi.

E un’architettura di test lab:

junos cisco ex design mpls

Partendo dallo stato fase 0 in cui abbiamo attivato la sola configurazione ospf / mpld / ldp, possiamo verificare la condizione di LDP Discovery ed LDP Session:

LDP Discovery and Session

Appena LDP è configurato per-interface un processo di discovery inizia; pertanto i router su cui è abilitato LDP trasmettono e ricevono LDP Hello incapsulati come di seguito:

1) in UDP header con source e destination port 646

2) in IPv4 header con TTL=1 e destination address 224.0.0.2 (all-router multicast address)

Questi pacchetti hanno il solo compito di creare adiacenze (non sono ruotabili) tra neighbors direttamente connessi.

NOTA: un secondo metodo per stabilire adiacenze conosciuto come extended-discovery or targeted-LDP permette di creare neighborship tra peer remoti multihop percui gli hello message sono unicast e con TTL>1

Verifica LDP hello adjacencies (UDP):

root@PE1>; show ldp neighbor

Address Interface Label space ID Hold time

10.0.0.2 em0.0 10.255.255.1:0 12

10.0.0.14 em1.0 10.255.255.33:0 14

root@PE1>; show ldp neighbor extensive

Address Interface Label space ID Hold time

10.0.0.2 em0.0 10.255.255.1:0 12

Transport address: 10.255.255.1, Configuration sequence: 1

Up for 00:24:10

Reference count: 1

Hold time: 15, Proposed local/peer: 15/15

Hello flags: none

Neighbor types: discovered

Address Interface Label space ID Hold time

10.0.0.14 em1.0 10.255.255.33:0 14

Transport address: 10.255.255.33, Configuration sequence: 0

Up for 00:25:46

Reference count: 1

Hold time: 15, Proposed local/peer: 15/15

Hello flags: none

Neighbor types: discovered

Transport address significa che LDP discovery innesca (trigger) la creazione di una sessione LDP-over-TCP tra ogni coppia di neighboring; l’indirizzo endpoint di queste sessioni sono precisamente il transport-address encoded in UDP Hellos message.

root@PE1>; show system connections | match “proto|646”

Proto Recv-Q Send-Q Local Address Foreign Address (state)

tcp4 0 0 10.255.255.11.59789 10.255.255.1.646 ESTABLISHED

tcp4 0 0 10.255.255.11.646 10.255.255.33.62370 ESTABLISHED

tcp4 0 0 *.646 *.* LISTEN

udp4 0 0 *.646 *.*

Verifica LDP Session (TCP):

root@PE1>; show ldp session

Address State Connection Hold time

10.255.255.1 Operational Open 21

10.255.255.33 Operational Open 21

root@PE1>; show ldp session extensive

Address: 10.255.255.1, State: Operational, Connection: Open, Hold time: 21

Session ID: 10.255.255.11:0–10.255.255.1:0

Next keepalive in 1 seconds

Active, Maximum PDU: 4096, Hold time: 30, Neighbor count: 1

Neighbor types: discovered

Keepalive interval: 10, Connect retry interval: 1

Local address: 10.255.255.11, Remote address: 10.255.255.1

Up for 00:38:30

Last down 00:38:31 ago; Reason: connection error

Capabilities advertised: none

Capabilities received: none

Protection: disabled

Local – Restart: disabled, Helper mode: enabled

Remote – Restart: disabled, Helper mode: enabled

Local maximum neighbor reconnect time: 120000 msec

Local maximum neighbor recovery time: 240000 msec

Nonstop routing state: Not in sync

Next-hop addresses received:

10.0.0.2

10.0.0.5

Queue depth: 0

Message type Total Last 5 seconds

Sent Received Sent Received

Initialization 1 1 0 0

Keepalive 230 230 0 1

Notification 0 0 0 0

Address 1 1 0 0

Address withdraw 0 0 0 0

Label mapping 10 11 0 0

Label request 0 0 0 0

Label withdraw 0 1 0 0

Label release 1 0 0 0

Label abort 0 0 0 0

Address: 10.255.255.33, State: Operational, Connection: Open, Hold time: 27

Session ID: 10.255.255.11:0–10.255.255.33:0

Next keepalive in 0 seconds

Passive, Maximum PDU: 4096, Hold time: 30, Neighbor count: 1

Neighbor types: discovered

Keepalive interval: 10, Connect retry interval: 1

Local address: 10.255.255.11, Remote address: 10.255.255.33

Up for 00:40:07

Capabilities advertised: none

Capabilities received: none

Protection: disabled

Local – Restart: disabled, Helper mode: enabled

Remote – Restart: disabled, Helper mode: disabled

Local maximum neighbor reconnect time: 120000 msec

Local maximum neighbor recovery time: 240000 msec

Nonstop routing state: Not in sync

Next-hop addresses received:

10.0.0.14

10.255.255.33

10.0.0.17

Queue depth: 0

Message type Total Last 5 seconds

Sent Received Sent Received

Initialization 1 1 0 0

Keepalive 239 276 0 0

Notification 0 0 0 0

Address 1 1 0 0

Address withdraw 0 0 0 0

Label mapping 10 18 0 0

Label request 0 0 0 0

Label withdraw 0 0 0 0

Label release 0 0 0 0

Label abort 0 0 0 0

root@PE1>;

From P1 Junos point of view:

Adjacencies:

root@P1>; show ldp neighbor extensive

Address Interface Label space ID Hold time

10.0.0.1 em0.0 10.255.255.11:0 12

Transport address: 10.255.255.11, Configuration sequence: 1

Up for 00:48:48

Reference count: 1

Hold time: 15, Proposed local/peer: 15/15

Hello flags: none

Neighbor types: discovered

Address Interface Label space ID Hold time

10.0.0.6 em1.0 10.255.255.2:0 13

Transport address: 10.255.255.2, Configuration sequence: 1

Up for 00:48:48

Reference count: 1

Hold time: 15, Proposed local/peer: 15/15

Hello flags: none

Neighbor types: discovered

Session:

root@P1>; show ldp session extensive

Address: 10.255.255.2, State: Operational, Connection: Open, Hold time: 24

Session ID: 10.255.255.1:0–10.255.255.2:0

Next keepalive in 4 seconds

Passive, Maximum PDU: 4096, Hold time: 30, Neighbor count: 1

Neighbor types: discovered

Keepalive interval: 10, Connect retry interval: 1

Local address: 10.255.255.1, Remote address: 10.255.255.2

Up for 00:51:02

Capabilities advertised: none

Capabilities received: none

Protection: disabled

Local – Restart: disabled, Helper mode: enabled

Remote – Restart: disabled, Helper mode: enabled

Local maximum neighbor reconnect time: 120000 msec

Local maximum neighbor recovery time: 240000 msec

Nonstop routing state: Not in sync

Next-hop addresses received:

10.0.0.6

10.0.0.9

Queue depth: 0

Address: 10.255.255.11, State: Operational, Connection: Open, Hold time: 24

Session ID: 10.255.255.1:0–10.255.255.11:0

Next keepalive in 4 seconds

Passive, Maximum PDU: 4096, Hold time: 30, Neighbor count: 1

Neighbor types: discovered

Keepalive interval: 10, Connect retry interval: 1

Local address: 10.255.255.1, Remote address: 10.255.255.11

Up for 00:51:47

Capabilities advertised: none

Capabilities received: none

Protection: disabled

Local – Restart: disabled, Helper mode: enabled

Remote – Restart: disabled, Helper mode: enabled

Local maximum neighbor reconnect time: 120000 msec

Local maximum neighbor recovery time: 240000 msec

Nonstop routing state: Not in sync

Next-hop addresses received:

10.0.0.1

10.0.0.13

Queue depth: 0

Possiamo vedere ora la stessa cosa dal punto di vista CISCO:

Verifica LDP hello adjacencies (UDP):

PE3#show mpls ldp discovery

Local LDP Identifier:

10.255.255.33:0

Discovery Sources:

Interfaces:

GigabitEthernet0/0 (ldp): xmit/recv

LDP Id: 10.255.255.3:0

GigabitEthernet0/1 (ldp): xmit/recv

LDP Id: 10.255.255.11:0

PE3#

PE3#show mpls ldp discovery detail

Local LDP Identifier:

10.255.255.33:0

Discovery Sources:

Interfaces:

GigabitEthernet0/0 (ldp): xmit/recv

Enabled: Interface config

Hello interval: 5000 ms; Transport IP addr: 10.255.255.33

LDP Id: 10.255.255.3:0

Src IP addr: 10.0.0.18; Transport IP addr: 10.255.255.3

Hold time: 15 sec; Proposed local/peer: 15/15 sec

Reachable via 10.255.255.3/32

Password: not required, none, in use

Clients: IPv4

GigabitEthernet0/1 (ldp): xmit/recv

Enabled: Interface config

Hello interval: 5000 ms; Transport IP addr: 10.255.255.33

LDP Id: 10.255.255.11:0

Src IP addr: 10.0.0.13; Transport IP addr: 10.255.255.11

Hold time: 15 sec; Proposed local/peer: 15/15 sec

Reachable via 10.255.255.11/32

Password: not required, none, in use

Clients: IPv4

PE3#

Verifica LDP Session (TCP):

PE3#show mpls ldp neighbor

Peer LDP Ident: 10.255.255.3:0; Local LDP Ident 10.255.255.33:0

TCP connection: 10.255.255.3.646 – 10.255.255.33.53156

State: Oper; Msgs sent/rcvd: 108/110; Downstream

Up time: 01:15:12

LDP discovery sources:

GigabitEthernet0/0, Src IP addr: 10.0.0.18

Addresses bound to peer LDP Ident:

10.255.255.3 10.0.0.18 10.0.0.21

Peer LDP Ident: 10.255.255.11:0; Local LDP Ident 10.255.255.33:0

TCP connection: 10.255.255.11.646 – 10.255.255.33.62370

State: Oper; Msgs sent/rcvd: 475/408; Downstream

Up time: 01:06:04

LDP discovery sources:

GigabitEthernet0/1, Src IP addr: 10.0.0.13

Addresses bound to peer LDP Ident:

10.0.0.1 10.0.0.13

PE3#

PE3#show mpls ldp neighbor detail

Peer LDP Ident: 10.255.255.3:0; Local LDP Ident 10.255.255.33:0

TCP connection: 10.255.255.3.646 – 10.255.255.33.53156

Password: not required, none, in use

State: Oper; Msgs sent/rcvd: 111/113; Downstream; Last TIB rev sent 37

Up time: 01:17:50; UID: 2; Peer Id 1;

LDP discovery sources:

GigabitEthernet0/0; Src IP addr: 10.0.0.18

holdtime: 15000 ms, hello interval: 5000 ms

Addresses bound to peer LDP Ident:

10.255.255.3 10.0.0.18 10.0.0.21

Peer holdtime: 180000 ms; KA interval: 60000 ms; Peer state: estab

Capabilities Sent:

[Dynamic Announcement (0x0506)]

[Typed Wildcard (0x050B)]

Capabilities Received:

[Dynamic Announcement (0x0506)]

[Typed Wildcard (0x050B)]

Peer LDP Ident: 10.255.255.11:0; Local LDP Ident 10.255.255.33:0

TCP connection: 10.255.255.11.646 – 10.255.255.33.62370

Password: not required, none, in use

State: Oper; Msgs sent/rcvd: 493/423; Downstream; Last TIB rev sent 37

Up time: 01:08:42; UID: 3; Peer Id 0;

LDP discovery sources:

GigabitEthernet0/1; Src IP addr: 10.0.0.13

holdtime: 15000 ms, hello interval: 5000 ms

Addresses bound to peer LDP Ident:

10.0.0.1 10.0.0.13

Peer holdtime: 30000 ms; KA interval: 10000 ms; Peer state: estab

Capabilities Sent:

[Dynamic Announcement (0x0506)]

[Typed Wildcard (0x050B)]

Capabilities Received:

[None]

PE3#

From P3 Cisco point of view:

Adjacencies:

P3#show mpls ldp discovery detail

Local LDP Identifier:

10.255.255.3:0

Discovery Sources:

Interfaces:

GigabitEthernet0/0 (ldp): xmit/recv

Enabled: Interface config

Hello interval: 5000 ms; Transport IP addr: 10.255.255.3

LDP Id: 10.255.255.33:0

Src IP addr: 10.0.0.17; Transport IP addr: 10.255.255.33

Hold time: 15 sec; Proposed local/peer: 15/15 sec

Reachable via 10.255.255.33/32

Password: not required, none, in use

Clients: IPv4

GigabitEthernet0/1 (ldp): xmit/recv

Enabled: Interface config

Hello interval: 5000 ms; Transport IP addr: 10.255.255.3

LDP Id: 10.255.255.4:0

Src IP addr: 10.0.0.22; Transport IP addr: 10.255.255.4

Hold time: 15 sec; Proposed local/peer: 15/15 sec

Reachable via 10.255.255.4/32

Password: not required, none, in use

Clients: IPv4

P3#

Session:

P3#show mpls ldp neighbor detail

Peer LDP Ident: 10.255.255.33:0; Local LDP Ident 10.255.255.3:0

TCP connection: 10.255.255.33.53156 – 10.255.255.3.646

Password: not required, none, in use

State: Oper; Msgs sent/rcvd: 121/119; Downstream; Last TIB rev sent 39

Up time: 01:24:43; UID: 1; Peer Id 0;

LDP discovery sources:

GigabitEthernet0/0; Src IP addr: 10.0.0.17

holdtime: 15000 ms, hello interval: 5000 ms

Addresses bound to peer LDP Ident:

10.0.0.14 10.255.255.33 10.0.0.17

Peer holdtime: 180000 ms; KA interval: 60000 ms; Peer state: estab

Capabilities Sent:

[Dynamic Announcement (0x0506)]

[Typed Wildcard (0x050B)]

Capabilities Received:

[Dynamic Announcement (0x0506)]

[Typed Wildcard (0x050B)]

Peer LDP Ident: 10.255.255.4:0; Local LDP Ident 10.255.255.3:0

TCP connection: 10.255.255.4.57530 – 10.255.255.3.646

Password: not required, none, in use

State: Oper; Msgs sent/rcvd: 119/117; Downstream; Last TIB rev sent 39

Up time: 01:24:24; UID: 2; Peer Id 1;

LDP discovery sources:

GigabitEthernet0/1; Src IP addr: 10.0.0.22

holdtime: 15000 ms, hello interval: 5000 ms

Addresses bound to peer LDP Ident:

10.0.0.25 10.0.0.22 10.255.255.4

Peer holdtime: 180000 ms; KA interval: 60000 ms; Peer state: estab

Capabilities Sent:

[Dynamic Announcement (0x0506)]

[Typed Wildcard (0x050B)]

Capabilities Received:

[Dynamic Announcement (0x0506)]

[Typed Wildcard (0x050B)]

P3#

LDP Label Mapping

Appena una coppia di neighbour stabilisce una sessione LDP comincia uno scambio di label mapping che associa una determinata IP Prefix ad una Label MPLS; questa associazione forma il Label Information Base (LIB) in ogni router

IP Prefix è corrispondente ad una FEC (Forwarding Equivalent Class)

La verifica di questa LIB per i Junos è attraverso questi comandi:

root@PE1>; show ldp database

Input label database, 10.255.255.11:0–10.255.255.1:0

Label Prefix

299792 10.0.0.16/30

299824 10.0.0.20/30

299936 10.0.0.24/30

3 10.255.255.1/32 # implicit-null equivale ad una istruzione di forwarding che permette una funzione di pop label

299888 10.255.255.2/32

299808 10.255.255.3/32

299840 10.255.255.4/32

299776 10.255.255.11/32

299904 10.255.255.22/32

299792 10.255.255.33/32

299936 10.255.255.44/32

Output label database, 10.255.255.11:0–10.255.255.1:0

Label Prefix

299776 10.0.0.16/30

299808 10.0.0.20/30

299840 10.0.0.24/30

299872 10.255.255.1/32

299888 10.255.255.2/32

299792 10.255.255.3/32

299824 10.255.255.4/32

3 10.255.255.11/32

299904 10.255.255.22/32

299776 10.255.255.33/32

299856 10.255.255.44/32

Input label database, 10.255.255.11:0–10.255.255.33:0

Label Prefix

24 10.0.0.0/30

23 10.0.0.4/30

22 10.0.0.8/30

3 10.0.0.12/30

3 10.0.0.16/30

26 10.0.0.20/30

28 10.0.0.24/30

30 10.0.0.28/30

21 10.255.255.0/30

19 10.255.255.1/32

18 10.255.255.2/32

25 10.255.255.3/32

27 10.255.255.4/32

17 10.255.255.11/32

16 10.255.255.22/32

3 10.255.255.33/32

29 10.255.255.44/32

Output label database, 10.255.255.11:0–10.255.255.33:0

Label Prefix

299776 10.0.0.16/30

299808 10.0.0.20/30

299840 10.0.0.24/30

299872 10.255.255.1/32

299888 10.255.255.2/32

299792 10.255.255.3/32

299824 10.255.255.4/32

3 10.255.255.11/32

299904 10.255.255.22/32

299776 10.255.255.33/32

299856 10.255.255.44/32

root@PE1>;

From P1 JUNOS router

root@P1>; show ldp database

Input label database, 10.255.255.1:0–10.255.255.2:0

Label Prefix

300064 10.0.0.16/30

300000 10.0.0.20/30

300080 10.0.0.24/30

299936 10.255.255.1/32

3 10.255.255.2/32

299984 10.255.255.3/32

300016 10.255.255.4/32

299952 10.255.255.11/32

300032 10.255.255.22/32

300064 10.255.255.33/32

300080 10.255.255.44/32

Output label database, 10.255.255.1:0–10.255.255.2:0

Label Prefix

299792 10.0.0.16/30

299824 10.0.0.20/30

299936 10.0.0.24/30

3 10.255.255.1/32

299888 10.255.255.2/32

299808 10.255.255.3/32

299840 10.255.255.4/32

299776 10.255.255.11/32

299904 10.255.255.22/32

299792 10.255.255.33/32

299936 10.255.255.44/32

Input label database, 10.255.255.1:0–10.255.255.11:0

Label Prefix

299776 10.0.0.16/30

299808 10.0.0.20/30

299840 10.0.0.24/30

299872 10.255.255.1/32

299888 10.255.255.2/32

299792 10.255.255.3/32

299824 10.255.255.4/32

3 10.255.255.11/32

299904 10.255.255.22/32

299776 10.255.255.33/32

299856 10.255.255.44/32

Output label database, 10.255.255.1:0–10.255.255.11:0

Label Prefix

299792 10.0.0.16/30

299824 10.0.0.20/30

299936 10.0.0.24/30

3 10.255.255.1/32

299888 10.255.255.2/32

299808 10.255.255.3/32

299840 10.255.255.4/32

299776 10.255.255.11/32

299904 10.255.255.22/32

299792 10.255.255.33/32

299936 10.255.255.44/32

root@P1>;

Possiamo vedere ora la stessa cosa dal punto di vista CISCO:

PE3#show mpls forwarding-table

Local Outgoing Prefix Bytes Label Outgoing Next Hop

Label Label or Tunnel Id Switched interface

16 299904 10.255.255.22/32 1516 Gi0/1 10.0.0.13

17 10.255.255.22/32 0 Gi0/0 10.0.0.18

17 Pop Label 10.255.255.11/32 0 Gi0/1 10.0.0.13

18 299888 10.255.255.2/32 0 Gi0/1 10.0.0.13

19 299872 10.255.255.1/32 0 Gi0/1 10.0.0.13

22 No Label 10.0.0.8/30 0 Gi0/1 10.0.0.13

23 No Label 10.0.0.4/30 0 Gi0/1 10.0.0.13

24 No Label 10.0.0.0/30 0 Gi0/1 10.0.0.13

25 Pop Label 10.255.255.3/32 0 Gi0/0 10.0.0.18

26 Pop Label 10.0.0.20/30 0 Gi0/0 10.0.0.18

27 27 10.255.255.4/32 0 Gi0/0 10.0.0.18

28 28 10.0.0.24/30 0 Gi0/0 10.0.0.18

29 29 10.255.255.44/32 0 Gi0/0 10.0.0.18

30 30 10.0.0.28/30 0 Gi0/0 10.0.0.18

PE3#

From P3 CISCO router

P3#show mpls forwarding-table

Local Outgoing Prefix Bytes Label Outgoing Next Hop

Label Label or Tunnel Id Switched interface

16 Pop Label 10.255.255.33/32 0 Gi0/0 10.0.0.17

17 17 10.255.255.22/32 0 Gi0/1 10.0.0.22

18 17 10.255.255.11/32 0 Gi0/0 10.0.0.17

19 18 10.255.255.2/32 0 Gi0/0 10.0.0.17

20 10.255.255.2/32 0 Gi0/1 10.0.0.22

20 19 10.255.255.1/32 0 Gi0/0 10.0.0.17

23 24 10.0.0.8/30 0 Gi0/1 10.0.0.22

24 23 10.0.0.4/30 0 Gi0/0 10.0.0.17

25 24 10.0.0.0/30 0 Gi0/0 10.0.0.17

26 Pop Label 10.0.0.12/30 182 Gi0/0 10.0.0.17

27 Pop Label 10.255.255.4/32 0 Gi0/1 10.0.0.22

28 Pop Label 10.0.0.24/30 0 Gi0/1 10.0.0.22

29 29 10.255.255.44/32 702 Gi0/1 10.0.0.22

30 30 10.0.0.28/30 0 Gi0/1 10.0.0.22

P3#

WORK IN PROGRESS……..