QoS VoIP per Frame Relay su ATM Interworking con LLQ, PPP LFI e cRTP

Introduzione

In questo documento viene fornita una configurazione di esempio per la funzionalità Voice over IP con Multilink PPP su ATM e Frame Relay Interworking (VoIP con MLPoATM / MLPoFR). Gli esempi di configurazione sono incentrati sulla fornitura di Quality of Service (QoS) per supportare correttamente la voce su una WAN interconnessa ATM/Frame Relay. Gli esempi di configurazione usano anche il protocollo compressed Real Time Protocol (cRTP), supportato su ATM dal software Cisco IOS^® versione 12.2(2)T.

Il documento può essere letto come documento autonomo per le guide alla configurazione, gli esempi di configurazione e i comandi di verifica da utilizzare nella creazione della rete. Vengono inoltre fornite alcune informazioni preliminari per problemi specifici associati all'utilizzo dell'interoperabilità ATM/Frame Relay. Per ulteriori informazioni su QoS per VoIP su Frame Relay o PPP, consultare i seguenti documenti:

• Collegamenti VoIP over PPP con Quality of Service (priorità LLQ / IP RTP, LFI, cRTP)

• VoIP over Frame Relay con QoS (frammentazione, Traffic Shaping, priorità LLQ / IP RTP)

Prerequisiti

Requisiti

Prima di provare questa configurazione, accertarsi di soddisfare i seguenti requisiti:

È necessario avere familiarità con le seguenti aree tecnologiche:

• Access Control List

• Circuiti virtuali permanenti (PVC) ATM

• Circuiti virtuali permanenti Frame Relay (DLCI (Data-Link Connection Identifier))

• Gestione della larghezza di banda

• LLQ

• LFI

• Modelli virtuali e interfacce di accesso virtuale

• MLPPP

• cRTP

Componenti usati

Le informazioni fornite in questo documento si basano sulle seguenti versioni software e hardware:

• Cisco 3640 come router ATM

• Cisco 2620 come router Frame Relay

• Software Cisco IOS release 12.2(8)T (IP Plus)

Nota:  Come regola generale, l'ultima versione di manutenzione della linea principale di Cisco IOS 12.2 è la versione consigliata del software Cisco IOS da utilizzare per MLPoATM/FR. Il software Cisco IOS release 12.2T è richiesto sul router ATM se si usa cRTP.

Le funzionalità rilevanti sono state introdotte nelle seguenti versioni del software Cisco IOS:

• La tecnologia LFI è stata introdotta nel software Cisco IOS versione 11.3.

• LLQ è stato introdotto nel software Cisco IOS versione 12.0(7)T.

• LLQ su Frame Relay e ATM per PVC è stato introdotto nel software Cisco IOS versione 12.1(2)T.

• La funzionalità LFI di Multilink PPP per Frame Relay e circuiti virtuali ATM è stata introdotta nel software Cisco IOS versione 12.1(5)T.

• Il protocollo cRTP over ATM è stato introdotto nel software Cisco IOS versione 12.2(2)T.

Le informazioni discusse in questo documento fanno riferimento a dispositivi usati in uno specifico ambiente di emulazione. Su tutti i dispositivi menzionati nel documento la configurazione è stata ripristinata ai valori predefiniti. Se la rete è operativa, valutare attentamente eventuali conseguenze derivanti dall'uso dei comandi.

Convenzioni

Per ulteriori informazioni sulle convenzioni usate, consultare il documento Cisco sulle convenzioni nei suggerimenti tecnici.

Premesse

I problemi chiave per ridurre al minimo il ritardo end-to-end e l'eliminazione dell'effetto jitter per il VoIP su una rete interconnessa ATM/Frame Relay sono:

• Priorità rigida per il traffico vocale (LLQ (Low-Latency Queueing))

• Link Fragmentation and Interleaving (LFI)

• Frame Relay Traffic Shaping (FRTS) per voce

• Traffic Shaping ATM

Questi documenti forniscono utili fonti di ulteriori informazioni generali:

• Quality of Service per Voice over IP

• Configurazione della frammentazione e dell'interfoliazione del collegamento per Frame Relay e circuiti virtuali ATM

Configurazione

In questa sezione vengono presentate le informazioni necessarie per configurare le funzionalità descritte più avanti nel documento.

Nota: per ulteriori informazioni sui comandi menzionati in questo documento, usare lo strumento di ricerca dei comandi (solo utenti registrati).

Esempio di rete

Nel documento viene usata questa impostazione di rete:

Configurazioni

Nel documento vengono usate queste configurazioni:

• Frame Relay Connected Router

• Router connesso ATM

Nota: è importante notare che in questa configurazione, i due router sono connessi back-to-back su un Frame Relay a uno switch di interworking ATM. Nella maggior parte delle topologie, tuttavia, i router abilitati per la voce possono esistere ovunque. In genere, i router voce utilizzano la connettività LAN ad altri router, connessi a ATM/Frame WAN. In questi casi, i router connessi alla WAN, Frame Relay e ATM devono essere configurati per LLQ, LFI e MLPPP in modo da poter fornire il QoS e non i gateway voce, come mostrato in queste configurazioni.

!--- Note: This configuration is commented and numbered !--- in the order that commands should be entered.


version 12.2
service timestamps debug datetime msec
service timestamps log uptime
no service password-encryption
!
hostname FR
!
enable password cisco
!
username ATM password 0 cisco
voice-card 0
dspfarm
!
ip subnet-zero
!
!
!
!


!--- access-list 105 permit ip any any dscp ef specifies !--- that all traffic with Differentiated Services Code Point (DSCP) !--- are set to 40 falls into this access-list. !--- This class-map command defines a class of traffic called "voice". 

access-list 105 permit ip any any dscp ef 
access-list 105 permit udp any any  range 16384 32767
access-list 105 permit ip any any precedence critical
!
class-map match-all voice 
match access-group 105
!

!         
!

!--- This policy-map command defines a policy for LLQ called "VoIP" and !--- maps the "voice" class to the "VOIP" policy. !--- "priority" defines the amount of bandwidth reserved for the priority queue. !--- "class-default" specifies that the default class is also mapped to this policy. !--- "fair-queue" specifies that all other traffic is served in the WFQ.


policy-map VOIP 
  class voice 
    priority 48 
  class class-default  
   fair-queue 


!--- Note: Although it is possible to queue various types of !--- real-time traffic to the priority queue, !--- Cisco recommends that you direct only voice traffic !--- to it. Real-time traffic such as video or voice !--- could introduce variations in delay. Please note voice and !--- video should not be combined in the same PVC. !--- (the priority queue is a First In First Out (FIFO) !--- queue). Voice traffic requires that delay be !--- nonvariable in order to avoid jitter. !--- Note: The sum of the values for priority and !--- bandwidth statements needs to be less !--- than or equal to 75% of the link bandwidth. !--- Otherwise service-policy cannot be !--- assigned to the link. When configuring VoIP over a !--- 64 Kbps link to support two !--- voice calls, it is common to allocate more than 75% !--- (48 Kbps) of the link bandwidth to !--- the priority queue. In such cases, you can use the !--- max-reserved-bandwidth <#%> command in order to raise !--- available bandwidth to a value more than 75%.


!
!
!
fax interface-type fax-mail
mta receive maximum-recipients 0
!
interface Loopback0
 ip address 10.1.1.2 255.255.255.0
!
!
interface FastEthernet0/0
 ip address 172.17.111.16 255.255.255.224
 duplex auto
 speed auto
!
interface Serial0/0
 no ip address
 encapsulation frame-relay IETF
 no ip route-cache
 no ip mroute-cache
 frame-relay traffic-shaping
!

!--- Choose the frame relay interface to be !--- associated with the virtual interface. The !--- virtual template could equally have been associated !--- with the physical interface. !--- The "class mlp" associates the virtual template interface !--- defined in "interface Virtual-Template1" with a Frame Relay DLCI. !--- Associates a Frame Relay map class with a DLCI.


interface Serial0/0.1 point-to-point 
 no ip route-cache
 no ip mroute-cache
 frame-relay interface-dlci 16 ppp Virtual-Template1 
  class mlp 


!--- The interface command creates a virtual !--- template called Virtual-Template1. !--- A bandwidth of 64 Kbps is assigned to this !--- template interface. This bandwidth is used !--- by Cisco IOS to calculate the data fragment size as noted regarding !--- interleaving of PPP segments. !--- "ip rtp header-compression"—cRTP is supported in an ATM/Frame Relay Interworking !--- environment. It requires Cisco IOS Software Release 12.2(2)T on the !--- ATM router. !--- "service-policy output VOIP"—The VoIP policy created earlier is assigned !--- to this interface in the outbound direction. !--- PPP multilink is enabled and the !--- maximum delay per segment is specified. This bandwidth is !--- used by Cisco IOS to calculate the data fragement size as noted. !--- Interleaving of PPP segments is enabled, which allows !--- voice packets to be expedited. Voice !--- packets need only wait behind a single segment of !--- a previously queued data packet (for example, 10 ms !--- delay) rather than wait until the end of the !--- entire data packet. Cisco IOS calculates the !--- data fragment size using the following formula: !--- fragment size = delay x bandwidth/8

!
interface Virtual-Template1 
 bandwidth 64 
 ip unnumbered loopback0
 ip rtp header-compression 
 no ip route-cache
 load-interval 30
 max-reserved-bandwidth 99
 service-policy output VOIP 
 ppp multilink 
 ppp multilink fragment-delay 10 
 ppp multilink interleave 
!


!
ip classless
ip route 0.0.0.0 0.0.0.0 172.17.111.1
no ip http server
ip pim bidir-enable
!
!
!

!--- A map class called mlp is created. !--- With "no frame-relay adaptive-shaping", adaptive !--- shaping is disabled. You do not !--- want to exceed CIR and have voice packets !--- possibly queued within the Frame Relay network. !--- Waiting for a BECN to resolve this !--- situation could result in poor voice quality. !--- The frame-relay cir 64000 command forces the router to transmit !--- at the desired CIR rate rather than line !--- rate for the port. !--- "frame-relay bc 640" configures the Bc value to force the desired !--- Tc (shaping interval) value is 10 ms. !--- This formula should be used to determine !--- the Bc value to use: Tc = Bc/CIR. A !--- smaller Tc value reduces the interval a voice !--- packet has to wait to be sent. !--- As in "frame-relay be 0", the Be value should be set to zero !--- in order to avoid voice being sent as part of a burst !--- that is not guaranteed by the Frame Relay network.


map-class frame-relay mlp

 no frame-relay adaptive-shaping
 frame-relay cir 64000  
 frame-relay bc 640 
 frame-relay be 0 


!
call rsvp-sync
!
voice-port 1/0/0
!
voice-port 1/0/1
!
!
mgcp profile default
!
dial-peer cor custom
!
!
!
dial-peer voice 123 voip
 destination-pattern 123
 session target ipv4:10.1.1.1
 ip qos dscp cs5 media
 ip qos dscp cs5 signaling
 no vad
!
dial-peer voice 456 pots
 destination-pattern 456
 port 1/0/0
!
!
line con 0
line aux 0
line vty 0 4
 exec-timeout 0 0
 password cisco
 login
!
!
end

!--- Note: This configuration is commented only !--- where additional consideration is required from the !--- above configuration of the Frame Relay router.


version 12.2
service timestamps debug datetime msec
service timestamps log uptime
no service password-encryption
!
hostname ATM
!
enable password cisco
!
username FR password 0 cisco
memory-size iomem 25
ip subnet-zero
!
!
!
access-list 105 permit ip any any dscp ef
access-list 105 permit udp any any  range 16384 32767
access-list 105 permit ip any any precedence critical
!
class-map match-all voice
 match access-group 105
!
!

!--- Note: Matching commands to the Frame Relay !--- router side of the network.


!
!
policy-map VOIP
  class voice
    priority 48
  class class-default
   fair-queue


!--- Note: Matching commands to the Frame Relay !--- router side of the network.


!
!
fax interface-type fax-mail
mta receive maximum-recipients 0
!
controller T1 2/0
 framing sf
 linecode ami
!
!
!
!
interface ATM0/0
 no ip address
 ip route-cache
 no atm ilmi-keepalive
!

!--- "interface ATM0/0.1 point-to-point" chooses the ATM subinterface. !--- The physical interface could equally have been used. !--- "pvc 10/100" creates an ATM PVC. !--- "cbr 64"—A VBR PVC has been defined on this example. !--- This exapmle uses VBR non-realtime and the sustained !--- cell rate (SCR) should be equal to the peak !--- cell rate (PCR) in order to avoid bursting. !--- ATM cell tax and the possibility !--- of ATM bandwidth expansion due to poor !--- fragment/cell alignment, means that it !--- cannot be assumed that the PCR/SCR on the ATM !--- side should equal the CIR of the Frame Relay side. !--- Maintain the value of CIR on the Frame-Relay side to define !--- our SCR, in this case, 64 kbps. This value may in some networks !--- require some fine-tuning as the CIR on the Frame side does not !--- exactly match the SCR on the ATM but makes for a good-enough estimation !--- for most purposes. !--- Refer to Designing and Deploying !--- Multilink PPP over Frame Relay and ATM !--- for more information. !--- "encapsulation aal5snap" is required. !--- "protocol ppp Virtual-Template1" associates the virtual !--- template with the ATM PVC.


interface ATM0/0.1 point-to-point
 ip route-cache
 pvc 10/100 
  cbr 64 
  encapsulation aal5snap 
  protocol ppp Virtual-Template1 


!
!
interface loopback0
 ip address 10.1.1.1 255.255.255.0
!
interface Ethernet3/0
 ip address 172.17.111.15 255.255.255.224
 half-duplex
!
interface Ethernet3/1
 no ip address
 shutdown
 half-duplex
!
interface Virtual-Template1
 bandwidth 64
 ip unnumbered loopback0
 ip rtp header-compression
 no ip route-cache
 load-interval 30
 max-reserved-bandwidth 99
 service-policy output VOIP
 ppp multilink
 ppp multilink fragment-delay 10
 ppp multilink interleave


!--- Note: The virtual template is created in !--- exactly the same way as for the !--- Frame Relay router side of the network. !--- An additional consideration for !--- the ATM router is that the fragment size !--- should be optimized to fit into !--- an integral number of ATM cells. !--- Refer to Designing and Deploying !--- Multilink PPP over Frame Relay and ATM !--- for more information on this issue.


!
ip classless
ip route 0.0.0.0 0.0.0.0 172.17.111.1
ip http server
ip pim bidir-enable
!
!
call rsvp-sync
!
voice-port 1/0/0
 description FXS
!
voice-port 1/0/1
!
voice-port 1/1/0
 description FXO
!
voice-port 1/1/1
!
!
mgcp profile default
!
dial-peer cor custom
!
!
!
dial-peer voice 456 voip
 destination-pattern 456
 session target ipv4:10.1.1.2
 ip qos dscp cs5 media
 ip qos dscp cs5 signaling
 no vad   
!
dial-peer voice 123 pots
 destination-pattern 123
 port 1/1/0
!
!
line con 0
line aux 0
line vty 0 4
 exec-timeout 0 0
 password cisco
 login
!
!
end

Verifica

Per verificare che la configurazione funzioni correttamente, consultare questa sezione.

Lo strumento Output Interpreter (solo utenti registrati) (OIT) supporta alcuni comandi show. Usare l'OIT per visualizzare un'analisi dell'output del comando show.

I comandi show sono utili per verificare lo stato operativo dell'ambiente di interworking ATM/Frame Relay, che include statistiche DLCI e PVC, lo stato dell'interfaccia fisica e virtuale, l'applicazione QoS (Policy) e informazioni cRTP:

• show ppp multilink interface interface-name: verifica se il bundle è attivo/inattivo, quale interfaccia di accesso virtuale è il bundle (bundle MLPPP) e quali sono i membri (collegamento PPP). Questo comando verifica anche se il vettore rilascia celle/fotogrammi (frammenti persi <> 0). L'unica perdita accettabile è causata da errori CRC (Cyclic Redundancy Check).

• show user: visualizza il numero associato all'interfaccia di accesso virtuale. È possibile utilizzare le informazioni di questo comando o del comando show ppp multilink per visualizzare le statistiche sull'interfaccia o cancellare il contenuto dell'interfaccia.

• show frame-relay pvc dlci: visualizza informazioni quali parametri di traffic shaping, valori di frammentazione e pacchetti ignorati. Questo comando mostra anche se l'interfaccia fisica è stata associata all'interfaccia virtuale.

• show atm pvc pvc: visualizza tutti i PVC ATM attivi e le informazioni sul traffico.

• show policy-map interface interface-name: visualizza tutte le operazioni LLQ e le interruzioni nel PQ. Per ulteriori informazioni sui vari campi del comando show policy-map interface, consultare il documento sulla descrizione dei contatori dei pacchetti nell'output del comando show policy-map interface.

  Nota: l'accodamento fantasia viene sempre applicato all'interfaccia virtual-access2. Le altre interfacce utilizzano l'accodamento FIFO.

• show ip rtp header-compression: visualizza le statistiche di compressione dell'intestazione RTP, se configurate. Le statistiche sono collegate all'interfaccia virtual-access2, che è l'interfaccia del bundle.

Di seguito sono riportati alcuni esempi di questi comandi:

FR#show ppp multilink interface virtual-access 2
Virtual-Access2, bundle name is ATM
Bundle up for 00:22:42
0 lost fragments, 0 reordered, 0 unassigned
0 discarded, 0 lost received, 231/255 load
0x2E5 received sequence, 0x10C31 sent sequence
Member links: 1 (max not set, min not set)
Virtual-Access1, since 00:22:42, last rcvd seq 0002E4 160 weight

Questo output visualizza il comando show users sul router Frame Relay.

FR#show users
Line User Host(s) Idle Location
67 vty 1 idle 00:00:00 10.1.1.1
Interface User Mode Idle Peer Address
Vi1 Virtual PPP (FR ) - 
Vi2 Virtual PPP (Bundle) 00:00:00 10.1.1.1
FR#

Questo output visualizza il comando show users sul router ATM.

ATM#show users 
Line User Host(s) Idle Location
131 vty 1 idle 00:00:00 64.104.207.95
Interface User Mode Idle Peer Address
Vi1 Virtual PPP (ATM ) - 
Vi2 Virtual PPP (Bundle) 00:00:02 10.1.1.2
ATM#

Questo output mostra il comando show frame-relay pvc.

FR#show frame-relay pvc 16
 PVC Statistics for interface Serial0/0 (Frame Relay DTE)
 DLCI = 16, DLCI USAGE = LOCAL, PVC STATUS = ACTIVE, INTERFACE = Serial0/0.1
  
     input pkts 2301 output pkts 2295 in bytes 152266 
     out bytes 151891 dropped pkts 0 in FECN pkts 0 
     in BECN pkts 0 out FECN pkts 0 out BECN pkts 0 
     in DE pkts 0 out DE pkts 0 
     out bcast pkts 0 out bcast bytes 0 
     5 minute input rate 9000 bits/sec, 9 packets/sec
     5 minute output rate 9000 bits/sec, 9 packets/sec
     pvc create time 23:46:56, last time pvc status changed 00:22:56
     Bound to Virtual-Access1 (up, cloned from Virtual-Template1) 
     
!--- PPP link interface.

     cir 64000 bc 640 be 0 byte limit 80 interval 10 
     mincir 64000 byte increment 80 Adaptive Shaping none
     pkts 2296 bytes 152053 pkts delayed 9 bytes delayed 375
     shaping active 
     traffic shaping drops 0
     Queueing strategy: fifo
     Output queue 0/40, 0 drop, 0 dequeued
FR#

In questo output viene mostrato il comando show atm pvc 10/100 sul router ATM.

ATM#show atm pvc 10/100 
     ATM0/0.1: VCD: 1, VPI: 10, VCI: 100
     CBR, SusRate: 128
     AAL5-LLC/SNAP, etype:0x0, Flags: 0x820, VCmode: 0x0
     OAM frequency: 0 second(s), OAM retry frequency: 1 second(s)
     OAM up retry count: 3, OAM down retry count: 5
     OAM Loopback status: OAM Disabled
     OAM VC state: Not Managed
     ILMI VC state: Not Managed
     InARP frequency: 15 minutes(s)
     Transmit priority 1
     InPkts: 729, OutPkts: 729, InBytes: 49700, OutBytes: 51158
     InPRoc: 0, OutPRoc: 729
     InFast: 729, OutFast: 0, InAS: 0, OutAS: 0
     InPktDrops: 0, OutPktDrops: 0/0/0 (holdq/outputq/total)
     CrcErrors: 0, SarTimeOuts: 0, OverSizedSDUs: 0, LengthViolation: 0, 
     CPIErrors: 0
     OAM cells received: 0
     F5 InEndloop: 0, F5 InSegloop: 0, F5 InAIS: 0, F5 InRDI: 0
     F4 InEndloop: 0, F4 InSegloop: 0, F4 InAIS: 0, F4 InRDI: 0
     OAM cells sent: 0
     F5 OutEndloop: 0, F5 OutSegloop: 0, F5 OutRDI: 0
     F4 OutEndloop: 0, F4 OutSegloop: 0, F4 OutRDI: 0
     OAM cell drops: 0
     Status: UP
   PPP: Virtual-Access2 from Virtual-Template1 
    
!--- MLPPP bundle interface.

ATM#

Questa è la procedura show policy-map sul router Frame Relay.

FR#show policy-map interface Virtual-Access2
Service-policy output: VoIP
Class-map: voice (match-all)
15483 packets, 959502 bytes
30 second offered rate 24000 bps, drop rate 0 bps
Match: ip dscp 40 
Weighted Fair Queueing 
Strict Priority 

!--- LLQ Strict Priority Queue for voice.

Output Queue: Conversation 24 
Bandwidth 48(kbps) Burst 1500 (Bytes)
(pkts matched/bytes matched) 15536/962784
(total drops/bytes drops) 0/0 

!--- No drops in the voice queue.

Class-map: class-default (match-any)
139 packets, 19481 bytes
30 second offered rate 1000 bps, drop rate 0 bps
Match: any 
Weighted Fair Queueing
Flow Based Fair Queueing
Maximum Number of Hashed Queues 16 
(total queued/total drops/no-buffer drops) 0/0/0

Questo output mostra il comando show policy map sul router ATM.

ATM#show policy-map interface Virtual-Access2 
Service-policy output: VOIP
Class-map: voice (match-all)
11293 packets, 699718 bytes
30 second offered rate 24000 bps, drop rate 0 bps
Match: ip dscp 40 
Weighted Fair Queueing
Strict Priority 

!--- LLQ Strict Priority Queue for voice.

Output Queue: Conversation 24 
Bandwidth 48 (kbps) Burst 1500 (Bytes)
(pkts matched/bytes matched) 11352/703376
(total drops/bytes drops) 0/0 

!--- No drops in the voice queue.

Class-map: class-default (match-any)
63 packets, 9772 bytes
30 second offered rate 0 bps, drop rate 0 bps
Match: any 
Weighted Fair Queueing
Flow Based Fair Queueing
Maximum Number of Hashed Queues 16 
(total queued/total drops/no-buffer drops) 0/0/0
ATM#

Questo output mostra il comando show ip rtp header-compression sul router Frame Relay.

FR#show ip rtp header-compression
RTP/UDP/IP header compression statistics:
Interface Virtual-Access1:
Rcvd: 0 total, 0 compressed, 0 errors
0 dropped, 0 buffer copies, 0 buffer failures
Sent: 0 total, 0 compressed,
0 bytes saved, 0 bytes sent
Connect: 16 rx slots, 16 tx slots,
0 long searches, 0 misses 0 collisions

Interface Virtual-Template1:
Rcvd: 0 total, 0 compressed, 0 errors
0 dropped, 0 buffer copies, 0 buffer failures
Sent: 0 total, 0 compressed,
0 bytes saved, 0 bytes sent
Connect: 16 rx slots, 16 tx slots,
0 long searches, 0 misses 0 collisions

Interface Virtual-Access2:
Rcvd: 23682 total, 23681 compressed, 0 errors
0 dropped, 0 buffer copies, 0 buffer failures
Sent: 327 total, 233 compressed,
8821 bytes saved, 5159 bytes sent
2.70 efficiency improvement factor
Connect: 16 rx slots, 16 tx slots,
0 long searches, 94 misses 0 collisions
71% hit ratio, five minute miss rate 0 misses/sec, 0 max

Questo output mostra il comando show ip rtp header-compression sul router ATM.

ATM#show ip rtp header-compression
RTP/UDP/IP header compression statistics:
Interface Virtual-Access1:
Rcvd: 0 total, 0 compressed, 0 errors
0 dropped, 0 buffer copies, 0 buffer failures
Sent: 0 total, 0 compressed,
0 bytes saved, 0 bytes sent
Connect: 16 rx slots, 16 tx slots,
0 long searches, 0 misses 0 collisions, 0 negative cache hits

Interface Virtual-Template1:
Rcvd: 0 total, 0 compressed, 0 errors
0 dropped, 0 buffer copies, 0 buffer failures
Sent: 0 total, 0 compressed,
0 bytes saved, 0 bytes sent
Connect: 16 rx slots, 16 tx slots,
0 long searches, 0 misses 0 collisions, 0 negative cache hits

Interface Virtual-Access2:
Rcvd: 283 total, 233 compressed, 0 errors
0 dropped, 0 buffer copies, 0 buffer failures
Sent: 25341 total, 25340 compressed,
955537 bytes saved, 564463 bytes sent
2.69 efficiency improvement factor
Connect: 16 rx slots, 16 tx slots,
0 long searches, 1 misses 0 collisions, 100 negative cache hits
99% hit ratio, five minute miss rate 0 misses/sec, 0 max

Risoluzione dei problemi

Consultare questa sezione per risolvere i problemi di configurazione.

In questa sezione vengono forniti alcuni debug di esempio per chiarire la configurazione LFI di MLP e come esempi pratici per risolvere i problemi relativi alla configurazione.

Comandi per la risoluzione dei problemi

Lo strumento Output Interpreter (solo utenti registrati) (OIT) supporta alcuni comandi show. Usare l'OIT per visualizzare un'analisi dell'output del comando show.

Nota: consultare le informazioni importanti sui comandi di debug prima di usare i comandi di debug.

• debug ppp negotiation: illustra il processo di duplicazione delle due interfacce di accesso virtuale per rappresentare i collegamenti del bundle PPP e PPP. L'interfaccia di accesso virtuale 1 (Vi1) è il collegamento PPP a cui è associato il PVC (ATM o frame). L'interfaccia virtuale 2 (Vi2) è il collegamento al bundle PPP a cui sono allegati i criteri di coda.

• debug ppp multilink fragment: illustra il concetto di pacchetti di dati più grandi da interfogliare con pacchetti voce più piccoli. L'interfoliazione si verifica sull'interfaccia Vi2 (livello MLP) poiché all'interfaccia del bundle è stata assegnata una coda elaborata.

Questo è l'output del comando debug ppp negotiation.

FR(config-if)#no shut
FR(config-if)#^Z
FR#
FR#
6d23h: %LINK-3-UPDOWN: Interface Virtual-Access1, changed state to up
*Mar 7 23:20:42.842: Vi1 PPP: Treating connection as 
a dedicated line 

!--- Vi1 is the PPP link to which the PVC is bound.

*Mar 7 23:20:42.842: Vi1 PPP: Phase is ESTABLISHING, Active Open
*Mar 7 23:20:42.842: Vi1 LCP: O CONFREQ [Closed] id 197 len 19
*Mar 7 23:20:42.842: Vi1 LCP: MagicNumber 0xF44128D2 (0x0506F44128D2)
*Mar 7 23:20:42.842: Vi1 LCP: MRRU 1524 (0x110405F4)
*Mar 7 23:20:42.842: Vi1 LCP: EndpointDisc 1 FR (0x1305014652) 

!--- Router FR at one end of PPP discovery.

*Mar 7 23:20:42.858: Vi1 LCP: I CONFREQ [REQsent] id 14 len 20
*Mar 7 23:20:42.858: Vi1 LCP: MagicNumber 0x294819D4 (0x0506294819D4)
*Mar 7 23:20:42.858: Vi1 LCP: MRRU 1524 (0x110405F4)
*Mar 7 23:20:42.858: Vi1 LCP: EndpointDisc 1 ATM (0x13060141544D) 

!--- Router ATM at the other end of PPP discovery.

*Mar 7 23:20:42.858: Vi1 LCP: O CONFACK [REQsent] id 14 len 20

*Mar 7 23:20:42.862: Vi1 LCP: MagicNumber 0x294819D4 (0x0506294819D4)
*Mar 7 23:20:42.862: Vi1 LCP: MRRU 1524 (0x110405F4)
*Mar 7 23:20:42.862: Vi1 LCP: EndpointDisc 1 ATM (0x13060141544D)
*Mar 7 23:20:42.870: Vi1 LCP: I CONFACK [ACKsent] id 197 len 19
*Mar 7 23:20:42.870: Vi1 LCP: MagicNumber 0xF44128D2 (0x0506F44128D2)
*Mar 7 23:20:42.870: Vi1 LCP: MRRU 1524 (0x110405F4)
*Mar 7 23:20:42.870: Vi1 LCP: EndpointDisc 1 FR (0x1305014652)
*Mar 7 23:20:42.870: Vi1 LCP: State is Open
*Mar 7 23:20:42.870: Vi1 PPP: Phase is FORWARDING, Attempting Forward
*Mar 7 23:20:42.874: Vi1 PPP: Phase is ESTABLISHING, Finish LCP
*Mar 7 23:20:42.874: Vi1 PPP: Phase is VIRTUALIZED
*Mar 7 23:20:42.942: Vi2 PPP: Phase is DOWN, Setup
*Mar 7 23:20:43.222: Vi1 IPCP: Packet buffered while building MLP bundle interface
6d23h: %LINK-3-UPDOWN: Interface Virtual-Access2, changed state to up 

!--- MLP level queuing.

*Mar 7 23:20:43.226: Vi2 PPP: Treating connection as a dedicated line
*Mar 7 23:20:43.226: Vi2 PPP: Phase is ESTABLISHING, Active Open
*Mar 7 23:20:43.226: Vi2 LCP: O CONFREQ [Closed] id 1 len 19
*Mar 7 23:20:43.226: Vi2 LCP: MagicNumber 0xF4412A53 (0x0506F4412A53)
*Mar 7 23:20:43.226: Vi2 LCP: MRRU 1524 (0x110405F4)
*Mar 7 23:20:43.230: Vi2 LCP: EndpointDisc 1 FR (0x1305014652)
*Mar 7 23:20:43.230: Vi2 MLP: 
Added first link Vi1 to bundle ATM 

!--- PVCs make up the bundle.

*Mar 7 23:20:43.230: Vi2 PPP: Phase is UP
*Mar 7 23:20:43.230: Vi2 IPCP: O CONFREQ [Closed] id 1 len 10
*Mar 7 23:20:43.234: Vi2 IPCP: Address 10.1.1.2 (0x03060A010102)
*Mar 7 23:20:43.234: Vi2 PPP: Pending ncpQ size is 1
*Mar 7 23:20:43.234: Vi1 IPCP: Redirect packet to Vi1
*Mar 7 23:20:43.234: Vi2 IPCP: I CONFREQ [REQsent] id 1 len 10
*Mar 7 23:20:43.234: Vi2 IPCP: Address 10.1.1.1 (0x03060A010101)
*Mar 7 23:20:43.234: Vi2 IPCP: O CONFACK [REQsent] id 1 len 10
*Mar 7 23:20:43.234: Vi2 IPCP: Address 10.1.1.1 (0x03060A010101)
*Mar 7 23:20:43.266: Vi2 IPCP: I CONFACK [ACKsent] id 1 len 10
*Mar 7 23:20:43.266: Vi2 IPCP: Address 10.1.1.2 (0x03060A010102)
*Mar 7 23:20:43.266: Vi2 IPCP: State is Open
*Mar 7 23:20:43.266: Vi2 IPCP: Install route to 10.1.1.1
*Mar 7 23:20:43.270: Vi2 IPCP: Add link info for cef entry 10.1.1.1

Questo output del comando è il comando debug ppp multilink fragment.

*Mar 7 23:16:08.034: Vi2 MLP: 
Packet interleaved from queue 24
*Mar 7 23:16:08.038: Vi1 MLP: O ppp UNKNOWN(0x0000) (0000) size 64 
*Mar 7 23:16:08.038: Vi2 MLP: Packet interleaved from queue 24
*Mar 7 23:16:08.038: Vi1 MLP: O ppp UNKNOWN(0x0000) (0000) size 64 
*Mar 7 23:16:08.038: Vi2 MLP: Packet interleaved from queue 24
*Mar 7 23:16:08.038: Vi1 MLP: O ppp UNKNOWN(0x0000) (0000) size 64 
*Mar 7 23:16:08.038: Vi1 MLP: O frag 0000829B size 160 
*Mar 7 23:16:08.042: Vi1 MLP: I ppp IP (0021) size 64 direct
*Mar 7 23:16:08.046: Vi1 MLP: I ppp IP (0021) size 64 direct

Informazioni correlate

• Progettazione e distribuzione di Multilink PPP su Frame Relay e ATM
• Collegamenti VoIP over PPP con Quality of Service (priorità LLQ / IP RTP, LFI, cRTP)
• VoIP over Frame Relay con QoS (frammentazione, Traffic Shaping, priorità LLQ / IP RTP)
• Supporto alla tecnologia vocale
• Supporto ai prodotti voce e Unified Communications
• Risoluzione dei problemi di Cisco IP Telephony
• Documentazione e supporto tecnico – Cisco Systems