CiscoForums.it

Salve a tutti,
mi sono appena avvicinato al mondo cisco con l'acquisto di un router 857, ma sfortunatamentte ho già dei problemi.
premetto che ho utilizzato SDM aggiornato alla ultima versione per la configurazione del router che in un primo momento sembrava funzionare benissimo.
Poi mi sono accorto che nel momento in cui volevo inviare delle e-mail con degli allegati qualsiasi queste nn riuscivano a partire, a differenza di piccole email di solo testo.
Altro problema è che non riuscivo neanche a effettuare l'invio della posta da browser, tipo g-mail, alice etc.. in sostanza blocco totale nel momento dell'upload.
La cosa strana è che in ricezione non ho nessun problema.
Ora spulciando nel forum ho trovato questo post
http://www.ciscoforums.it/viewtopic.php ... sc&start=0
che descrive il mioi stesso problema.
Infatti impostando il parametro MTU a 1452 al posto di 1500 sul mio MAC tutto funziona apparentemente.
Il problema è che sugli altri computer delle mia rete...MAC e PC non si è risolto nulla.
Ora come posso portare a 1500 l'MTU del Cisco, con SDM se si può, e per entrambe le interfacce???
Perchè prima non avevo questo problema e ora si... ?
Potrebbe essere il firewall???

Grazie per l'aiuto

Da SDM sinceramente non saprei ma da cli:

Se ho capito bene i primi 2 comandi mi impostano l'MTU dell'interfaccia ATM a 1500, ma il 3°, non essendoci il parametro MTU per le vLAN (sempre da quello che ho capito) cosa fà??

Scusate la mia ignoranza in merito, ma per usare i comandi CLI
inizio una sessione TElnet, metto log e pass.. e poi scrivo direttamente il codice che mi hai suggerito??

grazie tante per l'aiuto

user
pass
ena
conf t

Poi metti i comandi che ti ho dati.

Il terzo comando datermina la grandezza massima del campo dati del paccheto.

e la grandezza massima del pacchetto TCP non dovrebbe essere anche qui 1500? come per le altre interfacce?

Comunque proverò subito GRAZIE

e la grandezza massima del pacchetto TCP non dovrebbe essere anche qui 1500? come per le altre interfacce?

Non è la grandezza del pacchetto totale ma solo la grandezza del campo dati senza gli header e co.

Niente da fare, il problema rimane appena reimposto l'MTU della scheda di rete in automatico cioè a 1500..

questa è la configurazione dopo i comandi che mi hai suggerito :


Building configuration...

Current configuration : 14658 bytes
!
version 12.3
no service pad
service tcp-keepalives-in
service tcp-keepalives-out
service timestamps debug datetime msec localtime show-timezone
service timestamps log datetime msec localtime show-timezone
service password-encryption
service sequence-numbers
!
hostname CiscoRouter
!
boot-start-marker
boot-end-marker
!
logging buffered 51200 debugging
logging console critical
enable secret 5 $1$SA5t$fIs/MSsR.V5M2a6HUXYjV/
!
username xxxx privilege 15 secret 5 $1$Z7xK$nVc.Gte2Q9Ti8qEHsRTxK.
username xxxxx privilege 15 secret 5 $1$C2MG$vnJ8cCwj3tZ2p7k9VkQ32/
clock timezone PCTime 1
clock summer-time PCTime date Mar 30 2003 2:00 Oct 26 2003 3:00
aaa new-model
!
!
aaa authentication login default local
aaa authentication login sdm_vpn_xauth_ml_1 local
aaa authentication login sdm_vpn_xauth_ml_2 local
aaa authorization exec default local
aaa authorization network sdm_vpn_group_ml_1 local
aaa authorization network sdm_vpn_group_ml_2 local
aaa session-id common
ip subnet-zero
no ip source-route
ip dhcp excluded-address 192.168.0.1 192.168.0.99
ip dhcp excluded-address 192.168.0.254
!
ip dhcp pool sdm-pool1
import all
network 192.168.0.0 255.255.255.0
dns-server 212.247.156.66 212.247.156.70
default-router 192.168.0.254
!
!
ip cef
ip inspect name DEFAULT100 cuseeme
ip inspect name DEFAULT100 ftp
ip inspect name DEFAULT100 h323
ip inspect name DEFAULT100 icmp
ip inspect name DEFAULT100 rcmd
ip inspect name DEFAULT100 realaudio
ip inspect name DEFAULT100 rtsp
ip inspect name DEFAULT100 sqlnet
ip inspect name DEFAULT100 streamworks
ip inspect name DEFAULT100 tftp
ip inspect name DEFAULT100 tcp
ip inspect name DEFAULT100 udp
ip inspect name DEFAULT100 vdolive
ip inspect name SDM_LOW cuseeme
ip inspect name SDM_LOW ftp
ip inspect name SDM_LOW h323
ip inspect name SDM_LOW icmp
ip inspect name SDM_LOW rcmd
ip inspect name SDM_LOW realaudio
ip inspect name SDM_LOW rtsp
ip inspect name SDM_LOW esmtp
ip inspect name SDM_LOW sqlnet
ip inspect name SDM_LOW streamworks
ip inspect name SDM_LOW tftp
ip inspect name SDM_LOW tcp
ip inspect name SDM_LOW udp
ip inspect name SDM_LOW vdolive
ip tcp synwait-time 10
no ip bootp server
ip domain name netvin
ip name-server 212.247.156.66
ip name-server 212.247.156.70
ip ssh time-out 60
ip ssh authentication-retries 2
no ftp-server write-enable
!
!
!
!
!
crypto isakmp policy 1
encr 3des
authentication pre-share
group 2
crypto isakmp xauth timeout 15

!
crypto isakmp client configuration group xxxx
key xxxx.vpn
dns 212.247.156.66 212.247.156.70
pool SDM_POOL_1
max-users 1
netmask 255.255.255.0
!
!
crypto ipsec transform-set ESP-3DES-SHA esp-3des esp-sha-hmac
!
crypto dynamic-map SDM_DYNMAP_1 1
set security-association idle-time 600
set transform-set ESP-3DES-SHA
reverse-route
!
!
crypto map SDM_CMAP_1 client authentication list sdm_vpn_xauth_ml_2
crypto map SDM_CMAP_1 isakmp authorization list sdm_vpn_group_ml_2
crypto map SDM_CMAP_1 client configuration address respond
crypto map SDM_CMAP_1 65535 ipsec-isakmp dynamic SDM_DYNMAP_1
!
!
!
interface ATM0
mtu 1500
no ip address
no ip redirects
no ip unreachables
no ip proxy-arp
ip route-cache flow
no atm ilmi-keepalive
dsl operating-mode auto
!
interface ATM0.1 point-to-point
description $ES_WAN$$FW_OUTSIDE$
mtu 1500
pvc 8/35
pppoe-client dial-pool-number 1
!
!
interface FastEthernet0
no ip address
no cdp enable
!
interface FastEthernet1
no ip address
no cdp enable
!
interface FastEthernet2
no ip address
no cdp enable
!
interface FastEthernet3
no ip address
no cdp enable
!
interface Vlan1
description $ETH-SW-LAUNCH$$INTF-INFO-HWIC 4ESW$$ES_LAN$$FW_INSIDE$
ip address 192.168.0.254 255.255.255.0
ip access-group 103 in
no ip redirects
no ip unreachables
no ip proxy-arp
ip nat inside
ip virtual-reassembly
ip route-cache flow
ip tcp adjust-mss 1452
!
interface Dialer0
description $FW_OUTSIDE$
ip address negotiated
ip access-group 104 in
ip access-group sdm_dialer0_out out
no ip redirects
no ip unreachables
no ip proxy-arp
ip mtu 1452
ip inspect SDM_LOW out
ip nat outside
ip virtual-reassembly
encapsulation ppp
ip route-cache flow
dialer pool 1
dialer-group 1
no cdp enable
ppp authentication chap pap callin
ppp chap hostname [email protected]
ppp chap password 7 02100D550803013B1C
ppp pap sent-username [email protected] password 7 02100D550803013B1C
crypto map SDM_CMAP_1
!
ip local pool SDM_POOL_1 192.168.0.50 192.168.0.99
ip classless
ip route 0.0.0.0 0.0.0.0 Dialer0
!
ip http server
ip http authentication local
ip http secure-server
ip http timeout-policy idle 5 life 86400 requests 10000
ip nat pool Vin 192.168.0.1 192.168.0.253 netmask 255.255.255.0
ip nat inside source static tcp 192.168.0.50 4242 interface Dialer0 4242
ip nat inside source route-map SDM_RMAP_1 interface Dialer0 overload
ip nat inside source static tcp 192.168.0.50 4660 interface Dialer0 4660
ip nat inside source static tcp 192.168.0.50 6881 interface Dialer0 6881
ip nat inside source static tcp 192.168.0.50 1720 interface Dialer0 1720
ip nat inside source static udp 192.168.0.50 1720 interface Dialer0 1720
ip nat outside source list 1 pool Vin
!
ip access-list extended sdm_dialer0_out
remark SDM_ACL Category=1
permit ip any any
permit udp any any
permit tcp any any
!
logging trap debugging
access-list 1 remark INSIDE_IF=Vlan1
access-list 1 remark SDM_ACL Category=2
access-list 1 permit 192.168.0.0 0.0.0.255
access-list 100 remark auto-generated by Cisco SDM Express firewall configuration
access-list 100 remark SDM_ACL Category=1
access-list 100 deny ip host 255.255.255.255 any
access-list 100 deny ip 127.0.0.0 0.255.255.255 any
access-list 100 permit ip any any
access-list 100 remark pop3
access-list 100 permit tcp any eq pop3 any
access-list 100 remark smtp
access-list 100 permit tcp any eq smtp any
access-list 100 remark posta
access-list 100 permit tcp any eq 587 any
access-list 100 remark posta
access-list 100 permit tcp any eq 995 any
access-list 100 remark skype
access-list 100 permit tcp any eq 53800 any
access-list 100 remark skype
access-list 100 permit udp any eq 53800 any
access-list 100 remark azureus
access-list 100 permit tcp any eq 6881 any
access-list 100 remark azureus
access-list 100 permit udp any eq 6881 any
access-list 100 remark amule
access-list 100 permit tcp any range 4660 4662 any range 4660 4662
access-list 100 remark smtp
access-list 100 permit tcp any eq smtp any eq smtp
access-list 101 remark auto-generated by Cisco SDM Express firewall configuration
access-list 101 remark SDM_ACL Category=1
access-list 101 permit udp any any eq 1720
access-list 101 permit tcp any any eq 1720
access-list 101 permit tcp any any eq 6881
access-list 101 permit tcp any any eq 4240
access-list 101 permit tcp any any eq 4660
access-list 101 permit ip host 192.168.0.1 any
access-list 101 permit ip host 192.168.0.2 any
access-list 101 permit ip host 192.168.0.3 any
access-list 101 permit ip host 192.168.0.50 any
access-list 101 permit ip host 192.168.0.51 any
access-list 101 permit ip host 192.168.0.52 any
access-list 101 permit ip host 192.168.0.53 any
access-list 101 permit ip host 192.168.0.54 any
access-list 101 permit ip host 192.168.0.55 any
access-list 101 permit ip host 192.168.0.56 any
access-list 101 permit ip host 192.168.0.57 any
access-list 101 permit ip host 192.168.0.58 any
access-list 101 permit ip host 192.168.0.59 any
access-list 101 permit ip host 192.168.0.60 any
access-list 101 permit ip host 192.168.0.61 any
access-list 101 permit ip host 192.168.0.62 any
access-list 101 permit ip host 192.168.0.63 any
access-list 101 permit ip host 192.168.0.64 any
access-list 101 permit ip host 192.168.0.65 any
access-list 101 permit ip host 192.168.0.66 any
access-list 101 permit ip host 192.168.0.67 any
access-list 101 permit ip host 192.168.0.68 any
access-list 101 permit ip host 192.168.0.69 any
access-list 101 permit ip host 192.168.0.70 any
access-list 101 permit ip host 192.168.0.71 any
access-list 101 permit ip host 192.168.0.72 any
access-list 101 permit ip host 192.168.0.73 any
access-list 101 permit ip host 192.168.0.74 any
access-list 101 permit ip host 192.168.0.75 any
access-list 101 permit ip host 192.168.0.76 any
access-list 101 permit ip host 192.168.0.77 any
access-list 101 permit ip host 192.168.0.78 any
access-list 101 permit ip host 192.168.0.79 any
access-list 101 permit ip host 192.168.0.80 any
access-list 101 permit ip host 192.168.0.81 any
access-list 101 permit ip host 192.168.0.82 any
access-list 101 permit ip host 192.168.0.83 any
access-list 101 permit ip host 192.168.0.84 any
access-list 101 permit ip host 192.168.0.85 any
access-list 101 permit ip host 192.168.0.86 any
access-list 101 permit ip host 192.168.0.87 any
access-list 101 permit ip host 192.168.0.88 any
access-list 101 permit ip host 192.168.0.89 any
access-list 101 permit ip host 192.168.0.90 any
access-list 101 permit ip host 192.168.0.91 any
access-list 101 permit ip host 192.168.0.92 any
access-list 101 permit ip host 192.168.0.93 any
access-list 101 permit ip host 192.168.0.94 any
access-list 101 permit ip host 192.168.0.95 any
access-list 101 permit ip host 192.168.0.96 any
access-list 101 permit ip host 192.168.0.97 any
access-list 101 permit ip host 192.168.0.98 any
access-list 101 permit ip host 192.168.0.99 any
access-list 101 permit udp any any eq non500-isakmp
access-list 101 permit udp any any eq isakmp
access-list 101 permit esp any any
access-list 101 permit ahp any any
access-list 101 permit udp host 212.247.156.70 eq domain any
access-list 101 permit udp host 212.247.156.66 eq domain any
access-list 101 permit icmp any any echo-reply
access-list 101 permit icmp any any time-exceeded
access-list 101 permit icmp any any unreachable
access-list 101 remark smtp
access-list 101 permit tcp any eq smtp any eq smtp
access-list 101 permit tcp any eq pop3 any eq pop3
access-list 101 remark skype
access-list 101 permit tcp any eq 53800 any eq 53800
access-list 101 remark ssl
access-list 101 permit tcp any eq 995 any eq 995
access-list 101 remark amule
access-list 101 permit tcp any range 4660 4662 any range 4660 4662
access-list 101 deny ip any any
access-list 102 remark SDM_ACL Category=2
access-list 102 deny ip any host 192.168.0.50
access-list 102 deny ip any host 192.168.0.51
access-list 102 deny ip any host 192.168.0.52
access-list 102 deny ip any host 192.168.0.53
access-list 102 deny ip any host 192.168.0.54
access-list 102 deny ip any host 192.168.0.55
access-list 102 deny ip any host 192.168.0.56
access-list 102 deny ip any host 192.168.0.57
access-list 102 deny ip any host 192.168.0.58
access-list 102 deny ip any host 192.168.0.59
access-list 102 deny ip any host 192.168.0.60
access-list 102 deny ip any host 192.168.0.61
access-list 102 deny ip any host 192.168.0.62
access-list 102 deny ip any host 192.168.0.63
access-list 102 deny ip any host 192.168.0.64
access-list 102 deny ip any host 192.168.0.65
access-list 102 deny ip any host 192.168.0.66
access-list 102 deny ip any host 192.168.0.67
access-list 102 deny ip any host 192.168.0.68
access-list 102 deny ip any host 192.168.0.69
access-list 102 deny ip any host 192.168.0.70
access-list 102 deny ip any host 192.168.0.71
access-list 102 deny ip any host 192.168.0.72
access-list 102 deny ip any host 192.168.0.73
access-list 102 deny ip any host 192.168.0.74
access-list 102 deny ip any host 192.168.0.75
access-list 102 deny ip any host 192.168.0.76
access-list 102 deny ip any host 192.168.0.77
access-list 102 deny ip any host 192.168.0.78
access-list 102 deny ip any host 192.168.0.79
access-list 102 deny ip any host 192.168.0.80
access-list 102 deny ip any host 192.168.0.81
access-list 102 deny ip any host 192.168.0.82
access-list 102 deny ip any host 192.168.0.83
access-list 102 deny ip any host 192.168.0.84
access-list 102 deny ip any host 192.168.0.85
access-list 102 deny ip any host 192.168.0.86
access-list 102 deny ip any host 192.168.0.87
access-list 102 deny ip any host 192.168.0.88
access-list 102 deny ip any host 192.168.0.89
access-list 102 deny ip any host 192.168.0.90
access-list 102 deny ip any host 192.168.0.91
access-list 102 deny ip any host 192.168.0.92
access-list 102 deny ip any host 192.168.0.93
access-list 102 deny ip any host 192.168.0.94
access-list 102 deny ip any host 192.168.0.95
access-list 102 deny ip any host 192.168.0.96
access-list 102 deny ip any host 192.168.0.97
access-list 102 deny ip any host 192.168.0.98
access-list 102 deny ip any host 192.168.0.99
access-list 102 permit ip 192.168.0.0 0.0.0.255 any
access-list 103 remark auto generated by SDM firewall configuration
access-list 103 remark SDM_ACL Category=1
access-list 103 deny ip host 255.255.255.255 any
access-list 103 deny ip 127.0.0.0 0.255.255.255 any
access-list 103 permit ip any any
access-list 104 remark auto generated by SDM firewall configuration
access-list 104 remark SDM_ACL Category=1
access-list 104 permit udp any any eq 1720
access-list 104 permit tcp any any eq 1720
access-list 104 permit tcp any any eq 6881
access-list 104 permit tcp any eq 4242 host 192.168.0.50 eq 4242
access-list 104 permit tcp any any eq 4660
access-list 104 permit udp host 212.247.156.70 eq domain any
access-list 104 permit udp host 212.247.156.66 eq domain any
access-list 104 permit ahp any any
access-list 104 permit esp any any
access-list 104 permit udp any any eq isakmp
access-list 104 permit udp any any eq non500-isakmp
access-list 104 deny ip 192.168.0.0 0.0.0.255 any
access-list 104 permit icmp any any echo-reply
access-list 104 permit icmp any any time-exceeded
access-list 104 permit icmp any any unreachable
access-list 104 deny ip 10.0.0.0 0.255.255.255 any
access-list 104 deny ip 172.16.0.0 0.15.255.255 any
access-list 104 deny ip 192.168.0.0 0.0.255.255 any
access-list 104 deny ip 127.0.0.0 0.255.255.255 any
access-list 104 deny ip host 255.255.255.255 any
access-list 104 deny ip host 0.0.0.0 any
access-list 104 deny ip any any log
dialer-list 1 protocol ip permit
no cdp run
route-map SDM_RMAP_1 permit 1
match ip address 102
!
!
control-plane
!
banner login ^CAuthorized access only!
Disconnect IMMEDIATELY if you are not an authorized user!^C
!
line con 0
no modem enable
transport preferred all
transport output telnet
line aux 0
transport preferred all
transport output telnet
line vty 0 4
transport preferred all
transport input telnet ssh
transport output all
!
scheduler max-task-time 5000
scheduler allocate 4000 1000
scheduler interval 500
end


Forse da quello che ho visto è l?MTU del DialerO che è rimasto lo stesso??

Forse da quello che ho visto è l?MTU del DialerO che è rimasto lo stesso??

L'mtu della dialer metta 1492

conf t
int dialer0
mtu 1492

Nessun risultato, non riesco nemmeno ad accedere a Gmail tramite web..
Ho provato anche mettendo L'MTU del Dialer0 a 1500 ma niente.
Ho provato a reipostare a 1492 ma nn cambia niente..
Sono alla frutta??

Che ios hai?
Un bel aggiornamento direi che ci può stare

L' IOS 12.3(8)YI2
L'SDM 2.3.4
L?SDM lo aggiornata all'ultima versione l'IOS non l'ho mai fatta perchè nn so ne come ne dove recuperare i file per l'aggiornamento. Il sito di supporto di ciso per me è un labirinto!

ip tcp adjust-mss 1436

sotto la dialer, dovresti uscirtene, puoi provare ad alzare il valore per ottimizzare i pacchetti.

addirittura 1436??
Ma non dovrei avere un valore che no faccia da collo di bottiglia con le sche de di rete dei vari computer che hanno l'MTU a 1500??

Poi stocercando di trovare sul sito della cisco dove scaricare L'IOS aggiornata ma con la log e pass che ho nn mi fa accedere, qualcuno sa perchè??

Vi mostro uno show delle varie interfacce coinvolte, sarà utile??

CiscoRouter#show interface vlan1
Vlan1 is up, line protocol is up
Hardware is EtherSVI, address is 0016.c747.66d8 (bia 0016.c747.66d8)
Description: $ETH-SW-LAUNCH$$INTF-INFO-HWIC 4ESW$$ES_LAN$$FW_INSIDE$
Internet address is 192.168.0.254/24
MTU 1500 bytes, BW 100000 Kbit, DLY 1000000 usec,
reliability 255/255, txload 1/255, rxload 1/255
Encapsulation ARPA, loopback not set
ARP type: ARPA, ARP Timeout 04:00:00
Last input 00:00:00, output never, output hang never
Last clearing of "show interface" counters never
Input queue: 1/75/0/0 (size/max/drops/flushes); Total output drops: 0
Queueing strategy: fifo
Output queue: 0/40 (size/max)
5 minute input rate 2000 bits/sec, 4 packets/sec
5 minute output rate 1000 bits/sec, 2 packets/sec
111805 packets input, 72696897 bytes, 0 no buffer
Received 775 broadcasts, 0 runts, 0 giants, 0 throttles
0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored
104703 packets output, 82175005 bytes, 0 underruns
0 output errors, 1 interface resets
0 output buffer failures, 0 output buffers swapped out

CiscoRouter#show interface ATM0
ATM0 is up, line protocol is up
Hardware is MPC ATMSAR (with Alcatel ADSL Module)
MTU 1500 bytes, sub MTU 1500, BW 352 Kbit, DLY 1040 usec,
reliability 255/255, txload 1/255, rxload 1/255
Encapsulation ATM, loopback not set
Encapsulation(s): AAL5 AAL2, PVC mode
10 maximum active VCs, 1024 VCs per VP, 1 current VCCs
VC Auto Creation Disabled.
VC idle disconnect time: 300 seconds
Last input 16:32:50, output 00:00:07, output hang never
Last clearing of "show interface" counters never
Input queue: 0/75/0/0 (size/max/drops/flushes); Total output drops: 0
Queueing strategy: Per VC Queueing
5 minute input rate 0 bits/sec, 0 packets/sec
5 minute output rate 0 bits/sec, 0 packets/sec
112796 packets input, 77621609 bytes, 0 no buffer
Received 0 broadcasts, 0 runts, 0 giants, 0 throttles
0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored, 0 abort
109766 packets output, 74338043 bytes, 0 underruns
0 output errors, 0 collisions, 1 interface resets
0 output buffer failures, 0 output buffers swapped out

CiscoRouter#show interface ATM0.1
ATM0.1 is up, line protocol is up
Hardware is MPC ATMSAR (with Alcatel ADSL Module)
Description: $ES_WAN$$FW_OUTSIDE$
MTU 1500 bytes, BW 352 Kbit, DLY 1040 usec,
reliability 255/255, txload 1/255, rxload 1/255
Encapsulation ATM
112824 packets input, 77763356 bytes
109773 packets output, 74338999 bytes
0 OAM cells input, 0 OAM cells output
AAL5 CRC errors : 0
AAL5 SAR Timeouts : 0
AAL5 Oversized SDUs : 0
Last clearing of "show interface" counters never


CiscoRouter#show interface Dialer0
Dialer0 is up, line protocol is up (spoofing)
Hardware is Unknown
Description: $FW_OUTSIDE$
Internet address is 87.11.159.117/32
MTU 1492 bytes, BW 56 Kbit, DLY 20000 usec,
reliability 255/255, txload 1/255, rxload 1/255
Encapsulation PPP, loopback not set
Keepalive set (10 sec)
DTR is pulsed for 1 seconds on reset
Interface is bound to Vi1
Last input never, output never, output hang never
Last clearing of "show interface" counters 1d06h
Input queue: 0/75/0/0 (size/max/drops/flushes); Total output drops: 0
Queueing strategy: weighted fair
Output queue: 0/1000/64/0 (size/max total/threshold/drops)
Conversations 0/0/16 (active/max active/max total)
Reserved Conversations 0/0 (allocated/max allocated)
Available Bandwidth 42 kilobits/sec
5 minute input rate 0 bits/sec, 0 packets/sec
5 minute output rate 0 bits/sec, 0 packets/sec
112666 packets input, 73783774 bytes
109610 packets output, 70724143 bytes
Bound to:
Virtual-Access1 is up, line protocol is up
Hardware is Virtual Access interface
MTU 1500 bytes, BW 56 Kbit, DLY 20000 usec,
reliability 255/255, txload 1/255, rxload 1/255
Encapsulation PPP, LCP Open
Open: IPCP
PPPoE vaccess, cloned from Dialer0
Vaccess status 0x44, loopback not set
Keepalive set (10 sec)
Interface is bound to Di0 (Encapsulation PPP)
Last input 00:00:04, output never, output hang never
Last clearing of "show interface" counters 16:37:08
Input queue: 0/75/0/0 (size/max/drops/flushes); Total output drops: 0
Queueing strategy: fifo
Output queue: 0/40 (size/max)
5 minute input rate 0 bits/sec, 0 packets/sec
5 minute output rate 0 bits/sec, 0 packets/sec
58362 packets input, 62704427 bytes, 0 no buffer
Received 0 broadcasts, 0 runts, 0 giants, 0 throttles
0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored, 0 abort
35524 packets output, 3224974 bytes, 0 underruns
0 output errors, 0 collisions, 0 interface resets
0 output buffer failures, 0 output buffers swapped out
0 carrier transitions

che dite??? come ne esco non potendo aggiornare l'IOS, visto gli scarsi mezzi?

x Wizard..
ho visto che ci sono 2 parametri MTU nella Dialer0
1) MTU
2) IP MTU

bhe ho impostato il primo a 1550 e il secondo a 1500 e FUNZIONA!!
chi è così gentile da spiegarmi il perchè??

Comunque grazie x il consiglio, alla fine dando un pò di numeri ho risolto.