01-31-2002 03:08 AM - edited 03-01-2019 08:18 PM
I have configured a 2621 to access a network via a NT4 RAS server, using a modem on the aux port. This seems to work quite well. BUT, when I try to use this over a satellite link there seems to be a problem when the end to end delay exceeds a second or so. What I see is the packet leave the router but never return. Also occasionally there is a large amount of APPP65 traffic in and out of the router, for no apparent reason (something resyncing perhaps?). I also experience a problem where a ping request is replied to at the async port but never seems to meet the higher protocols, i.e. the request hits the router but not IP/ICMP as if it is stuck in a buffer or being dropped. I do not experience these problems if I am using the modem attached directly to the router. (The satellite provides the RS232 comms between router and modem)
Does anyone know of a timeout value that can be increased to allow better stability? or have any other ideas.
The router config
(BTW The modem printer command is because the modem has a weird interface where DCD (DSR) cannot be controlled and is always set high)
Current configuration:
!
version 12.0
service timestamps debug uptime
service timestamps log uptime
no service password-encryption
!
hostname Ocean
!
enable password ******
!
!
!
!
!
memory-size iomem 30
ip subnet-zero
no ip domain-lookup
!
chat-script SHORE ABORT ERROR ABORT BUSY "" "AT" "OK" "ATDT\T" TIMEOUT 60 CONNECT \c
modemcap entry paul:MSC=&c0*fl0*mf0&d6
!
!
!
interface Loopback0
ip address 132.0.214.4 255.255.255.255
no ip directed-broadcast
!
interface FastEthernet0/0
ip address 25.59.204.1 255.255.255.0
no ip directed-broadcast
no ip mroute-cache
speed auto
half-duplex
no cdp enable
!
interface Serial0/0
ip unnumbered FastEthernet0/0
no ip directed-broadcast
encapsulation ppp
ip ospf authentication-key NAVYNET
ip ospf cost 20
ip ospf hello-interval 15
ip ospf dead-interval 45
no ip mroute-cache
!
interface FastEthernet0/1
no ip address
no ip directed-broadcast
shutdown
duplex auto
speed auto
!
interface Async65
no ip address
no ip directed-broadcast
encapsulation ppp
dialer in-band
dialer pool-member 20
async default routing
ppp authentication pap chap ms-chap callin
ppp chap refuse
ppp pap sent-username NTDOMAIN\userid password **************
!
interface Dialer10
ip unnumbered Loopback0
no ip directed-broadcast
dialer pool 20
dialer string 123456789
dialer-group 1
no cdp enable
!
router ospf 1
area 0.0.0.0 authentication
network 25.0.0.0 0.255.255.255 area 0.0.0.0
!
ip classless
ip route 0.0.0.0 0.0.0.0 Dialer10 150
no ip http server
ip ospf name-lookup
!
access-list 101 permit ip any any
dialer-list 1 protocol ip list 101
!
line con 0
password letmein
login
transport input none
line aux 0
exec-timeout 0 0
script dialer SHORE
modem Printer
transport output none
stopbits 1
speed 19200
flowcontrol hardware
line vty 0 4
password letmein
login
!
end
01-31-2002 07:53 PM
We should compare the two different async chips the modem and the sat-modem are using and nail it down. What models are these two different devices? Hopefully some research with thier documentation can help us out.
Josh
02-01-2002 07:59 AM
I'm not sure what the chipset is but I do know that the modem is a Motorola codex 3265 fast and the mux is a GDC (General Datacom, I think) minimux (now obsolete!) The sat channel is seriously strange. All interfaces present as DCE and the cable to the modem is DCD from modem to RTS on sat channel (otherwise no comms at all end to end) TX / RX crossed, and DSR from sat channel to DTR on the modem. Flow control is handled by the sat channel at the 2621 end by RTS/CTS, but it looks to me like these are simply linked together (no output level at all from CTS without input from RTS. All signals jammed high on the modem. (DSR, DCD, DTR, RTS)
DCD is permanently high from the sat channel to the 2621 and DTR from 2621 seems to have no effect at all on the link or the remote modem, so I guess it's not passed through. RTS/CTS flow control as above.
Hope this helps.
Paul
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