dropping connections over private T1 with cisco 1751′s at each end
I keep dropping connection over a private t1 spanned between two 1751 routers. This is most apparent when I am trying to open large files (especially Access) that are greater than 3mb.
One of the routers is configured to also act as a dhcp server.
the following are the configurations:
STATEST#show startup-config
Using 1844 out of 29688 bytes
!
version 12.2
no parser cache
service timestamps debug uptime
service timestamps log uptime
service password-encryption
!
hostname STATEST
!
enable secret 5 ********
enable password ********
!
memory-size iomem 25
ip subnet-zero
!
!
no ip dhcp conflict logging
ip dhcp excluded-address 192.168.10.241 192.168.10.255
ip dhcp excluded-address 192.168.10.1 192.168.10.50
!
ip dhcp pool 192.168.10.0/24
network 192.168.10.0 255.255.255.0
default-router 192.168.10.4
dns-server 192.168.1.254 204.17.65.2
!
!
ip multicast-routing
ip cef
ip ssh time-out 120
ip ssh authentication-retries 3
!
crypto mib ipsec flowmib history tunnel size 200
crypto mib ipsec flowmib history failure size 200
!
!
!
interface FastEthernet0/0
ip address 192.168.10.4 255.255.255.0
ip helper-address 192.168.1.254
ip pim dense-mode
speed auto
half-duplex
!
interface Serial0/0
ip address 192.168.5.2 255.255.255.252
ip pim dense-mode
ip igmp join-group 224.0.1.0
ip igmp unidirectional-link
no fair-queue
serial restart_delay 2
service-module t1 framing sf
service-module t1 linecode ami
service-module t1 timeslots all speed 56
!
ip default-gateway 192.168.5.1
ip classless
no ip forward-protocol udp
ip route 0.0.0.0 0.0.0.0 192.168.5.1
ip route 192.168.1.0 255.255.255.0 192.168.5.1
no ip http server
ip pim bidir-enable
!
!
banner motd ^CWelcome to the State Street router. Unauthorized access is prohibited!^C
!
line con 0
password 7 *******
login
line aux 0
line vty 0 4
password 7 *******
login
!
end
=============================================
GEP#show startup-config
Using 1202 out of 29688 bytes
!
version 12.2
no parser cache
service timestamps debug uptime
service timestamps log uptime
service password-encryption
!
hostname GEP
!
enable secret 5 *******
enable password 7 *******
!
memory-size iomem 25
ip subnet-zero
!
!
!
ip multicast-routing
ip ssh time-out 120
ip ssh authentication-retries 3
!
crypto mib ipsec flowmib history tunnel size 200
crypto mib ipsec flowmib history failure size 200
!
!
!
interface FastEthernet0/0
ip address 192.168.1.4 255.255.255.0
ip pim dense-mode
speed auto
half-duplex
!
interface Serial0/0
ip address 192.168.5.1 255.255.255.252
ip pim dense-mode
ip igmp join-group 224.0.1.0
ip igmp unidirectional-link
serial restart_delay 2
service-module t1 framing sf
service-module t1 linecode ami
service-module t1 timeslots all speed 56
!
ip default-gateway 192.168.1.1
ip classless
ip route 0.0.0.0 0.0.0.0 192.168.1.1
ip route 192.168.10.0 255.255.255.0 192.168.5.2
no ip http server
ip pim bidir-enable
!
!
banner motd ^CWelcome to the GEP router. Unauthorized access is prohibited!^C
!
line con 0
password 7 *******
login
line aux 0
line vty 0 4
password 7 *******
login
!
no scheduler allocate
end
Software/Hardware used:
Software/Hardware used:
ASKED:
January 22, 2006 12:28 PM
UPDATED:
January 25, 2006 12:59 PM
Answer Wiki:
The interesting things I see about the configuration is the half-duplex setting on the F0/1 interfaces (make sure you don't have a duplex mismatch), neither side of your T1 is injecting timing, and are you certain it's sf and not esf framing on the T1?
Check your packet size to ensure that they aren't too large and require fragmentation. Also make sure that the Don't Fragment bit is not set on either the client or server side. You may have to change your MTU size and mangle the packets to remove the DF bit if this is your problem.
Finally, have you checked your Serial interface counters for interface resets and carrier loss? You might have a problem with the circuit.
Hope this points you in the right direction.
SF
To see all answers submitted to the Answer Wiki: View Answer History.
Sonyfreek makes several good points. Autodetect of ethernet speed and duplex is fraught with problems.
Something else I wondered about is whether these networks are routed or bridged?
Have you looked at the relevant logs on each side of the connection to see if there’s anything interesting?
Bob