Настроил вот так.

version 12.3
service timestamps debug datetime msec
service timestamps log datetime msec
no service password-encryption
!
hostname cisco1760
!
boot-start-marker
boot-end-marker
!
enable secret 5 $1$8Vbl$Hbwic4ZIjFSbR0QjdgnXw1
enable password xxxx
!
tdm clock E1 0/0 both export line
mmi polling-interval 60
no mmi auto-configure
no mmi pvc
mmi snmp-timeout 180
voice-card 0
!
no aaa new-model
ip subnet-zero
ip cef
!
controller E1 0/0
  channel-group 0 timeslots 1-31
!
interface FastEthernet0/0
  ip address 10.90.90.248 255.255.255.0
  speed auto
  full-duplex
!
interface Serial0/0:0
  no ip address
  encapsulation frame-relay
  no keepalive
!
interface Serial0/0:0.1 point-to-point
  ip address 10.90.90.247 255.255.255.0
  frame-relay interface-dlci 100
!
router eigrp 1
  network 10.0.0.0
  auto-summary
!
ip classless
no ip http server
!
snmp-server community public RO
!
line con 0
line aux 0
line vty 0 4
  password xxxx
  login
!
end

Надеюсь заработает.