Which Routing protocol for SAP purpose

[akonwar]

I have a router 1751 with 1 serial and 1 bri port. I also have a vsat connection (a gateway switch with ip)to my remote office. I want a setup like this
whenever my leased line / serial is down automatically switch over to vsat when its up go back to lease line.
if both serial and vsat are down use isdn.
Which routing protocol is best for this scenario. We want to connect SAP from our branch office to main office server. so the transition between mediums should take seamlessly or sap hangs. Please help!

 

[andf1]

How is the VSAT link connected to your network?

andf1

 

[akonwar]

Its connected through iDU to a switch connected to my router like this
vsat----idu-------ethernet switch-----router

 

[andf1]

OSPF or EIGRP could be used for this purpose. You will need to tune the protocol so that the VSAT has the higher metric. The easiest way to do this is to use the bandwidth command. Set the bandwidth on the interface to the VSAT to be lower the bandwidth on the serial. With this method however, the protocol hellos will send traffic over the VSAT up all the time.

If you do not want traffic flowing over the VSAT, you could use static routes. Assign the static route through the VSAT a higher adminstrative distance.

andf1

 

[routerman]

You'll have problems using the static route approach. I'd also recommend looking at a dynamic routing protocol such as EIGRP, but as Andf1 states there will be a small amount of traffic across the VSAT all the time.

The problem with the static is that it will point to the next hop via the Ethernet interface, as this is connected to a switch the Interface will never go down. Therefore in the event of the leased line failing you can switch to the VSAT link, but if that fails the router will not be aware of it and so it wont fall back to the ISDN. This was a requirement in your original post.

 

[akonwar]

I am attaching my config as suggested by our main office administrator.
version 12.2
service config
service timestamps debug uptime
service timestamps log uptime
service password-encryption
!
hostname mourigram_ppl_term
!!
memory-size iomem 15
ip subnet-zero
!
!
no ip domain lookup
!
isdn switch-type basic-net3
!
voice call carrier capacity active

!
!
mta receive maximum-recipients 0
!
!
!
interface Loopback0 ---what its required?----
ip address 10.76.10.17 255.255.255.255
!
interface FastEthernet0/0
description connected to EthernetLAN
ip address 10.76.160.1 255.255.255.0
speed auto
!
interface BRI0/0
no ip address
encapsulation ppp
dialer pool-member 1
dialer pool-member 2
isdn switch-type basic-net3
ppp authentication pap chap callin
!
interface Serial1/0
ip address 10.76.1.118 255.255.255.252
!
interface Serial1/1
no ip address
shutdown
!
interface Dialer2
ip address 10.50.4.64 255.255.255.0
encapsulation ppp
no ip split-horizon
shutdown
dialer pool 2
dialer remote-name IIPM
dialer idle-timeout 179
dialer string 01242398933
dialer load-threshold 200 outbound
dialer-group 1
ppp authentication chap pap
!
router ospf 100
router-id 10.76.10.17
log-adjacency-changes
network 10.76.1.118 0.0.0.0 area 10.76.0.0
network 10.76.160.0 0.0.0.255 area 10.76.0.0
!
router rip
version 2
passive-interface FastEthernet0/0
passive-interface Serial1/0
passive-interface Dialer1
passive-interface Dialer2
network 10.0.0.0
!
ip classless
ip route 10.51.0.0 255.255.0.0 10.52.1.0 11 name vsat2-remot
ip route 10.51.0.0 255.255.0.0 Dialer2 100 name isdn
ip route 10.52.0.0 255.255.0.0 10.52.1.0 11 name vsat2-remot
no ip http server
!
call rsvp-sync ---what does this do---
!
!
mgcp profile default-----donno about this too?---
!
dial-peer cor custom
!
no scheduler allocate
end

the above works but problem is that ospf works only when leased line is up? at other times sap still hangs and the transistion is not smooth. Please also tell me what above commands do where i have asked? Can any one send me links to learning ospf and eigrp?

 

[experimenter]

Your router is unable to detect the status of your VSAT link because it's connected to an ethernet interface. So you need the same dynamic routing protocol in the other side of VSAT link to listen/send advertizing packets. Then you can enforce router to obey your routing priority rules.

Bests,
Experimenter CCNP