Multilink T1 with diff ISP ?

[ben2001]

Do you know if I could setup Point to Point Multilink connection using two T1 line from different ISP? (ie. One T1 line provided by SBC, another by XO)

I am planning to setup the multilink to increase the throughput to the branch office and also provide backup link if one of the T1 failed.

Thanks

 

[gtmoore]

Yes we do it. We have 2 point to point T1's from MCI & Sprint and I set up multlink on both routers and it works fine. Just a note that the delay we have on both lines is the same and I am guessing yours will be comparible too. If you need a sample config I can provide.

Greg

 

[ben2001]

Great, if possible, please provide the sample config.

Thank you,

Ben

 

[ben2001]

One more question, do you need to let the ISP know about the multilink setup? (I don't know if they have to turn on certain settings/configuration).

Ben

 

[gtmoore]

I never had to tell the ISP anything... Below is an example of my Multilink on one of my routers..


interface Multilink1
ip address 192.168.xxx.xxx 255.255.255.252
no cdp enable
ppp chap hostname multi
ppp multilink
ppp multilink fragment disable
ppp multilink group 1
!
interface Serial0/0
description First T1
no ip address
encapsulation ppp
no ip mroute-cache
no fair-queue
service-module t1 clock source internal
service-module t1 timeslots 1-24
service-module t1 remote-alarm-enable
no cdp enable
ppp chap hostname multi
ppp multilink
ppp multilink group 1
!
!
interface Serial0/1
description Second T1
no ip address
encapsulation ppp
no ip mroute-cache
no fair-queue
service-module t1 clock source internal
service-module t1 timeslots 1-24
service-module t1 remote-alarm-enable
no cdp enable
ppp chap hostname multi
ppp multilink
ppp multilink group 1

 

[ben2001]

Thank you Greg.

 

[TransbeamtoCisco]

Hello Friends i am running a multilink examle
please figure it out why i am not having the full BW of two t1's . i am getting it around 2800kbps instead of 3100Mbps .is it normal or the below config is having some problem.
thanks with regards


7500 router---two t1's ---3600 router

************config of 3600************
no aaa new-model
ip subnet-zero
ip name-server 66.234.224.2
ip name-server 66.234.224.3
!
ip cef
interface Multilink1
description Transbeam Bouding Interface for S0/0 s0/1
ip address 66.234.246.158 255.255.255.252
no ip redirects
ip nat outside
no cdp enable
ppp chap hostname multi
ppp multilink
ppp multilink fragment disable
ppp multilink group 1
!
interface Ethernet0/0
ip address 10.0.0.1 255.255.255.0
ip nat inside
full-duplex
!
interface Serial0/0
no ip address
encapsulation ppp
no ip mroute-cache
no keepalive
no fair-queue
service-module t1 clock source internal
service-module t1 timeslots 1-24
service-module t1 remote-alarm-enable
no cdp enable
ppp chap hostname multi
ppp multilink
ppp multilink group 1
!
interface Serial0/1
no ip address
encapsulation ppp
no ip mroute-cache
no keepalive
no fair-queue
service-module t1 clock source internal
service-module t1 timeslots 1-24
service-module t1 remote-alarm-enable
no cdp enable
ppp chap hostname multi
ppp multilink
ppp multilink group 1

ip nat pool overld 66.234.246.158 66.234.246.158 prefix-length 24
ip nat inside source list 1 interface Multilink1 overload
ip nat inside source list 100 interface Multilink1 overload
no ip http server
no ip http secure-server
ip classless
ip route 0.0.0.0 0.0.0.0 66.234.246.157
!
!
access-list 1 permit 10.0.0.0 0.0.0.255
access-list 100 permit ip any any
dialer-list 1 protocol ip permit
dialer-list 1 protocol ipx permit

and config of ************7500*************

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
!
interface Multilink1
ip address 66.234.246.157 255.255.255.252
no ip redirects
no ip route-cache cef
no cdp enable
ppp multilink
no ppp multilink fragmentation
multilink-group 1

!
interface Serial5/1/0/10:1
description Transbeam Bonded
no ip address
no ip redirects
encapsulation ppp
no keepalive
no fair-queue
ppp multilink
multilink-group 1

interface Serial5/1/0/26:1
description Transbeam Bonded T1 #2
no ip address
no ip redirects
encapsulation ppp
no keepalive
no fair-queue
ppp multilink
multilink-group 1

 

[cns13]

Maybe someone can correct me if I'm wrong, but doesn't multilink work similar to Fast Etherchannel in that it doesn't truely mux the two links into one, but rather makes decisions on which of the two links to send packets down depending on which one has the most capacity at the time of transmission? In that kind of scenario you would only get the full throughput of two T1's simultaneously under the most ideal conditions. So the throughput you are getting sounds about right in that case.

Ben