multilink two T1's with WIC-1DSU-T1

[salmans]

I have two sites, with two T1's running between them. Site A has a 1721 with two WIC-1DSU-T1's and site B has two external CSU/DSU's that plug into Serial Interfaces on the 1721 there. I want to use multilink to bond the two T1's. I have been looking at configs that have been posted. From what I have gathered I need something like the following at site B (external CSU/DSU's):
---------- cut out ------------------------
interface Multilink1
ip address 192.168.1.1 255.255.255.252
ppp multilink
ppp multilink group 1

interface Serial0
no ip address
encapsulation ppp
ppp multilink
ppp multilink group 1

interface Serial1
no ip address
encapsulation ppp
ppp multilink
ppp multilink group 1
---------- cut out -----------------------
And at Site A I have the two WIC-1DSU-T1's, do I need to use some type of "controller" setup as well as what's above? I have static routes set up to take care of routing. Any help would be appreciated...thanks !!!

Do it right the first time, and there won't be a second time!

 

[JOAMON]

put the following on the multilink interface:
ppp multilink fragment disable
Are the external CSU's providing any clocking for the T1 circuits? If not the one of the routers should be setup as clock source internal for the serial interfaces.

 

[voltron1011]

Have you considered just keeping the two links sepperate (sepperate IPs) and then using EIGRP as your routing protocol. By doing this, you can load ballance the two links, and you won't lose your entire connection if one of the T-1's goes down.

 

[salmans]

The external CSU's are providing the clocking. Can I use the same config above on both ends or do I need to set up "controller" interfaces on the end with the WIC cards? I have read that bonding the T1's will provide better load balancing than EIGRP. Anyone else read that or have experience of that being true? Thanks.

Do it right the first time, and there won't be a second time!

 

[salmans]

This is what I mean by "controllers" interface. Below is a config for multilink but uses a "controller T1 0/0" Reading on cisco's website it sounds as if this is for newer technology.

Here's my config (using VWIC-2MFT-T1 card)

interface Multilink1
ip address 192.168.250.a 255.255.255.252
ppp multilink
ppp multilink group 1

interface Serial0/0:0
no ip address
encapsulation ppp
ppp multilink
ppp multilink group 1

interface Serial0/1:0
no ip address
encapsulation ppp
ppp multilink
ppp multilink group 1

of course with this card you have to configure the controller...

controller T1 0/0
framing esf
crc-threshold 320
clock source internal
linecode b8zs
channel-group 0 timeslots 1-24 speed 64
!
controller T1 0/1
framing esf
crc-threshold 320
clock source internal
linecode b8zs
channel-group 0 timeslots 1-24 speed 64

I'm not sure if I need to use the "controller" interface on the WIC side of the circuit. Any ideas? Thanks.

Do it right the first time, and there won't be a second time!

 

[JOAMON]

FYI...
When two T1's are bonded together and one link goes down you do not lose the connection...just 50% of the bandwidth. Have two T1's bonded point to point and tested by shutting one serial interface down. Slight pause while link re-negotiated speed but no connections dropped.

 

[bfason]

If using the wic-1dsu-t1 you won't use controller t1 0/0.

Configuration is done on the serial interface using the service-module command.

The default configuration is ESF, B8ZS using 24 timeslots that are NX64 so if attaching to a full T1 it is very likely that you won't have to configure the service module.

If you did have to make a change then it would look something like this:

interface Serial0
no ip address
service-module t1 timeslots 1-24 speed 64
service-module t1 framing ESF
service-module t1 linecode B8ZS
service-module t1 clock source line
encapsulation ppp
ppp multilink
ppp multilink group 1

The rest of the setup will be the same as the other router.

Hope this helps.

 

[salmans]

Yes bfason, that's exactly what I needed to know. Thank you very much! And thanks to all others for their input to. HAGO !!!

Do it right the first time, and there won't be a second time!