Multiple PPP Multilinks in 7609 router

[f-m-s-2000]

We have Cisco 7609 routers in our network. We are using ppp multilinks between the sites. Because of the high traffic volume, we have to use multiple multilinks. 7609 router doesn't allow ppp multlink to span SIPs, so we use multiple mulitilinks between sites on different SIPs. OSPF for load balancing will be used. THE PROBLEM IS: when we define the second ppp multilink between two 7609 routers, the new multilink stays "inactive". Can we use multiple multilinks to the same router? We have enabled the command IP CEF DISTRIBUTED, but we still face the same problem". IOS used is: 122-18.SXF6

[smothuku]

Hi ,

Remove 'encapsulation ppp' from multilink on both ends and check it..

[f-m-s-2000]

Hi,

I remover the encapsulation. Still the multilink shows down down and the serial up down

[bbaillie · Accepted solution]

Multilink needs to identify how to differentiate between bundles, this said if you use more than one multilink on a router you need to identify the member links of the bundle. When "not" using authentication the next method is to use an endpoint dicriminator for the serial links to facilitate the bundle identification by the local router. Endpoint discriminators are locally specific to the router so if each serial port is assigned to an individual multilink bundle then use unique endpoint discriminator values for each serial link, no need to make them match on source and target router. If more than one interface is assigned to the same multilink bundle they must have the same endpoint discriminator value. Long winded but here is the example from your posting, a bit shortened for reading ease.

interface Serial 2/0/0:1

encapsulation ppp

ip route-cache cef

ppp multilink

multilink-group 122

ppp multilink endpoint string multi122

interface Serial 2/0/1:1

encapsulation ppp

ip route-cache cef

ppp multilink

multilink-group 122

ppp multilink endpoint string multi122

When each link is assigned to an individual multilink bundle the discriminator values need to be different, have used this just to take advantage of LFI and allow the routing protocol do the load balancing.

Cheers,

Brian

[f-m-s-2000]

Hello Brian,

YOU ARE GREAT, MAN! :-)

As soon as I added the discriminator, the links went up. You really made my day.

Thank youoooooooooooooo

And many thanks for all the guys who particpated in this discussion.

Cheers,

[rajivrajan1]

hats off Brian

[aravindhs]

Hi !

Have you tried debugging yet ?

Remove the multilink config on the serial interfaces.

Try enabling some of these debugs ..

debug ppp < .. >

authentication CHAP and PAP authentication

bap BAP protocol transactions

compression PPP compression

error Protocol errors and error statistics

mppe MPPE Events

multilink Multilink activity

negotiation Protocol parameter negotiation

packet Low-level PPP packet dump

Then stick the multilink config on the member interfaces and look at what is happenning exactly in the box.

Cheers

Aravind

[alaa_aaaa]

i had the same issue and tried this solution but the problrm still seral links are up----down when it is bundeled inside the multilink interface but it is up---down when it is removed from the multilink interface.