Multilink redundancy

Unanswered Question
Jul 10th, 2009

I have configured two E1 in multilink. I am able to ping the multilink without any packet drops. However whenever my one of E1 goes down i get packet drops for next 30second until the traffic is shift to the other E1 which is up. Please advice what configuration changes are required to avoid packet drops

---------------Router 1---

interface Multilink1

ip address 192.168.1.1 255.255.255.0

ppp multilink

multilink-group 1

interface Serial1/0

no ip address

encapsulation ppp

ppp multilink

ppp multilink group 1

interface Serial1/1

no ip address

encapsulation ppp

ppp multilink

ppp multilink group 1

---------------Router 2---

interface Multilink1

ip address 192.168.1.2 255.255.255.0

ppp multilink

multilink-group 1

interface Serial1/0

no ip address

encapsulation ppp

ppp multilink

ppp multilink group 1

interface Serial1/1

no ip address

encapsulation ppp

ppp multilink

ppp multilink group 1

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Overall Rating: 4 (1 ratings)
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Rick Morris Fri, 07/10/2009 - 07:34

I am no expert in multi-link so I need to step through this.

Router 1 and Router 2 are they connected together via multi-link?

If so then I would recommend changing the subnet mask to a /30 instead of the /24

255.255.255.252

During testing are you pinging the 192.168.1.2 address from router 1?

do a sh ip route 192.168.1.2 and paste the results.

Rui Carlos Antunes Mon, 07/20/2009 - 04:26

When one of the E1's goes down, do you see the PPP Multilink session going down and then comingo back up (over the other E1)? Use "debug ppp negotiation" to check that.

If so, then the 30 seconds are probably the time it takes for the PPP Multilink session to be re-established over the backup E1.

u1kumar2002 Mon, 07/20/2009 - 08:23

Packet drops is occuring due to load balancing in round robin method of multilink. Till now i don't know the perfect solution but I use to perform two things:

1. Check the errors on individual interface if the errors are there resolve it with coordination from telco & service provider.

2. If the packet drop is occuring on regualar time interval basis. then shutdown the down inteface manually.

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