05-31-2006 08:21 AM - edited 03-03-2019 12:51 PM
Hi all,
I have 2 2811 routers with 4 T1 lines connecting them, I would like to use multilink. I have a few questions before I get started:
1. will there be downtime when I switch to multilink? or will traffic continue to pass thru?
2. Is creating a traffic class and policy manditory?
thank you
05-31-2006 08:35 AM
Nasir
There may be a brief interruption of traffic as you make the config changes to implement multilink (removing the IP address from the serial, assigning the serial to the multilink group, etc). How much interruption will also be affected by how well you coordinate the changes on both ends. But if you have your changes planned and can just paste the config changes into the config from a text file the interruption should be very small.
traffic class and policy may be desirable (depending on your environment) but they are not mandatory for using multilink.
HTH
Rick
05-31-2006 11:49 AM
Thanks for your response.
I have created the following configs: can you or anyone else see anything there that might give me problems when i apply it?
config of router A:
interface Multilink1
ip address 10.82.163.2 255.255.255.252
ppp multilink
ppp multilink-group 1
!
interface Serial0/0/0
description Connection to
bandwidth 1544
ip unnumbered FastEthernet0/1
ip accounting output-packets
no ip mroute-cache
no fair-queue
ppp multilink
multilink-group 1
!
interface Serial0/1/0
description Connection to
bandwidth 1544
ip unnumbered FastEthernet0/1
ip accounting output-packets
no ip mroute-cache
no fair-queue
ppp multilink
multilink-group 1
no shut
!
interface Serial0/2/0
description Connection to
bandwidth 1544
ip unnumbered FastEthernet0/1
ip accounting output-packets
no ip mroute-cache
no fair-queue
ppp multilink
multilink-group 1
no shut
!
interface Serial0/3/0
description Connection to
bandwidth 1544
ip unnumbered FastEthernet0/1
ip accounting output-packets
no ip mroute-cache
no fair-queue
ppp multilink
multilink-group 1
no shut
!
Config of router B:
interface Multilink1
ip address 10.82.163.1 255.255.255.252
ppp multilink
ppp multilink-group 1
!
interface Serial0/0/0
description Connection to
bandwidth 1544
ip unnumbered FastEthernet0/1
ip accounting output-packets
no ip mroute-cache
no fair-queue
ppp multilink
multilink-group 1
!
interface Serial0/1/0
description Connection to
bandwidth 1544
ip unnumbered FastEthernet0/1
ip accounting output-packets
no ip mroute-cache
no fair-queue
ppp multilink
multilink-group 1
no shut
!
interface Serial0/2/0
description Connection to
bandwidth 1544
ip unnumbered FastEthernet0/1
ip accounting output-packets
no ip mroute-cache
no fair-queue
ppp multilink
multilink-group 1
no shut
!
interface Serial0/3/0
description Connection to
bandwidth 1544
ip unnumbered FastEthernet0/1
ip accounting output-packets
no ip mroute-cache
no fair-queue
ppp multilink
multilink-group 1
no shut
!
once again thanks for the very useful info.
05-31-2006 12:02 PM
The main thing that I notice in your suggested config is that you are specifying ip unnumbered and ip accounting on the serial interfaces. When you configure multilink the multilink interface is the layer 3 interface which gets things like ip address and accounting (if desired) and the serial interfaces should not have these.
The original post asked about potential downtime when configuring multilink. This leads me to believe that the serial interfaces are already in use. How are they currently configured? That might have some affect on what you need to change as you go to multilink.
HTH
Rick
05-31-2006 12:26 PM
currently only 1 serial interface is active, we will soon be getting 3 additional T1 lines. In my configuration I just added the multilink commands to the interfaces.
Also, are you saying that I should remove ip unnumbered and ip accounting from the serial interfaces and place them on the multilink interface?
05-31-2006 12:35 PM
on the multilink bundle, int multilink 1;
enter
ppp multilink fragment disable
this will prevent fragmentation of induvidual frames @ Layer 2. this usually causes issues with anything but ping from working... so use it!
05-31-2006 12:40 PM
currently we use "ip authenication" for eigrp at the serial interface, shoul I apply that to the multilink interface or keep it at the serial interface?
05-31-2006 12:52 PM
As a rule of thumb when you create a virtual interface, like multilink interface, most/all of your layer 3 config should be configured under that int. With that said you need to configure the 'ip authentication' under the multilink int.
HTH,
Sundar
*Please rate all helpful posts.
05-31-2006 12:56 PM
Nasir
Sundar has said it well: most layer 3 parameters should be configured on the multilink and not on the physical serial interfaces. So to be explicit, yes you should remove the ip unnumbered and ip accounting from the serial interfaces. The ip authentication should go on the multilink.
HTH
Rick
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