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Yet another MLPPP "is the HW enough" question...

But since that I will within the hour start my car and travel for 260 miles....then a verification would calm my "nerves" a bit.

Hardware:

I will bring 2 routers with me:

Router 1:

Cisco 2901, 512MB DRAM + 1 GB of Flash: (extra: 2 Fa interfaces - on a "WIC" card)

Router 2:

Cisco 2821, 256 MB DRAM + 256 GB of Flash:

Both running the latest IOS release, 15.1

Have not - yet - decided on which one I should choose, leaning on the 2901....since that it has twice the DRAM installed and a faster CPU.

Misc information:

ISP provided 4x2mb/s - the site are extremely sensitive to latency.......

Cards used: VWIC2-2MFT-T1/E1 (since the installation is in Europe 4 E1:s will be used)

BGP and EIGRP is running on the router (BGP table are "huge"....)

Juniper WX-590 WAN Accelerator is installed

+200 regular users and (here is the "problem"): 20-25 CAD users up/downloading drawings up to 1GB in size.

Anyway, any tips or help in tuning the configuration will be very use- and helpful.

By the way, it is 03:00 AM here in Sweden...

Edit: a question: configuring the IP address; best practise to configure the address under the Multilink configuration statements or using a loopback interface (Multilink > ip unnumbered loopbackX)? Is there circumstances on where one of the two - possibilities - are preferred? If so, when and why?

Mike

  • WAN Routing and Switching
3 REPLIES

Re: Yet another MLPPP "is the HW enough" question...

Hi Mike

One drawback with Multilink bundle is you wont be able to notice if any of the physical link goes down because you will have the logical bundle up and running between the location, but you might end up with slightly poor performance compared to the normal condition when you have all the links up.

Do you have any specific reason to run a MLPPP bundle here?

If you still have a requirement to run MLPPP then you might better assign an ip address to the logical multilink interface rather inheriting from the loopback interface.

since you have mentioned the links are provided by the isp have you checked with your ISP on their comfort level in running/configuring MLPPP at their end?

regds

Re: Yet another MLPPP "is the HW enough" question...

spremkumar wrote:

Hi Mike

One drawback with Multilink bundle is you wont be able to notice if any of the physical link goes down because you will have the logical bundle up and running between the location, but you might end up with slightly poor performance compared to the normal condition when you have all the links up.



This is an issue with MLPPP, but I use snmp stats to monitor when one of my interfaces in the bundle go down; it works well.

John

HTH, John *** Please rate all useful posts ***
New Member

Re: Yet another MLPPP "is the HW enough" question...

Update 2010-05-10:

The AT&T engineer still claims that it is possible to add the "unframed" statement....below are my response back to him:

Jim,

Think this is a question for a Cisco tec.support team, read your attached document and I know what to do but there is still no possibility to set

VWIC-2MFT and VWIC2-2MFT cards with "option" unframed. Tried with C-2801, C-2811 and C-2901 with latest IOS but it's impossible.

One solutions is to use 4 VWIC-1MFT but I don't prefer that (only have 3 on the shelf).

Do anyone, have any idea on how to fix this problem, I mean how hard can it be for the AT&T guys to change on their side?

An update:

1. The 2901 was not able to recognize the VWIC-2-MFT card. Funny, when searching for information on support (2900) then the search returns 2 completly opposite results (on the Cisco web): one document that state the support, the other document does not (state the) support this card on 2900 series routers.

So, I ended up configuring the 2821 router instead.

Below is a transcript of a email conversation between I and en AT&T engineer:

Blue text the AT&T guy:

            !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

            My initial question (lacks all experience on how to configure a multilink PPP connection - very rarely used in Europe)

Can you check with one of your technican which router-commands I should set under each E1 controller described below.

XXXXXXXXXXXX XXXXXXXX
( XXXXX)

8192 KBPS (4xE1)  MLPPP (port USO = 3029BKXP)

Suppose clock source should be line

controller E1 0/0/0
channel-group 0 timeslots 1-31
!
controller E1 0/0/1
channel-group 0 timeslots 1-31
!
controller E1 0/1/0
channel-group 0 timeslots 1-31
!
controller E1 0/1/1
channel-group 0 timeslots 1-31

!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

AT&T Response:

I believe the E1s for XXXXXXXX are unframed 2048.   Recommend trying the E1 unframed with the Cisco defaults.


E1 Circuit, Unframed. (2048kbps):

controller E1 0/0/0

channel-group 0 unframed ! all timeslots are used for data

! Default Cisco settings provide clock source line, unframed, and HDB3 line coding.

E1 Circuit, Framed. If the access is framed E1 (1984kbps) rather than T1, with a built-in CSU, the

controller configuration is as shown below (the interface configurations are the same as with T1):

controller E1 0/0/0

channel-group 0 timeslots 1-31 ! Change timeslot range for fractional E1 access

! Default Cisco settings provide clock source line, CRC4 framing, and HDB3 line coding.

!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

My response:


Thanks for rapid information. Normally I always use Channel-group 0 unframed for 2048k circuits but it has been on one port E1 cards VWIC-1MFT or VWIC2-1MFT.

On these two ports E1 cards (VWIC-2MFT and VWIC2-2MFT) I don't have the possibility to configure Channel-group 0 unframed (see below).

Only choice is to use timeslots, if I leave these controllers with no channel-group values it's not possible to create S0/0/0:0 sub-interface(s) for the

multilink group.

XXXXXX01(config)#controller E1 0/0/0             
XXXXXXX01(config-controller)#channel-group 0 ?             
timeslots  List of timeslots in the channel group

XXXXXXX01(config-controller)#channel-group 0 unframed
                                              ^
% Invalid input detected at '^' marker.


XXXX01(config)#interface Serial0/0/0:0
                                       ^
% Invalid input detected at '^' marker.

The router has IOS version 12.4.25c with the AdvEnt feature set on ( + the latest available ROM monitor software)

So if anyone have any idea`s on what to do next then please advise me this router must go online today.....

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