Spirent TestCenter
How to configure a large scale
ANCP test (w/out True Topology)
February 11, 2013
Agenda
2

There are different ways to configure Spirent TestCenter (STC) to test
ANCP. We’ll go over the permutations.

What are the STC components involved in an ANCP configuration and
how do they fit together.

A step-by-step example covering one of the ways we can configure a STC
ANCP test (no True Topology and subs not sharing the AN’s VLAN).

Convert the (no True Topology and subs are not sharing the AN’s VLAN)
to
(no True Topology and subs are sharing the AN’s VLAN).

Notes/Caveats
PROPRIETARY AND CONFIDENTIAL
Different ways to configure an ANCP test
There are different ways to configure Spirent TestCenter (STC) to test ANCP.

With or without using True Topology (i.e., using "Incoming Links" and “Outgoing
Links")
• this is a STC configuration option

AN and subscribers sharing AN's VLAN or not
• An example of sharing
AN creates adjacencies and send PORT UP/DOWN message on VLAN 10 but subscribers are on
stacked VLANs (outer,inner) = (10,1-1024)
• An example of not sharing
AN creates adjacencies and send PORT UP/DOWN message on VLAN 10 but subscribers are on
stacked VLANs (outer,inner) = (99,1-1024)

In this "How To" we will cover the case where we're:
• not using True Topology; and
• subscribers are not sharing the ANs' VLAN

3
We'll also see how to easily change the case where the subscribers are sharing
the ANs' VLAN (and not using True Topology)
PROPRIETARY AND CONFIDENTIAL
STC components involved in an ANCP
configuration and how do they fit together

Access Node

Subscriber
• PPP - relay agent circuit/remote IDs
• DHCP - session IDs

Access loops
• "ties" ANs, Subscribers and line profiles together

Line profiles
• Associated with Access Loops
• Circuit-ID TLV
• Sub-TLVs
4
•
DSL type
•
Upstream data rate
•
Downstream data rate
PROPRIETARY AND CONFIDENTIAL
Step-by-step example

1024 Access Nodes (AN)

Each AN has 10 PPP
subscribers

Each set of 256 AN use a
particular “line profile”

VLAN Schema
• ANs use VLAN 10
• Subs “behind” ANi use stacked
VLAN
(outer 99,inner i)
• That is the AN and subs are not
sharing VLANs.

6
The following steps will
help guide you through
building a scaled
configuration to test this.
PROPRIETARY AND CONFIDENTIAL
Spirent TestCenter Port
Example ANCP test topology
1. Create the AN device blocks
7

First let’s create the device blocks that will represent the Access
Nodes.

You do this the same way you would any other device block.

We need 1024 of these
PROPRIETARY AND CONFIDENTIAL
2. Create the DSL line profiles
8

Note that you can do this later but I prefer to do them here so they are
available in a list to pick from.

Here we specify the sub-TLVs
in the DSL Line Attributes sent
in the Port Up and Port Down messages.

Since each group of 256 ANs will
use a different line profile, we will
create 4 line profiles.
PROPRIETARY AND CONFIDENTIAL
Use the “Access Loop Generator…” wizard to
create subscribers behind the ANs
9

Now that we have our first and second ANCP components created, the
ANs and Line Profiles, let’s now build the subscribers and associate them
to their respective ANs using Access Loops.

We’ll do the next set of steps 4 times, each time configuring the
subscribers behind a set of 256 ANs.
PROPRIETARY AND CONFIDENTIAL
3. Select Access Nodes

Set “Loop blocks
per access
node” to 1

Select 256 ANs

Note that you
can multi-select
by selecting the
1st AN, scrolling
down to the
256th AN and
<shift>+click

Then click on
any of the
checkboxes and
all 256 will be
selected.

Click “Next”
10
PROPRIETARY AND CONFIDENTIAL
4. Configure Subscriber Protocol

In this example the
subscribers will be
using PPP to obtain
an IP address.

It is common that
the subscribers
include an
identifier such as a
Circuit-ID.
• If you need it you
can configure it
here.[1]
• You will see that in the ANCP “Line Profile” you can configure a Circuit-ID
TLV. These may need to match but unfortunately because ANCP and PPP
(or DHCP) are separate protocols, these are configured separately. [2]
11
PROPRIETARY AND CONFIDENTIAL
5. Configure Subscribers

The “Access Loop Generator” wizard assumes that the subscribers will use
stacked VLANs and so has a default “Number of VLAN Tags in Stack” of 2. This
however will cause the creation of “True Topology” links which we didn’t want
to use because the ANs and the subscribers are not sharing the ANs’ VLAN.

So set the topmost AN to “0” and use “Copy Down” to make them all “0”
0
12
PROPRIETARY AND CONFIDENTIAL
5. Configure Subscribers (cont’d)

You can increase the “Subscriber Count” here to specify how many subscribers
are behind each AN.

In this example we want 10 subscribers behind each AN.

NOTE: it’s important to do this here so that all the subscribers will be
associated with a line profile and you can do them in bulk by using the “Copy
down” feature. [3]
13
PROPRIETARY AND CONFIDENTIAL
6. Configure Access Loop TLVs

Here you can use a wildcard to help you match your RADIUS server’s
Circuit-ID schema. [1] [2]

This TLV is sent in the
Port Up/Down messages.
14
PROPRIETARY AND CONFIDENTIAL
7. Select the line profile

Here we assign the line profiles created in the second step to each host.
For example the hosts behind Access Nodes 1 -256 use the “Line profile
1” line profile, Access Nodes 257 - 512 use the “Line profile 2” and so
on.

Click on “Assign profiles to device ranges”
15
PROPRIETARY AND CONFIDENTIAL
7. Configure Line Profile (cont’d)

This step creates the “Access Loop Blocks” which if you recall, tie the
ANs, subscribers, and Line profiles together. So this is a key step.

If any of the profiles are selected, deselect them all.

Now select the line profile you want these subscribers to use and click
“Finish”
16
PROPRIETARY AND CONFIDENTIAL
Repeat steps 3 through 7 for the remaining ANs
and subscribers and check your work

On “All Devices” select all the
device blocks from all the pages.

Then click on “Edit Access Loops”

In this example we want to use
the “Line profile 1” on the first
256 ANs and so on. So you can
scroll through to see that you
have the correct line profiles
associated with the ANs. [4]
17
PROPRIETARY AND CONFIDENTIAL
8. Fix Subscriber’s VLANs (and MACs)
18

Back in step 5, we set “Number of VLAN Tags in Stack” to 0. This means that
the subscribers currently have no VLANs and we need 2 so we’ll fix that here.

Find the “Encapsulation” column and on
the topmost device block, click on the “…”

Change the “# of VLAN Headers” to 2 and
click “OK”

Now this is IMPORTANT . Scroll over to the
“Vlan #1 Modifier” column and notice it’s set
to 1. We need to change that to “0”. So click
on “…” [5]

And set the “Step” value to “0” and click “OK”. Do this for “Vlan #2
Modifier” as well.
PROPRIETARY AND CONFIDENTIAL
8. Fix Subscriber’s VLANs (and MACs)
19

Now we’re going to copy down the encapsulation along with the VLAN modifiers.

Select all the subscriber device blocks. You can use the filter feature to filter the ANs
out by creating a new filter where the Tags field equals “Host”

Once you have only the subscriber device blocks filtered, click in the upper left corner
of the device grid and select “On all pages” (remember you have 1024 device blocks)
and clikc “OK”.
PROPRIETARY AND CONFIDENTIAL
8. Fix Subscriber’s VLANs (and MACs)
20

Now we can use
“Copy Down” to make
all the subscribers
device blocks have
2 VLANs.

There are 1024 device
blocks so this may take
a minute or two so
please be patient.
PROPRIETARY AND CONFIDENTIAL
9. Fix Subscriber’s VLANs (and MACs)

Now we just need to configure the VLANs to match the VLAN schema we
need. That was:
• Subs “behind” ANi use stacked VLAN (outer 99,inner i)
• Find “VLAN ID #1” column. This is the outer VLAN. Set the topmost device block’s to 99 and do
a “Copy Down” on all the filtered device blocks.
• Find “VLAN ID #2” column. This is the inner VLAN. Set the topmost device block’s to 1 and do
a “Fill Increment” on all the filtered device blocks.

21
Let’s do the same for the MAC addresses. Set the topmost device block’s
“Source MAC Address” and do a “Fill Increment” on say the 5th octet to insure
that none of the 10,240 subscribers will not have duplicate MACs.
PROPRIETARY AND CONFIDENTIAL
Step by step summary
1.
Create the Access Node (AN) device blocks
2.
Create the Line Profiles
3.
For each set of ANs use the “Access Loop Generator”
1. Select the ANs you want to configure subscribers for
2. Configure the subscriber protocol
1. PPP or DHCP or none
2. Circuit-ID
3. Configure subscriers
1. Set VLAN stack to ‘0’
2. Set subscriber count to N
4. Configure Access Loop TLVs
1. Circuit-ID
5. Associate the Line Profile needed for this set of ANs/subscribers
4.
22
Fix the subscriber VLANs and MACs
PROPRIETARY AND CONFIDENTIAL
Convert this configuration to
one where the subs are sharing
the AN’s VLAN
Convert this configuration to one where the
subs are sharing the AN’s VLAN

In this "How To" we will cover the cases where we're:
• not using True Topology; and
• subscribers are not sharing the ANs' VLAN

We easily change the case where the subscribers are sharing the ANs' VLAN by simply
changing the outer VLAN on all the subscriber device blocks from “99” to the ANs’ VLAN,
10.

Just like in Step 8, we filter out all the subscriber device blocks, change the topmost
device block’s “VLAN ID #1” to 10, select them all, and “Copy Down”.

Done! 
24
PROPRIETARY AND CONFIDENTIAL
Notes / Caveats
Notes/Caveats

[1] Circuit-ID wildcard usage may be a challenge when scaling an ANCP test. Basically for
each AN’s and PPP circuit-ID TLVs, the wildcards starting value will always default to 1 (or
similar) and hence for each AN and PPP subscriber device block, you’d have to go and edit
the start value.
One recommendation is to use a wildcard that is unique for each AN as well as subscriber
in the test, such as the MAC address wildcard. Of course this would mean that you’d have
to adjust your RADIUS server to expect that circuit-ID naming schema.
26
PROPRIETARY AND CONFIDENTIAL
Notes/Caveats

[2] ANCP and PPP (or DHCP) are separate protocols and so common attributes used in both
protocols, in particular the Circuit-ID, need to be configured twice. Once in ANCP and
once in the subscriber protocol, PPP or DHCP.

[3] If you miss this step, the additional subscribers will not have a line profile associated
to them and so:
27
•
There will be no Port UP/Down messages sent for those subscribers
•
It will be tedious to go back and “map” a line profile to those subscribers (see “3” below).
PROPRIETARY AND CONFIDENTIAL
Notes/Caveats (cont’d)

[4] If you “Edit Line Profiles…” and see multiple line profiles associated with an AN, you
will have to go into each one and delete the unwanted ones. So that is why Step 7 is so
important.
Of course, you can always delete all the subscribers you created in Step 5 and start again.


[5] Because the VLAN modifier defaults to step=1, if we don’t set the topmost subscriber
device block’s modifiers step=0, when we copy down, it will also copy down the modifier
setting.
As in the [4] above, if all else fails, just start again by set the topmost device block’s
encapsulation to a VLAN depth of 0 and copy that down and start Step 8 again.
28
PROPRIETARY AND CONFIDENTIAL
Thank You
Spirent Communications, Support Services