Setting an Optical Network on COSMOS Testbed

This wiki page contains the tutorial of setting up an optical network on the COSMOS Test-bed.

Authors:

Zehao Wang, Duke University <zehao.w[at]duke.edu>
Tingjun Chen, Duke University <tingjun.chen[at]duke.edu>

Description

Cosmos test-bed provides a possibility to create and use optical networks of various topologies. An example of how an optical network could be configured and used is provided. A simple experiment on switching of optical paths is described.

Experiment Topology and Resources Required

Figure 1. Topology setup of the experiment.

This experiment demonstrates optical switching between the short (1-hop) path, between srv1-co1 and srv1-lg1, and the long (2-hop) path, between srv1-co1 and srv2-lg1. It represents changing of the light path in C-RAN when a "Client" wants to dynamically change its base-band processing location between a nearby "Edge Cloud" and a further away "Central Cloud".

This experiment uses the following hardware resources and configurations:

• 3 compute servers and 4 ROADM units in the bed.cosmos-lab.org domain:

  srv1-co1.bed, srv1-lg1.bed, srv2-lg1.bed
  rdm1-co1 (10.104.1.1), rdm2-co1 (10.104.1.2), rdm1-lg1 (10.104.2.1), rdm2-lg1 (10.104.2.2)
  

• Interfaces on ToR switch sw-da-co1:

  Eth 1/1/1:1 (vlan 1066) srv1-co1 data1
  Eth 1/1/66  (vlan 1066) 10g dwdm tunable (connected to Calient 5.7.3)
  

• Interfaces on ToR switch sw-da-lg1:

  Eth 1/1/1:1 (vlan 1033) srv1-lg1 data1
  Eth 1/1/1:2 (vlan 1034) srv2-lg1 data1
  Eth 1/1/33  (vlan 1033) 10g dwdm tunable (connected to Calient 5.7.5)
  Eth 1/1/34  (vlan 1034) 10g dwdm tunable (connected to Calient 5.7.6)
  

• Comb source connected to Calient 5.8.5 and 5.8.8 via a 1x2 optical splitter.

Setting Up Optical Topology

Setting up an optical topology consists in connecting ROADM units accordingly to the needs of the experiment. ROADMs need to be connected correctly to each other and to ToR switch. All interconnections are realized by Calient S320 switch. In order to support the logical connections and to realize emulate real distance between a nearby Edge Cloud and a further Central Cloud, one could choose to pass the optical signal through 1 hop (via a pair of 10km fiber spools) or 2 hops (via a pair of 10km fiber spools with the 32km Manhattan dark fiber).

The following table summarizes all connections required for this experiment:

• For the comb source:

ID	Ports Connection		Devices Connection		Comment
1	5.8.5→1.1.1		comb_source_1 to ROADM1-CO1.port_1		Forming background traffic into ROADM1-CO1 add port 1
2	5.8.8→1.4.1		comb_source_2 to ROADM2-CO1.port_1		Forming background traffic into ROADM2-CO1 add port 1
4	5.7.3↔1.1.1		transceiver_3 with ROADM1-CO1.port_2		Connecting transceiver3 with ROADM1-CO1 add/drop port 1
5	1.1.8→5.5.1		ROADM1-CO1.line_port to fiber_spool_1		Connecting ROADM1-CO1 line out to the 10 km fiber spool
6	5.5.2→1.1.8		fiber_spool_2 to ROADM1-CO1.line_port		Connecting the 10 km fiber spool to ROADM1-CO1 line in
7	5.5.1→1.4.8		fiber_spool_1 to ROADM1-LG1.line_port		Connecting the 10 km fiber spool to ROADM1-LG1 line in
8	1.4.8→5.5.2		ROADM1-LG1.line_port to fiber_spool_2		Connecting ROADM1-LG1 line out to the 10 km fiber spool
9	2.1.8→4.6.1		ROADM2-LG1.line_port to dark_fiber_1		Connecting ROADM2-LG1 line out to the 34 km dark fiber
10	4.6.2→2.1.8		dark_fiber_2 to ROADM2-LG1.line_port		Connecting the 34 km dark fiber to ROADM2-LG1 line in
11	4.6.1→2.4.8		dark_fiber_1 to ROADM2-CO1.line_port		Connecting the 34 km dark fiber to ROADM2-CO1 line in
12	2.4.8→4.6.2		ROADM2-CO1.line_port to dark_fiber_2		Connecting ROADM2-CO1 line out to the 34 km dark fiber

• For the short route (1-hop, 10km):

ID	Ports Connection		Devices Connection		Comment
1	2.4.1↔5.7.5		ROADM1-LG1.port_2 with transceiver_5		Connecting ROADM1-LG1 add/drop port 2 to transceiver5 to emulate the connection to the edge cloud

• For the long route (2-hop, 10km + 32km):

ID	Ports Connection		Devices Connection		Comment
1	2.4.1↔5.7.6		ROADM2-CO1.port_2 with transceiver_6		Connecting ROADM2-CO1 add/drop port 2 to transceiver6 to emulate the connection to the center cloud

ROADMs Configuration

All of these configurations can be performed by Python scripts developed to work with the COSMOS test-bed. The Python commands send NETCONF commands to the ROADM.

Setting “Snake” Connection

Correct ROADM operation requires Line In port of a ROADM to always receive a light. That is why there is a dedicated transceiver (tengigabitethernet 1/33 on ToR) that sends light through all ROADMs by passing through loop-back connection on Calient S320 (port 5.5.1) and redirecting back, so the light is received on the same transceiver. This kind of connection is called “Snake”.

In order maintain this “Snake” for “Experiment_1” next connections form Table 1 must be in place: 1,3,5,6,8,9.

tengigabitethernet 1/33/1 on ToR configuration

Snake Interface (to passe through all ROADMs in loop): 60 (DWDM Channel C60) 1529,55 nm 196,00 Thz with frequency range [195.95,196.05] Thz

ROADM MUX/DEMUX configuration

• rdm1-co1: DEMUX ports: [5202 (drop2)]; MUX ports: [4101 (add1), 4102 (add2)]
• rdm2-co1: DEMUX ports: [5202 (drop2)]; MUX ports: [4101 (add1), 4102 (add2)]
• rdm1-lg1: DEMUX ports: [5201 (drop1), 5202 (drop2)]; MUX ports: [4101 (add1), 4102 (add2)]
• rdm2-lg1: DEMUX ports: [5201 (drop1)]; MUX ports: [4101 (add1)]

ALS Disable Sequence (for 60 seconds)

1. ROADM 4 booster,
2. ROADM 2 booster,
3. ROADM 3 booster,
4. ROADM 1 booster,

Setting Optical Connections

Configuring the the background traffic using comb source

• Forward direction

1.

• Backward direction

1.

Configuring the short route (1-hop)

• ROADM 4:

1. Enable MUX port 4102 “From ToR 1”
2. Add Connection “Exp1-FromTor1” with Input/ Output Port 4102/4201 with bandwidth [192.95;193.05] (python add_connection.py 10.104.1.4 1 10 in-service false 4102 4201 192950 193050 5 Exp1-FromTor1)
3. Enable DEMUX port 5202 “Towards ToR 1”
4. Add Connection “Exp1-TorwardTor1” with I/O Port 5101/5202 (python add_connection.py 10.104.1.4 2 10 in-service false 5101 5202 192950 193050 5 Exp1-TorwardTor1)

• ROADM 1:

5. Enable MUX port 4102 “From ToR 2”
6. Add Connection “From ToR 2” with I/O Port 4102/4201 with bandwidth [192.95;193.05]
7. Enable DEMUX port 5202 “Towards ToR 2”
8. Add Connection “Towards ToR 2” with I/O Port 5101/5202

Configuting the long route (2-hop)

• ROADM 4 (Same As For Connection 1):

1. Enable MUX port 4102 “From ToR 1”
2. Add Connection “From ToR 1” with I/O Port 4102/4201 with bandwidth [192.95;193.05]
3. Enable DEMUX port 5202 “Towards ToR 1”
4. Add Connection “Towards ToR 1” with I/O Port 5101/5202 with bandwidth [192.95;193.05]

• ROADM 1 <Not Same!>:

5. Enable MUX port 4101 “Through Port” (enabled for Snake)
6. Add Connection “Through In” with I/O Port 4101/4201 with bandwidth [192.95;193.05]
7. Enable DEMUX port 5201 “Through Port” (enabled for Snake)
8. Add Connection “Through Out” with I/O Port 5101/5201 with bandwidth [192.95;193.05]

• ROADM 2 (Same As For ROADM1):

9. Enable MUX port 4101 “Through Port” (enabled for Snake)
10. Add Connection “Through In” with I/O Port 4101/4201 with bandwidth [192.95;193.05]
11. Enable DEMUX port 5201 “Through Port” (enabled for Snake)
12. Add Connection “Through Out” with I/O Port 5101/5201 with bandwidth [192.95;193.05]

• ROADM 3 (Same As For ROADM4):

13. Enable MUX port 4102 “From ToR 3”
14. Add Connection “From ToR 3” with I/O Port 4102/4201 with bandwidth [192.95;193.05]
15. Enable DEMUX port 5202 “Towards ToR 3”
16. Add Connection “Towards ToR 3” with I/O Port 5101/5202 with bandwidth [192.95;193.05]

Configuring the Compute Nodes

1. Install net-tools:

sudo apt install net-tools

2. Configure interfaces the DATA1 interface on each server and assign IP addresses:

root@srv1-co1:~$ sudo ifconfig eno1 10.111.1.1 netmask 255.255.0.0 up
root@srv1-lg1:~$ sudo ifconfig eno1 10.111.2.1 netmask 255.255.0.0 up
root@srv2-lg1:~$ sudo ifconfig eno1 10.111.2.2 netmask 255.255.0.0 up

Experiment Execution

1. Establish the short route (1-hop)
2. Ping from srv1-co1 to srv1-lg1. From srv1-co1 to srv2-lg1 should not be pingable at this moment.

native@srv1-lg1:~$ ping 192.168.1.3
PING 192.168.1.3 (192.168.1.3) 56(84) bytes of data.
64 bytes from 192.168.1.3: icmp_seq=1 ttl=64 time=0.460 ms
64 bytes from 192.168.1.3: icmp_seq=2 ttl=64 time=0.423 ms

3. Switch to the long route (2-hop).
4. Ping from srv1-co1 to srv2-lg1. From srv1-co1 to srv1-lg1 should not be pingable at this moment.