ZYXEL MSAN 2U 5-Slot Temperature User Guide

June 9, 2024
ZYXEL

ZYXEL MSAN 2U 5-Slot Temperature

ZYXEL-MSAN-2U-5-Slot-Temperature

Product Information

MSAN/DSLAM

The MSAN/DSLAM is a product portfolio that includes different models of Central MSAN, Remote MSAN/DSLAM, and OSP. The product line includes IES6217, IES-5112, IES5212, IES5106, IES5206,IES4204, IES4105, IES-1000, VES1724-56B2, VES1724-55C, VES1724-58V,GES1316-FSA, GES1116-FSA, GES2104-R55, and GES2104-A55. The product line has features like PON interface, GE interface, VDSL2 interface, ADSL2+ interface, ADSL2+ combo interface, G.SHDSL.bis interface, VoIP interface, etc.

Product Usage Instructions

The MSAN/DSLAM product line has different models with different features. Before using the product, please refer to the user manual and select the model that best suits your needs. Follow the below instructions for usage:

  1. Firstly, check for the power supply of the selected model. Some models have a power supply of -36 to -72V DC, while others have a power supply of 100 to 240V AC.

  2. After checking the power supply, check for the operating temperature and humidity range of the selected model. Make sure to operate the device within the given range to avoid any damage.

  3. Next, check for the slot requirements of the selected model.
    Some models have a 2-slot requirement, while others have up to a 17-slot requirement.

  4. Check for the uplink and downlink requirements of the selected model. Some models have 1000BASE-SX/LX uplink, while others have 10G PON interface downlink.

  5. Check for the interface requirements of the selected model.
    There are various interface options available, such as PON, GE, VDSL2, ADSL2+, ADSL2+ combo, G.SHDSL.bis, VoIP interface, etc.

  6. Check for the maximum splitter ratio of the selected model. Some models have a maximum splitter ratio of 1:128, while others have a maximum splitter ratio of 1:256.

  7. Refer to the user manual for information on features like QoS, VLAN, IGMP, etc. and configure them accordingly.

  8. Make sure to manage the device using SNMP v2c, v3 Web management CLI management EMS management for better performance.

  9. Lastly, refer to the physical specifications of the selected model like dimensions (WxDxH), weight, etc. before installation.

MSAN/DSLAM product portfolio

ZYXEL-MSAN-2U-5-Slot-Temperature-1

ZYXEL-MSAN-2U-5-Slot-Temperature-2

Port density| | | | | | | | | | | | | | |
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---
ADSL2+| –| –| –| –| –| –| 24| 128| 360| 720| 1152| –| –| –| –
ADSL2+

Combo

| –| –| –| –| –| –| –| –| 240| 480| 768| –| –| –| –
SHDSL| –| –| –| –| –| –| 32| –| 240| 480| 768| –| –| –| –
VDSL2| –| –| –| –| 24| 24| –| 96| 240| 480| 768| –| –| –| –
VoIP| –| –| –| –| –| 24| –| 256| 360| 720| 1152| –| –| –| –
VDSL2/

Vectoring

| –| –| –| 24| –| –| –| –| –| –| –| 96| 192| 2 x 192| 3 x 192
1G AON| –| –| –| –| –| –| –| –| 120| 240| 384| 80| 200| 400| 600
PON| –| –| –| –| –| –| –| –| –| –| –| 32| 64| 160| -*
10G PON| –| –| –| –| –| –| –| –| –| –| –| 16| 32| –| –
G.fast| 4 (106 MHz)| 16 (106 MHz)| 8 (212 MHz)/

16 (106 MHz)

| –| –| –| –| –| –| –| –| –| –| –| –

  • By project request| | | | | | | | | | | | | |

Key Features

Category Model Key features
Central MSAN IES-6000



| •    Maximum 1152-port VoIP density, 1152-port ADSL2+ density, 768-port ADSL2+ combo density, 768-port SHDL density, 768-port VDSL2 density, or 384-port Gigabit Ethernet density

•    Flexible ACL, VLAN-aware DHCP, and anti-IP/MAC address spoofing to prevent malicious attacks

•    DHCP option 82 and PPPoE IA features support versatile IP address assignment

•   Full redundancy of management card and power module

•   Comprehensive QoS to enhance triple-play experience

•   Field-proven IGMP snooping and proxy for IPTV deployments

•   Sophisticated OAM&P features

•   Temperature-hardened for flexible installation

| IES6217


| •    Maximum 192×3-port vectoring VDSL density, 600-port Gigabit Ethernet density

•    Flexible ACL, VLAN-aware DHCP, and anti-IP/MAC address spoofing to prevent malicious attacks

•    DHCP option 82 and PPPoE IA features support versatile IP address assignment

•   Board-Level Vectoring (BLV) and System-Level Vectoring (SLV)

•   Full redundancy of management card and power module

•   Comprehensive QoS enhanced triple-play experience

•   Field-proven IGMP snooping and proxy for IPTV deployments

•   Sophisticated OAM&P features

•   Temperature-hardened for flexible installation

| IES-5112




| •    Maximum 720-port ADSL2+ density, 480-port ADSL2+ combo density, 480- port SHDSL density, 480-port VDSL2 density, 720-port VoIP density, or 240- port Gigabit Ethernet density

•    Flexible ACL, VLAN-aware DHCP, and anti-IP/MAC address spoofing to prevent malicious attacks

•    DHCP option 82 and PPPoE IA features support versatile IP address assignment

•   Full redundancy of management card and power module

•   Comprehensive QoS to enhance triple-play experience

•   Field-proven IGMP snooping and proxy for IPTV deployments

•   Sophisticated OAM&P features

•   Temperature-hardened for flexible installation

| IES5212




| •    Maximum 192×2-port vectoring VDSL density, 400-port Gigabit Ethernet density, or 160-port GPON density

•    Flexible ACL, VLAN-aware DHCP, and anti-IP/MAC address spoofing to prevent malicious attacks

•    DHCP option 82 and PPPoE IA features support versatile IP address assignment

•   Board-Level Vectoring (BLV) and System-Level Vectoring (SLV)

•   Full redundancy of management card and power module

•   Comprehensive QoS enhanced triple-play experience

•   Field-proven IGMP snooping and proxy for IPTV deployments

•   Sophisticated OAM&P features

•   Temperature-hardened for flexible installation

| IES-5106





| •    Maximum 360-port ADSL2+ density, 240-port ADSL2+ combo density, 240- port SHDSL density, 240-port VDSL2 density, 360-port VoIP density, or 120- port Gigabit Ethernet density

•    Flexible ACL, VLAN-aware DHCP and anti-IP/MAC address spoofing to prevent malicious attack

•    DHCP option 82 and PPPoE IA features support versatile IP address assignment

•   Comprehensive QoS to enhance triple-play experience

•   Field-proven IGMP snooping and proxy for IPTV deployments

•   Sophisticated OAM&P features

•   Temperature-hardened for flexible installation

| IES5206






| •    Maximum 192-port vectoring VDSL density, 200-port Gigabit Ethernet density, 64-port GPON density or 32-port XGS-PON density

•   Supports symmetric XGS-PON for residential, cloud, and enterprise services

•    Flexible ACL, VLAN-aware DHCP, and anti-IP/MAC address spoofing to prevent malicious attacks

•    DHCP option 82 and PPPoE IA features support versatile IP address assignment

•   Board-Level Vectoring (BLV) and System-Level Vectoring (SLV)

•   Full redundancy of management card and power module

•   Comprehensive QoS enhanced triple-play experience

•   Field-proven IGMP snooping and proxy for IPTV deployments

•   Sophisticated OAM&P features

•   Temperature-hardened for flexible installation

Central MSAN| IES4204






| •    Maximum 96-port vectoring VDSL density, 80-port Gigabit Ethernet density, 32-port GPON density, or 16-port XGS-PON density

•    Supports symmetric XGS-PON for residential, cloud, and enterprise services

•    Flexible ACL, VLAN-aware DHCP, and anti-IP/MAC address spoofing to prevent malicious attacks

•    DHCP option 82 and PPPoE IA features support versatile IP address assignment

•    Full redundancy of management cards and power module

•    Comprehensive QoS enhanced triple-play experience

•    Field-proven IGMP snooping and proxy for IPTV deployments

•    Sophisticated OAM&P features

•    Temperature-hardened for flexible installation

---|---|---
Remote MSAN/ DSLAM| IES4105




| •    Maximum 128-port ADSL2+ density, 96-port VDSL2 density, or 256-port VoIP density

•    Flexible ACL, VLAN-aware DHCP, and anti-IP/MAC address spoofing to prevent malicious attacks

•    DHCP option 82 and PPPoE IA features support versatile IP address assignment

•    Comprehensive QoS enhanced triple-play experience

•    Field-proven IGMP snooping and proxy for IPTV deployments

•    Sophisticated OAM&P features

•    Temperature-hardened for flexible installation

| IES-1000


| •    Maximum 24-port ADSL2+ density, or 32-port SHDSL density

•    Two Fast Ethernet interfaces for uplink

•    Supports 802.1p QoS, priority queuing, 802.1q VLAN tag, and multicast

•    1U, DC or AC power, and built-in POTS splitter

•    2 FE electrical interface for uplinks and subtending

| VES1724-56B2 VES1724-55C VES1724-58V





| •    Maximum 24-port VDSL2 density (VES1724-56B2, VES1724-58V), 24-port VoIP density (VES1724-58V), or 24-port vectoring VDSL density (VES1724-55C)

•    Complies with VDSL2 standards including ITU-T G.993.2, G994.1, and G.997.1

•    VDSL2 bonding and G.INP

•    SIP and H.248 for smooth voice over IP migration (VES1724-58V)

•    AC or DC dual-power with battery charge (VES1724-58V)

•    Fanless design for energy-saving and energy-saving and extended product life (VES1724-56B2, VES1724-55C)

•    Comprehensive QoS enhanced triple-play experience

•    Sophisticated OAM&P features

•    Temperature-hardened for flexible installation

| GES1316-FSA GES1116-FSA


| •    G.fast with G.vectoring and VDSL2/35b fallback (GES1316-FSA)

•    Multi-service interfaces including G.fast, VDSL2, GPON, and fiber-based GbE

•    Flexible ACL, VLAN-aware DHCP, and anti-IP/MAC address spoofing to prevent malicious attacks

•    Field-proven IGMP snooping and proxy for IPTV deployments

•    Comprehensive QoS enhanced triple-play experience

•    Sophisticated OAM&P features

•    AC/DC dual-power with battery charge function

•    Fanless design for energy-saving and extended product life

•    Temperature-hardened for flexible installation

OSP| GES2104-R55/A55


| •    G.fast with G.vectoring and VDSL2 fallback

•    Multi-service interfaces including G.fast, VDSL2, GPON, and fiber-based GbE services

•    Flexible ACL, VLAN-aware DHCP, and anti-IP/MAC address spoofing to prevent malicious attacks

•    Field-proven IGMP snooping and proxy for IPTV deployments

•    Comprehensive QoS-enhanced triple-play experience

•    Sophisticated OAM&P features

•    Environmental-hardened for flexible installation

•    Fanless design for energy-saving and extended product life

Feature Matrix

| | Central MSAN| | | | | |
---|---|---|---|---|---|---|---|---
| | IES6217| IES5212| IES5206| IES4204| IES-6000| IES- 5112| IES-5106
Product name| | 14U 17-slot Temperature- Hardened Chassis MSAN| 8.3U 12-slot Temperature- Hardened Chassis MSAN| 5U 6-slot Temperature- Hardened Chassis MSAN| 2U 4-slot Temperature- Hardened Chassis MSAN| 12.5U 17-slot Temperature- Hardened Chassis MSAN| 8U 12-slot Temperature- Hardened Chassis MSAN| 5U 6-slot Temperature- Hardened Chassis MSAN
Power| | -36 to -72 V DC| -36 to -72 V DC| -36 to -72 V DC or

100 to 240 V AC

| -36 to -72 V DC or

100 to 240 V AC

battery charger

| -36 to -72 V DC| -36 to -72 V DC| -36 to -72 V DC
Power redundancy| Yes| Yes| Yes| Yes| Yes| Yes| Yes
Operating temperature| -40°C to 65°C| -40°C to 65°C| -40°C to 65°C| -40°C to 65°C| -40°C to 65°C| -40°C to 65°C| -40°C to 65°C
Operating humidity| 10% to 95% RH| 10% to 95% RH| 10% to 95% RH| 10% to 95% RH| 10% to 95% RH| 10% to 95% RH| 10% to 95% RH
Slot| Uplink| 2/1| 2| 2/1| 2| 2/1| 2| 1
Downlink| 15/16| 10| 4/5| 2| 15/16| 10| 5
Interface| | | | | | | |
Uplink| 1000BASE- SX/LX| 8| 8| 8| 4 + 4| 4| 4| 4
10000BASE-SX/LX/ZX| 8| 8| 8| 4 + 4| 2| 2| 2
Downlink| 10G PON interface| –| –| 32 XGS-PON| 16 XGS-PON| –| –| –
PON interface| –| 160| 64| 32| –| –| –
GE interface| 600| 400| 200| 80| 384| 240| 120
VDSL2 interface| 192 x 3 (Vectoring)| 192 x 2 (Vectoring)| 192 (Vectoring)| 96 (Vectoring)| 768| 480| 240
ADSL2+ interface| –| –| –| –| 1152| 720| 360
ADSL2+ combo interface| –| –| –| –| 768| 480| 240
G.SHDSL.bis interface| –| –| –| –| 768| 480| 240
VoIP interface| –| –| –| –| 1152| 720| 360
PON| | | | | | | |
Maximum splitter ratio| GPON 1 : 128| GPON 1 : 128| 10G PON: 1 : 256

GPON: 1 : 128

| 10G PON: 1 : 256

GPON: 1 : 128

| –| –| –
Type B protection| Yes| Yes| Yes| Yes| –| –| –
AES| | Yes| Yes| Yes| Yes| –| –| –
SFP digital diagnostic management| Yes| Yes| Yes| Yes| –| –| –
QoS| | | | | | | |
802.1p priority queue| 8| 8| 8| 8| 8| 8| 8
802.1q tag-based VLAN| Yes| Yes| Yes| Yes| Yes| Yes| Yes
SPQ/WFQ| | Yes| Yes| Yes| Yes| Yes| Yes| Yes
DBA| | Yes| Yes| Yes| Yes| –| –| –
Security| | | | | | | |
IGMP v2, v3| | Yes| Yes| Yes| Yes| Yes| Yes| Yes
IGMP fast leave| | Yes| Yes| Yes| Yes| Yes| Yes| Yes
Multicast VLAN| | Yes| Yes| Yes| Yes| Yes| Yes| Yes
MLDv1 & MLDv2 snooping and proxy| Yes| Yes| Yes| Yes| Yes| Yes| Yes
Management| | | | | | | |
SNMP v2c, v3| | Yes| Yes| Yes| Yes| Yes| Yes| Yes
Web management| Yes| Yes| Yes| Yes| Yes| Yes| Yes
CLI management| Yes| Yes| Yes| Yes| Yes| Yes| Yes
EMS management| NetAtlas EMS| NetAtlas EMS| NetAtlas EMS| NetAtlas EMS| NetAtlas EMS| NetAtlas EMS| NetAtlas EMS
Physical specifications
Dimensions (WxDxH)(mm/in.)| 440 x 275 x 622/

17.32 x 10.83 x 24.49

| 440 x 275 x 370/

17.32 x 10.83 x 14.57

| 440 x 275 x 222/

17.32 x 10.83 x 8.74

| 440 x 285 x 89/

17.32 x 11.22 x 3.5

| 440 x 250 x 544/

17.32 x 9.84 x 21.41

| 440 x 250 x 363/

17.32 x 9.84 x 14.29

| 440 x 250 x 215/

17.32 x 9.84 x 8.46

Weight (kg/lb.)| | 25.5/56.22| 15.5/34.17| 13/28.66| 10.6/23.37| 15/33.07| 13.34/29.41| 10.2/22.49
| | Remote MSAN/DSLAM| | | | | OSP
---|---|---|---|---|---|---|---
| | IES4105| IES-1000| VES1724-56B2 VES1724-55C VES1724-58V| GES1316- FSA| GES1116- FSA| GES2104- R55/A55
Product name| | 2U 5-slot Temperature- Hardened Chassis Remote MSAN| 1U 2-slot Remote MSAN and Line Cards| 24-port Temperature- Hardened VDSL2 Box DSLAM| 8/16-port Temperature-Hardened G.fast DPU| 16-port Temperature-Hardened G.fast DPU| 4-port Environmental-Hardened G.fast DPU
Power| | -36 to -72 V DC or

100 to 240 V AC or dual power

| -36 to -72 V DC or

100 to 240 V AC

| -36 to -72 V DC or

100 to 240 V AC

| -36 to -72 V DC or

100 to 240 V AC

battery charger

| -36 to -72 V DC or

100 to 240 V AC

battery charger

| 100 to 240 V AC or reverse power feeding
Operating temperature| -40°C to 65°C| 0°C to 50°C| -40°C to 65°C| -40°C to 60°C| -40°C to 65°C| -40°C to 65°C
Operating humidity| 10% to 95% RH| 10% to 95% RH| 10% to 95% RH| 10% to 95% RH| 10% to 95% RH| 10% to 95% RH
Slot| Uplink| 1| –| –| –| –| –
| Downlink| 4| –| –| –| –| –
Interface| | | | | | |
Uplink| 100BASE-SX/LX| –| 2| –| –| –| –
| 1000BASE-SX/LX| 2| –| 2| –| –| 1
| 10000BASE-SX/LX/ZX| –| –| –| 2| 2| –
Downlink| VDSL2 interface| 96| –| 24| –| –| –
| ADSL2+ interface| 128| 24| –| –| –| –
| G.SHDSL.bis interface| –| 32| –| –| –| –
| VoIP interface| 256| –| 24 (IES1724-58V)| –| –| –
| G.fast interface| –| –| –| 8/16| 16| 4
QoS| | | | | | |
802.1p priority queue| 8| 8| 8| 8| 8| 8
802.1q tag-based VLAN| Yes| Yes| Yes| Yes| Yes| Yes
SPQ/WFQ| | Yes| Yes| Yes| Yes| Yes| Yes
Security| | | | | | |
IGMP v2, v3| | Yes| Yes| Yes| Yes| Yes| Yes
IGMP fast leave| | Yes| Yes| Yes| Yes| Yes| Yes
Multicast VLAN| | Yes| Yes| Yes| Yes| Yes| Yes
MLDv1 & MLDv2 snooping and proxy| Yes| –| Yes| Yes| Yes| Yes
Management| | | | | | |
SNMP v2c, v3| | Yes| –| Yes| Yes| Yes| Yes
Web management| Yes| Yes| Yes| Yes| Yes| Yes
CLI management| | Yes| Yes| Yes| Yes| Yes| Yes
EMS management| Yes| Yes| Yes| Yes| Yes| Yes
Physical specifications
Dimensions (WxDxH)(mm/in.)| | 441.2 x 262 x 88.8/

17.37 x 10.31 x 3.5

| 440 x 320 x 44/

17.32 x 12.60 x 1.73

| 440 x 250 x 44.35/

17.32 x 9.84 x 1.75

| 440 x 250 x 44.25/

17.32 x 9.84 x 1.73

| 440 x 250 x 44.25/

17.32 x 9.84 x 1.73

| 438 x 216 x 104/

17.24 x 8.5 x 4.09

Weight (kg/lb.)| | 3.2/7.05| 3.7/8.16| 4.7/10.36| 6.0/13.23| 6.0/13.23| 13/28.66

Line Card Information

Linecard type| Model| Description| IES6217| IES5212| IES5206| IES4204| IES-6000| IES- 5112| IES-5106| IES4105| IES-1000
---|---|---|---|---|---|---|---|---|---|---|---
Management

and switching cards

| MSC1324GB| Management and switching card with 2 10G and 4 GbE combo ports| | | | | •| •| •| |
MSC1324GC| Management and switching card with 2 10G and 4 GbE combo ports| | | | | •| •| •| |
| MSC1280XB| Management card with 8 10G SFP+ open slots| •| •| •| | | | | |
| MSC1240QA| Management card with 4 10G SFP+ open slots| | | | •| | | | |
| MSC1002GA| Management card with 2 GbE combo ports| | | | | | | | •|
VDSL line cards| VLC1424G-56| 24-port DMT-based VDSL2 line card, Annex A, 30a profile| | | | | •| •| •| |
| VLC1348G-51| 48-port DMT-based VDSL2 line card 17a profile, Annex A/Annex B| | | | | •| •| •| |
| VLC1348G-53| 48-port DMT-based VDSL2 line card 17a profile, Annex A/Annex B| | | | | •| •| •| |
| VLC1448X-51S| 48-port vectoring VDSL2 Annex A line card with built-in ETSI&ANSI POTS splitter, 17a profile| •| •| •| •| | | | |
| VLC1448X-51F| 48-port dual-line vectoring VDSL2 Annex A line card with built-in ETSI & ANSI POTS splitter, 17a profile| | | | •| | | | |
| VLC1448X-51D| 48-port dual-line vectoring VDSL2 Annex A line card (over POTS), 17a profile| | | | •| | | | |
| VLC1448X-51| 48-port vectoring VDSL2 Annex A/B/M/J line card, 17a profile| •| •| •| •| | | | |
| VLC1124A-51| 24-port VDSL line card, Annex A and 17a profile with built-in splitter| | | | | | | | •|
ADSL line cards| ALC1372G-51| 72-port Annex A ADSL2/ADSL2+ line card (over POTS)| | | | | •| •| •| |
| ALC1348G-51C| 48-port Annex L and Annex M ADSL2+/VoIP combo card| | | | | •| •| •| |
| ALC1132A-51| 32-port Annex A ADSL2/2+ line card (over POTS) with built-in splitter| | | | | | | | •|
| AAM1212-51| 12-port Annex A ADSL2/ADSL2+ module (over POTS)| | | | | | | | | •
VoIP line cards| VOP1164A-61| 64-port VoIP line card. H.248 or SIP| | | | | | | | •|
| VOP1372G-61 (SIP/H.248)| 72-port SIP/H.248 VoIP line card| | | | | •| •| •| |
Vectoring line card| VEC1001X| 192-port vectoring engine card| •| •| •| | | | | |
GbE line cards| GLC1320G-55| 20-port Gigabit Ethernet SFP (1000BASE-FX, 1000BASE-BX, and 1000BASE-LX)| | | | | •| •| •| |
| GLC1540X-55A| 40-port Gigabit Ethernet Line Card with 20 C-SFP/SFP Slots| •| •| •| •| | | | |
| GLC1440X-55A| 40-port Gigabit Ethernet line card (20 x C-SFP/SFP slots)| •| •| •| •| | | | |
GPON line cards| OLC3416B-IA| 16-port GPON Line Card| | •| •| •| | | | |
| OLC3416-42A| GPON line card with 16 GPON SFP open slots| | •| •| •| | | | |
10G PON line card| OLC3708-43A| 10G PON line card with 8 XFP open slots| | | •| •| | | | |
SHDSL line cards| SLC1348G-22| 48-port G.SHDSL.bis line card| | | | | •| •| •| |
| SAM1316-22| 12-port G.SHDSL.bis extension module| | | | | | | | | •

Corporate headquarters

Zyxel Communications Corp.
Tel: +886 3 578 3942
Fax: +886 3 578 2439
Email: sales@zyxel.com.tw
https://service-provider.zyxel.com

Zyxel Armenia
Tel: +374 96 584 694

Zyxel France
Tel: +33 (0) 4 72 52 97 97
Fax: +33 (0) 4 72 52 19 20

Zyxel Germany
Tel: +49 (0) 2405 6909 0
Fax: +49 (0) 2405 6909 99

Zyxel Italy
Tel: +39 011 2308000

Zyxel Turkey
Tel: +90 212 314 18 00
Fax: +90 212 220 25 26

APAC

Zyxel India
Tel: +91 11 4760 8800
Fax: +91 11 4052 3393
Email: info@zyxel.in

Zyxel Malaysia
Email: apac.sales@zyxel.com.tw

Zyxel Thailand
Tel: +66 (0) 2831 5315
Fax: +66 (0) 2831 5395
Email: info@zyxel.co.

North America

Zyxel USA
Tel: +1 714 632 0882
+1 800 255 4101 (free)
Fax: +1 714 632 0858
Email: keyaccount@zyxel.com

Zyxel Canada
Tel: +1 714 632 0882
+1 800 255 4101 (free)
Fax: +1 714 632 0858
Email: keyaccount@zyxel.com

For more product information, visit us on the web at https://service- provider.zyxel.com
Copyright © 2023 Zyxel and/or its affiliates. All rights reserved. All specifications are subject to change without notice.

References

Read User Manual Online (PDF format)

Loading......

Download This Manual (PDF format)

Download this manual  >>

Related Manuals