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SMB router, multiple ASDL's


Hi all,

I am looking to install new Cisco router to replace old network which has got 4 ADSL connection, going to 4 different routers.

What I want to achieve is to have one router, which is capable of having up to 4 ADSL connections, 78mbps each and load balance vlans per link.

As I'm not looking into spending thousands, I've had a brief look on Cisco website and I found some cool routers.

Cisco 1921 and Cisco 1941, both of them have expansion slots etc.

Would they support 4 ADSL connections?

I've had a look, but can't find an answer.

All the best!

18 Replies 18

Seb Rupik
VIP Advisor VIP Advisor
VIP Advisor

Hi there,

I don't belive there is a dual ADSL2 HWIC card. You best bet is to install four ADSL2 HWICs. According to this table:

Your router options are:

Cisco 2811, 2911,2821,2921, 2851,2951 3825,3925,3845 and 3945




Thanks for that

Would Cisco ASA 5506 support 4 adsl, since it has got 8 ports? I could plug ADSL to modem to it converts it to ethernet.

Hello again,

I thought from your original post that you wanted the ADSL dialer interfaces to be configured on a Cisco router?

If you are proposing having four separate other-vendor ADSL modems and plugging them into an ASA, then yes that would work using PBR to balance your VLANs between the links. It would just take up a lot of space in your comms cabinet!





Yes, that was my original thought however it seems to be expensive and I am looking to spend £1000 maximum on the router/firewall.

I need something that would support 4x78mbps connection so 312 mbps throughput in total.

I saw ASA 5506-X which could do that, do you know anything equivelent however a router for this price?

Take a look at the ISR G2 column here:

The 350 Mbps just beats your reuqirment but is only available on the 3945, and a quick look on ebay shows these are more than £1k.

The ASA5506-X can be picked up for around £500 and is just shy of your requirment at 300 Mbps (multiprotocol).  Although it won't offer some of the router functions you may require, and it does come with some (optional) liceses which you may want to include in your costings if you want to use its firewall capabilites.




Yeah, that is true although I found 2951 (2nd hand) for 875GBP on eBay and ADSL HWICS for 30GBP each so I could actually make it within 1k budget for the router.

Now I know it will sound funny, however the line speeds will be different. We will have 5 ADSLs running at 25 mbps each. I am thinking, should I get ASA and L3 switch, or a router?

According to Cisco website ASA 5506-X can support 300 mbps multiprotocol and obviously it would support 5 ADSLs as it has got 8 interfaces in total.

On the other hand I could get a router.

What would you recommend in this scenario? This won't now change and configuration will remain with 5 ADSLs running at 25mbps each.


Having an ASA on your network will provide some security nice-to-haves on your network; do you have any firewall capability on your network already?

Regarding a router, do you have any requirement for dynamic routing, VPNs? However getting the throughput for under a grand is not possible.

If you are just trying perform PBR, then you could go for a 2nd-hand 3750G, but these don't support IP SLA, so if an ADSL router went down part of your PDR would suffer.

I'd go for the 5506. It does PBR, IP SLA, dynamic routing is progressing (IPv6), client/ site VPN and firewalling and just about hits your peak throughput requirement.




Thanks for your input again. I greatly apperciate it.

I don't have any firewall capability on my network already and I wouldn't require dynamic routing or VPNs. It will be a simple network without any internal services like file sharing. It will be used for end devices to connect to the cloud based services.

I'm convinced with ASA 5506 because it can support even up to 7 ADSLs and I will be left with one link to the LAN which is all I need.

5506 will definetely hit throughput requirement and even exceed it as at the moment there only will be approx 125 mbps maximum throughput available.

Would ASA be capable of load balancing the LAN to WAN traffic between 5 ADSLs? Let's say ADSL 1 is 90% utilised, move traffic to ADSL 2 - something like that? I would like to be able to utilise all links at the same time as there is about 50 clients.

Would routing per vlan be the only option to balance the traffic and ultise all interfaces at the same time? let's say, floor 1 vlan 1019 go out via int gig 0/0, floor 2 vlan 1020 go out via int gig 0/1 and so on?

So you want your firewall (ASA) to act as your router?

Don't get me wrong but I guess you are overlooking your needs with what your budget allows you.

The ASA just takes care of filtering what comes from one interface directed to another interface, and that's it. It won't do a proper load balance or have the capability to have your DSL lines plugged onto it. You still need your DSL lines terminated somewhere, which then provides each of these terminations with an IP address. And even so, I'm not aware of ASA doing this load balance as you need. ASA can do static routing -- ie, "for this source IP use this IP as gateway", "for protocol X and port Y use that IP as gateway", or "use this IP as gateway IF this other IP is not alive", and so on -- but "if one DSL has some load already then use that other DSL line", that's dynamic, and you need either a router capable of doing load balance, or a dedicated load balance solution with multiple routers.

As a side note, the ADSL WIC cards you found for £30 might very likely be ADSL1 interfaces, capable of 8Mbps downstream max. Make sure you are looking for HWIC-1ADSL or HWIC-ADSL-B if you have ISDL and plan to use around 20Mbps per line.


Thanks for your input. You made some good points.

Just to summarise:

1. In my understanding ASA can actually support ADSL lines as far as they go into the modem which will then convert the ADSL cable to Ethernet, which then can be connected to one of the eight ports on the ASA. Please correct me if I'm wrong. 

2. ASA can only support load balance only by static routing so we can enforce specific subnets/vlans to go out via specific interfaces/IPs. Please correct me if I'm wrong. 

3. To allow dynamic routing so traffic is moved in between the interfaces, I need to configure policy based routing which can only be supported by the router. We are looking at 125mbps total throughput so even 1941/k9 would support it. It has got 2 gigabit ethernet ports and 3 expansion slots. Could I install ethernet HWIC to support 5 ADSL lines on this router? Would this be better way of approach for this change? If not, would I be better off with increasing the budget to get a router which can support 5 ADSL hwics to take full advantage of PBR?

Feels like you are looking at the ASA as an "advanced switch", by using the ASA's 8 RJ45 ports and doing some "magic" on it. It would not work as you want, but will surely be more expensive.

The ASA is more likely a "90% protection, 5% switching, 5% routing". A router is, uh, 90% routing, 5% protection, 5% switching. Not on these exact percentages actually, but you got the idea. Anyway, you are looking for a way to share the load of all DSL lines while providing some control over it, so you really need a router, not a firewall.

If you are terminating the DSL lines at the router, then you need one slot per DSL line, one WIC/HWIC card for each DSL line, and one Ethernet interface for your LAN traffic. You will be responsible to upgrade each WIC/HWIC if your ISP decides to upgrade your service, or to replace them if you go with different service or provider (ie, from plain ADSL to ADSL2, VDSL or Cable).

If you are deploying one DSL modem for each DSL line, and each DSL modem will provide you their own IP address, then you don't need any WIC/HWIC on your router. You only need two Ethernet interfaces, Gigabit preferred, being one for WAN traffic, other for LAN traffic. And a switch to have all these DSL modems and your WAN port on your router talking together.

Now, if all you want is "if traffic is from VLAN1, then use DSL modem #1" and so on, then yes, the ASA would do that fairly easily. However it might be a little hard to make it smart, should one line goes down.


I understand, I think in my scenario router is a must, plus it will be more scalable because we might be able to get some VDSL connections later, at the moment only ADSL2+ is available. 

Each of the ADSL2+ lines will go into a modem. At this point, I'd like to clarify one point because I don't understand your sentence. You said I will need two gigabit interfaces, one for WAN and one for LAN and a switch to have all these DSL modems and your WAN port on my router talking together.

Did you mean I will need a switch WIC/HWIC installed on my router so that all DSL modems can be plugged into a router? Let's say 1941/k9 support about 150 mbps of throughput and has got 2 gigabit ports built-in already. Did you mean that I will need to install additional HWIC card to have 4 more ports to support 5 ADSL connections? This will give 6 in total on the router, 1 built-in for LAN, 1 built-in for ADSL2+ and HWIC for another 4 ADSL2+.

If you want to plug the phone lines directly into your router, and not on the modems provided by your ISP, then you will need DSL HWICs. One DSL HWIC to each phone line with an active DSL service. A switch is not required at the DSL side, as all lines will be on the router itself. The 1941, however, has slots for only two HWICs, so to use 6 DSL services, you will need something bigger than the 1941. In fact, something WAY bigger. I don't think there is any ISR with that many HWIC slots - they usually have a maximum of 4 slots.

If you are going to use the modems provided by your ISP, and using the router for just routing, then no, you don't need any DSL HWIC. Just the two Ethernet ports. The switch is needed to have the Ethernet ports on all the DSL modems accessible to the router at once.

For the second solution (using the ISP provided modems), instead of getting a network switch, you can get an EHWIC, which is basically an Ethernet card for your router, and have all the DSL modems' Ethernet ports plugged directly to your router thru these Ethernet ports, so no external switch will be needed. One less equipment to manage.

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