Around 3 years ago I blogged about using a Cisco 887VA Router as a VDSL Modem. As far as I recall I actually documented the configuration whilst getting ready to sell it, as I was downsizing my network.
Well, my network has since creeped back up in both size and complexity so I wanted to swap out the venerable Huawei HG612 VDSL modem for something else that could be rack mounted (cos bling). A quick google suggested the Cisco 887VA was still a good way to go, so I purchased another.
This time around I was a little more concerned it wouldn't be able to handle the throughput of my VDSL connection (50 Mb/s Down, and 16 Up). I think previously when swapped the previous modem for the 887, I ran a test on speedtest.net, and called it good when it showed a similar result to the Huawei.
I've since come to realise theres a bit more to it than that, with things like packet size and UDP vs TCP having quite a large impact on a devices maximum throughput, so I thought I should test the 887 more thoroughly before making it permanent.
Throughput Testing
To test the throughput I used Mikrotik's Bandwidth Test which is built into their routers. For the remote side I spun up a cheap VPS and installed Mikrotiks "Cloud" router. Unfortunatly I don't have the facility to emulate a full speed (80/20 Mb/s) VDSL connection so I had to use my own 50/16 link. It's not quite a fair test as both local utilisation and congestion within my ISPs network might impact the results, but it should give a ball park indication that the 887 can cope with the throughput.
I compared the Cisco 887VA with the original Huawei HG612 and a ZyXEL VMG1312-T20B.
Here's the results. All speeds are measured in MB/s:
Red indicates a failed test, either the modem locked up, or I was unable to get a reliable reading.
As you can see, the Cisco outperformed the Huawei in every test. The Zyxel was a little faster on the Upload side but that might have been down to the line rate at the time of the test - the difference certainly isn't large enough to be concerning.
Furthermore when running a full speed bi-directional TCP test, the CPU on the Cisco 887VA was around 20%, suggesting suitable headroom to support a full speed 80/20 VDSL connection but YMMV.
Power Testing
Another thing I hadn't previously tested was power usage. Some Cisco gear can be incredibly power hungry (100W+ ) which isn't ideal, so I wanted to check the power consumption.
I plugged it into a tasmota'd socket which indicated the consumption was around 11 Watts which is fairly palatable.
Configuration
The 887VA I received was on a newer IOS version than my previous one (15.3 vs 15.1) so the previous config didn't work properly.
Below is the revised and slightly simplified configuration. As before I'm not a Cisco expert and this configuration is fairly niche, so I can't make any guarantees it's the most efficient or secure setup, but I'm happy with it.
It's configured to support Baby Jumbos allowing a full 1500 byte packet to pass over the PPPoE connection, and also setup to use VLAN 101 on the VDSL side - a common requirement for most (all?) UK providers.
The router is assigned the IP 192.168.15.1/30 for management, with the expectation that a downstream router will be on 192.168.15.2/30 and any connections are NATed from this IP. You could add static routes instead if you wish.
You can plug the downstream router into any of the 4 FastEthernet ports on the front of the 887.
The config:
version 15.3 service timestamps debug datetime msec service timestamps log datetime msec service password-encryption no service password-recovery ! hostname MODEM-01.WD18-01 ! boot-start-marker boot-end-marker ! aqm-register-fnf ! enable secret 9 PASSWORD ! no aaa new-model ! ! ! ! ! ! ! ! ! ! ip domain name lan.marrold.co.uk ip cef no ipv6 cef ! ! ! ! ! multilink bundle-name authenticated ! ! ! ! ! ! ! license udi pid C887VA-K9 sn FCZ1941950P license boot module c800 level advipservices ! ! vtp mode transparent username admin privilege 15 secret 9 PASSWORD ! ! ! ! ! controller VDSL 0 operating mode vdsl2 modem 0 modem ukfeature ! vlan 100-101 ! ip ssh version 2 ip scp server enable ! ! ! ! ! bridge irb ! ! ! ! ! interface ATM0 no ip address no ip route-cache shutdown no atm ilmi-keepalive ! interface Ethernet0 mtu 1508 no ip address no ip route-cache ! interface Ethernet0.100 no ip route-cache ! interface Ethernet0.101 encapsulation dot1Q 101 ip virtual-reassembly in no ip route-cache bridge-group 1 ! interface FastEthernet0 no ip address ! interface FastEthernet1 no ip address ! interface FastEthernet2 no ip address ! interface FastEthernet3 no ip address ! interface Vlan1 mtu 1508 no ip address ip virtual-reassembly in bridge-group 1 ! interface BVI1 mtu 1508 ip address 192.168.15.1 255.255.255.252 ip virtual-reassembly in ! ip default-gateway 192.168.15.2 ip forward-protocol nd no ip http server no ip http secure-server ! ! ip route 0.0.0.0 0.0.0.0 BVI1 192.168.15.2 ! ! access-list 10 permit 192.168.15.0 0.0.0.3 access-list 10 deny any ! control-plane ! bridge 1 protocol ieee bridge 1 route ip ! ! mgcp behavior rsip-range tgcp-only mgcp behavior comedia-role none mgcp behavior comedia-check-media-src disable mgcp behavior comedia-sdp-force disable ! mgcp profile default ! ! ! ! ! line con 0 no modem enable line aux 0 line vty 0 4 logging synchronous login local transport preferred none transport input ssh ! scheduler allocate 20000 1000 ! end
Conclusion
So to conclude, I think the Cisco 887VA is a suitable replacement for the Huawei HG612 modem and doesn't introduce a new bottle neck on my ~50/16 VDSL line, and whilst untested I think it would perform adequately on a full speed 80/20 line.
Should you rush out and buy one? Probably not, I mostly got one for the aesthetic of rack mount gear. One benefit of the Cisco is some more detailed line stats, shown below.
Should you rush out and buy one? Probably not, I mostly got one for the aesthetic of rack mount gear. One benefit of the Cisco is some more detailed line stats, shown below.
MODEM-01.WD18-01#show controllers VDSL 0 Controller VDSL 0 is UP Daemon Status: Up XTU-R (DS) XTU-C (US) Chip Vendor ID: 'BDCM' 'BDCM' Chip Vendor Specific: 0x0000 0xC190 Chip Vendor Country: 0xB500 0xB500 Modem Vendor ID: 'CSCO' ' ' Modem Vendor Specific: 0x4602 0x0000 Modem Vendor Country: 0xB500 0x0000 Serial Number Near: FCZ1941950P C887VA-K 15.3(3)M6 Serial Number Far: Q10H7000598_39 Modem Version Near: 15.3(3)M6 Modem Version Far: 0xc190 Modem Status: TC Sync (Showtime!) DSL Config Mode: VDSL2 Trained Mode: G.993.2 (VDSL2) Profile 17a TC Mode: PTM Selftest Result: 0x00 DELT configuration: disabled DELT state: not running Trellis: ON ON SRA: disabled disabled SRA count: 0 0 Bit swap: enabled enabled Bit swap count: 0 0 Line Attenuation: 0.0 dB 0.0 dB Signal Attenuation: 0.0 dB 0.0 dB Noise Margin: 4.6 dB 6.0 dB Attainable Rate: 51916 kbits/s 19204 kbits/s Actual Power: 12.5 dBm 7.6 dBm Per Band Status: D1 D2 D3 U0 U1 U2 U3 Line Attenuation(dB): 12.8 31.8 52.3 4.8 23.9 38.4 N/A Signal Attenuation(dB): 12.8 31.8 52.3 4.8 23.0 37.4 N/A Noise Margin(dB): 4.6 4.5 4.5 6.0 6.0 6.0 N/A Total FECC: 5208174 1991 Total ES: 147 300 Total SES: 95 0 Total LOSS: 3 0 Total UAS: 2498 2498 Total LPRS: 0 0 Total LOFS: 3 0 Total LOLS: 0 0 Full inits: 2 Failed full inits: 0 Short inits: 0 Failed short inits: 1 Firmware Source File Name (version) -------- ------ ------------------- VDSL embedded VDSL_LINUX_DEV_01212008 (1) Modem FW Version: 130205_1433-4.02L.03.A2pv6C035j.d23j Modem PHY Version: A2pv6C035j.d23j Vendor Version: Ap6v35j.23j 68 DS Channel1 DS Channel0 US Channel1 US Channel0 Speed (kbps): 0 58563 0 19204 SRA Previous Speed: 0 58326 0 19201 Previous Speed: 0 58326 0 19201 Reed-Solomon EC: 1189 509842 0 322 CRC Errors: 3838 3838 378 378 Header Errors: 0 0 0 0 Interleave (ms): 0.00 0.00 0.00 0.00 Actual INP: 2.00 49.00 0.00 0.00 Training Log : Stopped Training Log Filename : flash:vdsllog.bin
Update 06/10/2021
I have now been using the 887VA as my VDSL modem for several months without any issues and annecdotally my speed has since increased to 60Mb/s down and 18Mb/s up which it still manages to handle without any problem.
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