Cisco 887VA VDSL – Ethernet bridge on Sky Fibre Unlimited Pro

After successfully configuring the Cisco 887VA on my Sky Fibre Unlimited Pro connection I started to configure NAT and ACLs to allow all of my devices to work properly. For the most part this wasn’t an issue, until I came to all of the games consoles in the house.

We pretty much have a console in every room in the house, totalling 3 x Xbox 360s, a PS3 and a PS4. I blogged a while ago about setting them all up to use UPnP on pfsense to map inbound ports on demand in order to get an open NAT type in game. Now that worked well, but unfortunately the Cisco box doesn’t support UPnP or NAT-PNP by design. The reason for the deliberate lack of these features is simple; Cisco IOS devices are enterprise devices, and no enterprise want users to be able to dynamically NAT ports to internal resources.

While I agree that UPnP or NAT-PNP is a security risk in the enterprise, many other vendors support the features but provide means to restrict which devices may use them, similar to how pfsense does.

The console all tend to use the same ports to connect to the internet. However, when they use UPnP they can use alternative ports if the UPnP router refuses to open the requested ports because another device is using them. This is all good on consumer routers which tend to have UPnP enable as standard. The biggest problem I have with the 887 is that the ports would have to be manually NATed to the console that as currently in use, and the other console would struggle to work properly.

This issue pretty much rules out the feasibility of using the 887 in our house as a conventional router. I did however wonder is I could simply replace the Openreach Modem with the 887 and continue to use my trusty Firebox x750 running pfsense as my firewall. I started to play with my config. After a quick config erase and reload I had a blank canvas to play with.

I decided to try a bridge group first. I shutdown the ATM interface and created the required sub interface on the eth0 interface as below. I also put the sub interface in a bridge group.

interface Ethernet0
no ip address
no ip route-cache
!
interface Ethernet0.101
encapsulation dot1Q 101
no ip route-cache
bridge-group 1
!
interface ATM0
no ip address
no ip route-cache
shutdown
no atm ilmi-keepalive

I then tried to pt a FastEthernet interface into the bridge group, which failed as layer 2 interfaces are not allowed in bridge groups. To get around this I created a vlan and placed that into the bridge group. I then stick Fa0 into the clan. Notice the config line “ip virtual-reassembly in”. It is required.

interface Vlan100
no ip address
ip virtual-reassembly in
no ip route-cache
bridge-group 1
!
interface FastEthernet0
description ~ Uplink to Firewall ~
switchport access vlan 100

Then I set the protocol on the bridge group.

bridge 1 protocol ieee

Finally I disable the routers routing engine.

no ip routing

It worked. I was impressed!.

I know many people this the 887VA is an expensive router to just use as a bridge. I disagree. I have had issues with my line for a few months, caused by broken insulation on the drop wire. The drop wire has been replaced now but OpenReach didn’t re-enable DLM, meaning the line never really built any speed up since the drop wire was replaced. Considering it was sitting at 52Mbs sync our of 80, and the DSLAM is approximately 80 meters from my master socket, this wasn’t acceptable. After 8, yes eight, engineer to my house, none of which were interested in the history of the fault and none of which were willing to do the OGEA reset I requested to set the line speed back to 80Mbs to train down to a stable speed, I have pretty much given up on OpenReach.

Enter 887VA. When I started using this router as a bridge two days ago, the sync speed was already 5Mbs up from the OpenReach Modem. I decided to hammer the connection using Iperf and monitor it for errors. I set iperf away all night at the maximum speed of the line and checked it in the morning. There were a total of 7 CRCs and no drop outs. Result. I shutdown “controller vdsl 0” and brought it back up to find another 1.3Mbs sync speed. I repeated this procedure again the next night and yet again gained another 0.9 Mbs sync speed, bringing me to just under 60Mbs.

Another benefit of using the 887VA is the fact I can see my full line stats. Bonus.

I’m going to continue to try and increase my line speed over the next week and see how high I can get it. If only I could use the “del noise-margin” command.

 

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