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[aesmith]

Hi,

Ever since I've been having Internet troubles I've regretted not having decent managed equipment on the line, and since Cisco is what I'm most at home with I was thinking of using an 877 on my 20CN DSL Max.  At work we've deployed loads of them, together with the later 887s, 897s and the equivalent i/f cards in modular routers.   However in these installations factors like onsite maintenance, consistent management and reliability have been more important than wringing the last bit of speed from the line.   Hence my wondering what experience people have had with these, how do they compare at the low DSL level with some of the alternative DSL modems or modem/routers?   I'm saying 877 rather than the later models as they're available pretty cheap secondhand.

Thanks,  Tony S

[Weaver]

The DSL in the 877 is fine if you are on a decent ie. short line. From the rumours I've heard, its DSL hardware is ok but not outstanding. Others might no more.


If you are on a long line, you might consider an Ethernet WAN port and something good such as the DLink DSL-320B modem available only from

    the AAISP shop http://aa.net.uk/broadband-accessories.html


for £20, so cheap that there's little risk. (I say "only" because you need one preprogrammed to be in modem-only mode with the (nasty) router functions hidden, and that's where you can get them from in the good configuration.)

[aesmith]

Cheers.  I'll see how it goes, I'd prefer to have router with integral DSL so I can put any service policies right on the WAN interface (accepted that it's still a bit virtual in that it's the dialler rather than ATM).   However I don't have a very high bar to compare it with, all I have to hand is Linksys and Plusnet's rotten 2704N, I'm sure neither are superstars in DSL quality.

Regarding that D-Link modem, do A&A put special software on or something, or is it just that they've configured it for convenience? 

[Weaver]

There’s absolutely nothing special that AA have done to it, they confirmed this to me recently. It's just that that config is right and with the out-of the-factory config it's a router and a quite cheesy one too, so I am told.

You should of course absolutely avoid having a separate modem because of MRU/MTU 1492 problems. As your service is 20CN if you have a two-box solution, then you would have to _suffer MRU/MTU 1492_ (instead of 1500) with any modem (including the DLink) I can think of, apart from the Draytek Vigor 130 (and older 120), which is magical. (The DLink can only do MRU 1500 on 21CN.)

If you had a very long line then lightning proof-ness would be one slight reason in favour of a two-box setup. Absolutely definitely no guarantees there at all, from bitter personal experience.

[aesmith]

Not looking good with a Cisco 877, it reports 3dB greater loss, and connects around 10% slower than my Linksys.   So it looks like my ideal connection may be Cisco Ethernet to Ethernet router and a PPPoE/ADSL modem.

[Weaver]

That's what I thought.

If your line is long, as I said earlier, you might want to try the aggressive DLink out, there's nothing to lose as it's soo cheap.

MTU 1500: out of interest, might want to check out whether or not the Cisco speaks RFC 4638. Won't help under 20CN though with the DLink or almost every other modem. The only option to get MTU 1500 would be a Draytek Vigor 130 or 120 (not fast on a long line), which works because it speaks PPPoA on the WAN side of things, just like a normal modem, then PPPoE over the Ethernet link only. So that depends on RfC4638, on whether it's a long line, and on whether you're bothered about MTU 1492.

I remember now, didn't you say you were getting 4 Mbps d/s now? So it's not tooo long a line. There are benefits to be had from experimenting with modems still, but they probably won't be as great as with my "63.5" dB line.

[aesmith]

Cisco 877 probably doesn't support MTU over 1500, most of the low end routers don't on their switch ports.  Would have to be a model with a dedicated WAN Ethernet, and as it happens I have such a router on loan at the moment.   Question regarding the D-Link modem - it seems to only have one Ethernet, so I assume that's used both for PPPoE and for admin access to line stats.  Do you address that link on your LAN subnet, or do you use a separate /30 between router and modem?   I guess there's no way to get stats via SNMP?  That was a major reason for wanting Cisco so I can use standard monitoring tools.

[Weaver]

I am unable to help as I've never looked into getting stats out of one, which is something I would like to do, but would end up with quite a lot of spaghetti given that I have three modems.

I'm imagine that sufficient work would allow someone to get access to stats on the device.

I just have a straight direct link Ethernet cable from the modem to one of four ports on the router, three of which are configured for PPPoE and the fourth is straight Ethernet to the LAN and a fairly big Ethernet switch.

So sorry, I'm not much use. This question has been addressed before, so other kitizens might well be able to give you a proper answer.

[ Aside:  As detailed elsewhere, I need to break the modem-to-router links with a length of fibre so as to protect the router and everything else from lightning. If I want more than three modems I need to multiplex four or more onto a VLAN switch, because the router understands VLAN-tagged PPPoE links. That would have the benefit of reducing the number of optical barrier links at the cost of putting the VLAN switch into the expendables' zone, so I could lose three modems, one small switch and one fibre media converter to lightning in the most pessimistic case. ]

[Weaver]

As regards SNMP, I suspect the manual for the DLink devices can be found on the web, if so, it might talk about SNMP support.

Another thought, if you invest £20 in one (a good plan) from the A & A shop, doesn't matter whether you are a customer or not, ask A & A staff if anyone knows about SNMP capabilities. RevK's merry band spent some time checking out the DLink and investigating its capabilities, looking for bugs and so-on, before recommending it as their top modem for ADSL (not VDSL2) and configuring it properly in modem-only mode (having decided that as a router it was nasty).

[aesmith]

I tried a Cisco 1801 the other day, and interestingly although it's the same generation as the 877 (ISR, not ISR G2) it's connection was much better.  Reported attenuation was the same as my two domestic routers, and synch speed comparable if not actually higher.  Unfortunately it is firstly only a loan router, and secondly the dsl i/f is faulty in that it drops after a period of minutes or hours, and doesn't reestablish unless the router is power cycled.    However it does point the way to a potential router with both proper mainstream management support and good performance on a long line.   (Need to see if I can borrow an 887 as well for comparison)