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OVERKILL

join:2010-04-05
Peterborough, ON
reply to godrick

Re: Best IOS for 1801W

Ummm, I can probably dig one up from an 871W if you just want the basics? That work?


godrick

@bethere.co.uk
My issue is that CCP wants to put each SSID -- I use different ones for 802.11a and 802.11g -- onto a different VLAN.

I would just like to have something like the setup I have in the config posted earlier in this thread.

What does your 871w setup look like, compared to 12.4.x?


OVERKILL

join:2010-04-05
Peterborough, ON
reply to godrick
Just a single SSID with WPA2/AES. So probably not going to work for you


godrick

@bethere.co.uk
Well I went back to the setup in the config posted above for the wireless settings and it all works, but Cisco Configuration Professional does not show all my interfaces.

It seems that it wants to add Vlans for each SSID, which adds more complexity than I need.

I suspect that it may have been my TCP window size (too big that may have been causing the stalls). Now I am just left with a few

08-09-2010 19:45:53 Local7.Warning xxxx 275: 000271: Sep 8 18:45:52.527 UTC: %FW-4-TCP_OoO_SEG: Dropping TCP Segment: seq:-636260334 1452 bytes is out-of-order; expected seq:3658682958. Reason: TCP reassembly queue overflow - session x to y on zone-pair ccp-zp-in-out class ccp-protocol-http

despite my having upped the tcp reassembly queue length to the max.

Now to put in ips...

HELLFIRE
Premium
join:2009-11-25
kudos:18
reply to godrick
@rolande / cramer
Thanks for the insight into MTU for DSL. I remember hearing it had something to do with ATM,
but I'd forgotten all the nuts and bolts details. I'll have to file that away for future
reference if I ever have to do a config for DSL on Cisco.

@godrick
I don't have a W model router, but having done some AP configs before, wierd that CCP would
want VLANs attached to an SSID. Did you try VLAN1?

Regards


OVERKILL

join:2010-04-05
Peterborough, ON

1 edit
reply to rolande
How would this apply to an ADSL2+ connection with an external DSL modem? With an internal HWIC?

Would one be better served to use the 1432 mss and an MTU of 1472 or the "standard" values of 1452 for mss and MTU of 1492?

cramer
Premium
join:2007-04-10
Raleigh, NC
kudos:9
With an external modem, it's PPPoE. With an internal WIC/HWIC, it's either PPPoA (vc-mux) or PPPoEoA (llc-snap). LLC/SNAP is the least efficient as it adds the greatest amount of overhead. (we're only talking a few bytes here. ATM is >90% of all overhead.)


OVERKILL

join:2010-04-05
Peterborough, ON
So with an external modem (via Ethernet) one should use an MSS of 1452 for PPPoE?

I have both, which is why I was wondering. Currently using an external modem (to trial VDSL2, may buy a VDSL2 HWIC depending on how the trial goes) as well as an HWIC-1ADSL; same ISP/connection for both DSL configs, it is PPPoE.

My traditional approach has always been 1452/1492 for this style of connection but the discussion between yourself and Roland had me re-visit that and of course ask the questions I've now asked

cramer
Premium
join:2007-04-10
Raleigh, NC
kudos:9
I've been putting together a little MTU FAQ, but it's just a bunch of numbers in notepad at the moment

The answer depends on what the modem is doing. vc-mux or llc-snap? VC-MUX adds no overhead. SNAP adds 8 bytes. So, if the modem is setup as aal5snap... [48*31 - 8] - [8(snap)] - [8(pppoe)] = 1464 (mtu) - [40(ip)] = 1424 (mss) And when I say (pppoe), that's 6 bytes for PPPoE plus the 2 byte ppp header. For pure vc-mux PPPoA... [48*31 - 8] - [2(ppp)] = 1478 (mtu) - [40(ip)] = 1438 (mss)


OVERKILL

join:2010-04-05
Peterborough, ON

1 edit
reply to godrick
It would appear as though the modem is doing llc-snap.......

So it looks like I need to change some values!

Now, I was taught that you set the MTU on the dialer and the mss on the inside interface. I assume this is the correct practice?

For example my Dialer0 had ip mtu 1492 on it, whilst my fa0/0 had ip tcp adjust-mss 1452.

Second guessing a few things since this discussion started

cramer
Premium
join:2007-04-10
Raleigh, NC
kudos:9
I set everything on the dialer. I don't want or need traffic not passing through the DSL line limited for it's crappy overhead.


OVERKILL

join:2010-04-05
Peterborough, ON
Ahhhh, OK. Cisco documentation has the configuration done in the same manner I indicated above, hence my reason for following it.