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Posted by on November 12, 2006, 11:17 am
Hi,
I've this problem with a Cisco 877; if a user is downloading at maximum
rate for a while, the connection goes bananas.. I can reach the cisco
to reload it, but there is no more internet-access. The LEDs are as
normal, except the recieve and send LED aren't blinking... I noticed
the CPU-load is continues on 100% when downloading at full speed, if
the download is capped, the CPU-load lowers also.
I disabled the http-management-thing and tried to remove as much from
the config as possible. There's only one VPN-tunnel active on the
router, but it's hardly used.
This is a 20 mbit ADSL connection while the maximum speed is 14.5 mbit.
The connection trained at 20 mbit though (seen this myself at the
privider).
Used IOS: c870-advipservicesk9-mz.124-6.T2
The same problem exist with a 878 (also a 12.4.6 IOS). First I thought
it was a provider thing but it seems not. The 877 is on another line
and another provider.
I would say the continues CPU-load is causing this problem, but I'm not
sure. Anyone experienced something like this?
TIA
Jos
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Posted by Charlie Root on November 12, 2006, 12:46 pm
Hi,
> This is a 20 mbit ADSL connection while the maximum speed is 14.5 mbit.
> The connection trained at 20 mbit though (seen this myself at the
> privider).
I have recently tested performance of Cisco 876 router (which is basically
the same as your 877 but for ADSL-over-ISDN) using Agilent N2X tester. My
observation is that top performance of this router at small packets is
roughly 6Mbps, while with large packets it could go a bit higher - slightly
over 10Mbps. So this is at most half of the line rate you have.
> The same problem exist with a 878 (also a 12.4.6 IOS). First I thought
> it was a provider thing but it seems not. The 877 is on another line
> and another provider.
Same with 878. I have tested 878 with QoS enabled, the performance decreases
dramatically - it can't even do 2Mbps on small packets. According to Cisco
performance datasheet, 870 routers can deliver upto 12.8Mbps and upto 25Kpps
in ideal conditions and this values can never be exceeded, but will decrease
as you add features (NAT, firewall, routing, QoS etc.)
Don't expect anything much greater in this price range of routers. I have
tested also DrayTek 2800 and 2900 series routers - they're even worse. While
Cisco 870 ISR routers perform much better as soon as packet size increases
to 128Byte, with DrayTek packet size has to be at least 768Byte to get
decent troughput.
If you use 20Mbps line, you have to get something like Cisco 1800 series
router.
Hope this helps.
Cheers,
iLya
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Posted by on November 12, 2006, 2:22 pm
Charlie Root wrote:
> Hi,
> > This is a 20 mbit ADSL connection while the maximum speed is 14.5 mbit.
> > The connection trained at 20 mbit though (seen this myself at the
> > privider).
> I have recently tested performance of Cisco 876 router (which is basically
> the same as your 877 but for ADSL-over-ISDN) using Agilent N2X tester. My
> observation is that top performance of this router at small packets is
> roughly 6Mbps, while with large packets it could go a bit higher - slightly
> over 10Mbps. So this is at most half of the line rate you have.
> > The same problem exist with a 878 (also a 12.4.6 IOS). First I thought
> > it was a provider thing but it seems not. The 877 is on another line
> > and another provider.
> Same with 878. I have tested 878 with QoS enabled, the performance decreases
> dramatically - it can't even do 2Mbps on small packets. According to Cisco
> performance datasheet, 870 routers can deliver upto 12.8Mbps and upto 25Kpps
> in ideal conditions and this values can never be exceeded, but will decrease
> as you add features (NAT, firewall, routing, QoS etc.)
> Don't expect anything much greater in this price range of routers. I have
> tested also DrayTek 2800 and 2900 series routers - they're even worse. While
> Cisco 870 ISR routers perform much better as soon as packet size increases
> to 128Byte, with DrayTek packet size has to be at least 768Byte to get
> decent troughput.
> If you use 20Mbps line, you have to get something like Cisco 1800 series
> router.
I agree that this sounds like too much for an 870 however it is
worth checking that there is not something amiss.
Please post:-
sh run ! < -- please sanitise.
!sh tech ipmulticast ! < -- produces a password-removed config and not
! < -- too much else if you do not have
m'cast configured
!when the router is under stress
sh proc cpu ! < -- first few lines.
!when it has stopped frowarding traffic
sh mem ! < -- first few lines
sh buff ! < -- all
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Posted by on November 13, 2006, 3:18 am
> I have recently tested performance of Cisco 876 router (which is basically
> the same as your 877 but for ADSL-over-ISDN) using Agilent N2X tester. My
> observation is that top performance of this router at small packets is
> roughly 6Mbps, while with large packets it could go a bit higher - slightly
> over 10Mbps. So this is at most half of the line rate you have.
oops, my mistake. The other router was this 876.
But thanks a lot for your clear answer. I tested a little bit yesterday
and as long as I stay below 80% of CPU-usage ( around 12 mbit
downloading) the router stays online.
If you want I can run the tests just to make sure. Maybe later today.
thanks,
Jos
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Posted by on November 13, 2006, 3:22 pm
Today I called the reseller and he confirmed all this:
-the maximum routeable traffic (he used other words, but I hope you'll
understand this...) is for the 800 series 12 mbit.
-if I want to use the full bandwidth, I need a 1800 series.
Anyway, thanks for your answers! Maybe I'll put the router in the
freezer or something, see what happens then... ;-)
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> The connection trained at 20 mbit though (seen this myself at the
> privider).