We have a strange network performance problem. We have a 2Mb leased line
terminated at each end by a Cisco 2600 router. A Digital Alpha DS20 is
present in both locations, along with a network of NT boxes. One Alpha is
loaded with VMS 7.1-2 and the other with 7.2-1. The network at either end
is Switched ethernet.
So we have
| NT boxes| |DS20 (7.2-1)|
____|___________|______ Location A
|Baystack 350 |
|10/100 switch |
|Cisco 2651 router|
| (2Mb link)
|Cisco 2621 router|
| 3500 switch |
_________|____________ Location B
| NT boxes| |DS20 (7.1-2)|
All boxes can connect over IP, but performance varies dramatically depending
on the destination box.
In summary, performance declines dramatically when the Alpha is the
recipient of the data, and is OK otherwise. The alpha in location B has only
recently moved there. They used to talk quite happily to each other before
this, when the second Alpha was in another location again. The only things
that have changed are the routers at each end (used to be Nortel ARN
routers) and the seond Alpha now plugs into a Cisco switch rather than a
Nortel Baystack 350 it plugged into before.
There appears to be no congestion on the link. Can anyone think of any
reason why the choice of router (Cisco) would have such an effect, but only
on traffic to the Alphas? Or should I be looking at something else? Some
measurements on performance are given below. .
- An FTP put from the DS20 in A to the DS20 in B is dreadful at about 25kB/s
- An FTP put from the DS20 in B to the DS20 in A is also not good at about
- An FTP put from any NT box to any NT box (over the link) is about 170kB/s
in both directions
- An FTP put from an NT box in A to the DS20 in B is again about 25kB/s
- An FTP get from an NT box on one side of the link to a DS20 on the other
is about 170kB/s
- Local performance from NT boxes to Alpha's (both PUT and GET) seems OK at
about 4MB/s in both locations
Any help greatly appreciated!!