- This topic has 3 replies, 1 voice, and was last updated 11 years, 2 months ago by pix.
15th April 2011 at 11:37 #66186BlackholeGuest
Can anyone explain for me the issue like this. For our network, we use 3 Ater PS links for GPRS from BSC-MFS and 2 links from MFS-SGSN. However, from indicator in NPO, we only see Ater PS congestion, the Gb interface is OK.
If we simply understand that GPRS traffic just be forwarded from BSC-MFS-SGSN, so how can we have congestion in ater PS, not Gb interface when the number of links used for AterPS is bigger?
We are using use Alcatel BSS equipment.15th April 2011 at 13:16 #66187pixGuest
the data that go through the Ater PS and Abis are coming from the RLC layer. It includes RLC signalling,, retransmission, etc, and also RLC headers. The RLC blocks carry small amount of data, so the ration header vs data is not as efficient as LLC.
On the Gb interface, the only data are user data + network signaling (GMM / SM). The headers are small, the frames are big. The ratio header vs data is more favourable.
On top of that, the way the Ater and Abis resources are managed is not as efficient as the way the Gb interface is managed (on Ater/Abis : E1 = circuit switch, on Gb : Frame Relay or IP = packet switch).
So you understand why Ater PS congestion can happen easily, while Gb congestion doesn’t.
On top of that, NPO does not provide Gb congestion indicators. The closest thing you get to Gb congestion is DL LLC frames rejected due to congestion, but that is congestion in the MFS, not congestion in the Gb links.
To know Gb congestion, you must know the Gb usage (LLC throughput) compared to the Gb capacity.
pix19th April 2011 at 08:13 #66188BlackholeGuest
Thank you for your explanation, it seems to be clear for me. We just met the problem of Packet Handover from Ecrisson 3G to Alcatel 2G and they think of the problem of congestion from our BSC site. Do you know that there’s any Indicator from Alcatel’s MFS site to show the handover success rate of packet data (we can only see the problem from 3G, so I wonder there’s some indicators from 2G site to show that the handover request already come to the MFS itself). I just can see handover success rate 3G_2G from BSC site, which show Cs only.20th April 2011 at 21:07 #66189pixGuest
in packet, we talk about “reselection”, not “handover”.
so look for indicators called “incoming reselection 3G 2G” or “inter RAT”, or something similar.
I’ll try to look for it at work tomorrow.