Hi Neels, On Thu, Dec 07, 2023 at 02:19:08AM +0100, Neels Hofmeyr wrote: > That means that each MGW client tells osmo-mgw exactly what AMR and HR formats > to send to the RTP peer, and also restricts exactly which format to expect > from > that RTP peer. So BSC and MSC need to know things about BTS and BSS, in > advance: > - the BSC needs configured knowledge of each BTS's octet-align and > gsm-hr-format. > - the MSC needs configured knowledge of what the BSC will do. > - what if there are divergent formats in different BTS of a BSS, does MSC > need to know that too? > There is certainly no way to indicate octet-align nor HR variant in > standard A interface proto.
IMHO, the BSC and its colocated MGW should "hide" all the RAN-internal details from the MSC. A MSC should never have to know anything specific about each and every BTS, or even how many BTS there are. The AoIP interface is the only where the RTP format / codec types / payload types are specified. We should always use what's specified in TS 48.103. So if a BTS has some differnt format on the Abis side, the bsc-colocated MGW would need to convert to the one format specified by TS 48.103 on AoIP > - 'octet-align=(0|1)' is a defined standard fmtp that already exists, and it > may be necessary to forward this accurately to PBX. We may not get around > having to explicitly set this. Yes, following the spec where there is one is a good idea. > - GSM-HR format is a new fmtp we are inventing now. So the idea is most > relevant here: if we can always just autodetect the right thing to do, then > why introduce a non-standard fmtp? (plus all the MGW client vty cfg needed) I would do whatever is less effort here, given that the interest in GSM-HR is very low in 2023, and we have to conserve our capacity to where it really matters. -- - Harald Welte <[email protected]> https://laforge.gnumonks.org/ ============================================================================ "Privacy in residential applications is a desirable marketing option." (ETSI EN 300 175-7 Ch. A6)
