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OAM pings

Be3G
Grafter
Posts: 6,111
Thanks: 1
Registered: ‎05-04-2007

OAM pings

It seems that my new ADSL2+ WBC connection dislikes something that my old ADSL1 connection allowed: OAM pings. I first encountered this problem when my ADSL connection was switched over to ADSL2+, and I suddenly found that I couldn't connect - I could sync, but nothing beyond that worked. Upon investigating the router logs, I found lots of 'OAM loopback response not received' messages. I eventually discovered, after some tweaking, that these were indicative of the reason I couldn't connect: I had my router set up to automatically determine VPI and VCI values, which it tried to do by sending those OAM pings or whatever they are. This worked fine when on ADSL1 and CBC, so presumably back then the OAM pings were being responded to - whereas on ADSL2+/WBC, they weren't.
Now fast forward a week and a half to two days ago, at which point I bought myself an ethernet modem (Netgear DM111P) to replace the router (Linksys WAG54GS) for reasons that are beyond the scope of this post. The Netgear, however, has a couple of diagnostic tools, one of which is an automated series of tests for various things. Included in the tests are 'Test ATM OAM F5 segment ping', and 'Test ATM OAM F5 end-to-end ping', both of which fail.
Now, until I had my initial problem with my WBC connection, I'd never heard of these OAM things, so I don't purport to be an expert on them at all. However, this Cisco webpage states the following:
Quote
The ATM OAM Ping feature sends an ATM Operation, Administration, and Maintenance (OAM) packet to confirm the connectivity of a specific permanent virtual circuit (PVC). The status of the PVC is displayed when a response to the OAM packet is received. The ATM OAM Ping feature allows the network administrator to verify PVC integrity and facilitates ATM network troubleshooting.

Judging from that, it sounds like they're something that probably should be enabled. So what I'm wondering is, does anyone else find that OAM pings aren't working on their ADSL2+/WBC connection - i.e. is this a problem specific to my connection, or a characteristic of BT's ADSL2+/WBC service? And if it is a characteristic of the service in general, is this a problem - i.e. are OAM pings important enough that they really should actually be working? My interest in these OAM pings is especially piqued because I seem to be having strange problems with my WBC connection, where I'll periodically lose the connection without losing sync, then have trouble regaining the reconnection... so I do wonder if the lack of working OAM pings might have anything to do with that.
4 REPLIES 4
Be3G
Grafter
Posts: 6,111
Thanks: 1
Registered: ‎05-04-2007

Re: OAM pings

Well, it seems the lack of OAM pings had nothing to do with my disconnection problems, as they were inadvertently fixed by BT fiddling with something one night, whilst OAM pings still don't appear to work according to my modem's diagnostic tests. Does anyone (perhaps from Plusnet) have any thoughts about these? I get the impression that they're supposed to work, so could there possibly be a fault with BT's ADSL2+ service?
dave
Plusnet Help Team
Plusnet Help Team
Posts: 12,257
Thanks: 306
Fixes: 4
Registered: ‎04-04-2007

Re: OAM pings

Hi Thomas,
Sorry for not responding, I thought I'd mentioned what we were looking at on IRC, I guess I hadn't. We're looking into why this isn't working and whether it's something that's designed to be like this or not or whether it's that needs fixing. I'll let you know.
Dave Tomlinson
Enterprise Architect - Network & OSS
Plusnet Technology
Be3G
Grafter
Posts: 6,111
Thanks: 1
Registered: ‎05-04-2007

Re: OAM pings

Right Ok thanks - I certainly hadn't seen anything on IRC!
dave
Plusnet Help Team
Plusnet Help Team
Posts: 12,257
Thanks: 306
Fixes: 4
Registered: ‎04-04-2007

Re: OAM pings

I'm having problems finding anything out about this in the various BT documentation, so might take a bit of time to get the answer. I have a contact with BT I can ask so will see if they know.
Dave Tomlinson
Enterprise Architect - Network & OSS
Plusnet Technology