RBS is often times run on on AMI D4 circuits. Also, RBS is generally not run on inter-office trunks. At least that was the case a few months ago when I worked on a DMS-500. --------------------------------------------- Chad Skidmore Director of Network Engineering Northwest Nexus, Inc. http://www.nwnexus.com 1-888-NWNEXUS
-----Original Message----- From: Robert E. Seastrom [mailto:rs@bifrost.seastrom.com] Sent: Thursday, September 10, 1998 11:08 AM To: cskidmor@nwnexus.net Cc: goemon@sasami.anime.net Subject: Re: Inter-CO signaling?
of course, robbed bit signalling and AMI have nothing to do with one another...
From: Chad Skidmore <cskidmor@nwnexus.net> Cc: "'nanog@merit.edu'" <nanog@merit.edu> Date: Thu, 10 Sep 1998 10:47:04 -0700 MIME-Version: 1.0 X-Mailer: Internet Mail Service (5.5.1960.3) Content-Type: text/plain Sender: owner-nanog@merit.edu
Try making an ISDN call from one to the other at a 64k rate. If you can get through then there are at least some trunks setup as ESF B8ZS clear channel. I suspect that they are probably some older trunks running AMI D4.
The other thing you could do is just ask them.
--------------------------------------------- Chad Skidmore Director of Network Engineering Northwest Nexus, Inc. http://www.nwnexus.com 1-888-NWNEXUS
-----Original Message----- From: Dan Hollis [mailto:goemon@sasami.anime.net] Sent: Wednesday, September 09, 1998 5:22 PM To: 'nanog@merit.edu' Subject: Inter-CO signaling?
Is there any way to determine if inter-telco links are using robbed bit signaling? Eg from GTE to USwest in the Seattle area.
I suspect RBS may be causing lots of v.90 problems in GTE country in Seattle. But id like to know how to confirm this. And just maybe, get it fixed.
-Dan
On Thu, 10 Sep 1998, Chad Skidmore wrote:
RBS is often times run on on AMI D4 circuits. Also, RBS is generally not run on inter-office trunks.
I have a feeling RBS is being used for inter-telco trunks (eg USwest to GTE). And its killing v.90 in Seattle. If a telco is running RBS on a trunk, any way to get them to remove it? Also, any way to get the telco to tweak digital pads? Eg what magic incantation do you say to the telco. -Dan
RBS is often run on B8ZS/ESF too. The reason it is not commonly run on inter-office trunks is because of a remarkable new innovation called SS7. Perhaps you have heard of it. Anyway, since the bits in robbed-bit signaling are "robbed" from the superframe not from your DS0, it is irrelevant to your throughput. ---Rob From: Chad Skidmore <cskidmor@nwnexus.net> RBS is often times run on on AMI D4 circuits. Also, RBS is generally not run on inter-office trunks. At least that was the case a few months ago when I worked on a DMS-500. --------------------------------------------- Chad Skidmore Director of Network Engineering Northwest Nexus, Inc. http://www.nwnexus.com 1-888-NWNEXUS
-----Original Message----- From: Robert E. Seastrom [mailto:rs@bifrost.seastrom.com] Sent: Thursday, September 10, 1998 11:08 AM To: cskidmor@nwnexus.net Cc: goemon@sasami.anime.net Subject: Re: Inter-CO signaling?
of course, robbed bit signalling and AMI have nothing to do with one another...
From: Chad Skidmore <cskidmor@nwnexus.net> Cc: "'nanog@merit.edu'" <nanog@merit.edu> Date: Thu, 10 Sep 1998 10:47:04 -0700 MIME-Version: 1.0 X-Mailer: Internet Mail Service (5.5.1960.3) Content-Type: text/plain Sender: owner-nanog@merit.edu
Try making an ISDN call from one to the other at a 64k rate. If you can get through then there are at least some trunks setup as ESF B8ZS clear channel. I suspect that they are probably some older trunks running AMI D4.
The other thing you could do is just ask them.
--------------------------------------------- Chad Skidmore Director of Network Engineering Northwest Nexus, Inc. http://www.nwnexus.com 1-888-NWNEXUS
-----Original Message----- From: Dan Hollis [mailto:goemon@sasami.anime.net] Sent: Wednesday, September 09, 1998 5:22 PM To: 'nanog@merit.edu' Subject: Inter-CO signaling?
Is there any way to determine if inter-telco links are using robbed bit signaling? Eg from GTE to USwest in the Seattle area.
I suspect RBS may be causing lots of v.90 problems in GTE country in Seattle. But id like to know how to confirm this. And just maybe, get it fixed.
-Dan
rs@bifrost.seastrom.com ("Robert E. Seastrom") writes:
RBS is often run on B8ZS/ESF too.
The reason it is not commonly run on inter-office trunks is because of a remarkable new innovation called SS7. Perhaps you have heard of it.
Anyway, since the bits in robbed-bit signaling are "robbed" from the superframe not from your DS0, it is irrelevant to your throughput.
Uh, no. If robbed bit signaling is used, every single DS0 gets exactly one bit clobbered out of every six PCM samples (750us). Out of 24 frames (an "Extended Super Frame"), those four stolen bits form the familiar ABCD signaling pattern. (24 bit long pattern in the framing bit signals the synchronization of the 24 frame sequence so you can distinguish A from B, et cetera.) (Perhaps you're thinking of FDL, which is carried purely over the framing bit as a 4Kbps channel and doesn't affect any of the DS0s.) Dan Hollis originally posted:
Is there any way to determine if inter-telco links are using robbed bit signaling? Eg from GTE to USwest in the Seattle area.
I suspect RBS may be causing lots of v.90 problems in GTE country in Seattle. But id like to know how to confirm this. And just maybe, get it fixed.
I doubt strongly that RBS would be the problem, since V.90 is designed to work correctly with RBS channels. Two things to check: - If they're using channel banks between you and the customer's switch (like if they dropped you cheap T1s by putting them line-side on your switch, rather than trunk- side), then you lose. 24Kbps will be about the maximum. - Some misconfigurations will merely cause lots of errors and poor performance rather than abject failure. Check AMI versus B8ZS (look for coding violations), and check for clocking problems (extremely frequent slips noted by FDL). -- James Carlson, Consulting S/W Engineer <carlson@ironbridgenetworks.com> IronBridge Networks / 55 Hayden Avenue 71.246W Vox: +1 781 372 8132 Lexington MA 02421-7996 / USA 42.423N Fax: +1 781 372 8190 "PPP Design and Debugging" --- http://people.ne.mediaone.net/carlson/ppp
someone here in our office was saying you can extract this out of the modem after and during the call. Consult your modem manual for specific directions, but I think they said it was at&v1 - jared On Thu, Sep 10, 1998 at 03:09:45PM -0400, Robert E. Seastrom wrote:
RBS is often run on B8ZS/ESF too.
The reason it is not commonly run on inter-office trunks is because of a remarkable new innovation called SS7. Perhaps you have heard of it.
Anyway, since the bits in robbed-bit signaling are "robbed" from the superframe not from your DS0, it is irrelevant to your throughput.
From: Chad Skidmore <cskidmor@nwnexus.net>
RBS is often times run on on AMI D4 circuits. Also, RBS is generally not run on inter-office trunks.
At least that was the case a few months ago when I worked on a DMS-500.
From: Robert E. Seastrom [mailto:rs@bifrost.seastrom.com] of course, robbed bit signalling and AMI have nothing to do with one another...
From: Chad Skidmore <cskidmor@nwnexus.net>
Try making an ISDN call from one to the other at a 64k rate. If you can get through then there are at least some trunks setup as ESF B8ZS clear channel. I suspect that they are probably some older trunks running AMI D4.
From: Dan Hollis [mailto:goemon@sasami.anime.net]
Is there any way to determine if inter-telco links are using robbed bit signaling? Eg from GTE to USwest in the Seattle area.
I suspect RBS may be causing lots of v.90 problems in GTE country in Seattle. But id like to know how to confirm this. And just maybe, get it fixed.
-- Jared Mauch | pgp key available via finger from jared@puck.nether.net | http://puck.nether.net/~jared/
On Thu, 10 Sep 1998, Jared Mauch wrote:
someone here in our office was saying you can extract this out of the modem after and during the call. Consult your modem manual for specific directions, but I think they said it was at&v1
ATY11. USR modems only. This gives a frequency response chart from which one can deduce whether there are multiple A-D conversions in the line. I dont know if you can get anything else from them though. -Dan
From: "Robert E. Seastrom" <rs@bifrost.seastrom.com> Anyway, since the bits in robbed-bit signaling are "robbed" from the superframe not from your DS0, it is irrelevant to your throughput. This is actually not correct; my memory was at fault. Robbed bit swipes the 8th bit of each timeslot during the 6th and 12th frame for superframe; the 6th, 12th, 18th, and 24th frame for ESF. Of course, you would not be reading this right now had cskidmor@nwnexus.net not taken the liberty of re-adding NANOG to the cc: list after I explicitly stripped it and sent personal mail in an effort to keep the noise down on the list. :) ---Rob
participants (5)
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Chad Skidmore -
Dan Hollis -
James Carlson -
Jared Mauch -
Robert E. Seastrom