Subject: ifSpeed on T1 and Frame Relay

From: Rob Steinberger <[email-masked]>
Date: Fri, 03 Apr 1998 14:38:10 -0500

All,

Sorry if this has been discussed in the IETF before, but it has become
a hot topic locally.

Should the ifSpeed for a T1 interface be 1.54Mb or should it be 3.08Mb
in that it can sustain 1.54Mb in both the transmit and receive
directions.  The same question holds for frame relay.  We are
currently reporting the number of DS0s times the rate of each DS0.
Should this be twice this number to account for its full duplex
nature?

Thanks for any responses.

Rob Steinberger
Paradyne Corporation

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From: Gary Hanson <[email-masked]>
Date: Fri, 3 Apr 1998 12:20:49 -0800 (PST)

Rob,

> in that it can sustain 1.54Mb in both the transmit and receive

The latest <draft-ietf-trunkmib-ds1-mib-08.txt> for the DS1-MIB is
unambiguous on this point.  In section 3.1 it says to use 1544000
for the ifSpeed for DS1 lines.

> directions.  The same question holds for frame relay.  We are

If a ds1(18) interface is used for Frame Relay, its ifSpeed will
still always be 1544000.

RFC 2115 says that the frameRelay(32) interface's ifSpeed is the
"access rate for the frame relay interface" and then goes on to
say that this "could be different from the speed of the underlying
physical interface, e.g. in a fractional T1 case the access rate
could be 384 kbits/s".  For a bundle of N DS0s, this would thus be
N x 64000.

Although the latest <draft-ietf-trunkmib-ds0-mib-05.txt> for the
DS0-MIB and DS0BUNDLE-MIB does not clarify what ifSpeed should be
for the ds0Bundle(82) interface, I would assume in a bundled-DS0
case, the ifSpeed of the ds0Bundle interface would be the same as
the frameRelay interface.

And, of course, the ifSpeed of each ds0 would be 64000, again per
the latest draft.

> Should this be twice this number to account for its full duplex

No.

> Thanks for any responses.

I hope this helps.

Regards,
Gary

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From: Gary Hanson <[email-masked]>
Date: Fri, 3 Apr 1998 12:20:49 -0800 (PST)

Rob,

No.

I hope this helps.

Regards,
Gary

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From: Gary Hanson <[email-masked]>
Date: Fri, 3 Apr 1998 12:28:10 -0800 (PST)

Oops, I just mistakenly wrote the following:

> [...]

Section 3.2 says it clear as day: "n * 64000 for ds0Bundle".  I had
looked but must have blinked at the wrong moment....

Regards,
Gary

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From: Gary Hanson <[email-masked]>
Date: Fri, 3 Apr 1998 12:20:49 -0800 (PST)

Rob,

No.

I hope this helps.

Regards,
Gary

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From: Gary Hanson <[email-masked]>
Date: Fri, 3 Apr 1998 12:28:10 -0800 (PST)

Regards,
Gary

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From: Gary Hanson <[email-masked]>
Date: Fri, 3 Apr 1998 12:28:10 -0800 (PST)

Regards,
Gary