Mlt/Lacp Groups And Port Speed; Clocking And 10 Gigabit Ethernet - Nortel 8600 Configuration Manual

Note that these values include FCS bytes.
The default maximum Ethernet frame size supported by the Ethernet
Routing Switch 8600 is 1950 bytes. The 10 Gbit/s module also supports
this frame size. To support a jumbo frame system, set the SF/CPU MTU
to 9600 bytes on the Edit, Chassis, Chassis tab. You can also use the
config sys set mtu CLI command or the set mtu <1522|1950|9600>
NNCLI command. Interface ports can pass jumbo frames by default.
If a jumbo frame enters on an interface and is destined to egress a chassis
interface that does not support jumbo frames, it is gracefully dropped.

MLT/LACP groups and port speed

Ensure that all ports that belong to the same MLT group or Link
Aggregation Control Protocol (LACP) group use the same port speed, for
example, 1 Gbit/s, even if you use autonegotiation. The software does not
enforce this requirement.

Clocking and 10 Gigabit Ethernet

To determine whether each incoming data bit is a one or a zero, the
module must know when to sample the incoming data stream. The module
determines the appropriate sampling time through clocking. Ethernet
modules have internal clocks and can regenerate a clock signal from the
incoming data stream.
Nortel recommends internal timing, unless you have a specific requirement
for loop timing in a system, because the transmit side operates even if a
failure occurs on the incoming Receive Side Signal.
You can configure clocking only for 10 Gbit/s ports.
For a port that uses the internal clock and directly connects to another
port, the other side of the link can be either internal or line (loop) clocking.
For a port set for line clocking, configure the other port for internal clocking
to avoid a potential timing loop.
By default, each 10 Gbit/s WAN port generates the transmit clock from
its own internal clock. However, a line timing option is provided for
applications that involve synchronization to SONET equipment and timing
hierarchies. You must manually change clock settings from internal to line
timing.
For more information about clocking and synchronization applications, see
Nortel Ethernet Routing Switch 8600 Planning and Engineering — Network
Design (NN46205-200).
NN46205-503 04.01 21 December 2009
Copyright © 2008-2009 Nortel Networks. All Rights Reserved.
Nortel Ethernet Routing Switch 8600
Configuration — Ethernet Modules
Ethernet module concepts 19