F1-Series linecard has been
a part of Nexus 7000 product family for a while now but it has not gained much
popularity due to its limitation, mainly on the lack of L3 routing capability
and FEX support. Yet, F1 linecard is the only linecard that supports Fabricpath,
but unless Fabricpath is one of the requirements, you might be better off with
the older M1 series. However, this is about to change. Cisco has recently come
out with a new F2 series linecard that overcomes a lot of drawbacks on the
F1.
This article provides
highlights of the F2-series linecard capabilities and points out things that
need to be taken into consideration when purchasing a F2 linceard, whether it is
for a new install or upgrade to your existing Nexus 7000. Here I assume that you
are already familiar with the Nexus existing product family. For additional
product detail, please consult Cisco website.
Highlights:
- F2 has 48 ports 1G/10G at linerate
(=480G), which requires five FAB2 (5 x 110 = 550G). This essentially nullifies
the concept of dedicated/shared mode in M1 Series (ie. M1 only has 80G
backplane).
- F2 supports, for the most part, the
combined features of M1 and F1 (eg. L2/L3, FEX, Fabricpath etc.) EXCEPT MPLS,
LISP, OTV due to hardware limitation (see detail in release notes).
Design/Purchase
Considerations:
-
F2 linecard cannot be mixed with M1 linecard in the same VDC. This makes F2 more
favorable to a new install, whether a new chassis or new
VDC.
- NX-OS Release 6.0 is
required.
- FAB2 is more expensive then FAB1, hence their corresponding
bundles. However, F2 linecard is less expensive than 10G M1 linecard, and
given that F2 offers an increase number of “dedicated” port from 8 to 48 per
linecard, the number of F2 linecard required will most likely be less compared
to the M1 option, which can equates to significant cost saving that even
compensate for the additional cost of FAB2.
- There
is no F2 copper linecard at this point. The options are to use GLC-T, or if
100/1000 is required, fabric extender. This includes routers that only have
FastEthernet as the 2K supports routed port on 7K.
-
Ports on F2 linecard can be allocated in different VDC but have to be done in a
port-group of four.
- We can no longer achieve N+1
redundancy on the fabric without sacrificing performance. Given a single FAB2
failure, the F2 will only have access to (550-110 = 440G < 480G)
backplane.
- F2 linceard has lower
Switch On Chip (SoC) performance (eg. MAC Table, IPv4/IPv6, ACL entries etc.) than M1 (both non-XL and
XL) but this should still be enough for most environments (See datasheet for
detail)
New Install/Upgrade Tips and
Caveats:
-
If you have selected Nexus 7009 for a new install, 7009 only support FAB2 so the
remaining decision will be whether to go with M1 or F2 linecard. Unless you have
a requirement that cannot be accommodated by the F2, it is natural to choose F2
over M1.
- If you have selected Nexus 7010 or 7018
for a new install, you have a choice of FAB1 and FAB2 bundles. FAB1 bundle
itself may appear to be cheaper, but depending on how many M1 linecard is
required in the design, the total cost might end up higher than an equivalent
design using FAB2/F2.
- If you have existing FAB1,
they need to be replaced with five FAB2 in order to realize the maximum speed.
However, FAB1 and FAB2 can co-exist in the same chassis during migration period
without downtime.
- Upgrading existing VDC
may be cost prohibitive as all M1 linecards will need to be replaced with F2.
Using F2 on a new VDC deployment may make more sense.
Conclusion:
F2-series lincecard provides more
flexibility to a Nexus datacenter design. With faster backplane on the FAB2,
this also increases the 10G port density supported by a chassis. Obviously,
there are some
caveats that needs to be kept in mind especially when you
need to use M1 linecard to realize some unsupported features of
the F2 in the same deployment (in different VDC of
course).
Additional
Resources:
Cisco
Nexus 7000 48-Port 1 and 10 Gigabit Ethernet F2-Series
Module
Cisco
Nexus 7000 Series NX-OS Release Notes, Release 6.0
Author: Metha Chiewanichakorn ,
CCIE#23585 (R&S/Security/Service Provider)
