Re: Question about big Gig E rings
- From: thcollicutt <thcollicutt@xxxxxxxxx>
- Date: Mon, 04 Jun 2007 11:51:29 -0000
On Jun 1, 2:57 pm, "stephen" <stephen_h...@xxxxxxxxxxxx> wrote:
"thcollicutt" <thcollic...@xxxxxxxxx> wrote in message
news:1180616379.947377.26470@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
We are looking at building a province wide fiber network for
connection of various government offices.
4 hubs - partially meshed
56 pops- one connection to nearest hub, backup connection to next
nearest hub
2-300 sites - connected to neares pop
The hubs and pops are to be connected with gigabit fiber (not low
dispersion). Sites will be connected to the pops by whatever method
makes the most sense for the site. All fiber links are <90Km, and
most <80Km.
Hubs are connected as follows
B ==> 6 fibers via North route ==> C
B ==> 6 fibers via South route ==> C
D ==> 6 fibers via North route ==> C
D ==> 6 fibers via South route ==> C
D ==> 6 fibers ==> B : Regenerated to keep < 90Km
A ==> 6 fibers via North route ==> B
A ==> 6 fibers via South route ==> C : Regenerated to keep < 90Km
(North and south routes connecting to D are different routes than
connecting to A or C, as all are on different rings)
We are considering small server farms at the hub sites, with backup
servers at othe hubs. VoIP might be considered in the near future.
It has been suggested that SONET is the only option that is open to
us, due to the fast redirect of traffic if there is a fiber failure.
I have seen various vendors advertise equipment that would allow
Ethernet to be used, but with what is probably proprietory protocols
or implimentations.
you can do fast rerouting with Ethernet pipes - as long as your route at the
nodal points.
We have shown OSPF based rerouting on Cisco Cat 6500s at sub 50 mSec in the
lab - but it takes a fair amount of tuning to get there.
you need the GigE links to give "loss of light" on a fault so the equipment
can react immediately - shouldnt be a problem if you are driving dark fibre
directly.
we are just commissioning a similar network for a customer - dual central
hubs with GigE to each location.
However we are using "legacy" modern SDH to drive the plumbing at STM-64 /
9.8 Gbps and carving the GigEs out of that since we need non IP services as
well.
We are looking to combine core government, health care, and the school
system on the same infrastructure. We are looking at the possibility
of VLANs, QinQ, VRF-lite, perhaps CWDM.
MPLS is probably the best way to do this, if all you need to do is move
packets.
Fast reroute on MPLS equipment converges as quickly as SDH (european flavour
of SONET used here in UK).
Although MPLS can support lots of VPN structures "on top", the boring
conventional service is routed IP VPNs - which means these are the ones
which are well known, well behaved and that a lot of trained engineers know
how to build and look after.
I have worked on Cisco MPLS a lot - good, loads of features, but expensive
and you need to lab test to find out which code versions will work with the
features you need. Just about all the other router manufacturers also
support it, as well as traditional telecoms suppliers (Alcatel specifically
seems to make reliable MPLS stuff)
What you have said implies that routed IP is going to do what you need - so
start with that as the design baseline.
MPLS allows each of your logical overlays to choose their own addressing,
QoS, topology and various other things, so will reduce the complexities of
glueing several networks together and making them play nice.
Is SONET the solution of choice, or am I correct in thinking that this
can be accomplished using Ethernet? Has anyone used these vendor
solutions for providing resiliency?
SONET / SDH equipment has benefited from the same improvements in
performance / chip scale as anything else made of complex electronics.
The problem you may have is the kit is almost always optimised for a telco
and use on a large scale, so needs expensive management tools and so on, and
you may find maintenance etc from a 3rd party "harder" than routing style
equipment.
If you go down the SONET route then you are going to be acting like a telco,
and be supplying pipes rather than IP networks to each (unless you build
that as another layer) - that may be a good design tradeoff depending on
what you want.
--
Regards
stephen_h...@xxxxxxxxxxxx - replace xyz with ntl- Hide quoted text -
- Show quoted text -
50 ms or less failover is good, but currently we have a network of
rented lines with no failover and a 4 hour repair time. I think
failover of a minute or two may fail the desired time for VoIP, but it
is significantly faster than anything we have now.
I must say that the carriers we have been using have been quite good
at getting these lines back up and running on the rare occasion that
they go down, so I don't want to give the impression that the lines go
down all the time, or take a really long time to repair. I am just
noting the difference between SONET and current repair times.
I am not ready to jump into SONET for a new network, and I don't want
a 400+ km of fiber being controlled by Spanning tree. So, I am
looking at having multiple areas, and routing between them. The
server group has suggested that the central ring, which connects all
the hub sites, to be layer 2 so they can have the same IP subnet
present at each hub site for them to do their server redundancy. This
looks like it may complicate the design a bit. My experience with
MPLS is knowing what it is.
I'm going to have to go back and reread my stuff on OSPF and Spanning
tree. I was just curious, since I have a vendor coming in to explain
some optoelectronics they have for sale, whether my wish to remain
with ethernet based solutions is a reasonable one, and whether others
have been able to do someting similar.
.
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