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Member since
11-17-2004
26
Posts
10
Helpful
2
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Created by
Bill Ferguson
in Network Management
in Network Management
08-21-2018
05:52 AM
08-21-2018
05:52 AM
In my experience, as long as the RX power level exceeds the minimum value (-20 dBm), it works. Distance is secondary to span loss, Distance is (almost*) irrelevant.
Cisco (and the industry) publishes the extremely conservative 10km because they know that many people don't have the proper fiber inspection and cleaning tools, because fiber quality varies greatly, and they can't predict the number of patches you will have. Also, many people don't even understand optical power measurement and span loss, but almost everyone understands what 10km is.
I have many spans that exceed 10km where I'm using LX optics. I like to keep the RX above -18 dBm.
The same thing happens with 10GE optics. I frequently exceed 10km with LR, and I often use ER optics on one side and LR optics on the other side to stretch the loss budget even further.
It's not so much that it's out of date, because we've always been able to exceed 10km if the span loss is low. That's what the LX standard is, and standards tend to never change.
*at some distance, chromatic dispersion comes into play and will compromise the clean signal, but at 1310nm, power loss is so much more significant that nobody even bothers with thinking about the dispersion affects.
... View more
03-06-2018
01:35 PM
You don’t provision both an OCHNC and an OCH Trail. You provision one or the other.
Provisioning an OCH Trail just requires that you provision internal patchcords (node view, Provisioning, ANS).
I prefer using OCHNC, because it requires fewer steps, but it doesn’t really matter.
Regardless, both will let you do what you want with the L2 services.
... View more
02-28-2018
02:24 PM
Well, DC TX needs to be connected to DC RX for the circuit to work bidirectionally, but this omission wouldn’t affect Line TX power.
Do have a setup file from CTP?
Has it been uploaded?
Are the internal patchcords provisioned?
Are the optical sides provisioned?
Did you launch ANS?
Is the power from the transponder being received at the ADD RX port?
Since you were able to build a circuit, I suspect at least some of the items above were completed, but sometimes we forget to launch ANS.
... View more
02-28-2018
08:53 AM
Yes, as long as you choose LAN mode and the XFPs are correct, it will work fine. If the provider were to connect with and OC192c port or circuit, you would change to WAN mode.
... View more
02-28-2018
08:46 AM
You need to create an OCHNC circuit, the muxponder needs to be cabled to the add/drop side correctly, and the muxponder trunk port needs to be enabled before the ROADM amplifier can transmit anything.
... View more
05-17-2017
09:21 PM
Agreed. Glass is glass is glass. If the specs are met, it's all the same. If you want to keep the rats away for good, use armored cable.
Considering you're looking for OM1 fiber which is close to obsolete, the low price you see is more indicative of a vendor trying to get rid of stock as opposed to just selling a crappy product.
Just buy the cheap stuff.
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05-17-2017
08:57 PM
It will definitely work if you use a mode-conditioning patch cord.
See here: http://www.cisco.com/c/en/us/products/collateral/interfaces-modules/transceiver-modules/product_bulletin_c25-530836.html
It could work if you use all normal MM cabling. It's hit-or-miss.
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05-17-2017
08:48 PM
I'm not extremely familiar with this, but my experience is that the TL1 connections are still required to authenticate with username and password. CTC does allow multiple logins by the same username. And it does keep track of the IP address of the remote host. So you shouldn't have a problem. If you're worried, you could create separate login accounts for each TL1 "user."
How old? Since you said Cerent, I'm envisioning R2.x . I can't even remember that far back. My guess is that if you're R7.x or higher, you're probably OK.
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05-17-2017
08:34 PM
If it's working with LR, and you're not RX'ing at -15 dBm on each side, don't worry about it. The documented Rx minimum for 10GBASE-LR is -14.4 dBm. So if you're at -13 dBm or higher, you're fine. If you're at -15 dBm, then you should swap them for ER.
It's not an issue of efficiency. It's about laser power and span loss. ER transmits with more power, and its loss budget is better. We budget to 0.35dB/km for 1310nm (LR), but only 0.25dB/km for 1550nm (ER and ZR).
In my experience, the conservative 10km and 40km (and 80km) limits are given for two reasons:
1. Dummy-proof the engineering. We usually know the span lengths. We don't always know the span loss. This also lets us ignore chromatic dispersion.
2. Limitation of liability. If it's 11km or 41km and it doesn't work, Cisco can always fall back on the specs. That said, TAC never asks what the distance is. They just check the RX levels.
Again, in my experience, span loss is what matters. I have successfully used LR optics on clean fiber spans significantly exceeding 10km. As long as you're above the minimum RX value, it will work.
Aside: 10km to 40km is a wide range. I get a lot of success (and save a little money) in the middle of this range (15-30 km) by using ER on one side and LR on the other side. You don't need to match the optics. Again, being above the minimum RX threshold is what's important.
***Yes, I know that it's important to consider dispersion, but I've never seen CD be as significant as span loss until we exceed 80km on G.652 fiber.
... View more
02-14-2017
11:08 AM
If you're never going to close the ring, then you should just create an open-ended single-home ring.
Otherwise, I'm not sure. One of the steps in establishing the dual-homed ring is to "Enable Service" on it. I don't know if you can do this if the ring isn't closed. Maybe you can.
However, I assume the main reason you want a dual-homed ring is so that you can use protected MPLS-TP tunnels for your various services. You won't be able to create protected tunnels until the CPT-50 ring is complete.
... View more
01-25-2017
04:13 PM
It's complicated. Refer to the documentation.
http://www.cisco.com/c/en/us/td/docs/optical/cpt/r9_7/cpt971_configuration/cpt971_configuration_chapter_011.html#concept_D133616E9BCD4C92AA2C8620A10525C5
These are important:
Limitations and Restrictions
These limitations and restrictions apply to the ring in CPT:
A maximum of 20 rings can be provisioned with CPT 600 and a maximum of 6 rings can be provisioned with CPT 200.
A maximum of 20 CPT 50 panels can be configured in a ring.
A maximum of 100 CPT 50 panels can be configured across all the rings, on a single CPT 600 or CPT 200.
The Resilient Ethernet Protocol (REP) configurations are internally provisioned on the ring.
A ring cannot be configured on the XFP port.
The east port cannot be same as the west port while creating a ring.
If a chassis is down, no services can be configured on the CPT 50 in a ring through CTC.
The ports that already have Fan-Out-Group (FOG) configured, cannot be used for creating a ring.
A single-homed ring and a dual-homed ring cannot be configured on the same node.
A CPT 600 or CPT 200 chassis cannot function as a PRC and WRC simultaneously.
Services can be configured on the dual-homed ring in the cisco IOS mode.
If a CPT 600 or CPT 200 chassis is used in dual-homed ring, it cannot be used in any other ring configuration.
Expect to have to call TAC. Good luck.
... View more
01-25-2017
04:09 PM
Continuous wave lasers are used in fiber optic networking, so you only have to be concerned with the first bullet.
150 mW is the same as +21.7 dBm. Commercial pluggable (SFP, XFP) fiber-optic laser transmitters don't exceed +5 dBm (and are typically at +1 dBm or less). As long as you're not aggregating multiple signals and amplifying them with DWDM you will be fine.
There are no lasers in the switch when you buy it. The lasers are part of the SFPs that you may or may not use. The max Tx power of the highest power SFP 1000BASE-ZX is +5 dBm, which is the same as 3.16 mW.
You'll be fine. You probably need multiple data sheets for evidence. You'll need one showing the SFPs that the switch can use, and you'll need the data sheets for those SFPs. The SFP data sheet is hyperlinked above.
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01-25-2017
03:54 PM
There's no need to worry. Virtually all single mode optical recievers are wide-band (1300-1600nm) capable, so they receive any signal without caring what the wavelength is. As long as you're not exceeding the max Rx value, you'll be fine.
The 1310 Tx is typically around -3 dBm, so the Rx port of the 1538.98 XFP would typically require about 5dB of attenuation to bring it below -7 dBm.
The 1538.98 Tx is probably around +1, so the Rx port of the 1310 SFP+ might need a little attenuation, but you're probably OK as is.
... View more
Created by
Bill Ferguson
in Network Management
08-21-2018
08-21-2018
In my experience, as long as the RX power level exceeds the minimum
value (-20 dBm), it works. Dista...
03-06-2018
You don’t provision both an OCHNC and an OCH Trail. You provision one or
the other. Provisioning an ...
02-28-2018
Well, DC TX needs to be connected to DC RX for the circuit to work
bidirectionally, but this omissio...
02-28-2018
Yes, as long as you choose LAN mode and the XFPs are correct, it will
work fine. If the provider wer...
02-28-2018
You need to create an OCHNC circuit, the muxponder needs to be cabled to
the add/drop side correctly...
05-17-2017
Agreed. Glass is glass is glass. If the specs are met, it's all the
same. If you want to keep the ra...
05-17-2017
It will definitely work if you use a mode-conditioning patch cord. See
here:
http://www.cisco.com/c/...
05-17-2017
I'm not extremely familiar with this, but my experience is that the TL1
connections are still requir...
05-17-2017
If it's working with LR, and you're not RX'ing at -15 dBm on each side,
don't worry about it. The do...
02-14-2017
If you're never going to close the ring, then you should just create an
open-ended single-home ring....
01-25-2017
It's complicated. Refer to the documentation.
http://www.cisco.com/c/en/us/td/docs/optical/cpt/r9_7/...
01-25-2017
Continuous wave lasers are used in fiber optic networking, so you only
have to be concerned with the...
Public Statistics
| Date Registered | 11-17-2004 08:26 AM |
| Date Last Visited | 08-24-2018 02:02 AM |
| Total Messages Posted | 26 |
| Total Helpful Votes Received | 10 |
