cannot connect E1 to SDH network via ONS 15305

Answered Question
Sep 1st, 2009


I have 3 ONS 15305 in a SDH ring. I connected three routers with ONS via E1 ports. but i can only connect them in a point to point basis. eg. i connected R1 with ONS1 and R2 with ONS2 and i did a cross connect between SDH and E1. I am able to ping the otherend routers. but the case becomes critical when i connect another ONS in the network with another router. pl help.

I have this problem too.
0 votes
Correct Answer by Tom Randstrom about 7 years 4 months ago

Glad to see you can at least get it to ping!

I would have thought that the spanning tree on 305 switches would have prevented a loop. Check to see if it is active using the link below:


Should your last SDH connection in your previous post's list:

ONS1 wan2/14 <-> ONS3 wan2/14

really be

ONS2 wan2/14 <-> ONS3 wan2/14?

Are the SDH circuits protected or unprotected? Are they set-up as revertive or non-revertive?

HOpe this helps!

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Overall Rating: 5 (3 ratings)
viyuan700 Wed, 09/02/2009 - 10:15

"but the case becomes critical when i connect another ONS in the network with another router"

Did you insert the 3rd ONS between 1 & 2. If yes then did you make connection in new ONS?

If you want to form a ring Don't make point to point circuit instead made protected circuit. So if your the ONS 1-OnNS 2-ONS 3-ONS 1 are connected like this and if u create a protecetd circuit. Protected circuit will be helpful suppose ONS1-ONs2 link is down but will be reachable via ONS 3.

Rajiv Dasmohapatra Wed, 09/02/2009 - 21:42

Tried to make a protected circuit. but i think i am missing something. could you help me out plz.

viyuan700 Thu, 09/03/2009 - 08:00

Can,t help with how to config kind of questions.

Do you have time to explain about what have u have tried till now maybe you are missing some step or some other technical thing.

Rajiv Dasmohapatra Thu, 09/03/2009 - 10:18

I have 2 port STM1 card, 8 port E1 card, 8 port Ethernet card in each of the three ONS 15305. I also have 3 routers each with one e1 port and integrated AIM/ATM.

1. I have connected the ONSs' in a ring.

2. I have also connected three routers each having an e1 card with the first e1 port of the ONSs.

now the problems.

1. if i plug out 1 FO from a STM1 port / one STM1 port gets disabled, the data flow stops. not a single router pings but the e1 ports are up.

2. same thing happens when i plug out / disable one e1 port from the router / ONS. No data flows from anywhere to anywhere. here the alarm led glows in the e1 port of every router.

i also need to know if i can provide redundancy / protection, if one link connection breaks (say ONS1-ONS2) with only two STM ports in ONS which is already used for the existing ring.

viyuan700 Thu, 09/03/2009 - 11:11

Few clarification ,

2 port STM1 card means you have 2 pair of Tx & Rx.

Plug out 1 Fo from STM 1 port means you are plugging out both Tx/Rx cable or ONLY 1 cable

From your explanation looks like that either you have connecetd 3 ONS in Linear topology or There is no protecetd circuit.

IF there is no protecetd circuit and you pull STM cable your router will not ping.

See if your connections are like this

1st Tx/Rx of ONS 1 connected to 1st Tx/Rx of ONS 2

2nd Tx/Rx of ONS is connecetd to 1st Tx/Rx of ONS 3

2nd Tx/Rx of ONS 2 is connecetd to 2nd Tx/Rx of ONS 3

If your connections are as per above then create a protecetd circuit (see manual how to create protecetd circuit) for a E1 between ONS 1 & 2, ONS 2 & 3, ONS 1& 3. You have to selecting E1 port where you are connecting your Router.

If you have connecetd 3 router as explained above and their are 3 protecetd circuit, then this is a redundant setup. You dont need anything else.

If above is working fine and you pull an FO you should be able to ping.

Let me know if you need any further technical detail.

Tom Randstrom Thu, 09/03/2009 - 12:16


I think the problem is you cannot interconnect three routers, each having one E1 interface).

In order to interconnect the three routers, you would need either the following:

Option #1

R1 to R2

R2 to R3

Option #2

R1 to R2

R2 to R3

R3 to R1

Option #1 requires one E1 interface on R1 & R3, and two E1 interfaces on R2. We can ping each router, but R1 & R3 need to pass through R2. If we create protected circuits on the 305s, then it is resilient for a cable cut.

Option #2 requires two E1 interfaces on each router. We can ping directly between each router. If we create protected circuits on the 305s, then it is resilient for a cable cut.

The other option would be to interconnect the Routers using Ethernet interfaces between the 305 and the router. Then circuits could be created between the 305s to form a protected ring. I have never set-up a 305 but looking at data sheet, the 305's Ethernet cards have layer 2 capabilities so you should be able to connect the Ethernet cards in a ring topology over VC-12 circuits. capabilities

let me know if this is making any sense.


Rajiv Dasmohapatra Fri, 09/04/2009 - 05:14

Thanks Tom.

Now i am trying to establish the ring via ethernet. but could not get to connect the routers via EoS. I have changed the concatenation to VC12 for WAN. I also did a WAN to SDH mapping for all the 50 channels. Made sure that the WAN channel number is same in all the ONSs' but could not figured it out what it could be.

and i checked for both Lcas and softlcas bidirectional.

pl help.

viyuan700 Fri, 09/04/2009 - 05:56

"Now i am trying to establish the ring via ethernet"

If you are trying to form ring using one ethernet prot at all 3 places then even with ethernet this system will not work.

This is not the way ring works in SONET/SDH. YOu can create ring between 2 end point like Tom has made,

select 1 ethernet port at ONS1 and select 1 ethernet port at ONS 2. Then this ring will be ONLY for circuit from ONS 1 to ONS 2.

Similarly you have to create circuits from other using different ethernet port or E1 port. Like ONS2 to ONS 3 & ONS 1 to ONS 3.

This way your individual circuit is redundant through SONET/SDH if you pullout cable the things will works without a problem as protection time is less than 50ms, much less than the routing protocol detection time.

Check how you have made connections if not done the way above then things will not work.

You can try one more thing create point to point circuit from ONS 1 to ONS 2, ONS 2 to ONS 3 and ONS3 to ONS 1. This way you have 3 Point to point links and you router can learn route from different way if one is broken. BUT in this way you cannot have the switching time of 50ms which SONET/SDH offers. Now for redundancy you are relying on routing protocol which ever you are using, so the convergence time will be as per the routing protocol used.

Tom Randstrom Fri, 09/04/2009 - 08:16

Having a hard time explaining because I have never worked hands-on with this product so I don't know the user interface and can't play with it.

I've attached another diagram as to what I want the network to look like. I can't seem to follow the user guides to truly understand how to accomplish set-up: One E100 LAN port to E100 card's internal switch to two WAN ports ; one WAN port connecting to each of the other two 305 node's E100-WAN-8 card (same config).

The circuits connecting the WAN ports can be protected using SNC for highest availability.

I hope what we are providing is helping not confusing you.

Good luck.

viyuan700 Fri, 09/04/2009 - 06:02

Thanks Tom,

I missed the point that there are only 1 E1 card in all routers. With one E1 port at 3 places he cannot make SDH ring those will be just 3 point to point connection and certainly didn't mean that.

Even with Ethernet port the things will not work as there is some other feature which is used in such situation. Have to check 15305 have that capability or not.

ATM card use some subinterfaces so u can use the same interface from making many circuits but i think then it has to terminate to a ATM switch not over E1.

Rajiv Dasmohapatra Fri, 09/04/2009 - 06:17

thanks vishwa,

To be very specific, i am facing problems creating P2P Ethernet over SDH liks. my connection is

Router <-> ONS <-> ONS <-> Router

but i am nor able to ping from R1 to R2 even when i did a WAN to SDH mapping.

I explained in detail the various parameters used in the previous post. anything left that i need to check?

viyuan700 Fri, 09/04/2009 - 06:52

Few things may sound silly here but sometime you make those so just check few points here,

1. When you map WAN port to STM 1 card of ONS 1(since there are 2 STM-1 card)check it is mapped to correct STM 1 port which is connecetd to ONS 2.

ONS1- STM -1 card 1 - STM -1 card1-ONS 2

ONS1- STM -1 card 2 - STM -1 card2-ONS 2

Sometimes it is possible you have connected to wrong port.

2. You can check you are mapping to same E1 at both ONS 1 & 2 (If mapped to E1 number 1 (VC 12) at ONS 1 and then on ONS 2 also use E1 (VC 12)number 1)

Sometimes you map to any E1 which also is not going to work.

Dont use LCAS etc as you dont need that just create the simplest EOS bidirectional circuit possible.

After these precautions. provide physical loop at different point to find the problem.

Like you can first loop ONS1 Tx to Rx Optical cable if you are able to ping then ONS 1 is working fine . Remove the loop connect to ONS 2.

There are soft loop in SDH boxes which you can check to see if it is reaching till ONS 2.

Finally make a physical loop for Etherenet port at ONS 2 and see if you are able to ping. Then your things should work

a long process but will tell you where exactly the problem is.

Rajiv Dasmohapatra Fri, 09/04/2009 - 07:28

I checked the STM1 ports, they are connected fine(3/1 in both ONS).

The ethernet ports which are connected to the routers are same in the ONSs' (lan 2/8, wan 2/16).

i am connecting the ethernet ports and led's in the ONS and router are glowing.

also checked the mapping for both. they are same.

one more thing. it gives alarms sequence indicator mismatch.

after all these it is sure that i am doing something wrong. could you tell me what steps i need to follow in edge craft to pass ethernet over SDH.

viyuan700 Fri, 09/04/2009 - 08:20

I have not worked Edge Craft of 15305 so cannot help in that.

see the explanation of sequence indicator mismatch on this link


This alarm appears when the received sequence (SQ) number is different from the expected sequence number. This is applicable only in non-LCAS mode

Possible problem

Check the configuration at the other end and verify the cross-connects

Is there any more alarms?

Did you used any loop to figure out where the problem is? IF we dont know where the problem is then difficult to find a solution.

Mapping a VC12 circuit to other end correctly means

Let see a circuit from Etherent Port is connect to First STM 1 port of ONS 1 then circuit at other ONS should also be at STM port which is connected to the same STM ONS 1.

If you cross the cable of STM ports or mapping to different STM port at both places, you will see the lights glowing but cannot communicate.

Tom Randstrom Fri, 09/04/2009 - 08:31

Explanation of WAN Port Channel Sequencing is found at Figure 5-53 of Cisco Edge Craft Software Guide r2.0.

Rajiv Dasmohapatra Sat, 09/05/2009 - 01:53

Hi Vishwa / Tom,

I suppose that i have done everything possible but i feel something is wrong. E1 over SDH is working fine, but i cannot get ethernet over SDH to work. even the point to point Ethernet over SDH is not working. any clues.

in the next post i will upload the screenshots.

Rajiv Dasmohapatra Sat, 09/05/2009 - 04:07

The screenshot for first ONS is attached. The same WAN to SDH mapping for Ethernet Over SDH & Cross connect for E1 over SDH has been done for the rest two ONS. but then the E1 is working but not the Ethernet.

Tom Randstrom Sat, 09/05/2009 - 20:28

I believe the problem might be in the way each node's WAN channels are mapped to SDH. I may be wrong but it is difficult to determine given the screen pictures you provided.

A STM-1 ring has a maximum capacity 63 E1s/VC-12s. If we need to interconnect a network containing 3 nodes, we need 3 circuits, A-B, A-C, B-C, to connect the EoSDH cards together. Each Ethernet WAN circuit can have a maximum of 21 VC-12 Channels (63 VC-12 within an STM1 divided by 3 circuits). You will need to reduce the WAN circuit sizes if other traffic (E-1s. etc) is being carried on the network.

Circuit Examples.


Node A

WAN Port 8

WAN Channels 1-21


Node B

WAN Port 8

WAN Channels 1-21


Node A

WAN Port 9

WAN Channels 22 to 42


Node C

WAN Port 9

WAN Channels 22 to 42


Node B

WAN Port 10

WAN Channels 43 to 63


Node C

WAN Port 10

WAN Channels 43 to 63

The circuits that connect the ends of a WAN Port's WAN Channel need to be on the same SDH VC-12 channel. Example, Node A, WAN Port 8, WAN Channel 1 must connect over the same SDH VC-12 as Node B, WAN Port 8, WAN Channel 1.

Is any of this helping?

I wish we had someone who has deployed the 15305 with EoSDH helping with your configurations.

Rajiv Dasmohapatra Sat, 09/05/2009 - 22:46

ok. i will try these. but for the initial testing i have only connected one ethernet ports of both the ONS to two routers and configured the aforesaid way for all the 50 channels. but then too i am not able to ping from Router1 to Router2.

one more question. Is it right to connect the ethernet port directly to a router or a L2 switch in between may help?

viyuan700 Sun, 09/06/2009 - 03:58

Can you provide things like

At ONS 1

which Lanport is selected as per ONS screen shot (OSC) it 2.1

Which channel is selecetd i can see in OSC channel 15 ended at 1.5.3 is used

Which vcgroup you have selected i see something 2.14 (but in alarm i see 2.9) which one you are using

In vcgroup their is option called bandwidth can you tell what bandwidth is selecetd

Need the same above mentioned point for other ONS also.

If possible take screen shots for both ONS or the data asked above.

You have several alarms critical also, as per those setting are different in other ONS.

Rajiv Dasmohapatra Sun, 09/06/2009 - 04:54

Oops, in the screen shot I mistakenly selected lan 2.1. the correct ports are given below.

LAN/WAN Used: (For All the ONS)

Lan port : 2.8

WAN port : 2.16

STM1 Connectivity:

ONS1 3.2 <-> ONS2 3.1

ONS2 3.2 <-> ONS3 3.2

ONS3 3.1 <-> ONS1 3.1


R1 fa0/0 <-> ONS 2.8

R2 fa0/0 <-> ONS 2.8

R3 fa0/0 <-> ONS 2.8

ONS settings (common for all ONS)


Bandwidth: 100 mbps 50 channels.

VCgroup : 2.16

concatenation: VC12

After the configuration of WAN to SDH mapping, no alarms regarding the VCgroup or SDH occurs. but i can't ping the routers.

Tom Randstrom Sun, 09/06/2009 - 07:24

With no SDH alarms for the VC group then need to look into the L2 settings.

What are the statistics showing on the 15305 LAN settings? Maybe create a static route in the 15305s for the connected router?

I am drawing straws.

viyuan700 Sun, 09/06/2009 - 15:17

Is your E1 working for E1 port when you take out cable as earlier you told it doesnot work.

If it is not working in protection mode and you have connected all the ONS the way mentioned here

STM1 Connectivity:

ONS1 3.2 <-> ONS2 3.1

ONS2 3.2 <-> ONS3 3.2

ONS3 3.1 <-> ONS1 3.1

Suppose you have create circuit between ONS 1 & 2. One circuit goes directly from ONs 1 to ONS 2 but other goes in ONS 1-ONS 3_ONS2 direction. For the other direction you have to pass through the E1 at ONS2 then it should work. You can try and then pull the cable.

One more design kind of precaution you can take here (when everything is working) is that if you are configuring any E1 for E1 ports then take Channel no 51-63 otherwise you will not be able to create a 100Mb circuit for Ethernet.

Hi Tom,

as mentioned in your other post, for ethernet do you have any setting apart from mapping E1 from WAN to SDH in 15454.

Rajiv Dasmohapatra Mon, 09/07/2009 - 00:07

I figured the problem for the non-working of the EoSDH. I created a vlan and put the lan and wan ports in the same vlan. it started working. I was of the impression that Lan1 is mapped with wan1 etc.. but later i figured out that any lan can work with any wan port.

thanks 2 you guys.

after the configuration of EoSDH. i am facing a loop kind of issue.

ONS1 wan2/15 <-> ONS2 wan2/15

ONS1 wan1/16 <-> ONS3 wan3/16

ONS1 wan2/14 <-> ONS3 wan2/14

when i am removing a STM1 cable from the port all the routers pings, but when i insert the cable once again the ping stops.

Correct Answer
Tom Randstrom Mon, 09/07/2009 - 09:15

Glad to see you can at least get it to ping!

I would have thought that the spanning tree on 305 switches would have prevented a loop. Check to see if it is active using the link below:


Should your last SDH connection in your previous post's list:

ONS1 wan2/14 <-> ONS3 wan2/14

really be

ONS2 wan2/14 <-> ONS3 wan2/14?

Are the SDH circuits protected or unprotected? Are they set-up as revertive or non-revertive?

HOpe this helps!

Rajiv Dasmohapatra Mon, 09/07/2009 - 19:40

hi Tom,

man, you are a life saver...

i enabled STP and Voila !!! the loop's gone.

thanks for all the help.

Now i am facing some MGX issue, i will start a new conversation for that. hope to see your reply there.

Thanks again for the help to both you guys..


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