The Cisco ONS is interoperable with our existing Cisco ONS UPSR architecture and it also gives us 16 rings of completely interoperable ONS. BLSR,Bi-directional Line Switched ring. There are two types of BLSR deployed in various networks. i. 2-fiber BLSR ii. 4-fiber BLSR. How is Bi-directional Line Switched Ring (SONET) abbreviated? BLSR stands for Bi-directional Line Switched Ring (SONET). BLSR is defined as Bi-directional.

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You, the client are of most extreme significance to us, and we are focused on being the entrance that maintains your sound way of life. Manual Span Upgrades are blrs provided as error recovery for the Span Upgrade Wizard, but they can be used to perform span upgrades.

Posted by Shankar BLR at In this example of an OC ring 48 STS-1s ring riing rate have been provisioned and there is no more bandwidth left on the ring.

Chapter 9, SONET Topologies

Subtending rings from an ONS reduces the number of nodes and cards required and reduces external shelf-to-shelf cabling. On the other hand, by leaving some LSPs over the link unprotected, the backup bandwidth can be reduced. In a four-fiber BLSR, two fibers are used as working fibers and the other two are used as protection fibers, to be utilized in the case of a failure. Nodes 2 and 3 each use two redundant OC-N bus cards for a total of four cards, with eight free slots remaining. John Wiley and Sons, Ltd.

In the case of an abnormal error, you must exit the wizard and initiate the manual procedure to either continue with the upgrade or back out of it. Protection channels that are not carrying extra traffic are terminated at the intermediate nodes. Intermediate nodes along the ring are provisioned so that the protection channel STS-1s carrying extra traffic are passed through the node.

For the case of adjacent node traffic the capacity advantage of the BLSR grows linearly with the number of nodes, however in most cases the traffic will likely resemble a distributed logical mesh still providing a capacity advantage but not quite as extreme as in the adjacent node traffic case.


For example, make the east port the farthest slot to the right and the west port the farthest left. UPSR capacity is equal to its bit rate. The circuit would normally travel from Node 1 to Node 4 to Node 7. To perform a span upgrade, the higher-rate optical card must replace the lower-rate card in the same slot. I think this is a real great article post. APS techniques involve reserving a protection channel dedicated or shared with the same capacity of the channel or element being protected.

Congratulations to the writer. If a problem occurs in the working traffic path, the receiving node switches to the path coming from the opposite direction.


Four-fiber BLSRs use two types of protection mechanisms during failure recovery, namely ring and span switching. For four-fiber BLSRs, use the same east—west connection pattern for the working and protect fibers. Node A is not adjacent to the fiber so all of its path selectors will switch based upon path integrity of each individual path independent of the status of any other path.

At the time of ring switching, those channels carrying service traffic are switched to the channels that carry the protection traffic in the opposite direction.

The input at node A travels clockwise on ring1 and egresses at node C.

With no extra traffic on the ring, under certain multiple point failures, such as those that cause node isolation, services from the same time slot but on different hlsr may contend for access to the same protection channel time slot. Please visit my site. If full protection is selected, CTC creates a second unique route between Nodes 3 and 9 which, in this example, passes through Nodes 2, 1, and Multiple span switches can coexist on the ring. The best possible answers are given here regarding the selection of an ideal supplement or cream or serum that possibly remains rkng be safe for health and do not cause any side effects.


At that point, traffic is switched back to the working bandwidth.

For rings that support extra traffic, extra rung is allowed on both sides of the node. This page was last edited on 2 Juneat You can also choose levels of circuit protection.

For this reason, before WDM protection schemes were defined, SONET protection mechanisms rin mainly adopted to guarantee optical network survivability. This makes the UPSR particularly easy to provision and manage.

This is really an interesting topic. Node A will therefore receive its signal from B on ring2.

Link protection

The extreme case of this is when all traffic is between adjacent nodes. For instance, if all the LSPs are to be protected, then the net capacity should equal the bandwidth of the protected link.

In this expamle ring1 is the working path. However, p- cycle planning is an NP-hard problem and is not scalable. Until all spans are upgraded, mismatched card types will be rinng.


Failures in high-speed networks have always been a concern of utmost importance. In a two-fiber BLSR, the protection fibers are contained within ging working fibers like a four-fiber BLSR and both the fibers are used to carry working rinng whilst keeping only half the capacity on each fiber for protection purposes. The three most notable ring-based protection techniques for mesh networks are ring covers, cycle double covers and p-cycles pre-configured protection cycles. You can perform in-service span upgrades for the following ONS cards:.

Therefore, BLSRs are suited for distributed node-to-node traffic applications such as interoffice networks and access networks. They can be provisioned with other cards or left empty.