Note The terms "Unidirectional Path Switched Ring" and "UPSR" may appear in Cisco literature. These terms do not refer to using Cisco ONS 15xxx products in a unidirectional path switched ring configuration. Rather, these terms, as well as "Path Protected Mesh Network" and "PPMN," refer generally to Cisco's SNCP feature, which may be used in any topological network configuration. Cisco does not recommend using its SNCP feature in any particular topological network configuration.
This chapter describes the card and port protection configurations for the Cisco ONS 15310-MA SDH. To provision protection, refer to the "Turn Up a Node" chapter in the
Cisco ONS 15310-MA SDH Procedure Guide. Chapter topics include:
•ONS 15310-MA SDH Card and Port Protection
•Automatic Protection Switching
•External Switching Commands
The Cisco ONS 15310-MA SDH has a pair of common control cards (15310E-CTX-K9), each with two optical ports, and up to four electrical cards (E1_21_E3_DS3_3 or E1_63_E3_DS3_3). 1:1 protection groups are supported for like pairs of electrical cards, and 1+1 protection groups can be set up between two optical ports on the same 15310E-CTX-K9 card or between the optical ports on two separate 15310E-CTX-K9 cards.
When two 15310E-CTX-K9 cards are installed, the 15310E-CTX-K9 card is 1:1 protected. The 15310-MA SDH can function in a single 15310E-CTX-K9 configuration mode.
3.2 ONS 15310-MA SDH Card and Port Protection
This section describes the card and port protection methods for the ONS 15310-MA SDH.
3.2.1 1:1 Electrical Card Protection
The ONS 15310-MA SDH chassis accommodates two types of electrical cards, the E1_21_E3_DS3_3 and E1_63_E3_DS3_3, and one type of common-control card, the 15310E-CTX-K9. Figure 3-1 illustrates one possible chassis configuration, with two 15310E-CTX-K9 cards and two pairs of E1_63_E3_DS3_3 cards.
The following examples show a few of the several possible ONS 15310-MA SDH chassis configurations:
•No electrical cards at all. This is the case if you choose to install Ethernet cards, such as the CE-100T-8 or ML-100T-8, instead of electrical cards. The Ethernet cards cannot be used to form a protection group.
•Unprotected electrical cards. This is the case if, instead of a pair of electrical cards in Slots 1 and 2 or 5 and 6, you install only a single electrical card in Slots 1, 2, 5, or 6. A filler card or Ethernet card must be installed in a slot where an input/output (I/O) card is missing.
•A single 15310E-CTX-K9 card. In this case, a filler card must be installed in a slot where a 15310E-CTX-K9 card is missing.
•A mix of electrical cards. An E1_21_E3_DS3_3 card can protect an adjacent E1_21_E3_DS3_3 card, an E1_63_E3_DS3_3 card can protect an adjacent E1_63_E3_DS3_3 card, and an E1_63_E3_DS3_3 card can protect an adjacent E1_21_E3_DS3_3 card. However, an E1_21_E3_DS3_3 card cannot protect an adjacent E1_63_E3_DS3_3 card.
Figure 3-1 ONS 15310-MA SDH Chassis Card Layout
The configuration of the backplane connectors creates two sets of paired (adjacent) expansion slots for electrical cards. Slots 1 and 2 are a pair and Slots 5 and 6 are a pair. When two electrical cards are plugged into either of the card-slot pairs, the ONS 15310-MA SDH automatically creates a 1:1 protection group for the two cards, if possible.If a protection group cannot be created (see the rules for protection group creation later in this section), one of the cards will be marked as UNKNOWN with the state as MISMATCH in CTC, because the ONS 15310-MA SDH cannot support two unprotected electrical cards in the 1-2 or 5-6 card slot pairs. The 1:1 automatic protection group is created when the second electrical card in a pair is either plugged in or is preprovisioned.
Unprotected is the default state for the first electrical card plugged into (or preprovisioned) in either the Slot 1-to-2 or Slot 5-to-6 card slot pairs. When the second card is plugged in or preprovisioned, the protection group is created, if possible.
When protection groups are created, the following rules must be noted:
1. The protection group will be automatically created if possible. If the node cannot create the protection group automatically, then the second card to be plugged in or preprovisioned will be shown as UNKNOWN with the state as MISMATCH in CTC.
2. If possible, the ONS 15310-MA SDH designates the cards in Slots 1 and 5 as working. If Slot 1 or 5 cannot be working (due to violation of one of the other rules), then Slot 2 or 6 will be the working slot.
3. Cards can protect like cards. In addition, an E1_63_E3_DS3_3 card can protect an E1_21_E3_DS3_3 card. However, an E1_21_E3_DS3_3 card cannot protect an E1_63_E3_DS3_3 card.
4. If the first card to be provisioned has existing circuits or is in use as a timing source when the second card is provisioned, then the first card must become the working card and cannot become the protect card.
5. The timing source will not switch to a protect card, when a soft reset is executed on the card that is used as a timing source.
6. Automatic protection groups default to nonrevertive. The protection group can be edited to turn on reversion and set a revert time. The protection group can also be edited to change the protection group name.
The following scenario does not result in the creation of a protection group because rules are violated:
1. Plug an E1_63_E3_DS3_3 card into Slot 1 and provision a circuit on it.
2. Plug an E1_21_E3_DS3_3 card into Slot 2.
The E1_63_E3_DS3_3 card needs to be the working card, because it has a circuit on it (see Rule 4). However, the E1_21_E3_DS3_3 card cannot protect the E1_63_E3_DS3_3 card (see Rule 3), so no protection group is formed.
The following scenario also does not result in the creation of a protection group because rules are violated:
1. Plug an E1_21_E3_DS3_3 card into Slot 1 and enable the retiming option on it.
2. Plug an E1_63_E3_DS3_3 card into Slot 2.
Because the E1_63_E3_DS3_3 card does not support retiming, it cannot become a protection card for the E1_21_E3_DS3_3 card, so no protection group is formed.
The following scenario results in the creation of a protection group because no rules are violated:
1. Plug an E1_21_E3_DS3_3card into Slot 1 and provision a circuit on it.
2. Plug an E1_63_E3_DS3_3 card into Slot 2.
A protection group is automatically formed, with the E1_21_E3_DS3_3 card operating as the working card, and the E1_63_E3_DS3_3 card operating as the protection card.
Automatic protection groups cannot be created or deleted by users. A protection group is automatically deleted when the protect card is deleted.
3.2.2 .LMSP Optical Port Protection
With two 15310E-CTX-K9 cards installed, four optical ports are available (two on each card). A Linear Multiplex Section Protection group can be created between any two pairs of optical ports with matched port rates.
A protection group can be created using two ports on the same 15310E-CTX-K9 card or between ports on adjacent 15310E-CTX-K9 cards. You can also create a 1+1 protection group on each card for a total of two protection groups. In this case, working and protection ports are provisioned on Slot 3 and working and protection ports are provisioned on Slot 4 (the same card can have both working and protect ports on it).
3.2.3 .15310E-CTX-K9 Card Equipment Protection
The ONS15310MA supports a single and dual 15310E-CTX-K9 card configurations. In the dual configuration, with a 15310E-CTX-K9 card inserted in Slot 3 and Slot 4, the 15310E-CTX-K9 card is also protected. One of the cards becomes the active card and the other becomes the standby card. Soft resets executed in the dual 15310E-CTX-K9 card configuration as well as in the single 15310E-CTX-K9 card configuration are errorless. Software upgrades in the single and dual configurations are also errorless.
In the dual configuration, there is a switchover from the active 15310E-CTX-K9 card to standby 15310E-CTX-K9 card during the soft reset of the active 15310E-CTX-K9 card. After the soft reset or software upgrade, the old standby 15310E-CTX-K9 card becomes the new active 15310E-CTX-K9 card. The old active 15310E-CTX-K9 card becomes the standby 15310E-CTX-K9 card.
The 15310E-CTX-K9 card is equipment protected in a dual 15310E-CTX-K9 card configuration. Any reset occurring on the active 15310E-CTX-K9 card that is triggered due to failure causes a switchover of the 15310E-CTX-K9 card, causing the old standby card to become the active card.
Note The ONS 15310-MA SDH and the 15310E-CTX-K9 card do not support SNCP switching for VC3 circuits containing BIP errors. The SF/SD alarm is not raised for VC3 circuits.
If there are any SNCP or 1+1 protected ports configured across the two 15310E-CTX-K9 cards, a protection switch will cause the port on the active 15310E-CTX-K9 card to become the active port for 1+1 or the SNCP selector.
Note•Any unprotected port on the 15310E-CTX-K9 card being reset may undergo a traffic loss when the 15310E-CTX-K9 is reinitialized.
•If protection exists between two optical ports on the same 15310E-CTX-K9 card and if that 15310E-CTX-K9 card is reset, the traffic might be affected when the 15310E-CTX-K9 card is reinitialized.
The two items above do not apply for a user-initiated soft reset or software upgrade. These resets are errorless
3.3 Automatic Protection Switching
Unidirectional switching allows traffic on the transmit and receive optical fibers to switch independently.
With nonrevertive 1+1 protection, automatic protection switching (APS) switches a signal after a failure from the working port to the protect port and the signal stays switched to the protect port until it is manually switched back. Revertive switching automatically switches the signal back to the working port when the working port comes back online. 1+1 protection is unidirectional and nonrevertive by default; revertive switching is easily provisioned using CTC.
3.4 External Switching Commands
The external switching commands on the ONS 15310-MA SDH are Manual, Force, and Lock Out. A Manual switch will switch traffic if the path has an error rate less than the signal degrade (SD). A Force switch will switch traffic even if the path has SD or signal fail (SF) conditions. A Force switch has a higher priority than a Manual switch. In 1+1 mode, however, if there is an SF condition on the protect line, the SF condition has a higher priority than Force, and Force cannot override the SF condition to make a switch to the protect line. Lockouts can only be applied to a protect port (in 1+1 configurations) and prevent traffic from switching to the protect port under any circumstance. Lockouts have the highest priority. In a 1+1 configuration you can also apply a lock-on to the working port. A working port with a lock-on applied cannot switch traffic to the protect port in the protection group (pair).