S-GW Engineering Rules

This appendix provides Serving Gateway-specific engineering rules or guidelines that must be considered prior to configuring the ASR 5x00 for your network deployment. General and network-specific rules are located in the appendix of the System Administration Guide for the specific network type.

The following rules are covered in this appendix:

Interface and Port Rules

The assumptions and rules discussed in this section pertain to Ethernet line cards and the type of interfaces they facilitate.

S1-U/S11 Interface Rules

The following engineering rules apply to the S1-U0/S11 interface:

  • An S1-U0/S11 interface is created once the IP address of a logical interface is bound to an S-GW service.
  • The logical interface(s) that will be used to facilitate the S1-U0/S11 interface(s) must be configured within an “ingress” context.
  • S-GW services must be configured within an “ingress” context.
  • At least one S-GW service must be bound to each interface, however, multiple S-GW services can be bound to a single interface if secondary addresses are assigned to the interface.
  • Depending on the services offered to the subscriber, the number of sessions facilitated by the S1-U0/S11 interface can be limited.

S5/S8 Interface Rules

This section describes the engineering rules for the S5 interface for communications between the Mobility Access Gateway (MAG) service residing on the S-GW and the Local Mobility Anchor (LMA) service residing on the P-GW.

MAG to LMA Rules

The following engineering rules apply to the S5/S8 interface from the MAG service to the LMA service residing on the P-GW:

  • An S5/S8 interface is created once the IP address of a logical interface is bound to an MAG service.
  • The logical interface(s) that will be used to facilitate the S5/S8 interface(s) must be configured within the egress context.
  • MAG services must be configured within the egress context.
  • MAG services must be associated with an S-GW service.
  • Depending on the services offered to the subscriber, the number of sessions facilitated by the S5/S8 interface can be limited.

S-GW Service Rules

The following engineering rules apply to services configured within the system:

  • A maximum of 256 services (regardless of type) can be configured per system.

CAUTION:

Large numbers of services greatly increase the complexity of management and may impact overall system performance. Only create a large number of services only be configured if your application absolutely requires it. Please contact your local service representative for more information.

  • The system maintains statistics for a maximum of 4,096 peer LMAs per MAG service.
  • The total number of entries per table and per chassis is limited to 256.
  • Even though service names can be identical to those configured in different contexts on the same system, this is not a good practice. Having services with the same name can lead to confusion, difficulty troubleshooting problems, and make it difficulty understanding outputs of show commands.

S-GW Subscriber Rules

The following engineering rule applies to subscribers configured within the system:

  • A maximum of 2,048 local subscribers can be configured per context.
  • Default subscriber templates may be configured on a per S-GW or MAG service.