Broadband Scalability and Performance
Walk-by User Support for PWLAN in ISG
9
Cisco ASR 1000 Series Aggregation Services Routers Software Configuration Guide
Redefining User Profiles to Use the ip:vrf-id and ip:ip-unnumbered VSAs
The requirement of a full virtual access interface when using the
lcp:interface-config
VSA in user
profiles can result in scalability issues, such as increased memory consumption. This situation is
especially true when the Cisco ASR 1000 Series Router attempts to apply a large number of per-user
profiles that include the
lcp:interface-config
VSA. Therefore, when updating your user profiles, we
recommend that you redefine the
lcp:interface-config
VSA to the scalable ip:vrf-id and
ip:ip-unnumbered VSAs.
The following example shows how to redefine a VRF named
newyork
using the ip:vrf-id VSA:
Change:
Cisco:Cisco-Avpair = “lcp:interface-config=ip vrf forwarding newyork”
To:
Cisco:Cisco-Avpair = “ip:vrf-id=newyork”
The following example shows how to redefine the Loopback 0 interface using the ip:ip-unnumbered
VSA.
Change:
Cisco:Cisco-Avpair = “lcp:interface-config=ip unnumbered Loopback 0”
To:
Cisco:Cisco-Avpair = “ip:ip-unnumbered=Loopback 0”
Walk-by User Support for PWLAN in ISG
In public wireless LAN (PWLAN) setups, a high number of ISG sessions might be unauthenticated
sessions from wireless devices that do not use the PWLAN service. These sessions are referred to in this
document as walk-by sessions, and users that use these sessions are referred to as walk-by users.
Walk-by sessions, if not dealt with in an optimized way, may consume a large portion of the hardware
resources. This resource utilization may lead to an increase in the number of ISG routers required for a
given PWLAN deployment. The concept of light-weight sessions is introduced to provide an
optimization for walk-by sessions.
The features for walk-by users are configured on a default session acting as a template. Walk-by users
are then assigned light-weight sessions that inherit features from a default session. The features are
configured only once on the default session, thereby optimizing the resource usage.
A lite session is a light-weight unauthenticated ISG session that inherits default session services. Lite
sessions are created on ISG to support walk-by users and optimize resource usage. A timer may be
specified to limit the duration for which the lite session can utilize the public wireless LAN (PWLAN)
services while remaining unauthenticated.
Restrictions for Walk-by Session Support for PWLAN in ISG
The restriction pertaining to the Walk-by Session Support for PWLAN in ISG feature includes:
•
On the ASR 1000 Series router, the Layer 4 Redirect (L4R) feature supports a maximum of 16
translation entries per walk-by session. For more information on the limit for the total number of
translations on the system, see
Layer 4 Redirect Scaling, page 4
.
