Tcp Applications Flags Enhancement; Tcp Show Extension; Tcp Mib For Rfc 4022 Support; Tcp Keepalive Timer - Cisco ASR 1000 Series Configuration Manual

Configuring TCP
See the "Configuring the MSS Value and MTU for Transient TCP SYN Packets" section for configuration
instructions.

TCP Applications Flags Enhancement

The TCP Applications Flags Enhancement feature enables the user to display additional flags with reference
to TCP applications. There are two types of flags: status and option. The status flags indicate the status of
TCP connections such as passive open, active open, retransmission timeout, and app closed for listening. The
additional flags indicate the state of set options such as whether a VPN routing and forwarding instance (VRF)
is set, whether a user is idle, and whether a keepalive timer is running. Use the show tcp command to display
TCP application flags.

TCP Show Extension

The TCP Show Extension feature introduces the capability to display addresses in IP format instead of the
hostname format and to display the VRF table associated with the connection. To display the status for all
endpoints with addresses in IP format, use the show tcp brief numeric command.

TCP MIB for RFC 4022 Support

The TCP MIB for RFC 4022 Support feature introduces support for RFC 4022, Management Information
Base for the Transmission Control Protocol (TCP). RFC 4022 is an incremental change of the TCP MIB to
improve the manageability of TCP.
To locate and download MIBs for selected platforms, Cisco IOS releases, and feature sets, use Cisco MIB
Locator found at the following URL:
http://www.cisco.com/go/mibs

TCP Keepalive Timer

The TCP Keepalive Timer feature provides a mechanism to identify dead connections.
When a TCP connection on a routing device is idle for too long, the device sends a TCP keepalive packet to
the peer with only the Acknowledgment (ACK) flag turned on. If a response packet (a TCP ACK packet) is
not received after the device sends a specific number of probes, the connection is considered dead and the
device initiating the probes frees resources used by the TCP connection.
The following parameters are used to configure TCP keepalive:
• TCP Keepalive idle time—The value of this parameter indicates the time for which a TCP connection
• TCP Keepalive retries—The value of this parameter is the number of unacknowledged probes that a
• TCP Keepalive interval—The time between subsequent probe retries.
can be idle before the connection initiates keepalive probes.
device can send before declaring the connection as dead and tearing it down.
IP Application Services Configuration Guide, Cisco IOS XE Release 3S (Cisco ASR 1000)
TCP Applications Flags Enhancement
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