Functionality of Configurable SCTP Buffer Sizes per Association

The amount of memory allocated for traffic buffers determines the maximum traffic rate and average message size that can be sustained for a specific network configuration. Memory is a constraint in achieving advertised capacity due to queuing, message storing and packet retention for retransmission over the Ethernet physical transport. As a general rule, the greater the Round Trip Time (RTT) for a packet, the greater the need for memory to store the unacknowledged packets being sent to the peer. Since each card has a finite amount of memory, the allocation is spread across all the links or connections on the card. This means that as a card’s hosted-association(s) buffer sizes increase, the maximum number of associations that can be hosted by the card decrease.

The SCTP buffer size is configurable per association. Within the constraints of memory on the card, each association can have 8 kb to 400 kb of send-and-receive buffer space for SCTP.

Table 5-15 lists the maximum memory available for SCTP buffers on each card type.

Table 5-15 SCTP Buffer Space per Connection, Card and Application

Application	Card	Max # Conns	Default Conn Buffer	Max Conn Buffer	Max Total Buffer
IPLIMx	E5-ENET/ E5-ENET-B	16	200KB	400KB	3200KB
IPGWx	E5-ENET/ E5-ENET-B	50	16KB	400KB	3200KB
IPSG	E5-ENET/ E5-ENET-B	32	200KB	400KB	6400KB
IPSG	SLIC	128	200KB	400KB	6400KB

Note:

No card or application combination supports the maximum number of connections with each connection having the maximum buffer size.