Technical data

10 Brocade ServerIron ADX Advanced Server Load Balancing Guide

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SIP SLB and call persistence

SIP server load balancing with non-DSR mode

Figure 5 shows a SIP server farm with proxy servers connected inline (non-DSR mode) with the

ServerIron ADX switch.

FIGURE 5 SIP Server Load Balancing with non-DSR mode

To maintain session persistence and transaction integrity, this implementation has the following

requirements:

• The SIP proxy server should use the same Call-ID for both legs of communication (for example,

for message exchange with both SIP clients within a given SIP dialog).

• For all outbound SIP communications, the proxy server should use the same UDP/TCP source

port as that used as the destination port for all inbound communications.

NOTE

If the proxy server uses a source port other than the one used as the destination port for inbound

communications, then the packets arriving from the proxy server go untranslated by the ServerIron

ADX. The proxy server IP address must be reachable from all SIP clients in such cases.