The IDS only officially supports the devices listed in the User's Guide and does not include the 3550 switch.
With that said, however, I have heard of users implementing unsupported configurations.
I am not familiar with the 3550 and it's operating system so I am not sure what it's capabilities are and what commands it supports.
If the 3550 is running IOS and has Router ACLs applied to virtual interfaces with ip addresses assigned to vlans, then you may be able to configure the sensor to think that the 3550 is a Cisco Router. You would be limited to creating ACLs on the routable interface of the 3550 and would be Router ACL applied to the interface rather than a VLan ACL. The difference being that the Router ACL is only applied against packets being Routed between vlans by the switch, while a Vlan ACL woudl be applied even if the packets stayed in the same vlan.
If the 3550 is instead running an operating system more like the Cat OS on the Cat 6K then it may support Vlan ACLs using the same commands as the Cat 6K running Cat OS. In which case you may be able to configure the sensor to thing it is a Cat 6K switch and use Vlan ACLs.
Be aware that IOS running on the Cat 6K also has Vlan ACLS but the syntax for Vlan ACLs in IOS is different than the syntax for Vlan ACLs in the traditional Cat OS. Because of this difference the sensor can not create Vlan ACLs on the Cat 6K running Native IOS (though it can create Router ACLs treating the switch like a router).
So if your 3550 support IOS like Vlan ACLs then it won't work.
If you do try and get it to work then keep in mind that this will not be supported by the TAC.
Table of ContentsIntroductionVersion HistoryPossible Future
UpdatesDocuments PurposeNAT Operation in ASA 8.3+ SectionsRule Types
Network Object NATTwice NAT / Manual NATRule Types used per SectionNAT
Types used with Twice NAT / Manual NAT and Network Obje...
[toc:faq]Introduction:This document describes details on how NAT-T
works.Background:ESP encrypts all critical information, encapsulating
the entire inner TCP/UDP datagram within an ESP header. ESP is an IP
protocol in the same sense that TCP and UDP are I...