What're your ARP/mac address timers? We've seen similar issues to this on 3550/3750s when we were still running an asymmetric routing setup, and the switch still had an ARP entry for a device, but the MAC address had expired. ~Matt
________________________________ From: [EMAIL PROTECTED] on behalf of Ed Butler Sent: Mon 4/2/2007 12:10 To: nsp Subject: Re: [c-nsp] 3750 acting as a hub - resolved I went through all the config changes that were made, and there was absolutely nothing that would have had this kind of affect that I can see. As an aside, a packet capture showed over half the packets had no data, eg 66 byte TCP packets. The problem righted itself after issuing a "clear mac-address-table dynamic" command. Why it happened in the first place is still a mystery to me, I would be interested to hear any thoughts. Regards, Ed Butler RapidSwitch Ltd DDI: 020 7106 0731 RapidSwitch Ltd, Sovereign House, 227 Marsh Wall, London, E14 9SD This email message is intended only for the addressee(s) and contains information that may be confidential and/or copyright. No representation is made that this email or any attachments are free of viruses. Virus scanning is recommended and is the responsibility of the recipient. RapidSwitch Ltd is registered in England & Wales Company No. 04535693, Registered Address: 3 Beacon Mews, South Road, Weybridge, KT13 9DZ. VAT Registration No. GB 794 3811 96. All prices exclude VAT unless otherwise stated. Quotations valid for seven days. -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Ed Butler Sent: 02 April 2007 16:20 To: nsp Subject: Re: [c-nsp] 3750 acting as a hub To reply to myself - just had an idiot moment. This is happening on other VLANs too on the switch, and started happening at some minor maintenance we made. Going to compare the before/after config to see what could cause the odd behaviour; I can't immediately thing of changes that would facilitate this. Regards, Ed Butler RapidSwitch Ltd DDI: 020 7106 0731 RapidSwitch Ltd, Sovereign House, 227 Marsh Wall, London, E14 9SD This email message is intended only for the addressee(s) and contains information that may be confidential and/or copyright. No representation is made that this email or any attachments are free of viruses. Virus scanning is recommended and is the responsibility of the recipient. RapidSwitch Ltd is registered in England & Wales Company No. 04535693, Registered Address: 3 Beacon Mews, South Road, Weybridge, KT13 9DZ. VAT Registration No. GB 794 3811 96. All prices exclude VAT unless otherwise stated. Quotations valid for seven days. -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Ed Butler Sent: 02 April 2007 16:11 To: nsp Subject: [c-nsp] 3750 acting as a hub We saw a surge in incoming traffic to a number of boxes on a certain VLAN on a 3750 stack earlier. The traffic appeared to be unicast traffic to a number of different boxes on the VLAN, but it was being broadcast to everything on that port - eg normal hub behaviour. This doesn't happen to other VLANs on the same box, and there's no apparent reason for the behaviour. Cisco 3750 stack running on 12.2(25)SED1. 1. No spanning tree issues: 3750#sh spanning-tree vlan 400 detail | in last Number of topology changes 79 last change occurred 17:09:44 ago 2. TCAM space looks fine: 3750#sh ip arp sum 3353 IP ARP entries, with 149 of them incomplete 3750#sh sdm pref The current template is "desktop default" template. The selected template optimizes the resources in the switch to support this level of features for 8 routed interfaces and 1024 VLANs. number of unicast mac addresses: 6K number of IPv4 IGMP groups + multicast routes: 1K number of IPv4 unicast routes: 8K number of directly-connected IPv4 hosts: 6K number of indirect IPv4 routes: 2K number of IPv4 policy based routing aces: 0 number of IPv4/MAC qos aces: 512 number of IPv4/MAC security aces: 1K 3750#sh mac-address-table count vlan 400 Mac Entries for Vlan 400: --------------------------- Dynamic Address Count : 77 Static Address Count : 0 Total Mac Addresses : 77 Total Mac Address Space Available: 2680 Regards, Ed Butler RapidSwitch Ltd DDI: 020 7106 0731 RapidSwitch Ltd, Sovereign House, 227 Marsh Wall, London, E14 9SD This email message is intended only for the addressee(s) and contains information that may be confidential and/or copyright. No representation is made that this email or any attachments are free of viruses. Virus scanning is recommended and is the responsibility of the recipient. RapidSwitch Ltd is registered in England & Wales Company No. 04535693, Registered Address: 3 Beacon Mews, South Road, Weybridge, KT13 9DZ. VAT Registration No. GB 794 3811 96. All prices exclude VAT unless otherwise stated. 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