I am assuming the switch/msfc is not running native ios..
Larry Letterman Cisco Systems [EMAIL PROTECTED] -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]]On Behalf Of MADMAN Sent: Monday, March 18, 2002 7:13 AM To: [EMAIL PROTECTED] Subject: Re: cisco switches (with MSFC) arp timer question [7:38635] Interesting that you brought the differance in the ARP timers up. I have seen some weird problems in a couple of network, things were not breaking but would see strange traffic, packets getting dropped etc. Bumped up the CAM timers on the Cat to match the routers, 14400. http://www.cisco.com/warp/public/473/62.shtml#casestudy8 This probably doesn't answer your question but it reminded me of the this issue!! Dave z z wrote: > > Hi > > One interesting scenario here. Two core switches (with > MSFC) running HSRP. Core 1 is the master for vlan 1, > and core 2 is the master for vlan 2. Understand MSFC > arp timer is 4 hours, but switch CAM timer is 300 > seconds. So there will be one problem: > > 1. Client 1 (vlan 1) wants to talk to client 2 > (vlan2). It will send one frame to client 2 using Core > 1s mac address as the destination mac, because Core 1 > is its gw. > 2. Core 1 will check its routing table and forward the > packet to client 2. Meantime, it will change the > frames source mac address to its own mac and the des > mac to client 2s mac address. > 3. Core 2 will just simply switch the frame to client > 2, because core 1 has done the routing. To core 2, its > arp table and aft table wont contains client 1s mac > address so far, since core 1 has translated the > frames source mac address. > 4. When client 2 wants to reply, it will send the > replying packets to core 2. Core 2 will arp for client > 1s mac address. When client 1 reply this arp request, > core 2 will add its mac address to both its arp table > and aft table. > 5. this is working fine so far. > 6. after 300 seconds, core 2s aft table time out. > However its arp table is still valid, so it wont do > any more arp request. When client 2 wants to talk to > client 1, core 2 will do the routing correctly, but > then flood the frames to all the switch ports. > > Is my theory correct? > > __________________________________________________ > Do You Yahoo!? > Yahoo! Sports - live college hoops coverage > http://sports.yahoo.com/ -- David Madland Sr. Network Engineer CCIE# 2016 Qwest Communications Int. Inc. [EMAIL PROTECTED] 612-664-3367 "Emotion should reflect reason not guide it" Message Posted at: http://www.groupstudy.com/form/read.php?f=7&i=38664&t=38635 -------------------------------------------------- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
