=?iso-8859-1?q?maine=20dude?= wrote: > > Hi, > > we have our network setup with 6509s in the floor risers > > as access switches, connected by fibre to a pair of 6509s in > the data > > centre which route between the vlans. > > Why if I do a tracert from my pc to a PC on a different vlan, > do I not see > > a hop indicating the routing between the vlans? > > Any idea's...?
There are so many possible reasons, it's hard to list them all. A generic comment is that Trace Route isn't very relible. Routers (and so-called "switching routers") may not send back the ICMP TTL Expired for numerous reasons, including: ICMP is rate-limited ICMP is disabled for security reasons ICMP is disabled for performance reasons ICMP is disabled for traffic that arrives and leaves on the same interface bugs (not with Cisco?! ;-) Another possibility is that the traffic really isn't flowing through the router. What addressing are you using? What default gateway is configured on the PCs? Is the router doing Proxy ARP? Are the PCs assuming Proxy ARP is in use? How are the devices physically connected? Are you sure VLANs are really delineating broadcast domains? I have run into situations where a PC ARPs for a device not in its subnet, due to having no default gateway configured or the default gateway set to itself. Due to a VLAN misconfiguration or some other reason for the PCs hearing each others broadcasts (like they are in the same hub or whatever), the other PC responds rather than the default gateway and subsequent traffic flows directly, without the router getting involved. Since you can't trust Trace Route, you would have to put a protocol analyzer on the networks to determine if this is happening. _______________________________ Priscilla Oppenheimer www.troubleshootingnetworks.com www.priscilla.com > > Thanks- > > > > > > > --------------------------------- > Get a bigger mailbox -- choose a size that fits your needs. > > Message Posted at: http://www.groupstudy.com/form/read.php?f=7&i=55214&t=55172 -------------------------------------------------- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
