Track cisco mac address port manual#
Track cisco mac address port full#
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So, once again into the CLI, I repeated everything until I returned to the source. But in this case, given how much everyone else had already worked on it (with no success), my hunch said the traffic followed an asymmetrical return path. IвЂ™d found the full, one-way Layer 2 path.ДЄt this point, it would be easy assume that the return path is symmetrical, and call it a day. Eventually, the MAC address-table entry didnвЂ™t point to a CDP neighbor, but instead pointed to a single physical interface with only one MAC address in the MAC address-table.ДЄt last. I moved to the next switch, repeated the whole process, moved to the third, ran the procedure again, moved on yet again вЂ¦ sigh. With the physical interface info, I could correlate with the CDP neighbors table, and find which neighbor to check next. Load-balance Algorithm on switch: source-dest-ipД¬rc8_hash: 11 Outgoing port id: Ethernet1/2 Missing params will be substituted by 0's. SWITCH-A# sh port-channel load-balance forwarding int port-channel 1 In this case, it was just using source and destination IP only.

The output shows which physical interface the packets are taking, as well as which load-balanceing algorithm the port-channel is using.

Track cisco mac address port full#

This command is full of options, and if you question-mark your way through it, you can tweak it a variety of different ways.В Remember the source and destination IPs? This is where youвЂ™ll use them. Sh port-channel load-balance forwarding-path int port-channel 1 vlan 101 src-ip 1.1.1.1 dst-ip 2.2.2.2 I had no clue which command would accomplish this. I needed to figure out which physical interface is actually forwarding the packets, since they lead to different switches. This is where things get a little tricky. Turns out the two physical interfaces connect to two different neighbors. V - VoIP-Phone, D - Remotely-Managed-Device,Дevice-ID Local Intrfce Hldtme Capability Platform Port ID S - Switch, H - Host, I - IGMP, r - Repeater, With this, I looked in the CDP neighbor table to see which neighbor these interfaces connect to.Д¬apability Codes: R - Router, T - Trans-Bridge, B - Source-Route-Bridge This showed which physical interfaces each port-channel contains. Group Port-Channel Type Protocol Member Ports I - Individual H - Hot-standby (LACP only) So, to find the physical interfaces included in that port-channel, I ran:ДЇlags: D - Down P - Up in port-channel (members) Guess what? The MAC was found on a port-channel. Once the originating switch and port was identified, I could begin looking for the path to the destination. VLAN MAC Address Type age Secure NTFY Ports However, before jumping in, I needed the source and destination MAC addresses, as well as source and destination IP address (more on this later).В Once the sever team provided all these, I began by finding the exact source switch and interface: The command mac address-tableВ alone was not going to cut it, as sometimes the switch would see the MAC address over a port-channel, and IвЂ™d need to know which interface in the port channel had forwarded the packet. It was going to be tricky though, since the core switches were using both port-channels and virtual port-channels.

Track cisco mac address port manual#

So, what was left was a manual Layer 2 trace, which means manually searching through the mac address-tables. ItвЂ™s been around since 12.2(18) and you can use either MAC address or IP address to run the trace.

Track cisco mac address port series#

Turns out Cisco does offer aВ Layer 2 traceroute utilityВ for IOS on both the Cisco 7600 series routersВ and Catalyst 3560 series switches. What I needed was a layer 2 traceroute tool. In a routed environment, this would be a no-brainer: traceroute would have your answer. So the crucial first question is вЂњwhat is the path?вЂќ If just one interface in the path doesnвЂ™t allow jumbo frames, the conversation breaks. Either every device in the forwarding path allows jumbo packets, or they donвЂ™t. In my experience, troubleshooting jumbo frames begins simply. The network team went to some effort to prove our innocence, and there was the usual veiled finger-pointing by everyone else, вЂњIвЂ™m not saying itвЂ™s a network problem, butвЂ¦вЂќ Yeah, yeah, we know: the network is assumed guilty until proven innocent. Some vlans that used jumbo frames worked fine, but one vlan simply wouldnвЂ™t work. During the first week, we ran into a problem forwarding jumbo frames.

The core is almost completely Layer 2, with most routing pushed to the distribution layer. IвЂ™ve recently been working in a data center environment with Nexus 70 switches in the core.

HereвЂ™s how I solved the problem without fancy Layer 2 traceroute tools. Ever been stuck trying to figure out the exact switching path that packets take through your network? Me too.