Re: PXE Booting

Joshua Schaffran · ‎04-03-2023

I am having some issue with getting PXE working on our network. We have 1 switch that PXE works on, but it really make no sense as to why it works there and on no of the others. We have our campus core which is a 6880 which host both our server VLAN and VLAN 212, which we use for PXE. The FEX 6800IA that is directly connected to the campus core is unable to PXE boot when a device is connected on VLAN 212 (all VLANs are allowed on the port channel to the FEX device). It does get a valid IP address and is able to reach the server VLAN which is where the SCCM server is hosted. Now the weird part, we have another 6880 with 5 FEX units off of it. This device is a layer 2 connection back to the campus core on a port channel. FEX unit 202 on this 6880, when a device is on VLAN 212, is able to PXE boot no problem. The gateway is on the campus core as x.x.212.1, VLAN 212 is set up with IP helpers to reach both DHCP and PXE, There are no VLAN configs on the second 6880 besides naming VLAN 212 to imaging.

At this point I am baffled, how can the down stream switch use PXE when the gateway host cannot? I have double triple, quadruple checked the ACLs and there is nothing there that would block PXE or VLAN 212 on the campus core. If I have missed something can someone please point it out? I know it is probably going to be something stupid that I am overlooking, but the help would be appreciated!

balaji.bandi · ‎04-04-2023

We have 1 switch that PXE works on - what switch it works? FEX or what model of switch, what is the configuration on that switch?

as long as you able to ping SCCP server using vlan 212 source that should work.

Can you post vlan 202 and vlan 212 config? ( bare in mind when i was testing if you have more than 4 helpers addresses the time out occurs, so move to PXE boot server on top of the list and test it)

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Joshua Schaffran · ‎04-05-2023

The switch that works is a FEX 6800IA switch.

VLAN 212 is able to ping the SCCM server.

There are only 3 helper addresses on VLAN 212, 2 for DHCP and 1 for PXE. I will try moving the helper address to the top and see if that fixed the issue.

balaji.bandi · ‎04-05-2023

Let us know how it goes, still issue i enable debug to identify the issue.

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Joshua Schaffran · ‎04-18-2023

I apologize for the delay in my response.

I moved the ip helper to the top of the list and had our service desk people test, but it did not change the results. Our config is as follows:

SCCM server = 10.100.10.65

DHCP = 10.100.10.10

DHCP backup = 10.100.10.11

Core 6880 Switch that hosts VLAN 212 (PXE does not work on FEX 199 connected to this switch)

interface vlan 212

ip address 10.100.212.1 255.255.255.0

ip helper-address 10.100.10.65

ip helper-address 10.100.10.10

ip helper-address 10.100.10.11

We have a switch that trunks off of FEX199 that also does not work with PXE.

We have a second location that is a layer 2 connection to another 6880:

FEX 202 (PXE works here on vlan 212)

all ports are access ports on vlan 212

We are not sure why PXE is working on the secondary switch and have no idea why it is not working on the gateway switch. Any help would be greatly appreciated!