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difference in how 5304/5406 and 2626/2810 forward its packets

Paulen
Regular Advisor

difference in how 5304/5406 and 2626/2810 forward its packets

All,

I have this strange issue that I can't find any good explanation for. Basically there seems to be some difference in how 5304/5406 and 2626/2810 forward its packets.

I have a setup with two Juniper routers and several ProCurve switches between. When I change management IP and def.gw to another subnet (I don't do routing on the switches) within the same VLAN of a 53/54 everything is fine. I reach my other router with no issues. But when I do the same trick on a 2510, 2626 or 2810 (i.e. adding another IP in same VLAN), I can't reach the other router. I have full connectivity and can reach the other switches in the same subnet. But not the def.gw.

This is actually a quite severe flaw, because there must be some issue with the forwarding database or the source/destination address.

Anyone else seen this?
3 REPLIES
Holger Hasenaug
Trusted Contributor

Re: difference in how 5304/5406 and 2626/2810 forward its packets

If routing is disabled you need to set the primary vlan to the vlan you configured an IP address on and on which your default gateway should work.

Example:

ip default-gateway 1.1.1.254

vlan 1
name "DEFAULT_VLAN"
untagged 1-24
no ip address
exit

vlan 30
name "VLAN30"
tag 23,24
ip address 1.1.1.1 255.255.255.0
exit

primary-vlan 30

Have fun
Paulen
Regular Advisor

Re: difference in how 5304/5406 and 2626/2810 forward its packets

There must be something else. I have changed routers or default gateways several times, but this seems like a deadlock situation. The traffic seems to leave the MX router, but never returns. Typically the setup is like this:

[Router]--[5304]--[2626]--..--[Router]

So either the 2626 doesn't understand what comes from the Juniper router, or the traffic between the 2626 and the router is silently dropped by the 5304. I have tried rebooting and clearing arp etc.
Paulen
Regular Advisor

Re: difference in how 5304/5406 and 2626/2810 forward its packets

Just to clarify; the switch gets ARP for the router. I just can't ping it. (.2 is neighbor switch, .1 is router)

gn-xx-s1(vlan-99)# sho arp

IP ARP table

IP Address MAC Address Type Port
--------------- ----------------- ------- ----
10.20.26.1 001f12-8cf94c dynamic 23
10.20.26.2 001ffe-92a500 dynamic 23