Hi Chad, How is this iBGP session formed? Is it over L3 links via the EX, or do they have a direct physical link?
If it is via the EX, then the issue may be with it not having a full routing table, like your MX80s. Packet is sent to the EX. It does a route lookup, and has its default route set at MX80 A. Packet is forwarded to MX80 A. Packet is received by MX80 A. It does a route lookup, and the best route is via MX80 B. Packet is forwarded to EX. EX receives packet. It does a route lookup. Default route is via... Do a route lookup for the destination on each of the MX's, see where it thinks it should be forwarding the packet. Regard, Dave On 13 October 2015 at 14:04, Chad Levy <[email protected]> wrote: > Hi Mark, > > The default gateway of the machine is the EX4500. > > I have since tried another scenario. If I place both ISPs on the same MX80, > and the same asymmetric route exists on the ingress and egress, there is no > longer an issue with connectivity. I only have an issue when the ingress and > egress paths traverse different MX80 devices. > > Thank you, > Chad > >> Subject: Re: [j-nsp] Asymmetric Routing >> To: [email protected]; [email protected] >> From: [email protected] >> Date: Tue, 13 Oct 2015 08:07:36 +0200 >> >> >> >> On 13/Oct/15 04:56, Chad Levy wrote: >> >> > Hi all, >> > >> > I am having an issue with a new set of Juniper MX80 routers and an EX4500 >> > switch. My topology is extremely simple, each MX80 has its own internet >> > provider running full BGP routes, and iBGP between the two. The EX4500 is >> > connected to both MX80 devices with /30 P2P running OSPF with route >> > redistribution. The MX80s are originating a default route to the EX4500 >> > via OSPF. >> > >> > I have a single /24 announced to both of my internet providers with a >> > machine connected to the EX4500 via a /30. >> > >> > Both MX80 devices can ping the machine, and vice-versa. My issue becomes >> > when I have an inbound route traverse "ISP A" on one MX, but the return >> > path tries to egress "ISP B" on the other MX. Traffic is dropped and never >> > reaches its final destination. The same behavior happens when the ingress >> > is on "ISP B" and egress on "ISP A". >> > >> > If the ingress and egress paths are symmetrical, connectivity is fine. >> > Additionally, if I override the OSPF learned route for the machines /30 on >> > the ingress MX80, and point a static route to the egress path MX80 for the >> > /30, traffic flows perfectly fine. >> > >> > I do not have any elaborate firewall filters or anything such as RPF >> > enabled, etc on any of the devices at this time. My carriers are also not >> > filtering any traffic on their side. >> > >> > Are there any default configurations in place on either the MX80 or EX4500 >> > that could cause this behavior? One MX80 is running JunOS 13.3, the second >> > MX and the EX4500 are both running JunOS 12.3. The behavior is similar to >> > using a pair of SRX devices in flow mode with traffic ingress on one >> > device, and egress on another. >> >> What is the PC's default gateway? The MX80's or the EX4500? >> >> Mark. > > _______________________________________________ > juniper-nsp mailing list [email protected] > https://puck.nether.net/mailman/listinfo/juniper-nsp _______________________________________________ juniper-nsp mailing list [email protected] https://puck.nether.net/mailman/listinfo/juniper-nsp
