Re: [j-nsp] MPLS VPN Load-balancing
Thanks, Harry. I just checked our routing and noticed that the traffic was entering the Juniper via a transit MPLS link to another PE, so the VPN label is the only label on the stack due to PHP. As such, if what Steven mentions is true re: ABC-chip hardware, then there is no entropy as the VPN label is the same. We are shifting the traffic to allow it to ingress as IPv4 to see if that changes anything. There are several VRFs that transit the link, each with a few source subnets and a single destination subnet. In these cases, the traffic rates are low and periodic ( 500kbps every 10 minutes or so, spread around). The meaningful traffic is exchanged between 5 IPs on two subnets (subnet A.1,.2,.3,.4,.5 to subnet B.1,.2.,3,.4,.5). Each stream is around 6Mbps. Do you know if there is a CFEB upgrade that uses a new chip architecture that would support a deeper hash key? Cheers, Chris On Aug 11, 2009, at 5:27 PM, Harry Reynolds wrote: but one particular subnet pair is exchanging quite a bit of traffic). All of the addresses are unique within our domain Can you clarify the nature of you test traffic to the busy subnet in question? 1. Number of vrf ingress interfaces? 2. Number of source-Ips 3. Number of destination ips w/in that subnet Basically, how many flows do you have heading to that busy subnet? IIRC, as an ingress node we would do an IP hash, and this should use the incoming interface and IP S/D addresses by default. On some platforms when you start adding additional hashes, such as a L4 port, you may start eating into the number of IP address bits that are actually hashed. Meaning, you gain port entropy but loose some granularity at the IP address level. Hence these knobs have a bit of variance for each person that test them, as their flow specifics may or may not benefit from some combination. As always, the more variance and the larger the number of streams the better the expected results. If there is a single pair of busy speakers on that subnet that would explain things. If you had 10 (or more) more or less equally active streams, and still had the results below, then that would seem broken IMO. I may be wrong, but if you only have 3 such streams, then each stream is independently hashed, and there is a 12 % chance (.50 x .50 x.50) you will get unlucky and find all three on the same link. HTHs. -Original Message- From: juniper-nsp-boun...@puck.nether.net [mailto:juniper-nsp-boun...@puck.nether.net ] On Behalf Of Christian Martin Sent: Tuesday, August 11, 2009 1:58 PM To: Steven Brenchley Cc: juniper-nsp@puck.nether.net Subject: Re: [j-nsp] MPLS VPN Load-balancing Steven, Thanks for the response. I was unaware of this limitation in the ABC- chip, but I am still curious as to why the incoming traffic to the PE, which should be hashed at IP only, is not properly balanced across the outbound (MPLS) links. The lookup is done on the IP header only, which should have enough entropy to create a reasonably balanced modulus. Unless the outbound FIB entries play a role somehow? I could see if this were a P and MPLS was coming in and out, but it is IP---push--push---forward... Also note that the outer label is of course different on the two links (learned via LDP). Cheers, Chris On Aug 11, 2009, at 4:08 PM, Steven Brenchley wrote: Hi Christian, The problem your hitting is a limitation of the M10i chip set. It can only look at the top two labels and since both top labels are the same for all this traffic it's going to look like the same flow and send it all across the same link. The only way I've been able to get a simulance of load balancing is by creating multiple LSP's between the same end points and manually push different traffic across the different LSP's. It's really clunky but there are no switches that will work around this limitation on the current M10i CFEB. If you where using a T-series, M320,M120, or MX router you don't have this limitation. They can all go deeper into the packet to determine load balance. On the a semi brighter side, on the horizon there are some new Ichip based CFEB's which will not have this limitation. I don't recall when those will be available but you could probably get a hold of your SE and get a time table from them. Steven Brenchley === On Tue, Aug 11, 2009 at 3:16 PM, Christian Martin christian.mar...@teliris.com wrote: NSP-ers, I have a Cisco---Juniper pair connected over a pair of T3 links. The Juniper acts as a PE and is pushing two labels for a specific route learned on the PE destined to a single remote PE well beyond the Cisco P. The traffic is destined to several IP addresses clustered in this subnet (sort of like 10, 11, 12, 13) and the forwarding table shows that there are two correctly installed next- hops - same VPN label, different LDP label (we have applied several
Re: [j-nsp] MPLS VPN Load-balancing
I think the issue is that on ABC/M-series we can either do a MPLS hash (up to two labels), or an IP/L4 hash. It does not seems that you can do both, but I read somewhere if you only do a 1 label hash then abc/m series can hash on the IP. Its so hard to keep this straight. Good thing there is only one junos else all hope would be lost. ;) T-series platforms with e-fpcs and MX can hash on multiple MPLS labels while *also* hashing on L3 and l4. This seems to jive with the docs at: http://www.juniper.net/techpubs/en_US/junos9.6/information-products/topic-collections/config-guide-policy/policy-configuring-load-balancing-based-on-mpls-labels.html Regards -Original Message- From: Christian Martin [mailto:christian.mar...@teliris.com] Sent: Wednesday, August 12, 2009 9:25 AM To: Harry Reynolds Cc: Steven Brenchley; juniper-nsp@puck.nether.net Subject: Re: [j-nsp] MPLS VPN Load-balancing Thanks, Harry. I just checked our routing and noticed that the traffic was entering the Juniper via a transit MPLS link to another PE, so the VPN label is the only label on the stack due to PHP. As such, if what Steven mentions is true re: ABC-chip hardware, then there is no entropy as the VPN label is the same. We are shifting the traffic to allow it to ingress as IPv4 to see if that changes anything. There are several VRFs that transit the link, each with a few source subnets and a single destination subnet. In these cases, the traffic rates are low and periodic ( 500kbps every 10 minutes or so, spread around). The meaningful traffic is exchanged between 5 IPs on two subnets (subnet A.1,.2,.3,.4,.5 to subnet B.1,.2.,3,.4,.5). Each stream is around 6Mbps. Do you know if there is a CFEB upgrade that uses a new chip architecture that would support a deeper hash key? Cheers, Chris On Aug 11, 2009, at 5:27 PM, Harry Reynolds wrote: but one particular subnet pair is exchanging quite a bit of traffic). All of the addresses are unique within our domain Can you clarify the nature of you test traffic to the busy subnet in question? 1. Number of vrf ingress interfaces? 2. Number of source-Ips 3. Number of destination ips w/in that subnet Basically, how many flows do you have heading to that busy subnet? IIRC, as an ingress node we would do an IP hash, and this should use the incoming interface and IP S/D addresses by default. On some platforms when you start adding additional hashes, such as a L4 port, you may start eating into the number of IP address bits that are actually hashed. Meaning, you gain port entropy but loose some granularity at the IP address level. Hence these knobs have a bit of variance for each person that test them, as their flow specifics may or may not benefit from some combination. As always, the more variance and the larger the number of streams the better the expected results. If there is a single pair of busy speakers on that subnet that would explain things. If you had 10 (or more) more or less equally active streams, and still had the results below, then that would seem broken IMO. I may be wrong, but if you only have 3 such streams, then each stream is independently hashed, and there is a 12 % chance (.50 x .50 x.50) you will get unlucky and find all three on the same link. HTHs. -Original Message- From: juniper-nsp-boun...@puck.nether.net [mailto:juniper-nsp-boun...@puck.nether.net ] On Behalf Of Christian Martin Sent: Tuesday, August 11, 2009 1:58 PM To: Steven Brenchley Cc: juniper-nsp@puck.nether.net Subject: Re: [j-nsp] MPLS VPN Load-balancing Steven, Thanks for the response. I was unaware of this limitation in the ABC- chip, but I am still curious as to why the incoming traffic to the PE, which should be hashed at IP only, is not properly balanced across the outbound (MPLS) links. The lookup is done on the IP header only, which should have enough entropy to create a reasonably balanced modulus. Unless the outbound FIB entries play a role somehow? I could see if this were a P and MPLS was coming in and out, but it is IP---push--push---forward... Also note that the outer label is of course different on the two links (learned via LDP). Cheers, Chris On Aug 11, 2009, at 4:08 PM, Steven Brenchley wrote: Hi Christian, The problem your hitting is a limitation of the M10i chip set. It can only look at the top two labels and since both top labels are the same for all this traffic it's going to look like the same flow and send it all across the same link. The only way I've been able to get a simulance of load balancing is by creating multiple LSP's between the same end points and manually push different traffic across the different LSP's. It's really clunky but there are no switches that will work around this limitation on the current M10i CFEB. If you where using a T-series, M320,M120, or MX router you don't have
Re: [j-nsp] MPLS VPN Load-balancing
We made the traffic change and now the balancing is even. I am going to change the config to label-1 payload ip (only) and then shift it back and see if we can in fact hash on the single label and the iP header. Hopefully this will suffice! Cheers, Chris On Aug 12, 2009, at 12:50 PM, Harry Reynolds wrote: I think the issue is that on ABC/M-series we can either do a MPLS hash (up to two labels), or an IP/L4 hash. It does not seems that you can do both, but I read somewhere if you only do a 1 label hash then abc/m series can hash on the IP. Its so hard to keep this straight. Good thing there is only one junos else all hope would be lost. ;) T-series platforms with e-fpcs and MX can hash on multiple MPLS labels while *also* hashing on L3 and l4. This seems to jive with the docs at: http://www.juniper.net/techpubs/en_US/junos9.6/information-products/topic-collections/config-guide-policy/policy-configuring-load-balancing-based-on-mpls-labels.html Regards -Original Message- From: Christian Martin [mailto:christian.mar...@teliris.com] Sent: Wednesday, August 12, 2009 9:25 AM To: Harry Reynolds Cc: Steven Brenchley; juniper-nsp@puck.nether.net Subject: Re: [j-nsp] MPLS VPN Load-balancing Thanks, Harry. I just checked our routing and noticed that the traffic was entering the Juniper via a transit MPLS link to another PE, so the VPN label is the only label on the stack due to PHP. As such, if what Steven mentions is true re: ABC-chip hardware, then there is no entropy as the VPN label is the same. We are shifting the traffic to allow it to ingress as IPv4 to see if that changes anything. There are several VRFs that transit the link, each with a few source subnets and a single destination subnet. In these cases, the traffic rates are low and periodic ( 500kbps every 10 minutes or so, spread around). The meaningful traffic is exchanged between 5 IPs on two subnets (subnet A.1,.2,.3,.4,.5 to subnet B. 1,.2.,3,.4,.5). Each stream is around 6Mbps. Do you know if there is a CFEB upgrade that uses a new chip architecture that would support a deeper hash key? Cheers, Chris On Aug 11, 2009, at 5:27 PM, Harry Reynolds wrote: but one particular subnet pair is exchanging quite a bit of traffic). All of the addresses are unique within our domain Can you clarify the nature of you test traffic to the busy subnet in question? 1. Number of vrf ingress interfaces? 2. Number of source-Ips 3. Number of destination ips w/in that subnet Basically, how many flows do you have heading to that busy subnet? IIRC, as an ingress node we would do an IP hash, and this should use the incoming interface and IP S/D addresses by default. On some platforms when you start adding additional hashes, such as a L4 port, you may start eating into the number of IP address bits that are actually hashed. Meaning, you gain port entropy but loose some granularity at the IP address level. Hence these knobs have a bit of variance for each person that test them, as their flow specifics may or may not benefit from some combination. As always, the more variance and the larger the number of streams the better the expected results. If there is a single pair of busy speakers on that subnet that would explain things. If you had 10 (or more) more or less equally active streams, and still had the results below, then that would seem broken IMO. I may be wrong, but if you only have 3 such streams, then each stream is independently hashed, and there is a 12 % chance (.50 x .50 x.50) you will get unlucky and find all three on the same link. HTHs. -Original Message- From: juniper-nsp-boun...@puck.nether.net [mailto:juniper-nsp-boun...@puck.nether.net ] On Behalf Of Christian Martin Sent: Tuesday, August 11, 2009 1:58 PM To: Steven Brenchley Cc: juniper-nsp@puck.nether.net Subject: Re: [j-nsp] MPLS VPN Load-balancing Steven, Thanks for the response. I was unaware of this limitation in the ABC- chip, but I am still curious as to why the incoming traffic to the PE, which should be hashed at IP only, is not properly balanced across the outbound (MPLS) links. The lookup is done on the IP header only, which should have enough entropy to create a reasonably balanced modulus. Unless the outbound FIB entries play a role somehow? I could see if this were a P and MPLS was coming in and out, but it is IP---push--push---forward... Also note that the outer label is of course different on the two links (learned via LDP). Cheers, Chris On Aug 11, 2009, at 4:08 PM, Steven Brenchley wrote: Hi Christian, The problem your hitting is a limitation of the M10i chip set. It can only look at the top two labels and since both top labels are the same for all this traffic it's going to look like the same flow and send it all across the same link. The only way I've been able to get a simulance of load balancing is by creating multiple LSP's between the same end points
Re: [j-nsp] MPLS VPN Load-balancing
Hi Harry, On Aug 12, 2009, at 6:50 PM, Harry Reynolds wrote: T-series platforms with e-fpcs and MX can hash on multiple MPLS labels while *also* hashing on L3 and l4. This seems to jive with the docs at: http://www.juniper.net/techpubs/en_US/junos9.6/information-products/topic-collections/config-guide-policy/policy-configuring-load-balancing-based-on-mpls-labels.html the following document mentions multiple labels + payload hashing is supported on M320 and T-series: http://www.juniper.net/techpubs/en_US/junos9.6/information-products/topic-collections/config-guide-mpls-applications/mpls-configuring-load-balancing-for-mpls-lsps.html There's no mention of I-chip based systems (M120 or MX) on this page. Does this imply those can also hash only on the first label + payload ? --Daniel. ___ juniper-nsp mailing list juniper-nsp@puck.nether.net https://puck.nether.net/mailman/listinfo/juniper-nsp
Re: [j-nsp] MPLS VPN Load-balancing
From what I know, I-chip is like T-series (lmnr) wrt hashing. http://www.juniper.net/techpubs/en_US/junos9.6/information-products/topic-collections/config-guide-policy/policy-configuring-load-balancing-based-on-mpls-labels.html I'm pretty sure that mx can do mpls plus ip payload, as per above. I have read the default for mpls is incoming interface and 3 labels (not using exp). There is some confusion as to whether enabling ip hashing affects/disables the label hash. I've seen both stated. This seems to document that, at least for pseudo wires, Ip payload forces a single label hash: http://www.juniper.net/techpubs/en_US/junos9.6/information-products/topic-collections/config-guide-policy/policy-configuring-load-balancing-for-ethernet-pseudowires.html The above makes it seem that Ip hashing for mpls is only supported for ethernet, but the previous link documents the same label 1, payload IP syntax in a generic context as providing hashing on label 1 and Ip SA/DA. So, seems to me that: 1. You should expect same for mx as for T 2. That we can factor 2 labels and IP SA/DA on above, or up top 3 labels 3. That using l3 only also adds ports (from l4), and requires no label hash. 4. There seems to be a special ethernet pseudo wire mode that allows for only 1 label and Ip payload, but not clear on whether its ports or just SA/DA. Maybe someone cane now clarify the above and we will have gotten somewhere. Hope this is not too stuffed up. Regards -Original Message- From: Daniel Verlouw [mailto:dan...@bit.nl] Sent: Wednesday, August 12, 2009 12:51 PM To: Harry Reynolds Cc: juniper-nsp Subject: Re: [j-nsp] MPLS VPN Load-balancing Hi Harry, On Aug 12, 2009, at 6:50 PM, Harry Reynolds wrote: T-series platforms with e-fpcs and MX can hash on multiple MPLS labels while *also* hashing on L3 and l4. This seems to jive with the docs at: http://www.juniper.net/techpubs/en_US/junos9.6/information-products/to pic-collections/config-guide-policy/policy-configuring-load-balancing- based-on-mpls-labels.html the following document mentions multiple labels + payload hashing is supported on M320 and T-series: http://www.juniper.net/techpubs/en_US/junos9.6/information-products/topic-collections/config-guide-mpls-applications/mpls-configuring-load-balancing-for-mpls-lsps.html There's no mention of I-chip based systems (M120 or MX) on this page. Does this imply those can also hash only on the first label + payload ? --Daniel. ___ juniper-nsp mailing list juniper-nsp@puck.nether.net https://puck.nether.net/mailman/listinfo/juniper-nsp
[j-nsp] MPLS VPN Load-balancing
NSP-ers, I have a Cisco---Juniper pair connected over a pair of T3 links. The Juniper acts as a PE and is pushing two labels for a specific route learned on the PE destined to a single remote PE well beyond the Cisco P. The traffic is destined to several IP addresses clustered in this subnet (sort of like 10, 11, 12, 13) and the forwarding table shows that there are two correctly installed next-hops - same VPN label, different LDP label (we have applied several different types of hashings and of course have our forwarding table export policy in place). Nevertheless, the Juniper is doing a very poor job load- balancing the traffic, and the Cisco is splitting it almost evenly. There is in fact a larger number of routes being shared across this link (about 20 or so VPN routes in different VRFs and thus different VPN labels – all sharing the same 2 LDP labels, but one particular subnet pair is exchanging quite a bit of traffic). All of the addresses are unique within our domain. Has anyone had issues with load-balancing a single subnet across an MPLS VPN link pair? Note again that this is a PE-P (J--C) problem and that the IP addresses are all arranged locally. I know Juniper are secretive about their hashing algorithm (can't lose any hero tests, can we?), but we are getting like 5:1 load share if we are lucky and are bumping up against the T3's capacity. The box is an M10i. As always, any help would be appreciated. Cheers, C show route forwarding-table destination 10.160.2.0/24 Routing table: foo.inet Internet: DestinationType RtRef Next hop Type Index NhRef Netif 10.160.2.0/24 user 0indr 262175 2 ulst 262196 2 Push 74 600 1 t3-0/0/0.1000 Push 74 632 1 t3-0/0/1.1000 PE-P next-hop count (all showing load-balancing in effect) show route next-hop 172.16.255.11 terse | match | count Count: 106 lines monitor interface traffic InterfaceLink Input bytes(bps) Output bytes(bps) t3-0/0/0 Up541252651233 (25667208) 691166913860 (35611752) t3-0/0/1 Up279149587856(8737568) 24893605598 (20112) Note that the Cisco is doing 25/9 Mbps and the Juniper 35/.02. ___ juniper-nsp mailing list juniper-nsp@puck.nether.net https://puck.nether.net/mailman/listinfo/juniper-nsp
Re: [j-nsp] MPLS VPN Load-balancing
Steven, Thanks for the response. I was unaware of this limitation in the ABC- chip, but I am still curious as to why the incoming traffic to the PE, which should be hashed at IP only, is not properly balanced across the outbound (MPLS) links. The lookup is done on the IP header only, which should have enough entropy to create a reasonably balanced modulus. Unless the outbound FIB entries play a role somehow? I could see if this were a P and MPLS was coming in and out, but it is IP---push--push---forward... Also note that the outer label is of course different on the two links (learned via LDP). Cheers, Chris On Aug 11, 2009, at 4:08 PM, Steven Brenchley wrote: Hi Christian, The problem your hitting is a limitation of the M10i chip set. It can only look at the top two labels and since both top labels are the same for all this traffic it's going to look like the same flow and send it all across the same link. The only way I've been able to get a simulance of load balancing is by creating multiple LSP's between the same end points and manually push different traffic across the different LSP's. It's really clunky but there are no switches that will work around this limitation on the current M10i CFEB. If you where using a T-series, M320,M120, or MX router you don't have this limitation. They can all go deeper into the packet to determine load balance. On the a semi brighter side, on the horizon there are some new Ichip based CFEB's which will not have this limitation. I don't recall when those will be available but you could probably get a hold of your SE and get a time table from them. Steven Brenchley === On Tue, Aug 11, 2009 at 3:16 PM, Christian Martin christian.mar...@teliris.com wrote: NSP-ers, I have a Cisco---Juniper pair connected over a pair of T3 links. The Juniper acts as a PE and is pushing two labels for a specific route learned on the PE destined to a single remote PE well beyond the Cisco P. The traffic is destined to several IP addresses clustered in this subnet (sort of like 10, 11, 12, 13) and the forwarding table shows that there are two correctly installed next- hops - same VPN label, different LDP label (we have applied several different types of hashings and of course have our forwarding table export policy in place). Nevertheless, the Juniper is doing a very poor job load-balancing the traffic, and the Cisco is splitting it almost evenly. There is in fact a larger number of routes being shared across this link (about 20 or so VPN routes in different VRFs and thus different VPN labels – all sharing the same 2 LDP labels, but one particular subnet pair is exchanging quite a bit of traffic). All of the addresses are unique within our domain. Has anyone had issues with load-balancing a single subnet across an MPLS VPN link pair? Note again that this is a PE-P (J--C) problem and that the IP addresses are all arranged locally. I know Juniper are secretive about their hashing algorithm (can't lose any hero tests, can we?), but we are getting like 5:1 load share if we are lucky and are bumping up against the T3's capacity. The box is an M10i. As always, any help would be appreciated. Cheers, C show route forwarding-table destination 10.160.2.0/24 Routing table: foo.inet Internet: DestinationType RtRef Next hop Type Index NhRef Netif 10.160.2.0/24 user 0indr 262175 2 ulst 262196 2 Push 74 600 1 t3-0/0/0.1000 Push 74 632 1 t3-0/0/1.1000 PE-P next-hop count (all showing load-balancing in effect) show route next-hop 172.16.255.11 terse | match | count Count: 106 lines monitor interface traffic InterfaceLink Input bytes(bps) Output bytes(bps) t3-0/0/0 Up541252651233 (25667208) 691166913860 (35611752) t3-0/0/1 Up279149587856(8737568) 24893605598 (20112) Note that the Cisco is doing 25/9 Mbps and the Juniper 35/.02. ___ juniper-nsp mailing list juniper-nsp@puck.nether.net https://puck.nether.net/mailman/listinfo/juniper-nsp -- Steven Brenchley - There are 10 types of people in the world those who understand binary and those who don't. ___ juniper-nsp mailing list juniper-nsp@puck.nether.net https://puck.nether.net/mailman/listinfo/juniper-nsp
Re: [j-nsp] MPLS VPN Load-balancing
but one particular subnet pair is exchanging quite a bit of traffic). All of the addresses are unique within our domain Can you clarify the nature of you test traffic to the busy subnet in question? 1. Number of vrf ingress interfaces? 2. Number of source-Ips 3. Number of destination ips w/in that subnet Basically, how many flows do you have heading to that busy subnet? IIRC, as an ingress node we would do an IP hash, and this should use the incoming interface and IP S/D addresses by default. On some platforms when you start adding additional hashes, such as a L4 port, you may start eating into the number of IP address bits that are actually hashed. Meaning, you gain port entropy but loose some granularity at the IP address level. Hence these knobs have a bit of variance for each person that test them, as their flow specifics may or may not benefit from some combination. As always, the more variance and the larger the number of streams the better the expected results. If there is a single pair of busy speakers on that subnet that would explain things. If you had 10 (or more) more or less equally active streams, and still had the results below, then that would seem broken IMO. I may be wrong, but if you only have 3 such streams, then each stream is independently hashed, and there is a 12 % chance (.50 x .50 x.50) you will get unlucky and find all three on the same link. HTHs. -Original Message- From: juniper-nsp-boun...@puck.nether.net [mailto:juniper-nsp-boun...@puck.nether.net] On Behalf Of Christian Martin Sent: Tuesday, August 11, 2009 1:58 PM To: Steven Brenchley Cc: juniper-nsp@puck.nether.net Subject: Re: [j-nsp] MPLS VPN Load-balancing Steven, Thanks for the response. I was unaware of this limitation in the ABC- chip, but I am still curious as to why the incoming traffic to the PE, which should be hashed at IP only, is not properly balanced across the outbound (MPLS) links. The lookup is done on the IP header only, which should have enough entropy to create a reasonably balanced modulus. Unless the outbound FIB entries play a role somehow? I could see if this were a P and MPLS was coming in and out, but it is IP---push--push---forward... Also note that the outer label is of course different on the two links (learned via LDP). Cheers, Chris On Aug 11, 2009, at 4:08 PM, Steven Brenchley wrote: Hi Christian, The problem your hitting is a limitation of the M10i chip set. It can only look at the top two labels and since both top labels are the same for all this traffic it's going to look like the same flow and send it all across the same link. The only way I've been able to get a simulance of load balancing is by creating multiple LSP's between the same end points and manually push different traffic across the different LSP's. It's really clunky but there are no switches that will work around this limitation on the current M10i CFEB. If you where using a T-series, M320,M120, or MX router you don't have this limitation. They can all go deeper into the packet to determine load balance. On the a semi brighter side, on the horizon there are some new Ichip based CFEB's which will not have this limitation. I don't recall when those will be available but you could probably get a hold of your SE and get a time table from them. Steven Brenchley === On Tue, Aug 11, 2009 at 3:16 PM, Christian Martin christian.mar...@teliris.com wrote: NSP-ers, I have a Cisco---Juniper pair connected over a pair of T3 links. The Juniper acts as a PE and is pushing two labels for a specific route learned on the PE destined to a single remote PE well beyond the Cisco P. The traffic is destined to several IP addresses clustered in this subnet (sort of like 10, 11, 12, 13) and the forwarding table shows that there are two correctly installed next- hops - same VPN label, different LDP label (we have applied several different types of hashings and of course have our forwarding table export policy in place). Nevertheless, the Juniper is doing a very poor job load-balancing the traffic, and the Cisco is splitting it almost evenly. There is in fact a larger number of routes being shared across this link (about 20 or so VPN routes in different VRFs and thus different VPN labels - all sharing the same 2 LDP labels, but one particular subnet pair is exchanging quite a bit of traffic). All of the addresses are unique within our domain. Has anyone had issues with load-balancing a single subnet across an MPLS VPN link pair? Note again that this is a PE-P (J--C) problem and that the IP addresses are all arranged locally. I know Juniper are secretive about their hashing algorithm (can't lose any hero tests, can we?), but we are getting like 5:1 load share if we are lucky and are bumping up against the T3's capacity. The box is an M10i. As always
